# Servo Drive For a lathe Compound



## lkrestorer (Dec 31, 2018)

I'm looking for some constructive help with an idea. For a couple of different reasons I would like to come up with a design for a servo-type power feed for a lathe compound. I have a Grizzly G4003 12x36 lathe and what I am picturing is a small servo or stepper motor mounted on the top of the compound and driving the.screw with a cogged belt or gear train connected at the manual handle.

I would compare this idea to a standard power feed installed on a Bridgeport but on a smaller scale. I'm not interested in CNC type operation but as long as I'm dreaming the idea of adjustable travel limit switches could be a future addition. I would like to have it with a speed control and a forward/reverse switch - probably remotely mounted both for safety and convenience.

There is one YouTube video that shows the beginnings of this type of project but it doesn't take it much farther.

I am not afraid of this type of project. I worked as an industrial electrician for 43 years and I have replaced the Chinese motor (that went up in smoke) and the sketchy wiring on this lathe and have converted my Bridgeport clone to variable speed VFD operation and built a pneumatic power drawbar for it. My uses for this equipment have gone from making parts for old tractors and engines to building little steam engines and cannons and making custom modifications to wheels for my Corvette.

So much for the dream. What I am asking all you fine gentlemen for is to be pointed in the right direction. I need parts and pieces. Where do I go to determine motor type and correct size? Where do I get something to give me a smooth speed control? What about the proper gearing or belting equipment?

I have been slogging around the internet and finding a lot of brick walls so I assume I'm looking in the wrong places. I even tried looking for some sort of CNC retro-fit device that I could convert to this use without any luck.

Help? Anybody?


----------



## lkrestorer (Jan 2, 2019)

I have to say I'm a bit disappointed. Since I posted my question There have been 65 people that have read it but nobody has replied to even tell me it's a crazy idea or to say "I dunno". I have been following HMEM off and on since 2009 and have found many good "how to" tips and have built an engine with another couple of them waiting for my attention. The people here have some great ideas and a lot of combined knowledge and experience. It has been very helpful. I had come up with a problem that I needed help with so I thought I would try to fit into the conversations. There are no amateur machinists in my area so the internet is my only real outside access to information.

I have been continuing my search and have found a couple of things. First, the idea of mounting a small motor on the compound is probably not going to work because of the lack of real estate. I did find another YouTube video showing a setup using a standard Chinese-made mill x-axis servo drive mounted to the compound. The drive is angled upward to clear everything so the handle and switches are on top. This would be fairly easy to accomplish but it is a large protrusion on that part of the operating area of the machine. I'm not sure if it would be too much in the way.

Am I being too impatient? Any comments?


----------



## bdrmachine (Jan 2, 2019)

Try looking on cnczone.com.  GeckoDrive (G201) and a nema 34 stepper motor maybe what you are looking for.  The drive electronics for the Gecko could be as simple as a pulse generator, to a old PC running a program like LinuxCnc.  
Are you close to the Duluth, Mn area?


----------



## RonGinger (Jan 2, 2019)

Not a  lathe, but I have a G0704 mill that has its Z handle up on the top of the machine, very awkward to reach. I mounted a stepper motor and built a simple Arduino board to control it. Instead of mechanical limits I made electrical ones. There is a button for up and one for down. When you have the axis at a place where you want a  limit you press the limit button. A red LED comes on, and there after the control will not pass that spot. You can set a limit for either extreme. This has worked well for me. When I built the box to house the driver I added one for the X axis, but I never got a round to doing the mechanical work.

I see no reason it would not work on a compound,as  long as you can mount a motor close enough without messing up other access.


----------



## dazz (Jan 2, 2019)

Hi
I trained as a Weapons Engineer so I know about control systems.  I am just finishing a VFD conversion for my Nardini MS350 lathe.  I have been looking at CNC control of the cross slide on the 2 lathes I have.  I have reached some conclusions that will probably help you.

You will need to know where the tool is on the Z axis.  There are two ways of doing this:
The cheap crappy way is to put an encoder on the tailstock end of the lead screw.  There are a number of reasons why this is a bad idea
The best option is to add a DRO to the Z axis.    The value of the Z axis would set the X axis at all points.   

The X axis position also needs to be known.    This will be powered so it can be done with a stepper motor (not so good) or a DRO scale (much better).

You will also need to know the A axis position for thread cutting.  You will also need control of the A axis position relative to the Z axis.  The common method of using a single point (magnet) pickup typically seen with Mach 3 on micro lathes is crap.    A hollow shaft encoder is the best, and most expensive option.  It is the rotary version of a DRO.  Another not so good option is to install a gear tooth sensor on the main spindle driven gear, most likely found inside the headstock.  

Modifying any top slide for CNC is too restrictive.  I think it is better to replace the top slide with a new power driven version.  You suddenly have a lot more design options.   On my Nardini, the cross slide has Tee slots that I could attach a powered version, much like a hydraulic copier.    Alternatively, it would only take a few minutes to remove the manual top slide and replace it.

Basically I plan to build an electronic version of a hydraulic copier but without the noise and leaking oil.  The stylus and template would be replaced by software.   This type of setup will almost have the capabilities of a full CNC conversion.   This concept has some similarities with the Electronic Lead Screw project that you have probably found.  My concept is closer to a full CNC retrofit.

You will need software to drive all this.  There are options but I favour LinuxCNC because it is fully programmable and I like doing that sort of stuff.


----------



## lkrestorer (Jan 2, 2019)

bdrmachine,
Thank you for pointing me to cnczone.com. This is a new place to me. The first thing I noticed was that I've just stepped into a whole new world where I 'm not familiar with any of the jargon and standing on the outskirts of the rest. You guys sound very familiar with the design of these things - I'm not. My world revolved mainly around: "Here's a pile of parts. I know they will work together so now go figure out how to put them together and install them so they will do what they are supposed to do." I'm not well versed in the design part of this stuff.

I looked at the Gecko site and will have to take time to look through their information. It looks like they have wiring diagrams and other stuff to study.I also need to familiarize myself with the stepper motor world and the differences with the NEMA sizes.

I'm not very close to Duluth, I'm halfway between Hastings and Red Wing.


----------



## lkrestorer (Jan 2, 2019)

RonGinger said:


> Not a  lathe, but I have a G0704 mill that has its Z handle up on the top of the machine, very awkward to reach. I mounted a stepper motor and built a simple Arduino board to control it. Instead of mechanical limits I made electrical ones. There is a button for up and one for down. When you have the axis at a place where you want a  limit you press the limit button. A red LED comes on, and there after the control will not pass that spot. You can set a limit for either extreme. This has worked well for me. When I built the box to house the driver I added one for the X axis, but I never got a round to doing the mechanical work.
> 
> I see no reason it would not work on a compound,as  long as you can mount a motor close enough without messing up other access.



This sounds like something else I'll have to look up. I'm not familiar with what an Arduino board is. I like the idea of the electrical limits and the method of setting them that you describe. Is this something that could be a stand-alone unit or is it dependent on a drive + motor combination to locate the positions ?


----------



## lkrestorer (Jan 2, 2019)

dazz said:


> Hi
> I trained as a Weapons Engineer so I know about control systems.  I am just finishing a VFD conversion for my Nardini MS350 lathe.  I have been looking at CNC control of the cross slide on the 2 lathes I have.  I have reached some conclusions that will probably help you. _and I like doing that sort of stuff_.



Whoops! You are taking my little idea too far into the CNC world.  Your project will result in a computer controlled machine. I want a manually controlled, variable speed drive for the compound (cross slide). The only "automatic" controls I may need are limits so that if it catches me momentarily out to lunch I won't destroy the machine. Basically, I would like a SERVO drive that's miniaturized to fit on the compound and operate like the ones on my mill do.

The idea of adapting the full-sized milling machine x-axis unit to fit my compound would result in a bigger-than-I'd-like piece of hardware sitting where it might get in the way. I do like the idea of the electrical limits with a stepper drive setup - if I can get my mind around what pieces to use.


----------



## Cogsy (Jan 2, 2019)

Just spitballing here, but how about something like a miniature axis drive as found on a mill? So a simple geared DC motor and small PWM controller for speed adjustment, then add a mechanical limit switch to each end of the travel for safety and a reversing switch. Very mechanical and shouldn't be overly difficult to mount up (depending on your machine). With a geared motor you wouldn't need belts or pulleys and could just drive the lead screw directly. Possibly make it 'quick change' where you remove the handwheel and slide on the electronic drive, so you can switch between the two systems as required.


----------



## john_reese (Jan 3, 2019)

Unless you are cutting a lot of tapers with the compound building a power feed for it seems like overkill.  I use my 1/2" cordless drill to drive the compound, or the rotary table, or the dividing head.  You probably own a drill that would work.


----------



## dazz (Jan 3, 2019)

Hi
As a professional Engineer, I make things complicated because I can.  No problem is so simple that it can't be made complicated.

OK if you are looking for a simple variable speed feed, then  a stepper motor would be simple to rig. Connect the stepper motor to a stepper drive output.  

Connect a variable frequency oscillator to the driver input.  I would use an Aduino but you might be able to find a kit or something off the shelf.  If you haven't used an Aduino before, they have a relatively shallow learning curve. 

The advantage of using a stepper motor is they perform best at slow speed.  DC motors etc perform better at higher speeds.  Steppers are also simple to drive.


----------



## Wizard69 (Jan 3, 2019)

I think you need to give people time to actually visit the site, especially over a holiday.

If you mean the compound and not the cross slide this is very doable.    I would likely choose a stepper instead of a servo, mainly for compactness.  The biggest problem is that you will need to fabricate and thus design a lot of parts.    

As for steppers, I'm not sure which size would be a proper recommendation, you may be able to get by with a relatively small stepper.   Maybe something as small as a size 17 stepper.    If you purchase a stepper with a through shaft you can mount a handle on the other end of the stepper.   

The biggest problem you will have is coming up with controls to drive the stepper.   In this regard it is probably a bit easier to go with a stepper.    However do realize that there are many Arduino solutions out there that  would get you 90% of the way, with the balance being a bit of programming and electrical work.

There are dozens of ways to go about this so it is up to you to decide which path to take.


----------



## john_reese (Jan 3, 2019)

I have no aversion to stepper motor drives.  I will be installing one on the X axis of my mill.  I, too, am a professional engineer (retired) but I do not share your philosophy of make it complicated.  I am a firm believer in the KISS approach.  Besides, I am old, grumpy and kind of lazy so I look for the easy way.


----------



## StephenB (Jan 3, 2019)

I had a little bench top horizontal mill that had little handles that fit onto 3/8" squares on the ends of the lead screws. perfect fit for a bbq spit motor I had. It worked ok and was very small. It did burn out after a while, but the thrift stores always seemed to have a bunch of those...


----------



## DJP (Jan 3, 2019)

I would like to go back to the beginning of this thread to ask why you need a motorized feed. Are you planning a high quantity production run? Why wouldn't a power drill take away any tedious effort much more simply while keeping you in direct control of the process? This is an hobby using old metal working machines as they were originally designed, right?


----------



## ignator (Jan 3, 2019)

lkrestorer said:


> I am picturing is a small servo or stepper motor mounted on the top of the compound and driving the.screw with a cogged belt or gear train connected at the manual handle.


I to, have wanted this on my large lathe. Nice constant feed would give quality finish. But an installation that keeps it out of the way, as well an engage clutch mechanism limits the location and coupling drive.
I've seen the battery drills used, but don't like speed control that is not repeatable.
.
I just don't understand why this tread has to turn into a pissing match about the right way to implement, when the question is straight forward as to a machine mounted mechanism.
.
I would like to see Ron Ginger's milling machine feed photos.
I've found links in youtube, that are reconfiguration mechanisms, and not left on the machine.
I've been looking for a small diameter motor with axially in line gear reduction that could be mounted next to the feed screw in the hollow between the way's.  I've not seen a hollow shaft motor that could be fitted on the crank end of the feed screw, but that solution would keep it clear of the work.
For reference, I've installed power tailstock feed using a milling machine after market table feed. This provides very consistent feed, that allows very deep holes and large drills to be used without grabbing. The only 'babysitting' is to clear the flutes in deep holes so the drill don't break.


----------



## TimTaylor (Jan 3, 2019)

DJP said:


> I would like to go back to the beginning of this thread to ask why you need a motorized feed. Are you planning a high quantity production run? Why wouldn't a power drill take away any tedious effort much more simply while keeping you in direct control of the process? This is an hobby using old metal working machines as they were originally designed, right?



Good question. My guess is to control consistency of the surface finish - same reason we use power feed to take a final cut on an OD. Any of the power drills I've seen don't have very accurate speed control, especially at lower speeds.


----------



## comstock-friend (Jan 3, 2019)

Yes, we got the 'what' he wants to do but not the 'why', plus the confusion of 'compound (cross slide)'. If the compound, I would assume it would be for the powered cutting of tapers. I would think that a Grizzly G4003 already has a powered cross feed (my Enco 12" does, probably the same lathe with a different badge). If the need is power cutting of tapers, instead of hanging a motor on the front, why not built the taper attachment on the back and be done with it. I love the taper attachments on my 9" and 13" South Bends. For the occasional short and sharp taper, the drill motor deal is the way to go!


----------



## TimTaylor (Jan 3, 2019)

A single, packaged solution might be hard to come by, or expensive...such as a power feed add-on for a mill.

That said, you could do it with a few parts......

This might be overkill, but it looks like it would do everything you want and then some - just add the stepper motor, driver board and power supply....such as driver shown in 2nd option....
https://www.amazon.com/dp/B011NJA38A/?tag=skimlinks_replacement-20

or these:

https://www.amazon.com/dp/B07B9ZQF5D/?tag=skimlinks_replacement-20
https://www.amazon.com/dp/B01J88T1AO/?tag=skimlinks_replacement-20

A nema-17 with reduction on the belt drive would probably have plenty of torque.

The first option directly supports limit switches, while with the 2nd it would take some additional interfacing, but nothing all that complex.......

All told, you're probably looking at around $75.00 or so


----------



## stackerjack (Jan 3, 2019)

Have you thought about a washing machine motor?
You wouldn't need a separate power supply and an old washing machine would have all the control circuitry you need.


----------



## joco-nz (Jan 3, 2019)

I have come across a couple builds that address adding a small DC motor to the top-slide (compound).  They generally all have the same look and how tight/elegant you make it will depend on what parts you can source.

Check this link:  https://www.sm-ee.co.uk/members/pro...er-feed-to-a-lathe-topslide-by-stuart-walker/


----------



## dazz (Jan 3, 2019)

Hi
If the requirement is to turn tapers or follow a template mechanically, the Denford Lathe design is one of the simpler to DIY.
http://www.denfordata.com/bb/viewtopic.php?t=3774

No precision parts needed.


----------



## TimTaylor (Jan 3, 2019)

Mechanical taper attachments work well and are easy to install IF your lathe has a telescoping cross slide lead screw. If it has a fixed screw, then you have to either remove the screw or modify it to be telescoping. Looking at the G4003 manual, from the parts drawing it looks to be a solid single lead screw, so modification or removal would be necessary to use a taper attachment.


----------



## lkrestorer (Jan 4, 2019)

I didn't have time to get back to this computer for a couple of days so I'm fascinated by the response it's gotten.

First, I apologize for complaining about nobody responding. I guess I jumped the gun a little bit and didn't consider the holidays getting in the way. I do appreciate the comments. You guys do know your stuff.

I am referring to the compound. The cross slide on the Grizzly is already powered. I made a gizmo to use my battery drill but the speed control stinks (meaning I can't maintain or repeat anything steady). The "need" for this was prompted by a few widely scattered taper projects with the latest being Brian Rupnow's "Crazy Joint". I really liked the style of pulleys that he shows in his set of prints so I wanted to duplicate them. It requires a concave side and a convex side to each pulley/flywheel with a 60 degree dish design. The setup on my lathe (to get the tool pointing the right direction) was to point the compound toward the operator at 60 degrees and feed the tool manually toward myself. I could have fed it away from the operator and ran the spindle in reverse but I prefer to run it forward. Note: "I prefer" just because it feels better to me. Other people will have other ideas but, understand, this is what got me thinking about a power feed. I enjoy making tools and modifying tools. It makes for fun exercises and makes me think above and beyond the normal. It's not a matter of need. It's a matter of want. Like I said above, I switched out my single phase motor for a three phase motor on my Grizzly mill (G9902) and hooked up a VFD so I would have the variable speed control and I built a power drawbar attachment because it was a nifty addition to my arsenal of tools. This is what I like to do.

Turning these pulleys requires a lot of metal removal and quite a few passes. I realized that reaching over the top of the machine put me in an uncomfortable position and caused my hand to cramp up with all the repetition (yes, I'm an old guy!). I realized that I didn't need to worry about surface finish until I got to the final passes but I tried on each successive pass to attain the ideal finish as I figure this is good practice. If I couldn't do it on the preliminary passes then I wouldn't be able to do it when it counted. The smooth and repeatable control of a power feed would be ideal.

Here is the video that shows pretty much what my machine would look like if I adapted a milling machine x-axis power feed to it:  
I was just hoping to find some way to put together something a bit more compact.

I do appreciate what you folks have to offer but my design ability is very limited and most of these items that have been mentioned are foreign to me.  I don't want to put anybody on the spot or hire a "designer" but what I really need is some honest soul to spec out the parts and sketch me a wiring diagram. I started this out in my first post by asking:  *What I am asking all you fine gentlemen for is to be pointed in the right direction. I need parts and pieces. Where do I go to determine motor type and correct size? Where do I get something to give me a smooth speed control? What about the proper gearing or belting equipment?
*
I've walked into a world that is slightly over my head. What I would like to do is sit down with a "buddy", share ideas and maybe build two of these things, one for each of us, but I don't have any "buddies" that share this hobby. I don't want somebody to do this legwork for me unless they enjoy the challenge.

TimTaylor,
Your parts list looks very interesting but I'm lost with how to put it all together.

Ignator,
Thank you. You hit the nail on the head. Take a look at the video I mentioned above and see if you think it would work without being a pain to work around.  That tailstock feed idea sounds interesting, too. Drilling with that would be a breeze.

comstock-friend,
The taper attachments that I've seen won't work with as steep of an angle as 60 degrees. Granted, the compound travel on my lathe is only 3-1/4 inches but the items I have made are within this range of motion. (like morse taper shafts)


----------



## Cogsy (Jan 4, 2019)

Here's a link to a cheap Chinese PWM controller - LINK.  With this thing, it has two sets of DC terminals, one set for input power and one set to the motor. You then have a push button for on/off of the motor and the control knob regulates the speed of the motor from 0 to 100%. I'm not sure what size geared motor you would need for your application, but for ease of wiring this thing can't be beaten. Wiring in a simple switch between the controller and the motor would give you simple change of direction too, so you could power feed in either direction. Adding in limit switches would also be a simple wiring job (as simple as adding in an on/off switch is) but mounting them in the right places would be more difficult. I don't see a solution getting much simpler than this setup, but I can't help with the required motor size. Sorry. Maybe have a search for geared DC motors on ebay and see what comes up.


----------



## ignator (Jan 4, 2019)

lkrestorer said:


> Take a look at the video I mentioned above and see if you think it would work without being a pain to work around. That tailstock feed idea sounds interesting, too. Drilling with that would be a breeze.


I've thought of putting a power feed just like that but it does appear to be huge and probably would be in the way. One of my projects is to repair the sleeve that came with my big lathe. The sleeve converts the lathe spindle taper to a #4 morse. Problem is the minor diameter of this adapter is .0045 inches too small, so it rocks in the spindle. I never noticed it for many years as it seems like it sits tight, and it has to be tapped out. So I want to mount the tool post grinder on the compound and dial in the correct angle for this 90mm metric taper. This milling machine power feed would be in the way of my tool post grinder. I've looked for a hollow shaft motor with a gear reduction, but no luck. 

This is a power feed on a 19 inch drill press. So originally I had the feed attached to the custom mounting stand, and it drove the pinion quill feed gear directly. The unit did not have enough torque. So I found a 10:1 gear box, and made some more conversion plates, and extension shafts. This works pretty good. And you still can operate the feed manually. The original gearing was 1 turn of the pinion, have 4 inches of quill. These power feeds are designed to drive lead screws of .1 to .2 inch pitch. So the original gearing was 4 inch pitch, just too much for the unit.






A little better lighting of the drill press power down feed.





My lathe is a 10x24 Jet. I added an extension to the tail stock and made a new quill that was much longer as the original only had 3.5" of travel, and some of that was the ejection of the #2 morse taper tool shank.


----------



## TimTaylor (Jan 5, 2019)

Sizing a motor is pretty straightforward:

First you need to determine how much torque you need to drive the compound slide screw under load.

If you choose to go the gear motor route as Cogsy suggested, just choose one that meets the torque requirements. 

If you want to go the stepper route, you need to calculate the torque multiplication required and that will determine the reduction ratio that gives you the needed torque. It's a simple calculation  just divide the required torque by the motor rated torque to get the reduction ratio: For example, with a Nema 17 stepper rated for 50 oz-in, a 2:1 ratio would give you 100 oz-in, 5:1 - 250 oz-in, etc. Yes there are some minor losses at high speed, but sized with a little reserve it won't be an issue.

The motor's steps per revolution, multiplied by the reduction ratio, gives you the number of steps per revolution of the feed screw. You can get fancy and calculate the pulse rates for given feed rates, but honestly you can eyeball the rate and do just fine - just like you would do in manually feeding.

As far as wiring, look at the 2nd link in my original post - the 3rd picture down on the left is a typical wiring diagram.....

Hope this helps!

Tim


----------



## lkrestorer (Jan 5, 2019)

joco-nz said:


> I have come across a couple builds that address adding a small DC motor to the top-slide (compound).  They generally all have the same look and how tight/elegant you make it will depend on what parts you can source.
> 
> Check this link:  https://www.sm-ee.co.uk/members/pro...er-feed-to-a-lathe-topslide-by-stuart-walker/



This brings up one of the points brought up previously. I call it the "compound" and that's what I've been searching for. This calls it the "topslide" and so did the YouTube video that I posted. I have to expand my searching.

Paul's version looks very close to what I want. The diagrams from this site just show the "before" and I'd like to see the "after". I hadn't heard of this site before (it's a long way from Minnesota!) but I will take some time to check it out closer.

I like this installation and I'll try to put all of this together. Some of you are going for the stepper and some are going to just a DC motor. I'm going to keep researching this and try to put something together.

My brain may have a better time with a DC motor, a power supply, a pot for speed control, a reversing switch and a timing belt with a couple of gears to give it a bunch of torque (even though it shouldn't need a lot).

The internet will be getting a workout and I'll see what I can dredge up.

Back to the search.


----------



## lkrestorer (Jan 5, 2019)

ignator said:


> I've thought of putting a power feed just like that but it does appear to be huge and probably would be in the way. One of my projects is to repair the sleeve that came with my big lathe.



You shouldn't have shown me that power fed tailstock. I'm going to have to put that into my "maybe-I-want-to-do-that" list. It looks like a very nice setup. My bag of gizmos that I like keeps getting bigger. I live by the idea that I can't die as long as there are still projects waiting.


----------



## lkrestorer (Jan 5, 2019)

dazz said:


> Hi
> If the requirement is to turn tapers or follow a template mechanically, the Denford Lathe design is one of the simpler to DIY.
> http://www.denfordata.com/bb/viewtopic.php?t=3774
> 
> No precision parts needed.


This is an option for tapers of length and shallow angles and something that I have considered. However, I don't think it would work with the hardware on my lathe without major modifications.


----------



## lkrestorer (Jan 5, 2019)

Cogsy said:


> Here's a link to a cheap Chinese PWM controller - LINK.  With this thing, it has two sets of DC terminals, one set for input power and one set to the motor. You then have a push button for on/off of the motor and the control knob regulates the speed of the motor from 0 to 100%. I'm not sure what size geared motor you would need for your application, but for ease of wiring this thing can't be beaten. Wiring in a simple switch between the controller and the motor would give you simple change of direction too, so you could power feed in either direction. Adding in limit switches would also be a simple wiring job (as simple as adding in an on/off switch is) but mounting them in the right places would be more difficult. I don't see a solution getting much simpler than this setup, but I can't help with the required motor size. Sorry. Maybe have a search for geared DC motors on ebay and see what comes up.



This might be a simple approach to what I'm after. I'll look at it a little closer. Thank you.


----------



## lkrestorer (Jan 5, 2019)

lkrestorer said:


> This might be a simple approach to what I'm after. I'll look at it a little closer. Thank you.



Oops, they won't ship to the U.S.

Searching again.

One of the problems with all of this time spent researching is that it takes away from the time I could be in the shop making "glitter" as my granddaughter calls it.


----------



## TimTaylor (Jan 5, 2019)

If you use a DC gear motor you shouldn't need any additional torque....


----------



## TimTaylor (Jan 5, 2019)

try searching "DC PWM speed controller" and "DC gear motor" on Amazon - lots of stuff there......


----------



## ignator (Jan 5, 2019)

lkrestorer said:


> You shouldn't have shown me that power feed tailstock.


I've never finished the same mod for the large lathe (18x40, 450x1000mm), but the parts are mostly made.
There are just too many other tasks to get done in retirement hell. Currently working on sanding 660sq.ft. of oak flooring.


----------



## Cogsy (Jan 5, 2019)

lkrestorer said:


> Oops, they won't ship to the U.S.
> 
> Searching again.
> 
> One of the problems with all of this time spent researching is that it takes away from the time I could be in the shop making "glitter" as my granddaughter calls it.


The link I gave was for eBay Australia but there would surely be identical units on the US or UK versions.


----------



## ignator (Jan 5, 2019)

Cogsy said:


> identical units on the US


http://rover.ebay.com/rover/1/711-5...0001&campid=5338413729&icep_item=192483020216


----------



## Wizard69 (Jan 10, 2019)

lkrestorer said:


> Oops, they won't ship to the U.S.
> 
> Searching again.
> 
> One of the problems with all of this time spent researching is that it takes away from the time I could be in the shop making "glitter" as my granddaughter calls it.


Hey glitter is important to young girls.

AS for the distraction of making machine modifications, fixtures and such; for many that is part of the journey into model engineering.   For some it becomes the main focus of the hobby.

Your interest in a drive assembly for the compound slide is not uncommon, ONE approach is to drive the cross slide with an external device.   An electric drill or screw driver are very common ways of driving this slide at a smooth feed rate.    Generally that is what most people are after - smooth feed rate to get a good finish.    Battery operated, variable speed, screw drivers often are preferred here due to the relatively low operating speed.   Find a way to key them to the compounds leadscrew knob and you are all set.

Now I've plum forgotten which size lathe you have here, but on the smaller lathes if you want a bolted on drive it might make lots of sense to develop a completely new compound.   I have a 9x20 and I do believe I could benefit from a longer compound slide that is frankly more rigid.   The real advantage in length here would be the ability to put the motor on top of the slide and drive it with some sort of gearing arrangement.   With your own design you could potentially design a mechanical drive that disconnects the motor for manual operation with the lead screw handles.   This way changing for manual to electronic drive is as simple as throwing the gear system in and out of engagement.   

Another simple possibility is to use a stepper with a double ended motor shaft.   Connect the stepper directly to the leadscrew on one end and put a handle on the other.   This is why I mentioned before that there is likely hundreds of ways to put a motor on that compound.    It is up to you to choose which one and how it should be designed.


----------



## Wizard69 (Jan 10, 2019)

lkrestorer said:


> This is an option for tapers of length and shallow angles and something that I have considered. However, I don't think it would work with the hardware on my lathe without major modifications.


That would depend upon your lathe as you note.   You can get a shallow taper mechanics like this to work on any lathe if you are willing to go through the mechanical design effort.   There are a number of tapers though that would benefit from accurate feed rates on the compound which brings us back to your original question.   I believe that your desire here is well founded as it can produce much better results off of the compound.   However deciding on the right approach is not easy

Which approach, that is between the taper slide attachment and a powered compound, should really be decided based upon your likely interests.   It could make sense to employ both methods as needs demand.

Whops for got to mention, such taper attachments can be used with most lathes.   On some you need to remove the cross slides leadscrew.   On some more drastic modifications are required.   In any case the attachments can be made to work.   The big problem is that the slides only cover a very narrow range of tapers.   So depending upon your needs you may end up with needing a powered compound anyways.   For the best quality on a low end lathe I would even go so far as to say that a taper attachment will be preferred (when used within its operating range).


----------



## ignator (Jan 10, 2019)

lkrestorer; I found this hollow shaft gear motor on eBay. But it's too big. In this case it's a 3 phase 220VAC motor, that could be powered with a VFD.
I'm looking for something like this but 1/2 its size. This one is 90w, and has 4 ft-lb of torque. More then enough to crank the compound even under load.


----------



## lkrestorer (Jan 11, 2019)

These ideas are pretty darn good but the idea has distracted me from the couple of projects that I'm working on. There have been plenty of times that I have had to suspend a project to make a tool so that I could continue the project. (I have even had to make a tool, to make a tool, to make a tool, to make my project - no kidding!) This time I backed off a notch and borrowed a higher quality cordless drill than the one I was using and by using my attachment gizmo I'm able to get an acceptable finish on the flywheels that I started out to make in the first place. Sometimes Milwaukee does make better tools than Harbor Freight.

The idea of the double ended shaft on a stepper motor may be the way to go. I have to look up dimensions and see if it would fit in the allotted space. It needs to be simple to use either the power feed or manually operate it for using the settings on the standard dial without major disassembly and installations each time.

I have been looking, and trying to study, the interesting makeup of stepper motor circuits but I realize I have a lot to learn before I can proceed in that direction. I even, almost, broke down and bought a cheapie x-axis mill drive off of Ebay. After experimenting with a "good" drill I think that staying with that will be the most worthwhile thing to do for now. That doesn't mean I'm throwing in the towel. It means that I'll be doing some more reading and searching and slot it in as a project to do between other projects. I've tried to convince my wife that I can't die until I have all my projects done. Right now I'm going to have to live to about the age of 562 years.

One of the fun aspects of this hobby is that every time you get involved in making any kind of a neat gizmo it opens up avenues to making other neat gizmos. In this case it has opened up an area of learning that I had never looked at before.

Right now I'm working on that "Crazy Joint" that Brian Rupnow came up with - because it looks really neat. And I'm restoring a 1929 John Deere 1-1/2 hp. engine - because it will look nice sitting with my John Deere tractor at shows next summer. My approach to both of them seems to contribute to the growing pile of chips in my shop.

I will continue - no matter how big of a mess it makes.


----------



## ignator (Jan 11, 2019)

lkrestorer said:


> The idea of the double ended shaft on a stepper motor may be the way to go.


That's why I'm looking for a hollow shaft, the idea, extend the existing shaft through this hollow shaft, then figure out a clutch to engage it to the motor shaft. When not engaged, the extended shaft along with the original scale and hand crank are used to manually operate the compound slide.


----------



## ignator (Jan 11, 2019)

lkrestorer said:


> my John Deere tractor


I assume this is an antique 2 cylinder model. I used to own a Series 60. I've been to a few of the 2 cylinder conventions here in Iowa.


----------



## animal12 (Jan 12, 2019)

Go to this site & search for DC motor controller  https://www.mpja.com/ & just DC motor & scroll up & down . yer bound to find most of what yer lookin for & for a pretty good price
animal


----------



## animal12 (Jan 12, 2019)

RonGinger , did you take any pic's or documentation during construction of yer project ? 
tks
animal


----------



## lkrestorer (Jan 14, 2019)

ignator said:


> I assume this is an antique 2 cylinder model. I used to own a Series 60. I've been to a few of the 2 cylinder conventions here in Iowa.



Yes, it's a 1939 "B" row crop. The 393'rd "Styled" Model B that was built. Restoring this old stuff is what got me started in hobby machining. Many of the worn out parts can be recreated easier than finding good usable replacements.


----------



## lkrestorer (Jan 14, 2019)

animal12 said:


> Go to this site & search for DC motor controller  https://www.mpja.com/ & just DC motor & scroll up & down . yer bound to find most of what yer lookin for & for a pretty good price
> animal



Oooh! Another new place to browse through. It looks like they might have some interesting stuff.


----------



## lkrestorer (Jan 14, 2019)

A lot of the DC motors that would maybe work for this have a built in gear train. I think this would be a problem because they would need a clutch of some sort and that means more parts and would be more complex. A double shaft stepper would be free wheeling with the power off and would revert to the handwheel when not being used without needing a clutch.


----------



## ignator (Jan 15, 2019)

lkrestorer said:


> A double shaft stepper would be free wheeling with the power off and would revert to the handwheel when not being used without needing a clutch.


Ones with enough torque would be large. Agree that adding a clutch mechanism complicates this.
I see the milling machine power feeds have some competition on eBay selling for ~$125USD (half of what they had been). Complaints are the keyway is metric, and does not come with the extension shaft to attach the original crank (for Bridgeport install). This would work on my big lathe, but would be in the way.


----------



## Wizard69 (Jan 20, 2019)

Actually steppers May suffer from cogging and may not feel Smith when turned.  Even worse the drive may short the windings  effectively locking the shaft.  Depending upon the feel you want to achieve yo may need to disconnect the stepper from the drive.  There are a number of factors here but you might not get the silky smooth feel of a plain mechanical leadscrew.  



lkrestorer said:


> A lot of the DC motors that would maybe work for this have a built in gear train. I think this would be a problem because they would need a clutch of some sort and that means more parts and would be more complex. A double shaft stepper would be free wheeling with the power off and would revert to the handwheel when not being used without needing a clutch.


----------



## Wizard69 (Jan 20, 2019)

ignator said:


> Ones with enough torque would be large. Agree that adding a clutch mechanism complicates this.
> I see the milling machine power feeds have some competition on eBay selling for ~$125USD (half of what they had been). Complaints are the keyway is metric, and does not come with the extension shaft to attach the original crank (for Bridgeport install). This would work on my big lathe, but would be in the way.


Those “Servo ”  type drives that are used on a Bridgeport mill are way to big for most lathe compounds.  Even some of the pictures posted earlier had me shaking my head.  

Given that the only way I see to do this up right is to design your own clutch mechanism.  Then use a compact motor to drive the compound when needed.


----------



## ignator (Jan 20, 2019)

Wizard69 said:


> Those “Servo ” type drives that are used on a Bridgeport mill are way to big for most lathe compounds.


Ikrestorer posted a photo he found of it being mounted on the compound. My reply was I believed it to be too big of a power feed in that location.
I copied that link here;


----------



## Wizard69 (Jan 22, 2019)

ignator said:


> Ikrestorer posted a photo he found of it being mounted on the compound. My reply was I believed it to be too big of a power feed in that location.
> I copied that link here;



Yep that is the one.   Probably OK for a special purpose late but for a genral purpose tool room lathe it would seemingly be in the way more than actually being useful.   This is the type of solution where you buy a second compound and swap compounds when you really need controlled feed.


----------



## Wizard69 (Jan 22, 2019)

err!    Auto correct madness, that Smith is suppose to be "SMOOTH".   This is why I mentioned using a mechanical clutch someplace in the past in this thread, if you want manual use and the smoothness of a mechanical only system you need to disconnect the stepper.    Of course with a simple belt drive you can just remove the belt.



Wizard69 said:


> Actually steppers May suffer from cogging and may not feel Smith when turned.  Even worse the drive may short the windings  effectively locking the shaft.  Depending upon the feel you want to achieve yo may need to disconnect the stepper from the drive.  There are a number of factors here but you might not get the silky smooth feel of a plain mechanical leadscrew.


----------



## lkrestorer (Jan 23, 2019)

In my forum browsing I ran across this thread:  https://www.homemodelenginemachinist.com/threads/arduino-rotary-table-for-dummies.26744/

This is about controlling a rotary table but there isn't really much difference with what I'm looking to do. It goes into the electronics in great depth for someone who hasn't played with this particular stuff much. I got a kick out of the fact that he asked his wife (with no previous experience) to put it together and she did it just fine. I am no stranger to electrical stuff, just to this type of equipment so my fascination level has taken a jump. bmac2 has gone into great detail suggesting components and that is really what I need.

His project is about exact positioning and the only exact positioning I would see a use for would be to establish travel limits. This could include adjustable limits to eliminate crashing the whole mess into a part being machined. With the different sizes of motors available I will try to find something that will work.

And that brings to mind another idea. I have seen the standalone rotary tables like this setup and thought that could be a fun accessory to have. I have an 8" Phase II table and wouldn't that be an interesting variation? The articles I've seen have been about the little tables but wouldn't an 8" work the same with just a more powerful motor?

Do you see where this is going? More projects! Bye, I'm heading for the shop.


----------



## SailplaneDriver (Jan 23, 2019)

Take a look at:

Thread
*Arduino Rotary Table for Dummies*

It shows stepper motor contols for a similar application but on a rotating table. You likely could adapt this method to your compound.


----------



## lkrestorer (Jan 24, 2019)

SailplaneDriver said:


> Take a look at:
> 
> Thread
> *Arduino Rotary Table for Dummies*
> ...



Yes, that was what I was referring to in my last post.  I'm going to do some digging and see where it takes me.  I needed some specific direction because this Arduino thing is very new to me.


----------



## TimTaylor (Jan 24, 2019)

lkrestorer said:


> Yes, that was what I was referring to in my last post.  I'm going to do some digging and see where it takes me.  I needed some specific direction because this Arduino thing is very new to me.



The hardware in bmac2's project is solid and will work, but you will need to modify the program code for the Arduino. Specifically, his program takes input from the user and then translates that into the number and direction of steps necessary to rotate the table to perform the desired action. Instead of steps per degree of rotation, you would need to modify the code to use steps per amount of travel. Additionally, his program uses a single constant step rate - to vary the feed rate you would need to add the necessary code to vary the step rate accordingly.

The Arduino uses a programming language that is structured very much like C++ and the programs are called sketches - you'll need to go to the Arduino website and download the development software (it's open source & free). If you are not familiar with the Adrduino environment, this might be a bit much to take on for a first project. There are lots of online tutorials, and "Arduino for Dummies" book is a good starting place. On the plus side, you can start with bmac2's sketch and modify it as needed for your application. If you do that, I'd strongly suggest making small changes, one at a time, and verifying each before going on........

To test your changes you will need a hardware setup the same as what bmac2 used: arduino board, display, keypad, plus a power supply, stepper driver and motor. Note that what can appear to be identical devices, such as the display, may have some differences when it comes to programming - read bmac2's entire thread and you will see what I mean. You can do the whole thing for well under $40.00 if you start with a small stepper for testing purposes. Then when you have everything working move up to the actual stepper you will use.

The programmed Arduino controller outputs step and direction, which are used by the stepper motor driver to control the stepper motor. This means you can choose any stepper motor with enough torque for your application and a driver and power supply rated with enough current for the motor.

While you can program the amount of travel, I would still advise using some type of limit switch arrangement to limit over-travel. You don't even have to include them in the Arduino program - just series them with the enable input to the stepper driver.  Same for an E-stop button.....

Hope this helps!

Tim


----------



## SailplaneDriver (Jan 24, 2019)

Chuck Fellow did a stepper RT design:

https://www.homemodelenginemachinist.com/threads/electronic-dividing-head-using-the-arduino.17896/

My recollection is that his sketch included a constant rotation mode. If all you want is variable speed rotation, you should be able to do so with an oscillator input into the stepper controller.


----------



## lkrestorer (Jan 24, 2019)

TimTaylor said:


> Hope this helps!
> 
> Tim


Thank you Tim.  I'm beginning to see the start of a new branch in my hobby world.  I thought that I was out of the studying world and just working on refining my techniques but it looks like this is just the beginning.  The intriguing thing about this is that it requires an understanding and  application of the electrical equipment along with the mechanical modifications to whatever you are trying to control.  Right now I'm happy I didn't jump the gun and buy a Chinese mill axis drive and modify it to fit my compound.  Actually, I'm wondering if trying to upfit my 8" rotary table would be a better place to start and leave the compound feed for another time. 

I understand your point about making only one change at a time.  That is an old troubleshooting and repair technique.  Never throw too many new variables into the mix and expect to understand what happened.  You may get your intended result but you won't know what did it.


----------



## lkrestorer (Jan 24, 2019)

SailplaneDriver said:


> Chuck Fellow did a stepper RT design:
> 
> https://www.homemodelenginemachinist.com/threads/electronic-dividing-head-using-the-arduino.17896/
> 
> My recollection is that his sketch included a constant rotation mode. If all you want is variable speed rotation, you should be able to do so with an oscillator input into the stepper controller.



Thank you.  More stuff to digest.


----------



## lkrestorer (Jan 24, 2019)

Okay, another question coming from this beginner.

I went to Amazon and looked up the "Arduino For Dummies" book.  What I found was around a dozen books for beginners.  Do any of you have serious recommendations as to which one to buy (and which ones to avoid!)  I'd like to get one but my biggest handicap is not knowing anything about what I want to learn.

Thank you.


----------



## TimTaylor (Jan 25, 2019)

You want the 2nd edition,,,,the one with the red band at the top. I think it's $22.94 from Amazon.

Be warned - Arduinos can be addictive! 

Tim


----------



## lkrestorer (Jan 25, 2019)

TimTaylor said:


> You want the 2nd edition,,,,the one with the red band at the top. I think it's $22.94 from Amazon.



OK, it's ordered.  I also installed the Arduino IDE software on my desktop computer so I could take a look at it.  I'm assuming that I can also install it on my shop laptop and transport files back and forth between them on a memory stick.  I'm not a Cloud guy, I want my stuff in my grubby little hands and not floating around in some mysterious cosmos hardrive.  (I've told my wife's Alexa to go pound sand a number of times!)

Without some instruction from the book I might as well be looking at the wall.  I played around with BASIC on a TRS-80 Model 4 back in the 80's but that has pretty much faded from memory - maybe a good thing.

As I'm looking back through this post I started, I find it interesting how it started as a thought for powering my compound to learning about micro computer programming.  Now I'm caught up in learning how to bring this full circle.  Thanks guys. This is getting interesting.


----------



## ignator (Jan 25, 2019)

lkrestorer said:


> OK, it's ordered.  I also installed the Arduino IDE software on my desktop computer so I could take a look at it.  I'm assuming that I can also install it on my shop laptop and transport files back and forth between them on a memory stick.  I'm not a Cloud guy, I want my stuff in my grubby little hands and not floating around in some mysterious cosmos hardrive.  (I've told my wife's Alexa to go pound sand a number of times!)
> 
> Without some instruction from the book I might as well be looking at the wall.  I played around with BASIC on a TRS-80 Model 4 back in the 80's but that has pretty much faded from memory - maybe a good thing.
> 
> As I'm looking back through this post I started, I find it interesting how it started as a thought for powering my compound to learning about micro computer programming.  Now I'm caught up in learning how to bring this full circle.  Thanks guys. This is getting interesting.



So now you need to look at getting one of the Arduino micro controllers. I've gotten the basic Uno (a copy from China) and the MEGA (also a copy, and not genuine, both from eBay). These use a different USB interface chip, and so a different software driver file needs to be installed to support these. Otherwise the IDE you loaded, works as expected. If you startup the IDE, and on the file menu, select Tools:Board a list of all the different products is shown supported by your download (others can be added). Here is where you'll select the product you are using so specific code can be compiled for it.
Note the first test program I would recommend is the LED blink program. It gives that quick feedback that everything is working. And you can modify the off and on times to give you a feeling you're changing code. Most Uno boards have the LED installed on the board, I have purchased one very cheap one where this was not installed.
There are many support sites and sample programs you can find on the internet, and youtube is your friend in many channels showing different programs operation and how they work.

There are starter kits on eBay that sell the Uno, CD with software, along with jumper wires, plug circuit board, keyboard, display and other sensor boards that you can do much learning from. They are in the ~$30-60USD range.


----------



## TimTaylor (Jan 25, 2019)

Welcome to the dark side!


Ignator makes some good suggestions. 

There's a tutorial series on Youtube done by Jeremy Blum that is pretty good - here's a link to #1 in the series;


Arduino is very much a hands-on programming environment, so you'll need at least a basic UNO compatible board and USB cable to get started. 

The starter kits are also a good suggestion - you get everything you need to get started & it's less expensive and easier than trying to figure out which individual pieces to order. There are a gazillion of the things on Ebay & Amazon that have slightly different combinations of parts - I'd suggest picking something in the mid range that has components related to what you want to do - there are at least a couple under $30 on Amazon that include a small stepper motor & driver, for example.

Be aware that some, especially on Ebay, are shipped directly from China and can take longer to get. I almost always use Amazon & go with a product that is "fulfilled by Amazon"  - they might cost a buck or two more, but delivery is more reliable.

Just my $0.02.............


----------



## ignator (Jan 25, 2019)

TimTaylor said:


> especially on Ebay, are shipped directly from China and can take longer to get



Yes, waiting 4-6 weeks is a pain. I will check the box "Item Location" for my local country and see what the prices are. As well I always select sort: "Price + Shipping lowest first". This sometimes fails in the auctions that have a selector, and they have one item that has nothing to do with the search criterion, that is ultra cheap to get you to click and look no further down the listings.
I do check amazon as well, as you never know what they have and if the price is close enough for the needed items.

I'm working on a design to convert one of the milling machine table feeds to have a shaft encoder (with quadrature output), and enable better speed control (feed rate) along with electronic travel limits. That's why I ended up with the MEGA board as it had a much higher clock speed, as I was counting the encoder with interrupts.  The biggest problem with these power feed units is the speed range on the potentiometer control is very narrow, from either no movement to too fast (maybe 1/10 of the full range). Even my Servo brand power feed has this same problem (shows how perfect the China copy is). I'm hoping to have an interface where you select the endmill cutter diameter, RPM, and number of cutting edges, and the feed rate (tooth loading) is controlled per a calculation. I never push any of my tooling, mostly dry cut, so I'm not looking to maximize, but improve some cutting speed.


----------



## MachineTom (Jan 25, 2019)

I have not done a servo install so my knowledge is limited in that field. But I have done a stepper install on my grinder, 2 axis. One of the benefits of the stepper install, was  industrial level components available used, at great prices.  I also did a 2 axis dividing head and slide build, using  the same type stepper components.  Both are running fine after  2+ years of use.

The build was detailed in the CNC forum here.


----------



## Wizard69 (Jan 25, 2019)

lkrestorer said:


> OK, it's ordered.  I also installed the Arduino IDE software on my desktop computer so I could take a look at it.  I'm assuming that I can also install it on my shop laptop and transport files back and forth between them on a memory stick.  I'm not a Cloud guy, I want my stuff in my grubby little hands and not floating around in some mysterious cosmos hardrive.  (I've told my wife's Alexa to go pound sand a number of times!)


You mentioned books and in that regard I have a couple of suggestions that are not directly Arduino related.    One would be to look for a good C++ text, but be aware that the Arduino environment is not a complete C++ installation.    While it is dated at this point in time Accelerated C++ by Barbara Moo and some other guy (past 50 here) is a good way to grab some of the basics of C++.    I wouildn't even want to guess at what is a good Arduino text, to be perfectly honest the Arduino web site is actually very good with getting started materials.

Assuming you have a decent computer / OS you can get up to speed with general programming by writing code for your computer.  Most Linux based distributions come with just about all the programming tools you might want.    It takes a lot more work to get a decent and flexible programming environment up in Windows.


> Without some instruction from the book I might as well be looking at the wall.  I played around with BASIC on a TRS-80 Model 4 back in the 80's but that has pretty much faded from memory - maybe a good thing.


My first computer was a VIC 20, needless to say nothing learned there is of any value these days.   In some ways the Arduino Mega chip is more powerful that those old machines.    If you buy into the more recent ARM based Arduino boards you will effectively have far more performance at your disposal.   The ARM based boards are will worth considering as 32 bit integers make for very easy programming and are very desirable for machine control.   All that being said you don't need much at all for a compound drive.

Which brings up another point there are other embedded solutions out there.   PIC mirco controllers are still popular, Texas Instruments has some interesting embedded solutions and so do others.     Arduino though has a massive following so help is everywhere.

As for BASIC programming I would suggest staying as far as possible away from that language.   There are micro controllers supporting BASIC in various ways but to put it bluntly BASIC is too evil to consider these days.   I'd opt for Assembly before considering BASIC.

However interpreted languages have some really significant advantages but there are modern approaches that are far better.   One example is Python for desktop solutions and Micro Python for embedded uses.    In the Linux/UNIX world Python and similar languages are referred to as scripting languages.    Python, in the form of Micro Python is one of the few that run embedded on micro controllers.   In any event I just wnated to point out an alternative to C++ or BASIC.


> As I'm looking back through this post I started, I find it interesting how it started as a thought for powering my compound to learning about micro computer programming.  Now I'm caught up in learning how to bring this full circle.  Thanks guys. This is getting interesting.



Programming is one of those skills that develops and is maintained with use.   It will take awhile to get into the swing of things.   My best suggestion is to get started right away with C++ on your PC writing short programs simply to learn.   

By the way you don't have to go digital is all you want to do is to fed the compound at smooth rate.   Digital just gives you the ability to do fancy things with the compound easier.


----------



## ignator (Jan 25, 2019)

MachineTom said:


> I have not done a servo install so my knowledge is limited in that field. But I have done a stepper install on my grinder, 2 axis. One of the benefits of the stepper install, was  industrial level components available used, at great prices.  I also did a 2 axis dividing head and slide build, using  the same type stepper components.  Both are running fine after  2+ years of use.
> 
> The build was detailed in the CNC forum here.


I looked up your post from 2 years ago. 
https://www.homemodelenginemachinist.com/threads/conversion-of-grinder-cnc.26329/#post-288472
I was hoping this was a solution for an all manual machine conversion.
I want to do similar on a small 6x12 harbor freight machine I've had for over 25 years.  It is a pain to manually grind even a small part. 
The vertical feed is very poor on this machine, as the method of screw backlash control was a brass component where two threads had a bolt to preload them in attempts to minimize backlash. Problem is the screw does not have a tight zero tolerance thrust bearing. I figured this out and use a half tenths indicating dial indicator to measure the feed. With a mag chuck, it's pretty easy to throw a part with too much grinding feed. I typically don't exceed one thou feed. OK, it's a cheap machine, that sorta works. 
Looks like I'll have to make shaft extensions to get any stepper motor's belt drive pulley placed.


----------



## TimTaylor (Jan 26, 2019)

ignator said:


> ..................
> I'm working on a design to convert one of the milling machine table feeds to have a shaft encoder (with quadrature output), and enable better speed control (feed rate) along with electronic travel limits. That's why I ended up with the MEGA board as it had a much higher clock speed, as I was counting the encoder with interrupts.  The biggest problem with these power feed units is the speed range on the potentiometer control is very narrow, from either no movement to too fast (maybe 1/10 of the full range). Even my Servo brand power feed has this same problem (shows how perfect the China copy is). I'm hoping to have an interface where you select the endmill cutter diameter, RPM, and number of cutting edges, and the feed rate (tooth loading) is controlled per a calculation. I never push any of my tooling, mostly dry cut, so I'm not looking to maximize, but improve some cutting speed.



Yes, the mega board has some additional capabilities that are really useful, more I/O pins and multiple serial ports can come in handy. I just ordered one for another project on my list.....

For the speed control sensitivity there are a couple solutions:
1. Putting a resistor in series with the pot will reduce the adjustment range and give you more sensitivity
2. Replacing your standard 270 degree potentiometer with a 10-turn pot will give you full range adjustment with about 12 times the sensitivity......

Tim


----------



## ignator (Jan 26, 2019)

TimTaylor said:


> For the speed control sensitivity there are a couple solutions:
> 1. Putting a resistor in series with the pot will reduce the adjustment range and give you more sensitivity
> 2. Replacing your standard 270 degree potentiometer with a 10-turn pot will give you full range adjustment with about 12 times the sensitivity......


Tim, I don't believe that solution will work, as the circuit is a half wave SCR triggered design. SCRs are triggered with injection of gate current, that is positive relative to the Cathode. A resistor may modify this, but a design change that controls the current pulse to fire the SCR is needed. These power feeds are minimal designs.
I scanned the schematic that was included in the Align brand manual;





It is a very smudged original copy. The SCR is in series with the motor armature. The field windings  are shown as "L". The SCR part number is S6008L, so it's a 600V 8amp TO220 device. 
I had taken a photo of the board as part of my project (still in limbo with other things of higher priority);

The schematic shows ZNR, they are MOVs. There is an adjustment pot on the board labeled as SVR-100, which is 100ohms. The speed pot is off board, and shown as VR-500.
Given this is a half wave speed control, that really limits the torque during low speed operation.


----------



## TimTaylor (Jan 27, 2019)

ignator said:


> Tim, I don't believe that solution will work, as the circuit is a half wave SCR triggered design. SCRs are triggered with injection of gate current, that is positive relative to the Cathode. A resistor may modify this, but a design change that controls the current pulse to fire the SCR is needed. These power feeds are minimal designs.
> ........


Yeah, that's a pretty minimal design all right. The MOV's are part of a snubber circuit to suppress any spikes or back emf. A better design would be one with two SCR's and diodes, or a triac, again with suitable snubber circuitry.

I still think the 10 turn pot used with the original circuit might get you enough sensitivity of adjustment.......easy & inexpensive experiment.......

Tim


----------



## rodw (Feb 15, 2019)

For what its worth my rotary table controller here also has a linear mode and you can store different configs so the one controller could be used on the tailstock and a rotary table and as a milling power feed just by selecting a different device.

https://www.homemodelenginemachinist.com/threads/interrupt-driven-rotary-table-controller.25091/
Even if you do build your own, the code would be a good tutorial on C.

I did think of powering the tailstock on my AL336 lathe as I did a lot of repetitive drilling that was affecting my shoulder. But I sold the lathe, purchased another larger one and outsourced the said parts. I would have used a NEMA23 269 Oz stepper and a reduction belt drive of about 3:1 or 5:1. Remember, there is also a reduction on the acme thread. I've got a couple of 24 volt electromagnetic clutches here that came out of old photocopiers that could be used to free the drive for manual operation. Once power is applied, they lock solid and are completely free when powerd off.  You can buy the clutches on alibaba. Programming a simple peck drilling cycle would be a good feature to add.


----------



## lkrestorer (Feb 16, 2019)

rodw said:


> For what its worth my rotary table controller here also has a linear mode and you can store different configs so the one controller could be used on the tailstock and a rotary table and as a milling power feed just by selecting a different device.



Again, it looks like I walked into a very interesting sideline to this machining hobby. This idea of a dual use controller got my attention.

I'm in the reading mode with this project now. I've also taken apart my 8" rotary table to clean and oil it while checking out how I would mount a stepper motor on it. I've moved away from the idea of a compound power feed (for now). There seems to be a whole lot more information on rotary table projects so I will start there.

First I have to get the proper hardware so I can have a test bed for learning the electronics. The table rotates very smoothly and freely and looking at the mounting possibilities I'm thinking of a NEMA 23 motor without any extra gearing. The idea of having both manual and powered capabilities makes sense to me so the idea of a dual shaft motor installed on the table with the hand crank in the outboard position seems like a good plan. The mounting pieces for this will make for a good machining project. That's where I start to come up short.

When searching Ebay for a motor I see many different Nema 23 types. First, I'm drawn to the ones with a cord rather than the ones with loose wires - obvious protection and easy connect/disconnect. Second, what voltage do I look for? I'm seeing everything from 3 volts to 24-48 volt motors. I understand that the power supply and the controller have to be matched to it and I lean toward the higher voltages. I'm assuming that the voltage is varied to vary the speed? (I'm more familiar with variable frequency drives on AC motors.) I suppose this should be a common sense answer but treat me as a pure novice. Does the power supply provide one set voltage and the controller (via the Arduino program) vary it to provide speed changes?

The table that I have is 90:1 and I'm not sure how this determines the particular motor specs that I require. (Remember, I come from a world where I'm used to buying a 25 hp. 480 volt 3-phase motor and just getting a VFD that's sized for it.)

Then there is the question of feed speeds for making smooth cuts and traversing speeds for positioning individual machining cuts - this is Arduino stuff, right?

I'm not going to buy the Arduino supplies until I have something to power with it and I would rather not buy 'any-old' motor just to play. I want the equipment that I will be using for my project.


----------



## ignator (Feb 16, 2019)

lkrestorer said:


> I'm assuming that the voltage is varied to vary the speed? (I'm more familiar with variable frequency drives on AC motors.) I suppose this should be a common sense answer but treat me as a pure novice. Does the power supply provide one set voltage and the controller (via the Arduino program) vary it to provide speed changes?


It does not work that way (speed control). A stepper motor has magnetic poles, and the rotor is moved in discrete angular steps. The speed is controlled by how fast the field winding is pulsed. The rotor in stepper motors is a permanent magnet. A quick search will bring up all the tutorial you want;
https://en.wikipedia.org/wiki/Stepper_motor
Never open a stepper motor and pull the rotor out of the stator, this will damage the magnetic strength (the photo in the wiki article has one opened, bad example). They use "keepers" to assemble them and do maintenance. But You should never have to worry about opening one up.
Do note that unpowered the stepper motor will have a cogging feel when rotating the shaft. And it will force the shaft to rest in one of these cogged locations, so you can't just put the shaft at any angular location.
The stepper specifications will indicate the number of cogs per revolution, so unless a micro stepper controller is used, you will live with these discrete angular positions.


----------



## lkrestorer (Feb 16, 2019)

ignator said:


> The speed is controlled by how fast the field winding is pulsed.



Thank you. Interesting, and now it makes more sense. This helps explain how they can hold a position with power on and not burn up.

But I'm still confused about selection. ->(from Wikipedia) *Stepper motors' nameplates typically give only the winding current and occasionally the voltage and winding resistance. The rated voltage will produce the rated winding current at DC: but this is mostly a meaningless rating, as all modern drivers are current limiting and the drive voltages greatly exceed the motor rated voltage.*

How the heck do I determine which motor to buy? Flashing back, again, you use a 240 volt motor on a 240 volt circuit and a 480 volt motor on a 480 volt circuit_. How do you spec a motor, and a power supply,  of this type?_ How do I know what goes with what?


----------



## lkrestorer (Feb 16, 2019)

Now I'm dreaming ahead about if (?) I can get a rotary table to work then the (original) idea of a powered compound and a powered tailstock would be fun additions to the lathe, too


----------



## ignator (Feb 16, 2019)

The stepper motor requires a stepper driver. The motor volt rating determines the power supply voltage that you connect to this stepper driver. This will limit the coil current to the motor designed max. But per your quoted wiki, you can set the motor current with the stepper driver that has this design feature. It is programmable with DIP switche 1-2-4-8 binary setting or straps.  This ensures that the winding's don't melt down. You may use a higher voltage then needed, but this is mainly to be able to run the motor at a faster speed, when this is important. You can exceed the stepping pulse rate, faster then the motor rotor can respond. This results in lost steps and that is a bad thing if you are driving a rotary table, and expect an exact angular change. This should not be a problem in your usage, as home hobbyist's aren't trying to remove material at maximum rate (at least not me, as tooling is on my nickle, and I dry cut).


----------



## rodw (Feb 16, 2019)

Its all pretty simple to get a stepper running. But there are a few  parts to it. 
1. A step generator (eg Arduino)
2. A stepper controller. I use this http://rover.ebay.com/rover/1/711-5...0001&campid=5338413729&icep_item=271115223142
3. a 5v supply to run the step and direction interface (perfect for an Arduino)
4. a 48 volt power supply with enough amps to match your stepper motor requirements
5. A stepper motor. These have standard frame sizes so a NEMA23 is perfect for this. 269 oz/inch torque is a good size.

Another alternative stepper controller is the Gecko G251x which is nice and compact.
https://www.geckodrive.com/g251x-digital-stepper-drive.html

Mounting is pretty easy. I removed the handle to expose 3 threaded holes on the mounting collar and bolted a plate to this. Then added  4 threaded posts long enough to get the stepper far enough away to accommodate a shaft joiner. You should be ale to use a solid joiner there as the threaded rods allow adjustment to get perfect shaft alignment.










This was a surplus NEMA23 stepper motor.  It does the job with  no missed steps on my 6" table but I'd go one that has a longer motor frame and more torque.

But be warned, its addictive and has probably cost me $10k building a bigger CNC machine!


----------



## lkrestorer (Feb 16, 2019)

Thank you 'rodw'. And, of course, all you other fine folks. I'm really getting a lot of good usable information from all of this. The "Arduino Rotary Table For Dummies" post is also getting my finger prints all over the pages. I have been spending my time this afternoon searching and sorting. I don't believe this will be a high priced project because Ebay can be a friend.

I'm changing my plans from a double shaft motor to a single shaft and will be trying to set the table up with powered-only operation as per the other posts. My 'itch to build' is getting stronger as I go.

I believe I'm getting a better understanding of how this works and I see it as a three part learning experience. There is the mechanical modification of the device to be controlled, the design and build of the electrical interface and the programming (and understanding) of the Arduino equipment. Then there is the gathering (and understanding) of the necessary materials to accomplish the task.

You will see the word 'understanding' three times in that last paragraph. That describes what I'm working on now - and I appreciate all the help.  When I make my purchases (soon!) I'll follow up with a list of them in this post.


----------



## Herbiev (Feb 16, 2019)

The stepper controller postage at $21 seems a bit steep. This mob has free postage 
https://m.banggood.com/DM542-Leadsh...er-for-3D-Printer-p-1397322.html?rmmds=search
Very impressive project tho.


----------



## lkrestorer (Feb 16, 2019)

Herbiev,

I took that DM542 info and plugged it into Ebay and came up with this:

http://rover.ebay.com/rover/1/711-5...0001&campid=5338413729&icep_item=372500492944

The prices are all over the map. I'm looking at the controllers that will accept up to 50 volts like the one that rodw suggested. I'm not familiar with 'Banggood' so I might stay with the proven world of Ebay.


----------



## rodw (Feb 16, 2019)

Banggood is OK. A friend of mine has used it  a lot.  ebay in Australia Sucks. Its flooded with stuff from China that ships from Australia in the description but is sent in bulk to us from China and then posted by a logistics company. Very annoying as it takes a lot more time to arrive. 

Just note that I linked to a DM542A, not a DM542. I think there is a difference. I can vouch for the Longs Motor one and am uncertain about Leadshine but they do make some good stuff. Just avoid the ones with a TB6560 ot TB6600 as they have a very poor reputation.

The other one that is popular with the Arduino set is the Pololu A4988 but its limited to 2 amps, 35 volts and does not have the more advanced features in the microstepping the others have. https://www.pololu.com/product/1182 It will get you going but torque will be limited....


----------



## ignator (Feb 17, 2019)

lkrestorer said:


> The prices are all over the map.


I typically do a generic search on eBay, "Stepper motor driver". This brought up over 4000 hits. I sort on price + shipping lowest first.
I found this;
http://rover.ebay.com/rover/1/711-5...0001&campid=5338413729&icep_item=283348655741
@$18 plus sales tax. But you need to know what motor your going to use first. The minimum current setting on this item is 1.4amps. Hence what motor are you wanting to drive.
This search also brought up motor driver packages, which may be of interest.


----------



## tjwal (Feb 17, 2019)

For those in the US, circuit specialists out of Phoenix has a good price.  I don’t know their shipping though.  I picked up a few of these on one of my snowbird vacations.
https://www.circuitspecialists.com/nema_23_stepping_motor_57bygh405a-d.html


----------



## ninefinger (Feb 17, 2019)

You can skip the arduino if all you want to do is drive the stepper forward or backward at a fixed or variable speed.  https://www.amazon.com/dp/B077SFDMFJ/?tag=skimlinks_replacement-20 
Its a stepper pulse and direction generator.  The link is amazon but available from many sources.  
Mike


----------



## rodw (Feb 18, 2019)

tjwal said:


> For those in the US, circuit specialists out of Phoenix has a good price.  I don’t know their shipping though.  I picked up a few of these on one of my snowbird vacations.
> https://www.circuitspecialists.com/nema_23_stepping_motor_57bygh405a-d.html



These are really designed for NEMA 34's which are too large for whatt is required where the small NEMA 23 is a much better option


----------



## rodw (Feb 18, 2019)

ninefinger said:


> You can skip the arduino if all you want to do is drive the stepper forward or backward at a fixed or variable speed.  https://www.amazon.com/dp/B077SFDMFJ/?tag=skimlinks_replacement-20
> Its a stepper pulse and direction generator.  The link is amazon but available from many sources.
> Mike



Personally , I think the Arduino gives much more flexibility so you can  program in other features like length of cut or peck drilling.


----------



## lkrestorer (Feb 18, 2019)

1) I can see the flexibility of using the Arduino because it looks like it can be programmed to do both simple traversing and the more complex (in my mind) positioning. Plus it looks like an interesting thing I'd like to try my hand at. I will be going this route.

2) My searches on Ebay do bring up a tremendous number of drivers and motors. I believe I'm understanding that the driver's maximum current output has to be the same or more than the motors maximum to get full range operation.

3) The motor's torque seems to be proportional to the length of the case (more wire inside = more oomph). This brings up the possibility of using a NEMA 34 motor that is much shorter than an (almost) comparable output NEMA 23 to limit overhanging length. I probably don't need a tremendously strong motor to turn an 8" rotary table but less length to get in the way might be nice. Then there is the cost factor. The NEMA 23 equipment is generally cheaper than the NEMA 34 equipment.

4) It was mentioned to stay away from the TB6560 and TB6600 drivers. What is the difference between the DM542, DM542A and the DM542T drivers? These all seem to be sized for NEMA 17 and NEMA 23 motors. The NEMA 34 motors have another bunch of drivers rated for them (higher current output). I realize that the current rating is the deciding factor but is one really better than the other as far as models go? Does the idea that 'you get what you pay for' hold true?  China seems to be the only place manufacturing any of this stuff and it's well known that all of their stuff isn't top-of-the-line. (Don't slam me for that. I'm using a Grizzly 12x36 lathe and a Grizzly Bridgeport clone - but I've had to do extensive rewiring of both of them.)

5) And then there is the voltage question.  It seems like the more robust setups use 48 volt power supplies. It's probably more efficient getting the higher currents with higher voltages but some of those units get pretty spendy. I'm seeing power supplies with 48 volts and 8.3 amps output for $19.99 and for $173.99.

I've come close to ordering this stuff several times but the more I dig the deeper the hole gets. I don't really want to end up with a pile of parts that doesn't work like it should and then have to start all over again. I can feel my understanding going up but this is a world that I haven't walked through before.


----------



## tjwal (Feb 18, 2019)

I’m using TB6600 drivers for the steppers I mentioned in message 86.  They only go to 42 volts but are significantly less expensive than the higher voltage drives.  I’m currently only using a 24V supply anyway.  Both the PS and the drivers can be replaced if need be.


----------



## rodw (Feb 18, 2019)

Forget NEMA 34's for your application. They are too big and bulky and have a torque output way more than you need. Waaayy overkill. Doubling the voltage at least quadruples the torque.  At 24 volts on my rotary table I had missing steps because of this. 48 Volts fixed this.  TB6XXX drives have a very poor reputation for reliability. That might be whats in a 542 and 542T but I'm not 100% sure. I do know the DM542A was a significant upgrade over the DM542. No-one said this would be cheap! Anyway, you have enough info to make a decision now and remember doing nothing is always an option!


----------



## lkrestorer (Feb 18, 2019)

rodw said:


> Anyway, you have enough info to make a decision now and remember doing nothing is always an option!



Well, thanks. I'm taking that as a kick in the pants. I do have a tendency to over analyze things - especially when I'm diving into uncharted waters.

I've ordered the Arduino board and supplies as was detailed in bmac2's Arduino Rotary Table for Dummies. I also ordered a motor:   NEMA 23, 114mm length, 4.2amp, 425 oz/in torque, and has mounted cord, dual shaft & threaded holes on the rear endplate in case I decide to reconnect the handwheel.

And I put in offers on a 48 volt, 4.2 amp power supply and DM542A driver (when somebody says 'best offer' I have to give it a try).


----------



## tjwal (Feb 18, 2019)

Rod 
I don’t understand why you quoted my message when you posted this



rodw said:


> These are really designed for NEMA 34's which are too large for whatt is required where the small NEMA 23 is a much better option



??
John


----------



## rodw (Feb 19, 2019)

tjwal said:


> Rod
> I don’t understand why you quoted my message when you posted this
> 
> 
> ...


 I have no idea now either now ...


----------

