# 12v Drill hacked to powerfeed for Mini Mill



## TroyO

Not a completed project... as a matter of fact it's just in the "Hmmm, I wonder....." stage. I already have a PC power supply hooked to my mill as an "Accessory supply" (Lights, maybe a coolant pump, power feed etc.)

I finally got to take a closer look, and see what I have that may work for the power feed.

The "doner" is a 12V Ryobi cordless drill. I took it apart and it looks like there's some mighty usefull bits in there. The motor, gear drive and clutch are all one assembly. (Cylindrical, about 1.25 diameter.) I got the chuck off, the output shaft is threaded outside with what looks like maybe a 3/8" regular thread and tapped left hand threads on the inside. I don't know if the threads are metric or Imperial. (Yet)

Mounting it should be dead easy.

Electrically.... some pleasant surprises. I think the motor controller can be hacked. It may take some fancy soldering, but the main circuit board has what is clearly a potentiometer "strip" on the trigger that I'm pretty sure I can isolate and replace with an outboard potentiometer. The Fwd/Rev switch is a seperate unit from the controller and can be easily replaced with a regular triple throw switch. 

I will take some pics next time I get to work on it and post them up, along with thoughts and how I manage (*if* I manage) to hack the speed control. I am pleasantly surprised by what I've seen in there... it looks like it may be easy to use not only the powertrain but even the speed controller too! I kind of figured it would be so proprietary there would be no chance of salvaging that part. It's obviously rated for it, and it's nice and small too.

This may end up being something like the $10 powerfeed... since the drill was a toss away.


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## T70MkIII

Looking forward to seeing your progress on this one, Troy. 

I've been thinking about an x-powerfeed for a while. I think I have an old 12v model train controller somewhere, and I'm sure I have a defuct cordless drill or electric window motor lying around.


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## itowbig

looking forward for some really great pics yup yup :bow:


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## TroyO

Consider me prodded... well, a little anyway. My parents are coming in to visit next week, wife has had me cleaning and scrubbing, LOL. Maybe I can really dive in on it after next week. 

Anyway... here's a couple of pics to get started. The body of the motor measured 1.45"

It's NOT a resistive trace like I thought it was. It's segmented on one side. Not a deal killer... actually in some ways it may be easier. From what I can see, there are 6 traces, each presumably activate a different speed. So, it won't be infinitley variable but it will have 7 speeds (Including stop, that is.)

I'm going to order one of these to run it...

http://www.mouser.com/ProductDetail...=sGAEpiMZZMvNbjZ2WlReYnqYHrQfuERsygueEKa171c=

It's a 7 postion rotary switch, "shorting" type. That, a double pole double throw switch for motor reversing and I think the electronics will be sorted.

Reversing switch I'm looking at is here:
http://www.mouser.com/ProductDetail...=sGAEpiMZZMvudeGI7i40XN5W0OOvRIfVYTvsRTE5jYs=


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## fourjc

I like your switch... I done this a few months ago and mounted the trigger in a box then made a rotary cam that depressed the switch for speed control... your method is much better.
I did not put a reverse on mine, figured that I will never need to reverse feed. It works fine but now I am thinking the reverse might be practical.
I had an electric clutch from an old copy machine, runs on 12 to 24 volts, I use this to turn the feed on and off without touching the speed (trigger in my case). I do have more pictures if interested.


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## TroyO

I'm picking this project back up again. Well, starting to anyway.

I gave up on hacking the original controller. I remain convinced it *could* be done the way I intended. I should have taken more care in taking it apart however. Inside the plastic casing were metal clips that connected various points on the board. The problem is they fell out when I cracked the plastic casing open and I wasn't able to figure out where they belonged, LOL.

So, I went the easy route and just bought a motor controller. I got this one from Ebay, just over $20 shipped. http://cgi.ebay.com/12V-15A-DC-Moto...546?pt=LH_DefaultDomain_0&hash=item3cb455fb5a

Yep... easy beat cheap this time.

It works just dandy, and I figured out a way to short the pot so I can use a momentary switch to kick it in to full speed mode. (Rapid). Plenty of torque even at low speeds.

So, here follows the stream-of-consciousness brainstorming session... LOL.

Controls:

1) Main power... probably one of those "Fighter pilot" flip switches as a pseudo emergency stop.
2) An indicator light... I will forget it is on.
3) Direction. Left/right.
4) Speed dial.
5) Go baby GO! (Rapid)

Hmm, anything else that would be handy?

I'm also debating whether I want the controls on the powerfeed unit, on the mill head or maybe even a pendant? Hmmm... nah, I have enough crap hanging out on my mill bench, pendant would just be something else to get tangled in.

Mechanical:
I have an extra table end like goes on the handwheel side. I got it once upon a time to see if I could work the bearing arrangement in to the Y axis. Turns out that wasn't very feasible, but it was only $6 and I got it shipped with some other stuff from Grizzly so the total wasn't much more.

18 P8689018 Y-AXIS BEARING SEAT $6.00 
(Although it's really the X axis bearing seat.)

I'm thinking/hoping I can bolt that to the other side of the table as a bushing/mounting block for this thing. If it works out I will probably try drilling 2 hole "pockets" to mount 2 round stock rails in there as a slide for the motor. Then the motor can slide in/out on rails and just engage the split end on the leadscrew. Hmmm, add a spring and a cam and it may really be just that easy? Mounting the motor should be pretty straight forward... it has two screws holding the clutch mechanism in place already. Simply remove and re-assemble after passing the screws through a mounting plate.

Hmm, I will need a solid table stop as well to overcome the clutch... right now the X can just screw off the end of the leadscrew. The table cap may fix that issue, though.... matter of fact I&#146;m pretty sure it does.

Finally... I&#146;d love to get it to sit flush with, or slightly under the top of the table. That way I can throw something long on there without interference.

OK... stream done... for the moment, LOL.

(Edit.. Not counting what was on hand and and not otherwise being used the total is now: $27
$21 Motor control
$6 DPDT switch
)


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## TroyO

I putzed with the design a bit today. The extra end cap at least helped me realize something.... the leadscrew is offset about 1/8th from the center. So, I could maybe machine the outside surface flat, then flip it over and ount it backwards... but by that time I might as well just go ahead and make a fresh one.

I used a method I have had luck with before, but haven't seen mentioned. I scanned the existing end cap and created a B/W JPG from it. After a bit of cleanup it looks like Pic 1. 

Then, I imported the JPG in to Inkscape, which is a freeware vector graphics app. Using the "Trace bitmap" tool I was able to then convert the shape into vector lines and edit them for some cleanup. Once it is a vector graphis it is very easy to scale/tweak/manipulate it. The overall size was way off after tracing, but by simply keeping the hight and width locked to the same ratio I was able to easily scale it back to match exactly.

And example of that is the CleanedUp.pdf. If I print that out from Inkscape I get a dead on 1/1 match of my end cap. Within a few thou for sure. It also is super handy for "curvy things" that are hard to measure. (Well, for me anyway.)

What good will that do ya? Well, now I can layout my part using the inkscape tools. It lets you place down to .0001 and although it's not the most advanced CAD type thing going... it's free and comparatively easy to use.

Now I have the layout... I can print it out as a reference, OR... glue it straight to the stock and work from that. (Depending on required accuracy.)

My untested and NOT reality checked end cap is in the endcap.pdf file.

(Edit... Grrr, not sure why but it thinks there is an inline image... there isn't. Just the 3 attachments. I also just updated the endcap pdf, found a couple of mistakes. there's probably more.. LOL.)

(Edit 2... got it, I had the wrong extension on it.) 

View attachment CleanedUp.pdf


View attachment EndCap.pdf


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## TroyO

The first version didn't pass the reality check. I guestimated the size of the drill end at 2.0. Ends up it was 2.25".

So, I changed to (2) 1/2" support rails, still should be plenty. Anyway, here's the current revision of the mounting plate. I still have a slide plate and maybe a rear support to do.

(Edit... PDF didn't show text, fixed it.)



View attachment EndCap2.pdf


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## TroyO

Made some progress yesterday... got the mounting plate and the motor mount done. I need to update the plans.. LOL, no plan ever survives contact with the project, does it?

I used 3/8" AL plate, 4" X something. The basic dimensions in the plan were fine, I just made some changes so I could add a flip down lever to keep it disengaged. 

So, motor mounting is sorted and so are the slides and the lever mechanism to disengage the leadscrew. That worked pretty well, actually. Now to make the adapter between the leadscrew and the motor, and make up the enclosure for it. 

I'm kind of waffling about the best way to make the enclosure. Maybe I will knock up a quick bending brake and just bend it out of some sheet steel. The other idea was to use some angle iron and use that on the 4 corners and just cover the rest with flat plates. As yet undecided.


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## mardtrp

Here's another "useless" bit of info re the 12 volt motor out of that drill.

The early version of this saw had a 12 volt motor fitted and when you bought the saw you had to buy the step down power pack to go with it. Now being only 12 volt, it soon let out the magic smoke, so for a replacement motor it would have been cheaper to just go and buy a brand new saw.

This is where this motor from the chuck away drill comes into it's own, it's the exact same motor, even got the same numbers stamped on it. A bit of mucking about and bingo, the saws like a bought one again.
I can buy these "second hand thrown away drills" from the recycle centre at the local tip for 5 bucks, good value, eh.

http://www.proxxon.com/us/html/37006.html

This latest version of the saw, has a 110 or 240 volt motor fitted, they had been down the path of replacement motors for to long, so changed it to something better.


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## TroyO

I made some more progress. First, I made a adapter from the drill spindle to the leadscrew. I had a really good day running the lathe and managed to get a decent surface finish and all of the bores the right size. Unfortunatly I also made it precisely the wrong length while I was at it. Grrr... LOL. ??? So anyway, that is shelved for a while (Until I feel like repeating my steps... which will doubtless not work as well next time, LOL.)

So, I moved on to bending a sheet metal "Box" for it. I had access to a bending brake but no experience using it so it's mostly close-ish. It's off about a 16th one one side, so I epoxied a metal strip to it to make up the difference. Not ideal, but it will get the job done.

I'm debating how pretty I want to make it.... thinking I might skim it with some bondo and actually paint it up.

I got my control panel laid up in a pattern I think will clear everything. I'm using the attached graphic for that. I ended up with a pretty decent open space on the graphic so I threw in a chart I thought would be handy.

Anyway... I will probably get some work done on it this weekend, and will take some pics while i am at it.


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## TroyO

I made some progress but I haven't taken pics yet... sometime this week I'm sure.

I did run in to a problem, and now that I'm (fairly) sure I have it figured out I figured I would write it up. 
It was an electronics puzzle. The potentiometer was set up in "The usual" fashion on that Ebay control. (3 leads, GND/Wiper/Positive 5V) I really wanted to have a "Go Baby Go!" switch that engaged full rapid while you held it down. Some futzing around with the circuit and I realized that by shorting the wiper to the +5V it would wind up the motor. Cool! The problem was, it wouldn't work when the speed was set below about 1/4 turn on the POT. I finally figured out why.... when the POT was turned "off" or low, what I was actually doing was shorting the +5V to the wiper, which in turn was at (or almost at) GND... Essentially shorting the GND and +5V leads together. 

Not good. Luckily I didn't blow the controller in the process.
Not wanting to run it that way, or liking the "Has to be on somewhat" for the GBG switch to work, I starting thinking about other answers. To that end, I tried "Hot wiring" the positive lead to the motor.... which had no effect. Apparently the controller is PWM controlling the ground lead. Great! So I then jumper the GND to the negative lead of the motor and sure enough WHIIIIRRR!

Hmmm, problem though.... if I do that from a dead stop it overloads that 10A power supply and it shuts down. By running the motor a little first, then jumping the ground it was fine and went happily up to full speed. 

Diagnosis: Power supply can't handle the rush current of the motor from a dead stop. I can however run the motor power from a dead stop through the PWM controller and not overload, presumably because the controller limits to 15A and that is within the surge capability of the power supply.

Re-think and consider the problem and it hits me... what I really need to do is get 5V to the wiper lead without shorting to GND in the process. Thinking back to my somewhat rusty electronics I starting thinking about pullup/pulldown resistors. 

The potentiometer is acting as a voltage divider. But what if I simply disconnect the negative lead to the POT with a momentary switch? That *should* give what is essentially infinite resistance to GND. Infinite Resistance to GND divided by anything the pot has between the +5v and the Wiper will always rise to VCC in this case 5V. And off the motor goes whirring away

I will need to replace my momentary switch with a NC (Normally Closed) instead of a NO (Normally Open) switch, but other than that it should give me a perfect full-speed override switch.

Im mostly almost kinda sure it will work, LOL. If it does I will post up a crap-o-cap schematic for it, maybe it will be of use to someone some day.


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## Troutsqueezer

This is kind of hard to follow without a schematic of some sort. If you remove the pot's connection to ground, the wiper voltage will rise to 5 volts as long as there is no load on the wiper. If there is any current being pulled through the wiper circuit, the pot will drop voltage across the wiper/5V supply terminals proportional to the amount of current flowing through the wiper. Might still work, hard to tell without circuit details though.


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## TroyO

To an extent I am flying blind... I don't have a schematic for the motor controller. I probably could go back and reverse engineer the board, BUT... the chip number has been obscured on the motor control IC.

I do suspect that the wiper input is high resistance since it is going to an IC though, so current *should* be minimal?

I attached a "Crap -o-Cad" version of what I am planning in regards to the rapid switch. It's easy enough to test it tonight when I get home. I will post a complete wiring guide when the dust settles. It has a directional switch with a diode to protect the controller, a main power switch and of course the Rapid function (if it works).

If it doesn't work, the next idea is a big fatty capacitor on the 12V input and going back to the high-current grounding of the Negative motor lead. The hope being that the capacitor would supply some of the surge current and allow the power supply to cope. (4700 uF, the biggest Rat Shack had.) I would really rather handle it on the "Low power side" of the motor controller though.

Last resort would just be a bigger power supply.... computer supplies are cheap and easily hackable. This one just fits so well, though!


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## TroyO

Whooo hoooo! That did indeed work exactly as expected.

I figured out why going through the controller keeps the power supply from overloading.... it has a "soft start" feature built in. It sounds like it goes through two stages. (WhiiiiiiiiiiIIIIIIIIIIIRRRR)

Now, the next question.... I was playing around with "trimming" the potentiometer by adding in some series resistors on the ground side. That works well, and I can pick the minimum speed by choosing various resistors. (As it comes, I had to turn it up by about 30% before the motor started turning.)

This one is more of a functional question.... do I want to set a minimum speed and use my directional control to turn it "off" or have the thing stop when I turn the speed knob all the way down? I'm kind of leaning towards the former... set minimum to a slow crawl and use the directional switch for "Off". It seems less likely to walk away from it while leaving the motor "humming" but not going anywhere.

I don't know how commercial units work... anyone have thoughs on the best approach?


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## Troutsqueezer

While I don't have a power feed on my mini mill, I've thought about scenarios for which I would use one. It seems to me that if one has to power feed at a slow crawl, there are reasons for it. Either the bite being taken by the end mill is fairly large or care must be taken because the bit is approaching some end point of the cut. There may be other reasons for going slow but for either of these, I think I would rather move the table by hand, getting a better feel for how the rubber meets the road, so to speak. 

My thought has always been that the power feed comes in most handy for those occasions when I have to traverse back and forth many times over a long distance because of the size of the work piece and the ol' arm with bursitis or tennis elbow is getting tired. In these instances, I would move the table at a fast clip. 

My take on it then, is to not worry about slow speed.


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## TroyO

I can see using it to feed instead of hand cranking... most commonly at some medium/moderate speed. The "Rapid" or "Go Baby Go" is for the rapid transit to and fro, the potentiometer is used to range it in between. The usual operation I see is as follows:

1) "Air cut" some distance and set the speed control to whatever makes sense for the material.
2) Position for a cut
3) Start the auto-feed in the direction you want and make a pass.
4) When the pass is clear, reverse the direction and hit the rapid button to get back to point 2).

I think the motor driven feed will be more consistant than I am by hand, possibly giving a better surface finish.

I'm now waffling the other way on whether the speed knob should range from stop-full or slow-full. No matter what speed I set as the minimum, there will always be some reason I want to go slower at some point (Not sure why, it just seems to work that way... no matter what I choose I always seem to find myself wishing I had slower/faster/longer/shorter available after I pick, LOL) so by picking "stop" I'm only limited by the minimum torque/speed ratio allowed by the motor controller and motor combination.


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## DaveH

As TroyO came to my rescue, then perhaps you won't mind if I mention the following. One of the most difficult tasks in milling is turning the handle slowly for any time longer than 5 minutes. It becomes exceedingly tedious. When using small mills below 3mm dia your feed will have to be slow and steady or they will just break.

Dave


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## TroyO

Well, she is done!

I could go back and finish the plans, if someone is interested. It started with a plan, and I ended up kind of winging it, LOL.

Pics of the last steps, and here is a video.

[ame]http://www.youtube.com/watch?v=VL4ltA3rlio[/ame]


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## chucketn

Nice job, TroyO. Very professional in looks and action. I'm going to have to go back through the thread and make note so I can copy!

Chuck in E. TN


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## DaveH

TroyO,

A very smart piece of work. Congratulations :bow: :bow: :bow:

Dave


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## TroyO

One of my goals was to have it flush or below the table top, and roughly even with the table back. The first case, so I could mount long stuff without interference, and the latter so as not to interfere with the installation of a soon to be installed DRO.

I almost made the first goal... LOL. The heads of the screws do interfere slightly with something being flat on the table. One the plus side, they can be pushed out of the way with minimal pressure. I hadn't counted on the slight play in the bronze bushing letting the unit cant at a little bit of an angle. Were I to do it again, I would knock 1/8" or so off the top of the motor mount just so it was well free and clear.

Other than that, this thing is working great, I got to try some sample milling with it last night and the finish was superb! (And my arms don't hurt from cranking either. ;-)


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## Troutsqueezer

One of the better looking ones I've seen. Nice work.


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## bearcar1

Pretty slick set up Troy, how does it seem to perform while under true milling conditions say aluminum plate using a fly cutter and say .010" DOC? I like your slide to engage feature as well. Could you perhaps use counter sunk screws on the to overcome your clearance issues?

BC1
Jim


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## TroyO

Actually, I could probably just take those screws out... LOL. There's still plenty of support.

But, alas.... when something is on the table the flex and give in the bushing also allows it to move enough so that while the screws touch they don't actually keep it from being bolted down flat. Which means... I'll never get a round tuit I'm willing to spend on it, LOL. But, yes... countersinking the screws would do the trick. 

I can maybe shoot a vid... no fly cutter (yet) though. How about a 3/4" rougher end mill plowing some serious meat off a chunk of AL? Hehehe... I just got to use one and am just flabbergasted to watch it chew at stuff. It's like magic! ;-P


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## TroyO

Here is a little video of it in action, although I think I had my feed rate a little too high on that first pass. (Or spindle speed too low.... )

Also note, the surface finish is only nice on end milling.... side milling leaves a series of grooves.

Bonus vid... I wanted to show a pass using the power feed anyway, figured I'd use the rougher and kill two birds with one stone.

So there you go, bearcar.... real world example. Now to start on my DRO, LOL.


[ame]http://www.youtube.com/watch?v=RHHaK9MHpLA[/ame]


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## ZipSnipe

Excellent Troy, probably one of the best hacks ever !!!!  Would be nice to see a wiring diagram of the whole set up.  I think when I build mine I will add two more rods for the unit to slide on to help keep it aligned as you mentioned yours canting a lil.

Great job !!!!!!!!!!!


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## Hopper

That's brilliant. THanks for posting the details. 
I am going to do this on my old Drummond lathe that has no fine feed facility other than cranking the leadscrew by hand. Much better than trains of clanky old gears!
And I see those old battery drills at garage sales for next to nowt all the time, never bothered to pick one up because the cost of a new battery is about the same as buying the whole thing!


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## cidrontmg

TroyO said:


> Well, she is done!
> 
> I could go back and finish the plans, if someone is interested. It started with a plan, and I ended up kind of winging it, LOL.
> 
> Pics of the last steps, and here is a video.
> 
> [



I'm interested, yes sir! Anything electrical and especially mechanical, I'd like to copy exactly as 1:1, if possible. Even the C-o-C would be great, but plans would be fantastic. 
The "Mini-Mill" is my pimped-up Quantum BF16Var., AFAIK, and I'm thoroughly fed up with winding forever the cranks.  
I've been fantasized about feed motors, steppers, servos, direct or 90º angle, gearing, belting, even chain drive, etc. Always exceedingly complicated. But my solution is by FAR the best, I think, it's pure genius.


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## Hopper

So, the 12v power supply is one from inside a fullsize desktop PC?
How many amps does it supply?


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## ZipSnipe

So apparently this is the originator of this idea and TroyO just made it better

http://www.progressivelogic.com/mf/powerfeed1.html


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## rodw

ZipSnipe said:


> So apparently this is the originator of this idea and TroyO just made it better
> 
> http://www.progressivelogic.com/mf/powerfeed1.html



Thanks for digging this up. It is very interesting! I just remembered I have a brand new el cheapo cordless drill in a box here which my 86 year old mother in law who lives in a nursing home won.


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## TroyO

I definitely wasn't the originator of the idea. It's been around for a while.

I'll look around and see what I can dig up for plans, that was actually a few PCs ago, LOL. But, the power feed is still going strong although the motor is feeling it's age. (I overheated it a few times pushing it too hard for too long.) Luckily I've already got another crap drill to replace it with, LOL.

I did knock up a quick schematic in CoC though. The colors are arbitrary and if wires connect they have an O but if wires just cross and don't connect there's no marking.

Hope that helps! The direction switch can be confusing you may want to google "motor reverse switch" because I'm sure someone out there has explained it better than I did.

The GoBabyGo switch disconnects the GND wire of the POT so the wiper lead gets pulled HIGH and makes the motor spin full blast. Sorry about the wrong schematic before, I was going from memory and my memory isn't that good.


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## ZipSnipe

Troy you are the man !!!!  Thanx for posting !!!!


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## rodw

Thanks for this thread. I ordered my Chinese motor controller today. I pulled a drill apart a week or so ago and made the first part to engage with the the mill table but have not had the time to get back to it. I am going to follow fourjc's approach and use a electromagnetic clutch so the motor sits behind the table as I don't have room in my tiny shed for it to stick out at the end of the table.


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## Davo J

Great work.
I am not up on electrics, I just looked at the ebay ones and they come with a pot, did you use another pot because yous didn't come with one, or did you need a finer pot?

I am using this for another project but read this post and thought thats perfect for what I want.

Thanks for posting it all.

Dave


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## rodw

Davo J said:


> Great work.
> I am not up on electrics, I just looked at the ebay ones and they come with a pot, did you use another pot because yous didn't come with one, or did you need a finer pot?
> 
> I am using this for another project but read this post and thought thats perfect for what I want.
> 
> Thanks for posting it all.
> 
> Dave



eBay links come and go. This is the one I ordered yesterday as it has a good match  with the 7 amp rating of the drill switch on my donor drill and because I want to use either 14.4 or 18.5 volts to agree with motor rating or proposed laptop power supply so needed better than 12volts. If you don't like the knob, it would not be hard to change it.

http://www.ebay.com.au/itm/200918663145?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649


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## TroyO

I'm pretty sure I just used the pot that came with it. I may have thrown a preetier knob on it but the pot is the same. Ohhh, and I noticed that the "Go Baby Go!" switch isn't listed as a switch... it is. It's a simple momentary push button switch that overides the speed control pot by shorting it to "Fast".

Ohh and I missed the quastion on the power supply... it's just a 10A max on the 12V rail on that one. Nothing fancy... the whole supply is rated at only like 280 watts.


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## Davo J

Thanks guys.
Yes the earlier link never worked as it must be to old, but I found it on ebay easily enough.

Another question If I buy say a 30 amp one which are only around $20 Australian can I use a smaller amp power supply, or would I be better off with a 15 amp or less.

Sorry for the questions, I can confidently wire cars, houses etc, but when it come to fine electronics I get lost.

Dave


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## aarggh

Dave, the stated 30A is just the maximum rating, but they are limited by whatever supply you use, so if you use the 30A board with a 1A (or whatever) power supply for a 0.5A motor, you'll only draw 0.5A (usually thereabouts allowing for efficiency, overhead, etc).

cheers, Ian


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## rodw

Davo J said:


> Thanks guys.
> Yes the earlier link never worked as it must be to old, but I found it on ebay easily enough.
> 
> Another question If I buy say a 30 amp one which are only around $20 Australian can I use a smaller amp power supply, or would I be better off with a 15 amp or less.
> 
> Sorry for the questions, I can confidently wire cars, houses etc, but when it come to fine electronics I get lost.
> 
> Dave



Dave,

Here's what I dug out of my drill for you





The controller is marked a maximum of 7 amps for what it is worth and I am hoping to get away with 3.5 amps.

And a close up of my clutch set up to drive the leadscrew.




Unfortunately the belt I have is not long enough and Gates in Australia were no help match this up to anything so I am going to use a flexible drive shaft so the motor can be misaligned.





So my question is, do you think you could cut the flexible shaft in half and silver solder it into a hole in some brass or 12L14?


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## rodw

Oh, and another link here
http://mikesworkshop.weebly.com/mill-power-feed.html


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## Davo J

Hi Rod, and thanks.
With the flex shaft whats it made of. If it's spring steel try not to get it to hot or it will go soft.

Dave


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## Hopper

Thanks for posting the additional details and circuit drawing.
I bought a used cordless drill for $5 - but it works so well and my sone and I have been using it for making a tool shadowboard behind the lathe, so will have to look for another one to canibalize for parts!

I got an old angle grinder too, so that I can use the gears out of it to make a right-angle drive reduction gearbox set up so the drill motor will sit snugly alongside the change gear quadrant on my old Drummond lathe, instead of poking out into mid air.


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## rodw

Davo J said:


> Hi Rod, and thanks.
> With the flex shaft whats it made of. If it's spring steel try not to get it to hot or it will go soft.
> 
> Dave



Dave, I am not really sure. Could be spring stuff. I have a couple of them so I might give it a go and see what happens. It sort of has a braided look so the solder has something to wick into. I guess I will find out what it is when I try to cut it!


----------



## Davo J

I just remembered something, If it's like whipper snipper (weed eater for the US) flex cable it will silver solder.
I have a few gas powered boats using those flex cables and they are silver soldered into brass.

Dave


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## rodw

Awesome. 

I'll give it a go once I sort out my shed after tipping my lathe over:wall:

Brass would be better than steel I take it?


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## Davo J

Steel would be fine, it would just need more heat.

Dave


----------



## rodw

My motor speed controller arrived yesterday. I was really impressed with the delivery time on this one.





Nothing is going to happen for a while as I have a lathe stand to start building this weekend.


----------



## ZipSnipe

Just ordered all my switches last nite. I am holding off the motor controller because I want to hack the one that comes with my drill if possible, if not then controller will be ordered.

Keep us posted Rod!!!!


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## rodw

ZipSnipe said:


> .
> 
> Keep us posted Rod!!!!



Well I hope you are patient, this will be a slow build in amongst the lathe stand I am starting today and the Arduino controlled Rotary table controller that I am working on.

This forum comes up with so many ideas!


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## ZipSnipe

Well ordered this dc speed controller from ebay today.


http://www.ebay.com/itm/281027916416?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

I also got the drill apart, unlike Troy's mine was especially difficult to get the chuck off.


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## rodw

ZipSnipe said:


> Well ordered this dc speed controller from ebay today.



ZipSnipe, it does not look like the controller you ordered has a forward and reverse switch. Will you just wire a switch on the motor output to reverse the motor polarity? Or have you got other ideas?

Glad you have the clutch intact still!


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## ZipSnipe

Good eye Rod, and I didn't even think about that when I ordered the controller.  But if you look closely at the trigger  and right above it is the reverse switch with motor wires running directly into it.  And that is all its doing is reversing the motor leads before they go into its lil controller.

I am trying to duplicate exactly what Troy has done with the following exceptions.

Using 4 shoulder bolts that will act as the sliding support for the feed. 

And for the top of the controller will be 1/4 aluminum plate( so the screws will recess and a sturdy surface)


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## ZipSnipe

Darn started reading the Ebay posting of the controller I bought.  The heading says 10 amp but the body of the ad says 5 amp.  Hopefully the body is worded wrong.  I wanted 10 amp as the motor is 12 amp( I know I was shocked to see that it was rated at that)


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## rodw

ZipSnipe said:


> Darn started reading the Ebay posting of the controller I bought.  The heading says 10 amp but the body of the ad says 5 amp.  Hopefully the body is worded wrong.  I wanted 10 amp as the motor is 12 amp( I know I was shocked to see that it was rated at that)



I think if you end up with a 5 amp one you would have grounds to raise an eBay dispute if the supplier won't send you a new one.

That's a big power draw you are looking at. What power supply are you going to use?


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## ZipSnipe

well contacted the seller sent him a link with the heading showing that it says 10 amp. He then sends me a heading back that says its 5 amp.

I guess I will pick up a 12 volt 5 amp wall wart now( they are used on LCD monitors)


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## MCRIPPPer

using a lower amp power supply wont help you. you cant give something less amps, only less volts, so that it draws less amps. most wall warts are just little transformers with bridge rectifiers and a capacitor. if you connect a high current load, the wall wart will supply more than its rated current, and get hot. so using a 5 amp wall wart to save the 5amp controller running a 12 amp motor, will not work too good. i bet the motor pulls far more than 12a under heavy load or when it starts from a dead stop. 


i am finding the power supply/speed control to be the most difficult part of my power feed. 

here is a link to my thread on mods which includes the power feed im making. 

http://www.homemodelenginemachinist.com/f28/my-mini-sx2-mill-mini-7x12-lathe-mods-so-far-20843/#post221697


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## ZipSnipe

I could be wrong about the motor amps, I know its a 14 volt motor but have not found the amps for it.  On the trigger it had said it was 12 volt 12 amp but I think that is what the trigger was rated at and not the motor.  In fact I know it can't be 12 amps, a table saw is around 12 amps and I know my screw gun is no where near the power of a table saw.

Any just waiting for the on/off switch to arrive, I got the motor  and controller mounted in the powerfeed box. I also need longer shoulder bolts.


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## MCRIPPPer

but your drill is only 14v. power(watts) is volts x amps. so 12 amps at 120 v will make much more power than 12a at 14v.


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## rodw

Don't forget that a motor will only draw maximum power at maximum load (torque). So if you are going to use the ratchet on a drill motor to protect from over travel, you will not be anywhere near a full load situation so power draw (amps) won't be anywhere near the rated capacity.

MCRIPPPer, if you had a surplus laptop power supply rated at 3.5 to  5 amps, I would give it a go. Worst case is it won't work as they usually have overload protection. Remember that typically in a circuit you would have at least 20% headroom in any specs so your 12 amp drill will probably only pull 10 maximum and on a SX2, probably a lot less than that. The only way you would know is if you put an amp meter on it while it was running.

I had an electric motor tested recently, it was rated at 12 amps on the plate and it was only drawing 6 under load which the repairer said was about normal. Work that out!

I would not get too worried about how much current it draws, my experience with cordless drills is that you know when they are working hard cos you can smell the battery and they don't last very long at that power level. The power feed is never going to tax it at that level and I expect it will be close to idle.


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## MCRIPPPer

it is true it will draw less as the rpm increases. at start up it will pull large amps if it is suddenly flipped on. i am having issues making a power system for my power feed because it wants so much power. it was a dewalt 18v drill. i measured the resistance of the motor and got 1.5 ohm, so when i connect the 18v to the motor, it is no wonder why it sparks and the wires even heat up (same size wires as the motor came with.) with the low resistance, the motor runs on very low voltage. it will happily move the table running only on a single AA cell. so maybe i will try to find a lower voltage source so it doesn't draw so much power.


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## ZipSnipe

Ok I am confused, when I read the beginning of this post, the NC  momentary switch is on the ground of the speed pot according to Troyo in post #14.
But  in his diagram on post #33 he mentions shorting the wiper and the load ,  which to me means you would need a NO momentary switch, am I right?


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## rodw

ZipSnipe said:


> Ok I am confused, when I read the beginning of this post, the NC  momentary switch is on the ground of the speed pot according to Troyo in post #14.
> But  in his diagram on post #33 he mentions shorting the wiper and the load ,  which to me means you would need a NO momentary switch, am I right?



I think you got it right. Somewhere, Troyco says his original drawing was wrong. I have not had time to play but in my mind, it makes sense to be able to short out the resistance by closing a NO switch between the central wiper and one end of the pot which is equivalent to turning the knob to full scale.


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## TroyO

I'm not sure that's what I did in the end. I may be able to get a chance to open it up to be sure this weekend but I suspect that the "best method" for the GoBabyGo switch is to disconnect the GND from the pot, which should let the wiper be pulled high through the potentiometer no matter it's position.

LOL, I just went back and re-read my own posts.... Post #14 of this thread is exactly what I ended up doing, I'm pretty-much-almost-sure. ;-)

I updated the Schematic from earlier, sorry I forgot about how I did it! LOL, I had the best intentions of documenting everything but there didn't seem to be all that much interets at the time so I dropped it.


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## ZipSnipe

Thanx again Troy for your help and great contribution to the DIY spirit !!   I have copied almost all that you have done with the exception that my drill motor was 14 volt and my controller is a 5 amp even though I ordered a 10 amp but ended up with a 5 amp.  So we will see what happens, just waiting on the power supply to arrive.


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## ZipSnipe

Power supply came in and go it hooked up and am happy to say, works almost perfect !!!!   The only things wrong were, the lighted power switch I bought is 125 volts and not 12 volts so the light doesn't work. And the momentary switch is not hooked up.  But other than that the speeds are right on and I like it.  I will replace the power switch tomorrow and give the momentary switch two more test tries tomorrow.


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## Davo J

rodw said:


> I think if you end up with a 5 amp one you would have grounds to raise an eBay dispute if the supplier won't send you a new one.
> 
> That's a big power draw you are looking at. What power supply are you going to use?


 

I agree, just start a paypal dispute and get you full money back as what you got is not what you paid for.
I have had 100% success with getting back what I wanted with the few problems I have had over the years.

Dave


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## canadianhorsepower

ZipSnipe said:


> Thanx again Troy for your help and great contribution to the DIY spirit !!   I have copied almost all that you have done with the exception that my drill motor was 14 volt and my controller is a 5 amp even though I ordered a 10 amp but ended up with a 5 amp.  So we will see what happens, just waiting on the power supply to arrive.


 
If you really want a 10 amp you only have to replace both transistor mounted on the heat sink to a higher rating
 as for your lighted switch use it as on and off on your power supply source
and you'll be fine
if you need clarifying please ask


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## ZipSnipe

Well had everything hooked up and it looks like 5 amps is not enough to move my table if the controller really is 5 amps.  It will move it some but then fades out and doesn't want to turn the motor. So I am assuming the controller is not pulling the amps that the motor needs. 

So Luc, all I need to do is change out the transistor? 

 I have two , one says this

P75NF75 &
CZ010   T
MAR 237
ST   3    (ST is slanted and the 3 is in a circle with a small symbol next to it)

The other transistor says this

L7812CV
G401X V6
CHN 249
ST  3  (same as above)


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## Hopper

You might hook a 12volt car or large motorbike battery up to it just to make sure the power supply is the problem. If it runs ok on the battery, you know the motor and mechanism are all good.


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## John Rudd

ZipSnipe said:


> Well had everything hooked up and it looks like 5 amps is not enough to move my table if the controller really is 5 amps. It will move it some but then fades out and doesn't want to turn the motor. So I am assuming the controller is not pulling the amps that the motor needs.
> 
> So Luc, all I need to do is change out the transistor?
> 
> I have two , one says this
> 
> P75NF75 &
> CZ010 T
> MAR 237
> ST 3 (ST is slanted and the 3 is in a circle with a small symbol next to it)
> 
> The other transistor says this
> 
> L7812CV
> G401X V6
> CHN 249
> ST 3 (same as above)


 
ZS, 
Those two devices you list, one is a mosfet ( first one) the other device is just a plain old 12 v regulator..

If the speed controller is rated for 5 amps then changing the mosfet device isnt going to help, the speedo is probably designed for 5 amps and is done with selective components...

You got a link to the speedo you bought?

I looked at the link for your speedo....Doesnt look like there's anything exciting about it in terms of current limiting...

RodW, Can you see anything on your board that looks like it could limit current to the mosfet?

Might be easier to buy or trade up your speedo for one of a suitable rating that meets your needs.....


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## ZipSnipe

You are correct John, upon further research I found the data sheet for the power regulator chip, it is rated at 1.5 amp.  So wouldn't this mean the board is actually  a 12v 1.5 amp speed controller rather than the 12 v 5 amp that the seller claimed?


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## purpleknif

Got a readout on my power supply and running in the low gear range on the drill I haven't pulled 4 amps yet


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## ZipSnipe

Purpleknif is yours connected to the table yet?  Mine ran fine until I connected it to the table.


I decided to remake my coupling, it was tapped out of whack so it might be causing some binding, I will also remake my mounting plate as my hole for the x axis screw was also off.


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## phansen39

The 7812 only powers the circuit not the motor. If you look at the 8 pin ic it is probably a ne555. The P75NF75 is rated at 80 amps. This powers the motor. With the small heatsink and small circuit traces it cannot source enough current.  If it is a ne555 looks like it drives the gate of the P75NF75 through a resistor. Might not have enough current output pulsed to  fully turn on the gate.


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## ZipSnipe

Thanx for the info Phansen,  I will be concentrating on fixing my screw ups with the table /powerfeed alignment. 

 My biggest mistake was when I went to make the mounting plate, I forgot to do my deduction for my edgefinder, I also tried to use a measurement for the leadscrew hole by just measuring it while it hung in place instead of measuring the supplied handle mount.

Luckily I discovered I don't have to remake the plate but will instead tap out the lead screw hole and plug it with a threaded insert with some Threadlock. Mill it flat and re drill for the leadscrew hole.

I won't to eliminate all mechanical binding before I go blaming the electronics again.  It works fine when not connected to the table , so once the binding is worked out, it should hopefully work smooth.


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## purpleknif

Yes mine is connected.. I have a Real Bull mill and it has an extra handwheel on the left end so I just took the handle off, made a bushing and couple it wit a socket and a square tapped to go in the drill


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## ZipSnipe

Hey Phansen, I want to correct my earlier statement, it does not do a dead crawl. In fact its pretty iffy at its slowest speed.  I am trying to determine the ground lead coming off the speed pot. I tried reading cont. between the pots contacts and ground but no luck. I assume that maybe one of the chips opens the ground to the pot when its not powered up. I want to try adding a resistor to the ground like Troyo mentions earlier in the thread.

I also corrected the alignment issue with the much better new coupling and lowered the motor mount so it sits more in line with the lead screw, this was a big improvement.  However with little effort I can hold the table and the clutch starts to kick in.  I am going to adjust the clutch setting one more time see if that helps, it looks like I have it set mid way but its possible I have the clutch cover on in the wrong spot which would mean looks are deceiving.


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## John Rudd

phansen39 said:


> The 7812 only powers the circuit not the motor. If you look at the 8 pin ic it is probably a ne555. The P75NF75 is rated at 80 amps. This powers the motor. With the small heatsink and small circuit traces it cannot source enough current. If it is a ne555 looks like it drives the gate of the P75NF75 through a resistor. Might not have enough current output pulsed to fully turn on the gate.


 
Mosfets are voltage driven devices not current like a transistor that has Hfe...

Like I said before, if the current is limted to 5 amps as the seller claims, then there must be a way in which it does this via a sensing network...Else if the mosfet is driven from the 555 then there isnt really a limit only the mosftet's Rds....and the power supply's current capability


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## ZipSnipe

Here are the results of testing the pot. Powered on and pot running motor at about half speed.

 I set my meter to dc 20 v, I had the com lead from the meter to the  power in ground, the red meter lead went to the right side of the 3  terminal pot and I got a 10.2 reading, then I touched to the far left  lead and got a 5 reading, heres where it went weird, I touched the  center pot and the motor speeds up and I got a reading of about 2

The good thing is I know I can now run my momentary switch to this  center wire to the ground so that I can have rapid traverse on the powerfeed.  But I  still don't know which is ground. I am assuming it might be the center wire but still not sure.

The reason for finding the pots ground is so I can try different resistors to slow it down like Troyo mentioned earlier in the thread.


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## phansen39

If you follow the board layout it looks like power is on pin 1 on the potentiometer header. So pin 2 shoud be the wiper. The other "ground" But is not really ground.
A NO switch between 2 and 3 should give full speed when turned on.


Does your meter have say a 200k ohm range?  The picture shows a 100k ohm pot. If you can meter that range. You can test exactly where the switch needs to go. If you look at the pot knob toward you and wires facing upward. The switch would go between the middle and right wires. This based a a couple of assumptions. Like turning the pot clockwise increases speed . It could very well need a dpdt switch and an external 100 k resistor.


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## ZipSnipe

I think the main problem I am having now is the motor is weak, I can grab it and stop it. So I am wondering if the controller is too small and that I may definitely need a 10 amp?


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## phansen39

Hook it up straight to its battery pack?


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## ZipSnipe

Ok my buddy came over he spotted that the hi lo shifter wasn't fully engaged and was making the motor weak. So now the motor is fine and strong.

So the only issue left is the slow speed is fluctuating a lil bit.  I am hoping that a resistor on the pot would maybe fix it.


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## ZipSnipe

Well tried resistors on the pot with no good effect.  So it has the power it needs , its just at its slowest setting its very jumpy, wants to either go super slow or super fast.  :-(


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## ZipSnipe

Just wanted to point what a friend told me, that if my pot is 100k and I am trying to induce resistance that I would need resistors that are under 100k , all the ones I tried were over 100 k except 1 and it was like 47ohm or something like that.

SO I am hunting for some lower value resistors and will report results


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## ZipSnipe

Decided and ordered a new controller last nite from a hopefully different Ebay seller, still out of China. 

http://www.amazon.com/gp/product/B00CW82ZPG/?tag=skimlinks_replacement-20

I really wanted to get this other one I found, 
http://www.electronickits.com/kit/complete/motor/CKMX033.htm
I see they don't use that 555 timer and was wondering if it would have been better, but again economics came into play and I went for the cheapie, I will probably get what I paid for.  Well see how it goes when it comes in.


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## ZipSnipe

If an electrics supply house was close by , yes. But since stuff is being shipped, the shipping charges are ridiculous. And thank you for putting that diagram up, that looks like an easy build.


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## ZipSnipe

Well new controller came in yesterday and hooked it up, runs perfect !!!  Runs slower speeds with out any erratic behavior like the previous controller
However it is larger so today I will be re drilling the mounting holes , I will also try the momentary switch out and see if I can get it to do the rapid traverse.


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## rodw

ZipSnipe said:


> Well new controller came in yesterday and hooked it up, runs perfect !!!  Runs slower speeds with out any erratic behavior like the previous controller
> However it is larger so today I will be re drilling the mounting holes , I will also try the momentary switch out and see if I can get it to do the rapid traverse.



Awesome you finally got it sorted. Don't you hate it when you are let down by others?

Be sure to document how you wire in the go fast switch. I got the Z axis scale of my DRO mounted last night and just have to mount the sensor to the saddle and I can come back to this project. I now know how much room I have left for the motor to mount up, so I will be revisiting this project. Accommodating the DRO was the main reason I had not made a start on this project. It is annoying sometimes that you have to do things in a specific order.

Also there is a build on madmodder that has incorporated limit switches which stop travel and knock it into go fast mode back the other way to restart the next pass. I will have to find the link for you.


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## ZipSnipe

Bummer, no rapid by shorting the wiper and ground together.  But upon further reading of Troyo's original post he said he used a NC switch on just the ground alone, so I will try that next.  Fortunately this controller is marked in English as to where the ground and wiper are.


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## rodw

I think you need to look at the circuit. I doubt shorting the wiper to ground is correct but I don't know much about electronics.

I would have thought the circuit would apply power to the wiper and the pot applies a resistance to reduce the voltage and thus change the speed.  I think that the wiper should be shorted to one of the other wires on the pot. The purpose would be to short out the pot so there is no resistance to the applied voltage.

Here is a link for more ideas I spoke about earlier.

http://mikesworkshop.weebly.com/mill-power-feed.html

I finished the X axis on my mill DRO last night at about 9:30 last night. I still have a bit of tidying up to do but once this is done (and I have some spare time) I will finally get to this.


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## ZipSnipe

Yeah I tried the wiper to the power, it speeds up for a split second and then cuts off.  I also tried disconnecting the ground.  On the other smaller controller I shorted the ground to the wiper and it sped the motor up but looks like this larger one isn't going to do it.

I think I seen somewhere they added a relay to create the rapid traverse.  So I might look into that some more, thanx for the link!!!


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## ZipSnipe

TroyO said:


> So I then jumper the GND to the negative lead of the motor and sure enough WHIIIIRRR!



Man, I have re read this post several times and I still missed this part where he tried jumping the gnd to motor negative.  Seems like an easy test to try.


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## ZipSnipe

Luc, can I do the same thing with a multi tester( I don't have a test light)? wouldn't the numbers jump around be the same thing as flashing?

I should also point out the power supply I have is one that only has the two prong plug, so should I wire up a three prong and run a ground in from the plug to maybe the body of the enclosure?


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## ZipSnipe

canadianhorsepower said:


> you can skip this test and go directly to this
> Disconnect one wire "make sure you know it's polarity" and replace it to a full ground or full live and try it,, you will have the same result
> cheers



I think I will buy a test light tomorrow, your first prescription sound easier and safer


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## John Rudd

Zipsnipe,

The output stage is either open collector transistor or open drain if its a mosfet...either way, the motor will be connected:

Motor positive to the main supply rail positive and the motor neg to the collector/drain...

Easiset way to make the motor spin faster on return to start is to temporarily short the mosfet so that the motor is now connected across the full supply rail....or connect the motor negative to the negative of the power input to your module........


I'd stay tuned more often to this forum if I didnt keep losing my password............I spend more time trying to login than replying to posts...


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## ZipSnipe

Well Luc , tried using my digital multi tester to see if I would get a bouncing reading on the wires you mentioned and all read 12 volt.

But I did a lil experiment, by touching one of the 555 timer leads to the wiper, it sped up like a charm.  I have to look at a 555 timer schematic again, I don't know if I am harming anything if I hook it up that way. I did it several times and no smoke or sparks and it seemed to work fine.


----------



## John Rudd

Maybe I ought to butt out of this conversation........?


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## ZipSnipe

I'm thinking this is working with coming off the 555 timer and putting a NO momentary between it and the wiper.  I tested it a lil more today with different speeds and letting it run a few minutes to see if anything got hot and all was well.

I do thank you Luc for your help, but I am a lil confused by "remove the ground wire from your motor and short your motor to ground
that should do it"  
Short my motor to ground? I am trying to picture this and I am getting nothing, sorry my electronics experience is kindergarten.


----------



## ZipSnipe

Well I am finished , she works good.  My motor alignment is still off a lil but not enough to hurt anything.  Here is a diagram of how I wired mine


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## rodw

Awesome! We want pics of the finished item though!

Glad you finally got it sorted out. I am a bit concerned I will have nothing to do once I can stop reading this thread of your trials and tribulations...


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## ZipSnipe

Luc that is why I am on these forums, a big thanx for Troyo for starting this thread.  Rod here is a pic from earlier, I will post a video once the mill is put back together.


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## MCRIPPPer

potentiometers are almost always wired as voltage dividers. this means that the two outer pins are connected to 0v and V+, and the center pin outputs a voltage between 0 and v+ depending on where the knob is turned. so all the controller does is read the voltage fromt he pot and turn it onto a pwm value. if you override the pot and just feed the right voltage into the controller, you can get a 100% speed. you need to find out if full speed is at low, or high input.


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## John Rudd

MCRIPPPer said:


> potentiometers are almost always wired as voltage dividers. this means that the two outer pins are connected to 0v and V+, and the center pin outputs a voltage between 0 and v+ depending on where the knob is turned. so all the controller does is read the voltage fromt he pot and turn it onto a pwm value. if you override the pot and just feed the right voltage into the controller, you can get a 100% speed. you need to find out if full speed is at low, or high input.


 
you are correct, however.....


Like I said in a previous post, there's no need to do that...

Just by pass the controller altogether by grounding the motor's neg terminal....

Horses and water springs to mind.........Ignore my experience and knowledge if you want...


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## ZipSnipe

Like this John? Maybe add a diode so it do feedback into the controller?


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## TroyO

Each controller will be a little different. Generally, one argument against grounding the negative lead of the motor is that it's usually "better" to use the control side of the device rather than just shunting power... the switch has to be big enough handle the full amperage load of the motor if you do it that way. Not many momentary switches are rated that high.

Zip, the wiring schematic you posted could be a problem, while it would be fine when the motor was in "fwd" mode, I think when you were in reverse mode you would them be shorting the positive side straight to ground. You would have to tap in to the ground wire after the controller but before the Fwd/Rev switch. (That's just with a quick look, I haven't fully figured out the whole circuit or anything.) Assuming whatever controller you are using works by PWM controlling the ground connection that would work if you can find a big enough switch that's suitable.

McRipper, one thing I figured out on my controller was that you couldn't just put power to the wiper because when the wiper was all the way down (electrically close to GND) when you applied the positive voltage you were essentially shorting through the pot. That was why I went with disconnecting the ground... the wiper gets pulled "high" because there's no ground connected to oppose the positive voltage. there's also no risk of shorting the controller out that way.

Keep at it, whatever it is it's not a waste of time. I'm sure if nothing else you are learning tons! Do you have a circuit diagram for the 555 device you are using? I may be able to help more if I knew how the controller was set up.


----------



## MCRIPPPer

TroyO said:


> Each controller will be a little different. Generally, one argument against grounding the negative lead of the motor is that it's usually "better" to use the control side of the device rather than just shunting power... the switch has to be big enough handle the full amperage load of the motor if you do it that way. Not many momentary switches are rated that high.
> 
> Zip, the wiring schematic you posted could be a problem, while it would be fine when the motor was in "fwd" mode, I think when you were in reverse mode you would them be shorting the positive side straight to ground. You would have to tap in to the ground wire after the controller but before the Fwd/Rev switch. (That's just with a quick look, I haven't fully figured out the whole circuit or anything.) Assuming whatever controller you are using works by PWM controlling the ground connection that would work if you can find a big enough switch that's suitable.
> 
> McRipper, one thing I figured out on my controller was that you couldn't just put power to the wiper because when the wiper was all the way down (electrically close to GND) when you applied the positive voltage you were essentially shorting through the pot. That was why I went with disconnecting the ground... the wiper gets pulled "high" because there's no ground connected to oppose the positive voltage. there's also no risk of shorting the controller out that way.
> 
> Keep at it, whatever it is it's not a waste of time. I'm sure if nothing else you are learning tons! Do you have a circuit diagram for the 555 device you are using? I may be able to help more if I knew how the controller was set up.




very good points. you are right about the potentiometer not getting along with a switch in some circumstances. but you could remove the potentiometer and apply a voltage to what was connected to the wiper, and "ground".

the best thing would be to find a motor driver with an h bridge so it already has the forward reverse control figured out in the microcontroller or whatever it uses to control the FETs.


you could probably buy a brushed dc motor controller from a hobby shop and build a 555 based circuit to synthesize the signal of an rc receiver.


----------



## ZipSnipe

Thanx Troyo, I was simply trying to figure out if that is what John Rudd meant by grounding the motor.  The way I currently have it wired up is in my post#102.  This works fine but it does not put the motor to full speed but rather just doubles the speed of the potentiometer.


----------

