# Enco (Rong Fu RF30) Mill/Drill Conversion



## cfellows (Nov 9, 2013)

I've been talking about this in another thread under Tool Modifications and decided it properly belongs here.

 I bought some SFU1605 Ball Screws with Ball Nuts on Ebay a couple of months back.  These were threaded end to end so I had fit machined shafting on the ends to adapt them to my mill/drill.  The ball screws are hardened but I was able to turn down the end with a carbide insert and finish it off with a small grinder attached to the lathe tool post.

 Here are some pictures of the Y-Axis that I've been working on the past couple of days.  First picture is the exiting Y-Axis lead screw nut and the machined aluminum replacement that will attach to the ball nut.







 Here's the original lead screw nut as it attaches to the Y-Axis Slide.






 And here's the aluminum replacement shown in place...






 And with the ball screw and nut in place...






 Here's the ball screw with the end turned down.  I actually had to extend the turned part another 1/4".






 Here's the ball screw assembly with the machined extension attached.  It was turned from 1" 12L14.






 And with the attachment...






 And here's a picture of the ball screw assembly in place...







 Next I'll be working on the X-Axis...

 Chuck


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## cfellows (Nov 11, 2013)

Had to do a bit of fiddling with Y-Axis, including adding about .030" in shims on top of the Y-Axis ball nut attachment. Now it's smooth as silk with no binding.

Today I started on the X-Axis.  Here is a picture of the ball screw, nut, and the two 12L14 pieces that will be turned to form the extensions.






That ball is about 1.25" shorter than the table but I don't think the table ever would move to the extreme on either end, so hopefully no real estate lost.

I'm comfortable now that I will be able to finish this project so today I bit the bullet and ordered a Gecko G540, 4 axis controller/driver. It has lots of good features and will drive steppers up to 3.5 amps. I think I will be able to use the MDI functions in the MACH3 Demo to move the axes around manually. 

Chuck


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## stevehuckss396 (Nov 11, 2013)

cfellows said:


> I think I will be able to use the MDI functions in the MACH3 Demo to move the axes around manually.



Screw that!!  The tradition is to write your name with a felt tip fine point pen. PM me your email address and ill send over the gcode. Board wont let me attach it. Hope you like Times New Roman.


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## cfellows (Nov 12, 2013)

One end of the X-axis now machined and fitted.











 Aligns nicely as is, no binding.

 Chuck


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## cfellows (Nov 12, 2013)

Forgot to include a picture of the X-axis ball nut attachment fixture.  It's made from 2" x 2" x 1/4" angle iron, milled and cut to shape.






 The contact surfaces are also milled flat and square to each other.

 Chuck


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## kuhncw (Nov 12, 2013)

Chuck, I'm enjoying your posts on converting your mill drill to CNC.  I think you will be surprised at how much use you will get out of it, even for one off parts.

At the absolute very least, operating in manual input mode,  it will be like having a smart power feed on your mill.  

Regards,

Chuck


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## cfellows (Nov 13, 2013)

kuhncw said:


> Chuck, I'm enjoying your posts on converting your mill drill to CNC. I think you will be surprised at how much use you will get out of it, even for one off parts.
> 
> At the absolute very least, operating in manual input mode, it will be like having a smart power feed on your mill.
> 
> ...



Thanks, Chuck. I've always felt like CNC was a money pit that I didn't really need. However, being a tinkerer and a lover of all things mechanical I've longed to have a CNC setup for many years. I finally decided that having the manual input movements would tip the scales in favor of having it, so here we go.

So far I have about $650 invested and I'll probably buy Mach3 which will be another $175. Hopefully FreeMill, which is free, will take care of my CAM needs.

Chuck


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## cfellows (Nov 13, 2013)

The mill/drill is back in play, ball screws and nuts installed on the X and Y axes.











 Both axes move freely with no binding and no discernible backlash.  Now I gotta start on the stepper motor mounts and finally, what to do with the Z-axis.

 Chuck


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## Herbiev (Nov 13, 2013)

Great work Chuck. Looking forward to the z axis mods.


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## cfellows (Nov 15, 2013)

Thanks, Herbie.

 Got started on the Z-axis mount. Here's a picture of what will be the stepper motor mount. It's 3.625" x 5.25"






I decided to mount the plate on the face of the Z-axis crank assembly.






I don't think two, 10-24 screws is enough support, so I decided to add a couple more.

Here I'm making a drilling jig to bore the two extra holes in the casting. 






It will also serve as a drilling guide for boring the mounting holes in the aluminum plate.






And here is the casting with the two addition threaded holes.






Here's the mounting plate with the mounting holes in place.






Next I'll need to machine the mounting holes for the stepper motor and finish machining the contours around the outside.

Chuck


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## LSEW (Nov 16, 2013)

Chuck, Looks really good so far. I was wondering, have you thought about what you will be using the mill for? From what I've seen on your Z work, it appears you were not planning to use a ball screw.  If you want to do any 3D work, you may wish you had spent the time. Just a thought. Keep up the good work.

maury


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## cfellows (Nov 16, 2013)

LSEW said:


> Chuck, Looks really good so far. I was wondering, have you thought about what you will be using the mill for? From what I've seen on your Z work, it appears you were not planning to use a ball screw. If you want to do any 3D work, you may wish you had spent the time. Just a thought. Keep up the good work.
> 
> maury



Thanks, Maury. I do plan to do some contour work which will require the Z-Axis to work with minimal backlash. The quill is spring loaded and I can increase the tension on it if I need to. If that doesn't work, I can always go back and change it although I expect that would take an inordinate amount of effort.

This morning I finished the Z axis mounting bracket. 
















I would liked to have done it on the Tormach down at the TechShop, but I'm still struggling with getting a drawing processed all the way through FreeMill, the free CAM program I'm using for the moment. So, I just machined it manually. Boy, you're right about the axes unwinding on you if you don't have the locks clamped down nice and tight. Even with a 3/16, 2 flute endmill running at pretty high RPM I could see the slot beginning to creep sideways on me.


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## cfellows (Nov 16, 2013)

I'm pairing 20 tooth with 48 tooth pulleys on the X-Y Axes.  I need a smaller pair for the Z axis and happened to have a 15 tooth pulley for the motor so to keep the ratio the same as the other axes, I needed a 36 tooth pulley.  I know it's not necessary to have the same gear ratio on all axes, but I like consistency.  I didn't have a 36 tooth pulley on hand and I didn't want to pay the outrageous price for one, so I decided to make one.  Here's a picture of the blanks I turned.






 I already had a cutter I had made a number of years ago from a 1/8" slitting saw. I had beveled the edges to the proper angle and used it once before to make another pulley.  Here it is chucked up in the mill, teeth already cut.  I'm using my Arduino powered dividing head to index the blank as I gut the gulleys.






 Unfortunately, I cut two of the gulleys twice as deep as they should be.  I had forgotten that my ball screws move the axes twice as far as before!  Made the correction and cut the rest of the teeth.  I don't think it was make much difference.
 Here's the (nearly) finished pulley.  






 Still need to bevel the edges of the teeth and bore out the hole in the center to the correct diameter.
 I also just realized that the electronic dividing head will make a nice 4th axis when I everything up and running.  Guess that 4th axis on the G540 will come handy after all!

 Chuck


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## cfellows (Nov 19, 2013)

Got the X-Axis motor bracket nearly finished. Here's the part that attaches to the mill table, with clamping screws drilled, tapped, and mounted.






And here it is with the motor attached.






Will trim off the bottom part of the motor bracket later when I get closer to finished with the project.

Chuck


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## cfellows (Nov 24, 2013)

Still plugging away on this thing.  I've spent the last few days experimenting with a couple of new Y-Axis bearing blocks.  I'm not happy with either one, so I'm back to using the original casting.  I am, however, replacing the two thrust bearings with somewhat larger angular contact bearings, back to back, to handle the side thrust from the belt tension.  Won't receive those until Tue or Wed, so I've been filling in with other parts.

Here's a picture of the Y-Axis motor mount (so far). Still have to make the part that attaches the motor to the arm.






Some folks on the CNCZone forum have expressed concern about the size of my steppers.  Hopefully they will be beefy enough if I don't try to coax too much speed out of them.  Otherwise, I may have to move up to Nema 34 motors with a higher torque rating.

 Chuck


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## stevehuckss396 (Nov 24, 2013)

cfellows said:


> Some folks on the CNCZone forum have expressed concern about the size of my steppers.
> 
> Chuck




The guy's at the zone expect results like a real production machine. Just get the best rear ratio physical size will allow. Put the biggest gear on the screw as you can and not hit anything, and put the smallest pulley on the motor as you can. That will give maximum torque. you wont have big speed for rapids but you will have the torque for cutting. Your not making 1000 of anything so who cares.

If I remember correctly you have Gecko drives so if you want to post up the motor specs I can calculate the best input voltage to your drives, for your motors based on the inductance of the coils. Thats if you haven't done it. That will also improve torque through out your RPM range. The higher the RPM the greater the benefit.


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## cfellows (Nov 24, 2013)

stevehuckss396 said:


> If I remember correctly you have Gecko drives so if you want to post up the motor specs I can calculate the best input voltage to your drives, for your motors based on the inductance of the coils. Thats if you haven't done it. That will also improve torque through out your RPM range. The higher the RPM the greater the benefit.



Thanks, Steve. The motor inductance is 6.8 mh per phase, 1.6 ohms resistance and are rated at 3 amps. The holding torque is 280 N cm which converts to about 396 oz in.  I bought a 24v, 15 amp power supply specifically for this application, but could buy a different if there would be a significant performance boost.  The driver is a Gecko G540 and will handle up to 50 volts DC for the motors.

As you said, speed is of little consequence to me. I have 20 tooth pulleys for the motors and either 48 or 60 tooth pulleys for the ball screws.

Here's the Y-Axis motor mount. It will be attached to the mounting arm with two 5/16" bolts through the 1 5/8" long slot. The bolts will be 3/4" apart which will give me 3/4" belt adjustment. 






I realize this could still slip, but with two bolts holding it, it should be much more secure.

Chuck


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## shepdog (Nov 25, 2013)

Excellent work...I've been hemming and hawing over CNCing my busy bee 1997 mill...don't suppose you have any saved drawing's you'd care to share?


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## canadianhorsepower (Nov 25, 2013)

> I think I will be able to use the MDI functions in the MACH3 Demo to move the axes around manually.


 
 Mach 3 has a nice jog mode, just tap your tab key and it will come up


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## LSEW (Nov 25, 2013)

Chuck, that is good placement for your "Y"motor. Good thinking. On my conversion the pulley for the "Y" limits the travel a little, making parts with just over 8" in the "Y" impossible. 

You may want to also check out the pulley size for the "Y" so this doesn't happen to you. You will want all the "Y" you can get.

maury


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## cfellows (Nov 25, 2013)

LSEW said:


> Chuck, that is good placement for your "Y"motor. Good thinking. On my conversion the pulley for the "Y" limits the travel a little, making parts with just over 8" in the "Y" impossible.
> 
> You may want to also check out the pulley size for the "Y" so this doesn't happen to you. You will want all the "Y" you can get.
> 
> maury



Thanks, Maury, the pulley on the Y-axis sticks out far enough that clearance isn't an issue.

Luc, thanks for the tip.  I'll give that a try when I get the drivers and motors hooked up.

Shepdog, you're welcome to whatever drawings I have, although I don't know if they'll be any help to you unless your machine is substantially the same as mine...

The angular contact bearings came in the mail today so I spent the rest of the afternoon and evening getting those installed. Since I was installing the bearings in the original bearing block casting, I went very slowly and was very careful not to screw something up. I did have one close call... I was very near the final OD and decided to press the bearing in and see how it fit. It wasn't real tight, but getting it back out was a wooley booger! I did finally get it out and bored the opening a little bigger so it is a sliding fit with no slop.

I also installed a regular ball bearing on the motor end of the X-axis ball screw. All the feed thrust is on the other end of the table which has dual thrust bearings, so this end just needs to handle the radial force from the belt. Also, in addition to the set screw which holds the extension onto the Y-axis ball screw, I put some Loctite 620 on it and also pinned it with a roll pin.

So, I ordered some connectors like these:







to connect the motors to the cables. I'm currently planning on using 4 conductor , 18 gauge stranded wire for the cables. Is that what most folks use? I'd like to use coiled cable like they used to use on telephone handsets, but have no idea where to find anything like that in the gauge I need. The other end of the cables want DB9 connectors for the Gecko G540.

Chuck


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## canadianhorsepower (Nov 25, 2013)

Chuck 
 here is the answer to your cable
http://www.cablescience.net/power-coils.php?osCsid=8cd9792d4a31ea5dce67b7905c1fc66b

 enjoy


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## stevehuckss396 (Nov 25, 2013)

cfellows said:


> Thanks, Steve. The motor inductance is 6.8 mh per phase, 1.6 ohms resistance and are rated at 3 amps. The holding torque is 280 N cm which converts to about 396 oz in.  I bought a 24v, 15 amp power supply specifically for this application, but could buy a different if there would be a significant performance boost.  The driver is a Gecko G540 and will handle up to 50 volts DC for the motors.
> 
> As you said, speed is of little consequence to me. I have 20 tooth pulleys for the motors and either 48 or 60 tooth pulleys for the ball screws.
> 
> ...



according to the math the drives would want 83 volts. The drives you selected max out at 50. You might be happier with a 48 volt power supply if you can find one.

Also something to think about. You probably bought one of those regulated power supplies. They try to maintain a constant output. The gecko drive is going to be taking an input voltage and trying to turn that into a constant current to the motors. Sometimes the two will try to fight each other and you might get some erratic behavior or some missed steps that are random. Best power supply for the geckos is a simple supply using a transformer, rectifier, and some capacitors.


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## cfellows (Nov 26, 2013)

stevehuckss396 said:


> according to the math the drives would want 83 volts. The drives you selected max out at 50. You might be happier with a 48 volt power supply if you can find one.
> 
> Also something to think about. You probably bought one of those regulated power supplies. They try to maintain a constant output. The gecko drive is going to be taking an input voltage and trying to turn that into a constant current to the motors. Sometimes the two will try to fight each other and you might get some erratic behavior or some missed steps that are random. Best power supply for the geckos is a simple supply using a transformer, rectifier, and some capacitors.


 
 Thanks, Steve.  I do have a large Variac that I can dial anything from 0 - 140 volts at up to 30 amps.  I've also got some pretty beefy bridge rectifiers that will handle up to around 25 amps.  I guess all I need is a large capacitor and I'm set.  Wonder if I'll have any problem with grounding?

 Chuck


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## Wizard69 (Nov 26, 2013)

cfellows said:


> Thanks, Steve.  I do have a large Variac that I can dial anything from 0 - 140 volts at up to 30 amps.  I've also got some pretty beefy bridge rectifiers that will handle up to around 25 amps.  I guess all I need is a large capacitor and I'm set.  Wonder if I'll have any problem with grounding?  Chuck



Whoa Chuck, you don't want to use a Variac here!    Most variacs don't isolate from mains, I'd much prefer that you go with a regular step down transformer.   That and an inadvertent adjustment would likely fry things.    The trick here is to find the right voltage output to keep you comfortably under the drivers maximum voltage.   You could also wind your own transformer if you are into that sort of thing.    I know sourcing the correct transformers is a pain, that is one reason why buying a transformer from a CNC parts vendor is so popular.  

Another issue, as DC voltages increase you need to be far more careful with respect to your safety.   The possibility of electrical shock will become an issue at higher voltages.   I mention this only because people are less cautious around the common 24 VDC and less supplies and often forget to be safe when higher voltages are present.


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## canadianhorsepower (Nov 26, 2013)

> according to the math the drives would want 83 volts


 
Steve--- how did you come out with this number


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## cfellows (Nov 26, 2013)

Wizard69 said:


> Whoa Chuck, you don't want to use a Variac here! Most variacs don't isolate from mains, I'd much prefer that you go with a regular step down transformer. That and an inadvertent adjustment would likely fry things. The trick here is to find the right voltage output to keep you comfortably under the drivers maximum voltage. You could also wind your own transformer if you are into that sort of thing. I know sourcing the correct transformers is a pain, that is one reason why buying a transformer from a CNC parts vendor is so popular.
> 
> Another issue, as DC voltages increase you need to be far more careful with respect to your safety. The possibility of electrical shock will become an issue at higher voltages. I mention this only because people are less cautious around the common 24 VDC and less supplies and often forget to be safe when higher voltages are present.



Thanks for the warning, Wizard. I'm always a little concerned about using variac's to run anything other than a motor. Can you point me to any vendors who sell transformers?

Chuck


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## stevehuckss396 (Nov 26, 2013)

canadianhorsepower said:


> Steve--- how did you come out with this number



You can read the whole story on the Gecko website but here are the highlights.



The voltage of your power supply is entirely dependent on the inductance rating of your motor, which we learned is translatable to the number of turns of wire in the stator. Every motor model will have a different inductance rating and will therefore have a different maximum voltage. To figure out what the maximum power supply voltage should be, use the following formula with the motors inductance in millihenries (mH) used for the L value.

32 * VL = VMAX

If you are using several different models of motors on the same power supply use the lowest inductance rating in the above formula. This will ensure that your motors will not overheat due to the voltage being too high.


I think my drives are fed with some 60-65 volts but my drives max voltage is 80. Chucks is only 50 so cant exceed that ever. In his case I would go 48 if possible. To get 48 DC the ac input voltage needs to be about 34 volts. CNC suppliers have some wierd voltage transformers so its possible but not likely. At any rate he will need about 125Watt minimum if he uses the 4th. Also will need a 1500-2000MFD capacitor as close to the input of the drive as possible.


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## idahoan (Nov 26, 2013)

Hi Chuck 

I have been enjoying your CNC conversion; thanks for taking the time to post your progress.

I converted my kneed mill years ago with an AhHa system (long out of business);p about 3 years ago I started a project to upgrade to servos, MACH and a quill drive. Originally I only did the X and Y. 
Things kind of got side tracked and well here I am 3 years later getting going on it again. 

I was able to get my old controller interfaced with MACH using a break out board from Homan Designs; what a major improvement from the old DOS program both in functionality and speed. I was able to double my rapids using MACH.

I curious to see how you handle your operator interface control panel etc.

I have resurrected my project and hope to make some progress on it this winter.

Thanks again for keeping us updated on your CNC project.

Dave


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## cfellows (Nov 27, 2013)

Thanks for the update, Steve.  For the time being, I will plan on using my 24 volt switching power supply.  I'll look to upgrading to a transformer system if I run into problems.

 Another question, what are you CNC guys using for CAM?  I'd like to keep my CAM cost under $300 if possible.  Most of my work can probably be handled by 2.5D but might want full 3D from time to time.

 Chuck


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## idahoan (Nov 27, 2013)

Hi Chuck

I use BobCAD it's quirky but capable; even if you haggle with them I'm not sure you could get it for $300.00 There are other low end solutions but I haven't tried any of them. It will be interesting to see what others are using.

Dave


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## canadianhorsepower (Nov 27, 2013)

> Another question, what are you CNC guys using for CAM? I'd like to keep my CAM cost under $300 if possible. Most of my work can probably be handled by 2.5D but might want full 3D from time to time.


 
 Chuck------- D2nc works great for $78.00
http://www.d2nc.com/html/purchase.html

 artsoft for Mach 3 works well also
http://www.machsupport.com/software/mill-wizard-beta/

 and their is also an addon for Mach3
http://www.machsupport.com/software/mach3-addons-for-mill/

 If you are planning in trying JOG MODE you might want to download different screen set for Mach3
http://www.machsupport.com/software/downloads-updates/screensets/

 enjoy
 Luc


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## Wizard69 (Nov 27, 2013)

stevehuckss396 said:


> You can read the whole story on the Gecko website but here are the highlights.  The voltage of your power supply is entirely dependent on the inductance rating of your motor, which we learned is translatable to the number of turns of wire in the stator. Every motor model will have a different inductance rating and will therefore have a different maximum voltage. To figure out what the maximum power supply voltage should be, use the following formula with the motor&#146;s inductance in millihenries (mH) used for the L value.  32 * VL = VMAX  If you are using several different models of motors on the same power supply use the lowest inductance rating in the above formula. This will ensure that your motors will not overheat due to the voltage being too high.  I think my drives are fed with some 60-65 volts but my drives max voltage is 80. Chucks is only 50 so cant exceed that ever. In his case I would go 48 if possible. To get 48 DC the ac input voltage needs to be about 34 volts. CNC suppliers have some wierd voltage transformers so its possible but not likely. At any rate he will need about 125Watt minimum if he uses the 4th. Also will need a 1500-2000MFD capacitor as close to the input of the drive as possible.



Actually he can come close fairly easily, 48 VDC is a fairly common bus voltage in the controls world.    The trick is finding supplies suitable for motion control work.     Searching for 48 VDC power supplies brings up a few possibilities:
 1 http://www.automationdirect.com/static/specs/suresteppower.pdf.   (Watch open circuit voltages)
2  http://www.automationtechnologiesin...witching-cnc-power-supply-kl-600-48-duplicate
3. http://www.ebay.com/bhp/stepper-motor-power-supply
4. http://www.kelinginc.net/SwitchingPowerSupply.html
5. http://www.wantmotor.com/ProductsListB.asp?id=90&Pid=75
6. http://www.omc-stepperonline.com/power-supply-c-5.html?zenid=qhf6b6nk5185l1ikvahli02il7
7. http://americanmotiontech.com/products/powersupplies/
8. http://www.omega.com/pptst/ps_series.html

These are just a few of the possibilities out there, if you go to a local electrical supply house they probably have access to something.    Many of the above supplies are switching supplies which come in two flavors, regulated and unregulated.   Even though the regulated supplies are offered for CNC systems you need to make sure the can handle voltage regeneration from your motors.  Omega for instance offers a voltage clamp device to deal with that.   Also the drive itself might have some protection against regeneration.   Another common voltage to look for is 42 volts.   

For the unregulated supplies you need to keep a very close eye on open circuit voltages as some will exceed driver limits.   I still prefer cheap and simple transformer rectifier solutions, however switch mode supplies can save space.    Also with a transformer approach it is easy to DIY, just buy a transformer with the right output voltage and current capacity.  As far as transformers go here are a couple of sources:

1. http://www.surplussales.com/transformers/HvLvTr-5.html.  They have almost exactly what you would need listed but it is sold out!   
2. http://www.toroid.com/standard_transformers/rectifier_transformers/rectifier_transformers_117V.htm   Very nice layout that makes selection easy. 

Some of the online vendors are real proud of their transformers or to put it another way the prices are insane, especially for used ones.    Like power supplies your local electrical supply house ought to have a bunch of items catalogued.   I'd shop around.   Of course you could DIY a power transformer too.


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## RonGinger (Nov 27, 2013)

I  have to agree with Luc's great suggestion of the mach wizards, but then since I wrote and support them I am slightly biased 

However, they are conversational wizards, not a real CAM system. They are fine for common shapes, like circles, rectangles, pockets, bolt circles, arc slots, etc. The set called "addons for Mach" were written to run under Mach3 and cost $50. The new nfsMill set is standalone and will run on any windows system. They are $75. They are kind of the quick and dirty approach, very simple and fast to use but less capable than a CAM system.

In full CAM software there are several good packages in the $200-300 range. I have used Sheetcam for several years and it has done very well for me. It is really aimed at the router or plasma guys, hence the name sheet. I have used it to make many parts for model engines. It reads dxf files and generates gcode. 

There are several very good products from Vectric. Cut2d and Cut3d are as the names suggest. Their interface is similar and work well. As I recall they are about $200 each. Vectric has a more expensive program, Vcarve pro aimed more at the sign makers, but I have used it for model parts, especially name tags and labels for boiler and locomotives. It is about $700, and would not be my choice for simple model work. I have it because they were at one of the early CNC workshops in Galesburg IL and offered a package deal.

There is also CAMBAM which is highly regarded. I have used it, but only in demo mode- it lets you run a limited number of sessions, I think 40. It is probably the most capable of these, but a bit steep on the learning curve. I think if I were starting fresh today I might pick CAMBAM because of its more advanced capability.


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## stevehuckss396 (Nov 27, 2013)

RonGinger said:


> There is also CAMBAM which is highly regarded. I have used it, but only in demo mode- it lets you run a limited number of sessions, I think 40. It is probably the most capable of these, but a bit steep on the learning curve. I think if I were starting fresh today I might pick CAMBAM because of its more advanced capability.




I have to agree. I have been a bammer for a few years and it never fails to amaze me. If you can afford it Chuck, its the one to get. Also there are more than a few users on the board so there will be help when you try to get going.


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## cfellows (Nov 28, 2013)

The basic license for CamBam is $149.  That certainly sounds reasonable.  I plan to download it and give it a try when I get things a little further along.

 Chuck


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## stevehuckss396 (Nov 28, 2013)

When your ready Chuck post a message of something you plan to make and supply the DXF file with a dimensioned drawing. I can CAM the part and send you the CB file. All you will need to do is load the file in CB. That way you can see what the process is for doing it and you will have a good idea what to do when you get going on your own.


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## cfellows (Dec 4, 2013)

Had the creeping crud which kept me out of the shop for a few days.  Got back on it today.  After installing a plain ball bearing on the stepper motor end of the table, I started on the connectors and making up the electrical cables.






 I finished the cables.  One end has the DB9 connector for the Gecko controller and the other end will connect to the steppers.






 I used 1.25" x 1/8" aluminum angle to hold the connectors.  As you can see, the angle is attached to the motor with zip ties which are clamped down pretty tight.  Doesn't seem to be any movement.






 I still need to solder the motor wires to the back end of the connector sockets.

 Chuck


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## canadianhorsepower (Dec 4, 2013)

Chuck,
            If I can sugest one thing dont use the angle plate 
 use a regular 1/8 and mounted with the motor screws trying to eliminate as much noise
 "electronic noise" as possible.
 with your set up the magnetic feild could cause some problem

 cheers

 Luc


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## cfellows (Dec 4, 2013)

canadianhorsepower said:


> Chuck,
> If I can sugest one thing dont use the angle plate
> use a regular 1/8 and mounted with the motor screws trying to eliminate as much noise
> "electronic noise" as possible.
> ...



Interesting.  So attaching a flat plate to the back of the motor wouldn't be subjected to so much of the magnetic field from the motor windings?

 Chuck


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## stevehuckss396 (Dec 4, 2013)

What about taking a piece of wire from the angle to the motor to bond them together? Would that work?


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## canadianhorsepower (Dec 4, 2013)

Sure but a capacitor is always your best freind when you do this
 I usualy use a 220 micro. 
 someone would say its an over kill
 but I"m the type of guy that prefer to smell bug repelent then being 
 bite by one of them


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## cfellows (Dec 4, 2013)

So how does electronic noise show up?  What does it affect?  If I use a capacitor, what do I hook the two ends to?

 Chuck


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## canadianhorsepower (Dec 5, 2013)

Chuck    having long wires does make electromagnetic feild 
 and if you would put a scope on your line instead of have a nice 
 square wave you would have some ripples in it. CNC use TTL 
 voltage is o-.8 volts and 2 to vcc their should be no response in between
 by having some noise  in your circuit  you could send a LO signal under .8
 but your noise can bring it up to1 volt this would really destroy the accuraci 
 of your program 
 hope I explained it clearly
 cheers

 Luc


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## cfellows (Dec 5, 2013)

Thanks, Luc, would you recommend that I shorten the leads between the motor and the connector or is better to keep the wires longer and just loop them out as far from the motor as possible?

 Thx...
 Chuck


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## mu38&Bg# (Dec 5, 2013)

Wait, which TTL signal is being sent down the stepper phase wires or near them? Unless you are in fact running encoder or limit signal wires along with the stepper leads, there is little to consider. If the stepper leads aren't twisted and shielded there will be noise, so make sure any signal wires are twisted and shielded. In an industrial application the motor would have a connector built into the case and proper shielded grounded cables. Any noise from the steppers and leads would be fed into the stepper drive and it should be designed to handle it unless it's so bad voltage induced in the motor wires exceeds the voltage limit of the drive, and it's already designed to handle that. BTW, the motor iron should contain virtually all of the flux from it's coils. If it does not, it's junk. At full current, the most it should pick up is a paperclip.

It seems the regulated switching power supply is the easy answer. Add some (a lot) capacitance if it's not rated for such duty. I'm really surprised that 10 years down the road of homebuilt CNC the power supply question still comes up. If you want to cobble one together the linear supply is easy, but if you're buying anyway what's the difference?


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## canadianhorsepower (Dec 5, 2013)

Thanks, Luc, would you recommend that I shorten the leads between the motor and the connector

_Yes that is the best practice always try to keep any wires as short as possible.If you can put your power supply in the same box then your stepper motor controler is even better.Many people uses a computer case to do so, having many fans to keep the temperature down will make thing even better._

_Sheilding the wires is a must, twist the wires together "like a women would braids her air" and not the way man twisted wires. after that I usualy use spay glue all over the wire and rap them in foil paper previously cut in 2nch wide strip about a foot long then put a heat shrink and heated up  and do this for all the bables._
_It could sound like a long process YES but you will love that CNC for a LONG TIME_

_I would still use capacitors across the terminal of the stepper motor_

_Like I said before I prefer to smell bug repelent then being bit by one_

_But I was wright someone tryes to say I'm wrong, OMG some people need a big ego to live_

_enjoy your build_

_Cheers_
_Luc_


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## cfellows (Dec 5, 2013)

I revised the connector mounts.  Hopefully these will be a little stronger and will be less prone to induced noise.







 The motors are all wired now and the cables are finished.  Next I need to find a DB25 cable and two timing belts for the X/Y drives.






 I also revised the X-axis motor mount.  






 It now has a sliding adjustment with two 3/8" bolts to secure it.  Don't think that's going to slip on me...

 Chuck


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## cfellows (Dec 6, 2013)

Just a general questions for you folks who have some experience with CNC... How important are LIMIT switches?  Anybody running without them?

 Chuck


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## LSEW (Dec 6, 2013)

My limit switches saved me a few times, would NOT recommend skipping them unless you don't mind repairing your machine after a crash.

maury


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## stevehuckss396 (Dec 6, 2013)

cfellows said:


> Just a general questions for you folks who have some experience with CNC... How important are LIMIT switches?  Anybody running without them?
> 
> Chuck



Never installed limit switches. If you run the machine to its outer limit it will skip steps and make a horrible noise but wont hurt anything. If you break your machine from maxing out a motor then you need to re-examine the way you built the machine.


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## idahoan (Dec 6, 2013)

Hi Chuck

  Well here is my .02$ worth; I ran my knee mill for years without working limit switches. They worked originally when I did the conversion but over the years a couple of the wires broke and I just jumped them out.


  My old round Pacific Scientific steppers didnt have enough power or speed to do any damage if you hit the end of travel. Although it was a pain to be cutting a large part and run out of travel, stall the motor and have to shift the setup and start over.

  I converted my machine over to Mach3 about 3 years ago and replaced all the switches and repaired the wiring. At this point I wouldnt be without them. Within Mach you can enter your axis travels and also a safe distance to start slowing down. The first thing you do is home your machine then Mach knows the exact travel limits of your machine and shows you on the monitor; it will let you know if your job is going to fit within these limits before you ever start machining.

  Also because of the safe limit distance you define you can do a rapid jog in to a limit and the software will start slowing down the axis when it reaches the distance away from the switch that you set. I think I have mine set at 1. The last inch of travel the axis ramps to a crawl as it comes into the switch.

  I used decent quality switches, Omron snap action switch with a roller actuator; surprisingly these easily repeat within .001 or less. So if I have fixture offset stored (G54, G55, etc.) I can shut my machine off and when I restart it and home it; I can go right back to that offset without having to pick it up again. I have checked this with an edge finder many times and its usually dead on.

  In my opinion it is really worth the time now while you are in the build phase to fab up some mounts and get them working; you will be glad you did.


  Dave


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## RonGinger (Dec 6, 2013)

I dont have them on any of my machines. I do have Home switches on the lathe, but unless you use  some kind of permanent vise or fixture on the mill its hardly worth the effort to Home on a mill.

For a stepper driven machine like you are doing I dont think limit switches are worth the trouble. The motors simply dont have enough power to break anything. If you run to the limit you will just stall the motor. You have of course lost your position with or without switches.

A suggestion for setup so you dont run out of room. With the CAD system print out a full size drawing of the part you are about to make. Move that paper around the table top as a guide to where to mount your stock. This has saved me running off the end of the stock, or hitting a clamp many times.


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## cfellows (Dec 7, 2013)

Thanks for the input, guys.  I may add limit switches at some point, but for now I think I will forego them.

 After some more work today, I am 2 timing belts and a DB25 cable away from having this thing operational.






 That's not to say that I'm finished... still have a bunch of tidying up to do including keying the pulleys, making guards and covers, and doing some cable routing, not to mention a bunch of testing and, most likely, some debugging.  But with the two belts installed and a DB25 cable to hook it up to the computer, it would be capable of making parts.  I looked all over town yesterday for a DB25 cable, but none was to be found.  So, I wound up buying one on Ebay and will have to wait several days for it to arrive.

 Chuck


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## stevehuckss396 (Dec 7, 2013)

Hello Chuck!

That stepper behind the table worries me a little. When the table moves all the way back that stepper won't contact the column will it?


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## cfellows (Dec 7, 2013)

stevehuckss396 said:


> Hello Chuck!
> 
> That stepper behind the table worries me a little. When the table moves all the way back that stepper won't contact the column will it?


 
 It could hit the column if the if the table was all the way to the right.  Most of the time it won't be a problem and if it ever is, the motor mount can be swiveled up so the motor is over the table.  

 Chuck


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## cfellows (Dec 8, 2013)

Waiting on belts and cables, so I started making the keyways in the pulleys today.  I plan to use a Woodruff key on the shaft.






 I figured it was easiest to use my keyway broach to make the slot in the pulley.  Naturally, I didn't have a 17mm bushing so I had to make one.  You can see that I milled two slots in the bushing, one shallower than the other.  I first made a pass using the deeper slot, the a second pass with the shallower slot to make the keyway in the pulley deeper.  Still need to do the pulley on the Y-axis.  It's kind of nerve-racking pushing a broach through the pulley using my hydraulic press.  Gotta make sure everything is completely lined up to keep from snapping the broach.

 Chuck


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## Wizard69 (Dec 8, 2013)

cfellows said:


> Just a general questions for you folks who have some experience with CNC... How important are LIMIT switches?  Anybody running without them?  Chuck



As far as I'm concerned they are very important.  I've seen lathes snap off substantial castiron mounting lugs when a servo ran away.    You probably aren't working with system hardware that powerful but damage can happen or sneaky things like loosening a coupling can happen.


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## cfellows (Dec 9, 2013)

Still waiting for the belts and the DB25 cable, so today I finished up the keyways.  






 I cut a standard keyway instead of woodruff.  That gave me a lot longer key.  I used a 3/32" carbide end mill to cut the keyway in the shaft.  Easier than I thought it would be.  I made the key out of some .093" sheet steel I had on hand. 

 Hope the cable and belts get her tomorrow.  I'm anxious to get this thing working!

 Chuck


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## cfellows (Dec 13, 2013)

Just a quick update.  The DB25 cable was delivered a couple of days ago.  I got the motors, the Gecko controller, cables and the power supply all hooked up.  Loaded up Mach3 and got everything configured.  The steppers all respond and move correctly to the Mach3 commands.  Even loaded up the G-Code file to print my name and ran it.  Unfortunately, I still haven't received my X & Y timing belts (Aarrgghh!).  So, even though the motors spin, the table doesn't move... Wish I'd ordered the belts sooner.  Now that the conversion is virtually done, the waiting is killing me!
 Chuck


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## stevehuckss396 (Dec 13, 2013)

cfellows said:


> Just a quick update.  The DB25 cable was delivered a couple of days ago.  I got the motors, the Gecko controller, cables and the power supply all hooked up.  Loaded up Mach3 and got everything configured.  The steppers all respond and move correctly to the Mach3 commands.  Even loaded up the G-Code file to print my name and ran it.  Unfortunately, I still haven't received my X & Y timing belts (Aarrgghh!).  So, even though the motors spin, the table doesn't move... Wish I'd ordered the belts sooner.  Now that the conversion is virtually done, the waiting is killing me!
> Chuck



Chuck! thats great to hear.

Quick note: when you get the belts on remember that the arrow keys on the keyboard are which way the tool is supposed to move, not the table. That means when you hit the left arrow the table should move right. When you hit the arrow to move toward you, the table should move away from you. When you arrow left and the table moves right its the same as the tool moving left.


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## cfellows (Dec 13, 2013)

stevehuckss396 said:


> Chuck! thats great to hear.
> 
> Quick note: when you get the belts on remember that the arrow keys on the keyboard are which way the tool is supposed to move, not the table. That means when you hit the left arrow the table should move right. When you hit the arrow to move toward you, the table should move away from you. When you arrow left and the table moves right its the same as the tool moving left.



Thanks, Steve, I had to double check, but turns out I did have it right.  I can tell from the direction the motors are turning which way the table will move.

Chuck


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## cfellows (Dec 17, 2013)

Got the belts today.  Here's a picture of the first job...







 Video is still uploading to Youtube... will post the link later.

 Chuck


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## kuhncw (Dec 17, 2013)

Chuck, that looks great.  You are going to love this thing. 

Regards,


Chuck Kuhn


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## cfellows (Dec 17, 2013)

Thanks, Chuck, here's the video...

 [ame]http://www.youtube.com/watch?v=mcI9PjygQRY[/ame]

 Chuck


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## barnesrickw (Dec 17, 2013)

That is very smooth.  Very nice work once again.


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## stevehuckss396 (Dec 17, 2013)

How freakin cool is that!

Do my name now!!


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## cfellows (Dec 18, 2013)

Thanks, Steve, Rick.  I think I ruined the only felt tip pen I have!

So, I want to do some profile cutting in 1/4" aluminum plate (I'm guessing it's 6061) using a 1/8" Kyocera, 2 flute solid carbide bit.  My milling spindle will only do about 2500 RPM.  How fast should I feed the work and what depth of cut would be best?  I've currently the feed rate set at 12 inches per minute.  I've looked at several web pages and they start talking about surface feet per minute, inches per tooth, and other terms that I just don't understand.

Chuck


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## barnesrickw (Dec 18, 2013)

Feed rate stuff? I only remember some of it from running CNC 13(?) years ago.  I'll bet you have a good enough feel and ear for it from all the milling you have done.  I only did it in one material so I only had to change RPM and FPM based on cutter diameter.


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## LSEW (Dec 18, 2013)

Chuck, the aluminum profiling I have done was with a 2 flute carbide bit at 1800 rpm. At the time that was the max spindle rpm. I cut .008 deep at about 1/3 the tool width. The problem you are going to run into is the tool will try to gum up(I assume you aren't running a coolant).  Stand by with a can of WD-40. 

With Mach it's difficult to stop and start again, but if your tool gums up you will probably break it. The low RPM helps to keep the tool clean because of less heat generation.

maury


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## cfellows (Dec 18, 2013)

LSEW said:


> Chuck, the aluminum profiling I have done was with a 2 flute carbide bit at 1800 rpm. At the time that was the max spindle rpm. I cut .008 deep at about 1/3 the tool width. The problem you are going to run into is the tool will try to gum up(I assume you aren't running a coolant).  Stand by with a can of WD-40.
> 
> With Mach it's difficult to stop and start again, but if your tool gums up you will probably break it. The low RPM helps to keep the tool clean because of less heat generation.
> 
> maury



Thanks, Maury.  I have plenty of time to make my parts, so speed isn't an issue.  I'm mostly interested a good finish and keeping the cutter sharp and clean.  If low RPM's and feed rates, do the trick, I'm all for it!

Chuck


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## canadianhorsepower (Dec 18, 2013)

Hi Chuck nice job
 tou might find these usefull
http://en.wikipedia.org/wiki/Speeds_and_feeds#Formula_to_determine_feed_rate

http://its.foxvalleytech.com/machshop3/speedcalc/feedratecalc.htm

 as for the cooler I really sugest AL9 a real aluminium cooler and it smells good
 if ever you do manage to get some aluminium to stick to your mill, not a big issue
 go to any hardware store by some muriatic acid "cement cleaner" and put your mill in it
 it will get of of htere like brand new
 be carefull with the handling it's verry corosive


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## stevehuckss396 (Dec 18, 2013)

cfellows said:


> Thanks, Steve, Rick.  I think I ruined the only felt tip pen I have!
> 
> So, I want to do some profile cutting in 1/4" aluminum plate (I'm guessing it's 6061) using a 1/8" Kyocera, 2 flute solid carbide bit.  My milling spindle will only do about 2500 RPM.  How fast should I feed the work and what depth of cut would be best?  I've currently the feed rate set at 12 inches per minute.  I've looked at several web pages and they start talking about surface feet per minute, inches per tooth, and other terms that I just don't understand.
> 
> Chuck



Aluminum I cut .025 deep steps at 30IPM with WD40.


Chuck!  Have you calibrated the screws yet. By that I mean set an indicator against the table and have Mach move the table say .050 and see if it really moves .050. I have an indicator with a 2 inch stroke so I check mine over one inch.


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## RonGinger (Dec 18, 2013)

Feedrate does matter on CNC, its not like on a manual machine where you can just crank a little faster or slower. But its pretty simple.

All materials and tool combinations have a best value for Surface Feed Per minute. For steel and normal HSS tools its about 75 to 100. For Aluminumits more like 250-300. Carbide tools can double those values. SFM is simply the 'rim speed' of the tool- Higher RPM makes it go up, larger diameter tool makes it go slower. All you need is material and tool dia and you can find SFM.

Chip Load is how big a chip you want each tooth to take, numbers like .001 are Ok on 1/4" or bigger tools, as small ass .0001 is not unreasonable for tiny cutters. Just multiply your SFm by the chip load. Obviously  Moving a tiny cutter through material at several inches per minute will quickly break the tool, and running to slow will just cause your chips to roll around and around in the cut, scoring the finish and dulling the tool. When its right teh chips just flow off teh work and the surface finish is great

Both calculations are simple math, and there are lots of tables and calculators around. The Mach wizards have several calculators.

It matters if you want decent, clean cuts.


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## diyengineer (Mar 9, 2014)

Looks good! 
 I have a cncmasters rf31 conversion and when I saw your brass ballnut holder for the short axis I laughed. I have the same one holding my ballscrew, what a pain it was to remove! The oem jb welded it in for a more solid connection since only one bolt holds it. They should have had it held by 2 pins and a single bolt so when you torque it, it doesn't twist. Looks good though. I bought a quill dro for mine, yet to put it on.


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## jerrylk (Jul 4, 2014)

Chuck I have an Enco mill drill, I think it's very similar to yours. Can you tell me who has a conversion kit available. Did you change over to Ballscrews? I currently have a Zentools 3axis machine running with Mach without a spindle and would like to convert the Enco. Any input would be appreciated.  Thanks.   JerryKnox 


Sent from my iPad using Model Engines


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## cfellows (Jul 4, 2014)

jerrylk said:


> Chuck I have an Enco mill drill, I think it's very similar to yours. Can you tell me who has a conversion kit available. Did you change over to Ballscrews? I currently have a Zentools 3axis machine running with Mach without a spindle and would like to convert the Enco. Any input would be appreciated. Thanks. JerryKnox
> Sent from my iPad using Model Engines


 
 Hi Jerry,

 I did convert over to SFU1605 ballscrews and nuts.  The ballscrews were unmachined and I had to turn down a 1/2" length on each end to 1/2" diameter so I could attached machined steel extension shafts to each end.  I custom made the ballnut attachment fixture for each axis.  The steppers I used were Nema23, 425 Oz In.  The motors drive the ball screws through XL timing belts with a 1:3 gear reduction.  For the stepper controller, I used a Gecko G540 4 axis controller.

 Chuck


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## jerrylk (Jul 5, 2014)

Thanks Chuck for the quick reply, do you have any info as far as measurments and suppliers? I also have the Gecko 540 and it works well. Are the Rong Fu and Enco the same machines, just different suppliers? I had a job in Springfield Mo. once and did go through the Grizzly Store, Quite the (Toy Store) I live near Chicago and they use to have an Enco outlet here. I bought the MillDrill from a private party. Im pretty new to this website so I have even more to learn.I keep seeing the not so Happy Face keep banging his head against the brick wall ( I can relate ) Great NAMES show this year, Talked to Dale Dietrich and got his plans for the T fitting engine, and Gbritnell had plans for a beautiful V-Twin. I heard this is a desease called Iron Defeciency.  Thanks again and any inof great help     Jerry


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## mnay (Nov 18, 2014)

Chuck,
I have enjoyed your post on the mill conversion and your many other build posts and projects.  I have been contemplating converting my knee mill to cnc.  Like you I am not worried about high speed cutting and can always upgrade to bigger motors someday.  Did you have a particular plan you followed or web site that was most helpful?  I have been browsing and studying for a couple of weeks, there is a lot of info out there, but I haven't found anything like a simple block diagram to follow.  Any advice from someone who has been there done that?
Looks like your conversion was a great success.
Thanks for your time and for all of the posts that we have to learn from.
Mike Nay


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## cfellows (Nov 19, 2014)

mnay said:


> Chuck,
> I have enjoyed your post on the mill conversion and your many other build posts and projects.  I have been contemplating converting my knee mill to cnc.  Like you I am not worried about high speed cutting and can always upgrade to bigger motors someday.  Did you have a particular plan you followed or web site that was most helpful?  I have been browsing and studying for a couple of weeks, there is a lot of info out there, but I haven't found anything like a simple block diagram to follow.  Any advice from someone who has been there done that?
> Looks like your conversion was a great success.
> Thanks for your time and for all of the posts that we have to learn from.
> Mike Nay



Thanks for the compliments, Mike, much appreciated.  Like you, I did visit a number of websites prior to and during my conversion.  None stand out in my memory as being a one-stop-goto reference although Bob Warfield's website, www.cnccookbook.com has a lot of good information.  I also started a build thread on CNC zone and got some good feedback there.  Unfortunately, there are a lot of different views out there and it can be difficult to sort out the good information and determine what will be required for your own application.  

One of my overriding concerns was not to make any modifications to the mill that couldn't be reversed.  I wanted to be able to easily convert it back to its original, manual operation later if needed.  

It turns out that the Nema 23, 425 oz in, 3 amp stepper motors were more than adequate for my conversion.   They have a pretty high inductance, so won't run as fast as some others, but have plenty of torque.  I originally used a 20 tooth timing pulley on the X and Y motors and 60 tooth pulleys on the lead screws but just recently I changed over to 40 tooth pulleys giving me a 1 to 2 ratio.  This speeded things up by 50 percent and I still seem to have plenty of torque.  

The ball screws I bought were SFU1605 from China.  I bought them with unfinished ends to save on cost.  Although they are hardened, I was able to machine them in my Logan 11" lathe using (sharp) carbide inserts.  Installing the ball screws is the most tedious part.  You have to make sure that the ball nut is in perfect alignment with end bearings so they turn freely and there is no binding or bending of the leadscrew.  I had to depend on some shimming, using trial and error, to get things in alignment.  And, of course, you have to eliminate any end play in the lead screw.  I replaced the thrust bearings with angular contact bearings although I'm not sure that was really necessary.

So far I've been very pleased with my results.  It's very accurate and, even though I'm extremely conservative on cutting speeds and depths, it's fast enough for me.  

If you're like me, you probably are focused on the mechanical aspect of the conversion and haven't thought much about the electronics or software considerations.  Those items will wind up costing a lot more than the steppers, ball screws and other mechanical parts.  For starters, I decided to use the Gecko G540 stepper controller.  At $260 (on ebay) it's pretty expensive but it was well worth it.  It's very robust, easy to configure, and seems to be relatively bullet proof.  My 24 volt, DC power supply was under $40, but if you decide to go with 48 volts or higher, the cost will be over $100 unless you are a better shopper than I am.  And, of course, you'll need a desktop computer with a parallel port if you plan to use Mach 3.  I bought a used one for about $75.

That brings us to the software.  You mostly need three pieces of software, CAD, CAM, and the G-Code translator and, the biggest problem is, they have talk to each other.  That basically means the CAD program has to be able to create a file format that the CAM program can read.  And the CAM program must create a G-Code file that the translator can read.  And, while there are standards, there are many standards, particularly if you get into full 3D, contour type CNC.  I haven't ventured into the murky waters of full 3D and probably won't.

Starting at the end, I bought a Mach3 license for about $160 and have been eminently pleased with it.  I still haven't learned all the ins and outs, but it was pretty easy to get up and running.  You'll also need a CAD program to do your drawings.  I use Visio for all of my 2D drawing and, since it will create DXF files, it works fine for me.  That brings us to the CAM software, which is a real bucket of worms.  It's by far the most complex part of the CNC equation and potentially the most expensive.  I couldn't find any free CAM software that was satisfactory so I settled for CAMBAM.  This was $149 and seems to be popular in the hobbyist community.  You can download a fully functional copy of it to play with and it's free for the first 40 sessions.  It's pretty intuitive and quick to learn the basics, especially for 2.5D CNC.  2.5D CNC means you can do 3D machining, but only 1, two-dimensional surface at a time, although you can string them together end to end as long as they are in the correct order.  CamBam will do 3D contouring using 3D printer input files (STL), but will not handle full on 3D CAD files such as IGES or other, more complex 3D file formats.  

This may be information you already have but thought it might be interest.

Chuck


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## mnay (Nov 19, 2014)

Chuck,
Thanks for taking the time for such a detailed response.  It was very helpful and I believe I have about figured out what to do.  What started this is a friend gave me a couple of stepper motors and drivers and I have always been interested in cnc at home for my hobby projects.  My used mill came with ball screws already installed so I have a little bit of a place to begin. Now to convince my wife to let me spend the money.  I will probably just buy a piece at a time and work at it.
Also I want to be able to loosen the belts and back the cnc away and use manual if I need to.  I liked the brackets you made for your steppers.  I will do something like that. 
Thanks again,
Mike


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## cfellows (Nov 19, 2014)

Mike, I forgot to mention that Home Shop Machinist magazine featured a multi-part article on converting a mill / drill to CNC.  I had found it to be interesting and helpful even though it was published starting in May 1990.  Hardware hasn't really changed much since then although it has gotten cheaper, thanks to the Chinese!

 I would definitely encourage you to move forward on the conversion.  You'll be sooooo glad you did.  It's really fun and interesting to see what you can do.

 If you've already got your ball screws installed and stepper motors on hand, you've got a real good start.  From a budgetary standpoint, this Stepper Controller is a lot cheaper than the Gecko G540:

http://www.ebay.com/itm/221464800449?_trksid=p2059210.m2749.l2649&ssPageName=STRK:MEBIDX:IT

 I'm starting a CNC Router Build and bought this controller to use with it.  I've read mixed reviews on it, but at that price, I figured I'd give it a try.  For the software, you can download a free version of Mach 3 and use it indefinitely as long as your g-code file doesn't exceed 500 lines.  It also has some built in wizards that let you cut profiles, pockets and drill holes without the need for CAD or CAM software.  And, if you can write your own g-code, you can do some pretty neat things in a lot less than 500 lines of code.  All this will let you get started with your CNC machine and buy or upgrade the software later.  

 Chuck


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## mnay (Nov 20, 2014)

Chuck,
Thanks again for your time.  I will keep you posted on my progress and may have a few more questions along the way.
Mike


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## mnay (Nov 25, 2014)

Chuck,
I looked like you made your own timing gears/sprockets.  Is there a certain type of belt that I need to use?  Sources?
Thanks again, Mike


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## mnay (Dec 17, 2014)

I have done some more research on my own and found several sources for belts and pulleys.  They are quite expensive. I  can see why you would machine your own.  I may buy one for a sample and do the same.
I have purchased a breakout board and am building a power supply for the steppers.  I will post some pictures when I have something to show.
Mike


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## RonGinger (Dec 17, 2014)

Give serious thought to using a direct shaft connect, no belts or pulleys. Look at a modern machine, like a Tormach and you will see that is what they did. Before the modern hi torque steppers pulleys were needed to get some torque boost, that is not the case now, particularly on a small machine. The only reason for using belts is when you need to get the motor into a position to keep it out of the way. 

I would also stay away form those ebay driver boards, they are really poor drivers. When you are spending several hundred dollars on a project you will soon forget you saved a few bucks on a driver when you get less than the best performance.


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## cfellows (Dec 18, 2014)

Mike, sorry, I hadn't visited this thread for a while and didn't see your question regarding the pulleys.  The pulleys and belts are the XL series which are 0.2" pitch.  I've bought pulleys and belts on EBay when I could find them at a reasonable price and I've made them.  The cutter is made froma 2" x 3/32" thick slitting saw.  







If you do a Google search on XL timing pulley dimensions, you'll find lots of diagrams showing the tooth profiles, depth, and pitch diameter.  I made this cutter a number of years ago and as I recall, I just mounted the cutter in the lathe and used a tool post grinder to bevel the sides of the teeth with the cutter spinning.  There is no side rake or clearance on the teeth, which is not ideal, but it works OK for cutting aluminum pulleys.  A suitable fly cutter with proper rake and clearances could be made quite easily and would also be fine for cutting aluminum.  Belts are sometimes available in the right size from Ebay or you can get them from Mcmaster and Grainger.  Stock Drive Products also has about any size you need, but their shipping costs tend to be prohibitive.

Ron, I used pulleys and belts on my machine because I didn't want the motors, which are pretty long, sticking out so far from the machine, particularly in my rather cramped workshop.  I also felt like I needed the extra torque of gearing them down since my Nema 23 steppers may not be quite beefy enough for direct drive.  It also makes it easier to use the machine manually by just removing the belts.  Nema 34 would have been more suitable, but the jump in cost is considerable, not just for the motors, but the larger power supplies and stepper controllers needed for the higher amps.

Chuck


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## mnay (Dec 18, 2014)

Chuck,
No need to apologize, I realize people are taking their time to answer lots of questions from me, but it is appreciated.  Thanks for your advice and the many threads we learn from. I will let you know once I make some progress worth reporting.  Still in the parts collecting, learning stage.

Ron, 
Thank you for you input.  I agree with you completely that to have a quality system I will need to spend the money.  I am having to experiment on the cheap for now, because of budget.  What started me down this road is that a friend upgraded his Tormach mill and gave the the old style steppers and some micro step drivers.  I believe they are probably powerful enough to direct couple and I believe I have figured out how to do that and still use my machine manually.  I am putting these on a bridgeport size mill that I pieced together over the years and it also happens to already have ball screws installed.  I my bother you folks with more questions as I go.  I am building a 48v power supply right now.  

Mike


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## Swifty (Dec 19, 2014)

I don't know much about conversion to CNC, but I assume that most motors have minimum step of 1.8deg, which on a .200" per rev leadscrew is .001" per step. If you gear it down, say at 2:1 ratio, won't this allow a movement of .0005" per step, as well as help with more torque? I've been thinking about making a CNC mill, just seem to prefer direct drive.

Paul.


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## blighty (Dec 20, 2014)

Swifty said:


> I don't know much about conversion to CNC, but I assume that most motors have minimum step of 1.8deg, which on a .200" per rev leadscrew is .001" per step. If you gear it down, say at 2:1 ratio, won't this allow a movement of .0005" per step, as well as help with more torque? I've been thinking about making a CNC mill, just seem to prefer direct drive.
> 
> Paul.



all correct. but there are pros and cons to all.... i wouldn't go with belts on a stepper but i would for a servo. i wouldn't gear down a stepper but i would a servo and so on.

 if you do gear down a stepper say 2:1 you would be right in saying you would double your torque and half your resolution, but you will also half your rapid speed. to get your resolution back..... most if not all drives have micro stepping, so the drive will split 1 step of a stepper (1.8deg) into 10 for e.g. now you have a stepper doing 2000 steps per rev or 0.18deg per step. this in turn opens up another can of worms over torque issues.

 using belts is another place where backlash can creep in. if you do need to gear down to get more torque, put bigger steppers on it. then the cost will go up, but will the cost of a bigger stepper out way the cost of pulleys, belts, mounts and time and effort in making it all.

there are lots of options all depending in what YOU want out of YOUR cnc mill. you just need to find what you need to fit your requirements...... then add 30% to it.


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## Swifty (Dec 20, 2014)

I can understand the problem with backlash, the more bits, belts and joins you have could be a problem. I'm still in the process of trying to understand all the controls needed, drivers etc and how they work.

Paul.


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## cfellows (Dec 21, 2014)

I just upgraded from 24v DC to 48v DC.  It's improved my rapid speed to a reliable 30 in sec.  I don't think it should have any affect on holding torque or cutting speeds, the latter being more a matter of material and depth of cut.

I don't think the timing belts on my machine introduce much if any backlash.  My mill has about .003" backlash on each axis and some, if not all of that may be the ball screws.


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## blighty (Dec 22, 2014)

30 inch a sec ????? you sure about that

 good with the volt change. when i did mine the norm was to take the rated volts of the stepper and times it by 20 to 25 and that was it.

3tho backlash not bad for a home build. i have a bit of backlash in mine, seems to be coming from the fixed end bearings. not much point in getting rid of it as the deflection in the column is more than the backlash.


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## cfellows (Dec 22, 2014)

blighty said:


> 30 inch a sec ????? you sure about that



Guess I meant 30" a minute!


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## Pertsa (Mar 6, 2015)

Hello!
Here is my version of rong fu 30 cnc. Z-axis is made also with ballscrew. I have solidworks 3d files of z-axis, if somebody wants them, I can upload these to download area.


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## barnesrickw (Mar 6, 2015)

If you had meant 30"/sec, I would have said you're Rong Fu.  &#128515;


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## Len-Tikular (May 7, 2015)

Pertsa said:


> Hello!
> Here is my version of rong fu 30 cnc. Z-axis is made also with ballscrew. I have solidworks 3d files of z-axis, if somebody wants them, I can upload these to download area.


 
Can anyone enlighten me on how the Ballscrew is held and driven. I just can't make it out, ? 
Maybe Pertsa you can post or send the drawings as you have suggested. I would be very grateful.
Chuck, I,m sorry to stomp all over your article,maybe my post can be moved ?
You did a great job of your conversion and thanks again for your help. I think I'm in favour of the Z axis under  ballscrew control.
Regards
George


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## cfellows (May 13, 2015)

Len-Tikular said:


> Can anyone enlighten me on how the Ballscrew is held and driven. I just can't make it out, ?
> Maybe Pertsa you can post or send the drawings as you have suggested. I would be very grateful.
> Chuck, I,m sorry to stomp all over your article,maybe my post can be moved ?
> You did a great job of your conversion and thanks again for your help. I think I'm in favour of the Z axis under  ballscrew control.
> ...



George, there is no problem  with other people posting related topics in this thread.  More information and questions are always welcome.

First, on the Z-Axis, I too felt that a ball driven Z-Axis would be better and most other folks have the same opinion.  However,  Using the existing Z-Axis feed was so much simpler to install and, so far, at least, it has worked flawlessly, even in when cutting harder materials like steel.  The weight of the spindle assembly is substantial, probably 15 pounds or more, and I've never had a cutter bounce or lift, even with pretty aggressive cuts.

The ball screws I bought from China had no finished ends.   I turned the ends down to half inch diameter shoulder  with a carbide cutting tool.  The ballscrew is hardened, but carbide will cut it with slow feeds.  You can also use a toolpost grinder to take it to final fit and finish if necessary... I didn't.

I then made a 17mm round shank to fit inside the existing X and Y table end bearings.  Each shank had socket with a grub screw to fasten on to the ends of the ballscrew.  The socket end of the shank has a larger outside diameter to accommodate the socket.

If you are attaching the motor directly to the ball screw, you can buy shaft couplers that will connect two different diameters.  These usually are 3 pieces with a rubber center so they will tolerate slight misalignment.

Hope this helps and don't hesitate to fire off more questions...

Chuck


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## Len-Tikular (May 13, 2015)

Thanks Chuck,
I value your input.
My reason to go to the Ballscrew Z axis is that I have lost major steps with the arrangement like yours. I broke a couple of cutters and that was on aluminium where the axis lost it's place and drove down through the material!!!! My set cut depth was only .25mm at the time and the tool plunged down about 6 - 8mm deep. I'm not sure if my accel values are correct with regard to the tool retracting. That's when I can here the stepper make a zip sound. I don't think my belt is slipping???
Is there anything more that I can tell you to help you help me what is going wrong ???

Regards

George:wall:


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## cfellows (May 13, 2015)

Len-Tikular said:


> Thanks Chuck,
> I value your input.
> My reason to go to the Ballscrew Z axis is that I have lost major steps with the arrangement like yours. I broke a couple of cutters and that was on aluminium where the axis lost it's place and drove down through the material!!!! My set cut depth was only .25mm at the time and the tool plunged down about 6 - 8mm deep. I'm not sure if my accel values are correct with regard to the tool retracting. That's when I can here the stepper make a zip sound. I don't think my belt is slipping???
> Is there anything more that I can tell you to help you help me what is going wrong ???
> ...



A couple of things come to mind, and please pardon me if I'm stating the obvious.  Just trying to cover all the bases.

First, of course, would be to check if the downfeed clamp is loosened.  I know, it sounds silly, but I frequently tighten my clamp to make the spindle assembly more rigid during level cutting then forget to loosen it when the Z-axis needs to move. :wall:

The second would be the speed setting on the rapid movement of the Z-axis.  If you are using Mach3, you can set the maximum rate of speed in the config/motor tuning menu option.  I have 425oz in nema 23 steppers with an inductance of 24 milli-henrys so, while they have a lot of low end torque, they won't spin very fast.  The gearing on my Z-Axis is such that it takes 48000 steps per inch of travel.  It seems to run consistently in both directions without skipping steps at about 15 inches per minute but I have it set to 10 with acceleration set to 1 in per sec per sec.  I keep it set really low since Z-Axis speed isn't really important to me.

I don't know how familiar you are with Mach3, but you can hold down the shift key while you press FN and Down Arrow or Up Arrow to do a rapid movement of the Z-Axis.  I set my speed by setting the speed at about 50 inches per minute and run the Z-Axis up and down several times using the computer keyboard.  If it skips steps, I drop the speed down another 5 in per minute and try again.  I repeat this until it moves smoothly without ever skipping.  Then I usually drop it down a few steps until I get the best sound from the stepper.

Hope this helps.

Chuck


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## Len-Tikular (May 13, 2015)

cfellows said:


> A couple of things come to mind, and please pardon me if I'm stating the obvious.  Just trying to cover all the bases.
> 
> First, of course, would be to check if the downfeed clamp is loosened.  I know, it sounds silly, but I frequently tighten my clamp to make the spindle assembly more rigid during level cutting then forget to loosen it when the Z-axis needs to move. :wall:
> 
> ...



Thanks Chuck,
Yep, I'm using Mach3
My steps per are set to 1910 (after tuning) that's very strange as that is no where near the 48,000 that you have set on yours. I copied your setup with a 15 Tooth Pulley and a 36 Tooth Pulley. 2.4:1 I also confirmed that it takes 10 turns of the crank for 1" movement on the quill.
I use Mach 3 with Micro-stepping drives. The drives are set for 2000 steps/revolution and is also set for 10 micro-steps per full step.
My velocity was set rather high at 600mm/minute so I'll bring that down a good deal.
So I'm a little confused with your 48,000 steps/per. Hmmmm
The drives I am using are MSD542 from Motion control products.
What did I do wrong ?
George


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## cfellows (May 14, 2015)

If you have Mach3 set up to use millimeters, then 1910 steps per mm is about right.  I have mine  set up in inches, so it takes 48000 steps to go an inch.

48,000 / 25.4 = 1890

600mm per minute is too high.  That's about 23in per minute and mine won't run that fast.  I think dropping your velocity down to around 300mm per minute would fix your issue.  

Sounds like your driver is working OK.  What do you have your current limited to?  Also the voltage on your power supply?

Chuck


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## Len-Tikular (May 14, 2015)

cfellows said:


> If you have Mach3 set up to use millimeters, then 1910 steps per mm is about right.  I have mine  set up in inches, so it takes 48000 steps to go an inch.
> 
> 48,000 / 25.4 = 1890
> 
> ...


Ok, that explains the steps/per nicely, thanks Chuck. Peak current is set to 4.2Amps. I am using a 48v 7.3 Amp Switched mode Power supply into 3 M60TH100-400s  4Nm Steppers, rated at 2.8v per phase at 4 amps. 3Mh.
I'll drop the velocity down to 200-300mm/min and see if that does the trick.
Many thanks
George


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## Len-Tikular (Jun 2, 2015)

That did the trick Chuck.
I bought some nice new 2 flute hi-helix cutters.
I managed to pocket a 52mm Dia hole 15mm deep at 400mm(15 inches) per minute at 1mm pass depth with no issues at all. I used parafin misting as a coolant.
Thanks for your help.
George


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## twobobbwana (Jun 5, 2016)

Chuck,

Given the benefit of hindsight, when converting your RF30, would you still go with the Nema 23 425oz, 48v DC, 3 to 1 geared combination ???

I'm converting a RF30 and am following your thread intently.


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## cfellows (Jun 6, 2016)

twobobbwana said:


> Chuck,
> 
> Given the benefit of hindsight, when converting your RF30, would you still go with the Nema 23 425oz, 48v DC, 3 to 1 geared combination ???
> 
> I'm converting a RF30 and am following your thread intently.



I did change the gearing to 2:1 which gives me more speed.  I can get up to about 16" per minute fast travel but I rarely run it at more than 4 inches per minute when cutting since I'm usually using 1/4" or smaller end mills.  I'm happy with the setup and wouldn't change anything else.  I sometimes wish I had a higher spindle speed, maybe 5000rpm, but I think the spindle bearings would overheat.  They already get pretty warm at 2500rpm.

Chuck


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## aussieatlarge (Apr 27, 2021)

Chuck. Just got started on my conversion. A few questions if you don't mind
I see that you used the existing mill end plates. I have opted to use BK12 and BF12 bearing blocks. Since you used the stock locations, do you recall what the measurement is between the mounting face and centre of the leadscrew for the x and y axis?
You ended up with a 2:1 gear ratio. Is it better to achieve the same torque with gears than with a higher torque stepper?


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## gbritnell (Apr 28, 2021)

Aussieatlarge
I'm sorry to tell you that Chuck is no longer with us.


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## aussieatlarge (Apr 29, 2021)

Sorry to hear. Thank you. for letting me know.


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