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Converting a Clausing Mill and Lathe, have a couple Q's
« on: April 27, 2011, 11:22:30 PM »
Hi there new to the board.  

I am planning to CNC a Clausing 8520 mini-mill along with a Clausing 11" lathe (Harrison M250) and have a couple questions.  

For the mill I have decided to use a Gecko G540 since they are just up the road form me and figured it would get me started and easily acquainted, well that and I'm feeling a bit lazy and don't want to have to do any extra wiring.  I am not looking for any fast rapids etc. so the plan is to run Nema 23 steppers geared down.  From what I have read the Gecko will handle my 4-axis as well as my spindle VFD, but lacks any decent amount of I/O's.  

I want to add at least 1 MPG along with the accompanying axis and multiplier selectors, and then of course there are the cycle stop, e-stop, run, hold, etc. switches.  I plan to maintain manual ability on the mill for sure, and use encoder feedback for DRO.  Therefore I obviously need an additional BOB, the ones I have been looking at are the SmoothStepper and the Sound Logic (roger machine) encoder boards.  So my questions are the following.

1) What are the strong points, weakness's of either of these, and can they both equally accomplish the necessary I/O's?  

2) Is it possible with either of these to fully control either Gecko or DMM servo drivers (if I choose in the future) and/or send pulse-train to other AC servo drivers?  

3) Can either of these boards do tool offset positioning and/or edge limit/homing using the encoder with a proper plugin in Mach??  

4) My mill has the original screws and they have ~.006" of lash, do either of these handle backlash compensation, or does Mach do this? Or should I replace the screws?

5) If neither of these can perform all my requests, is there another board that can?

6) Which are the best affordable through-shaft encoders that will interface well with either board for position feedback?

I have ordered the G540, steppers, and purchased a Mach license, now I just need to figure the BOB and encoder situation plus any other bits that I need to make a complete and proper system.  If neither of these bob's with encoders can perform limiting, which are the best switches to use, proximity, or mechanical?  

Other than that I am open to suggestion, any advice regarding things I should avoid, or try to implement, or if anybody has CNC'd one of these machines already and want to share their thoughts it would be greatly appreciated.  Lastly, is it at all possible to save to 2 instances of Mach one for mill and one for lathe, which would allow the use of a single computer, HMI interface, and bob to control 2 machines (each having their own drives and encoders) by swapping the DB25 input from one set to the other.  These are just home shop machines right next to each other, so I was thinking I could make one really nice setup (touchscreen, MPG's, AB switches and buttons) that could control both machines?? 

Thank you for any and all help.

« Last Edit: April 27, 2011, 11:28:46 PM by Biermann »
Re: Converting a Clausing Mill and Lathe, have a couple Q's
« Reply #1 on: April 28, 2011, 04:41:22 AM »
Hi Beirmann,

I would drop the manual/dro option. The MPG and jog buttons will  make the Manual mode unnecessary.
I see manual mode as a lot of work for little gain.

I have the G251 drives which are the drivers inside the G540 and really like them.

1. The G540 has an integrated BOB. The smooth stepper is a motion control board which requires a bob after it.

 You can go directly from the Smoothstepper to the G540 for the port 1 stuff and then get a second Bob for the port 2 I/O.
The Smoothstepper also  has port 3 for more I/O

2. You can control any step and direction driver.

3. Probing is done with one input and works from the P-port or the Smoothstepper. MSM has some nice probing routines or you can search for Himmykabibbles post on his probing macros Which is what I use on my machines.

4. Replace the screws. Backlash comp is not a replacement for worn out screws

6. If you must have the encoders go with the AMT-102 capacitive encoders. I really like them.

Consider a device like a PoKeys55 to run most of the I/O for the control panel. 55 I/Os will allow you to run a lot of buttons and such. It allows 1 cable from the control panel to the computer.


Mach  allows you to save multiple profiles so it is easy to set it up for more than 1 machine. I would suggest that you plan on two contolr setup in the future because there will be a time when you will want to run both machines. The second computer can also be backup for the 1st computer.

It is early here so I hope this all makes sense. Time to put the coffee on.


We never have the time or money to do it right the first time, but we somehow manage to do it twice and then spend the money to get it right.
Re: Converting a Clausing Mill and Lathe, have a couple Q's
« Reply #2 on: April 28, 2011, 02:31:27 PM »

Thank you for taking the time to answer my question point for point.  A few follow-up questions for you or anybody else that wants to answer or give suggestions:

1) Does the SmoothStepper have a encoder feedback plugin (for quasi closed loop) like the Sound Logic board?

2) Which BOB would you recommend?  The PMDX 126 looks really nice, but by time I purchase a SS and the BOB/PoKeys I am well into PLC price territory.  However pre-programmed plugins seem like a nice option vs. programming ladder and modbus.

3) One plus side I see is the SS can potentially run off a mITX PC since it is USB potentially saving money.  Is there a known unit that many people are using w/o issue?

4) If I drop the encoders for table positioning, can you suggest some robust switches and proximity sensors, and how many are needed each for table limits, homing, and tool-setting.

5) Regarding the AMT encoders, the only difference between the 102 and the 103 is just the angle of the socket pins?  Anybody sell a specific cable that fits the pin-outs?

6) Any special components I need for probing so I can get them ordered as well?

Thanks again.
« Last Edit: April 28, 2011, 02:33:51 PM by Biermann »
Re: Converting a Clausing Mill and Lathe, have a couple Q's
« Reply #3 on: April 28, 2011, 04:17:29 PM »
Hi Biermann,
Glad to help since I have the time and have been down the same road.

1. Not sure but I don't think so. Properly tuned you should never need Quasi closed loop.

2. I have a CandCnc board that works fine but they have upgraded to the U-bob and I have not needed another BOB.
I have used the C11G on a friends machine and it is working without any problems.

3. Search the Mach3 forums to see what people are using. I just picked up 3 good computers this week from the side of the road, that is how I save on computers to run CNC.

4. I am running the switches that came with my BTC Bridgeport. A friend gave me the ones that I using for my router. Hopefully some else has a few good suggestions.

5. Correct. I think that Digi-key does. Here is the link to one of the ones that they offer.


6. I use the probe from Wildhorse innovation on the Bridgeport and it works real well. The only fault is the wires as it broke after a few uses but was an easy fix.
If you just want to do tool length you can just use a piece of copper clad circuit board. Lots of info here and on the Zone.

We never have the time or money to do it right the first time, but we somehow manage to do it twice and then spend the money to get it right.
Re: Converting a Clausing Mill and Lathe, have a couple Q's
« Reply #4 on: April 29, 2011, 11:39:37 PM »
Thanks again TotallyRC for the answers.  I have been doing scripted searches of both CNCZ and here for answers to questions, but come up short often.  There are so many BOB's and secondary peripherals that no 2 systems are alike.  

Basically I decided to just buy a bunch of stuff and figure it out, anything I don't use on the mill I plan to re-purpose for the lathe.   So I bought a Smooth Stepper, the PMDX 126 w/ input board, a 5v psu, prox sensors, CUI encoders, cables, a Gecko 203v to power a bigger stepper for the knee, a Mitsu servo with 21:1 planetary for possible rotary axis or lathe tool changer, terminal blocks, and other bits.  

I checked out the Wildhorse sensor and it looks pretty neat, do you know the average positioning accuracy of it?  Other than that I am trying to determine the best sensors/switched for homing/limits and figuring the pulleys and screws for the drivetrain.

Any other help or suggestion is appreciated, Thanks!
Re: Converting a Clausing Mill and Lathe, have a couple Q's
« Reply #5 on: April 30, 2011, 03:43:08 AM »
Hi again Biermann,
You can't go wrong with the smooth stepper as most of the bugs have been worked out and it is actively being developed.

The Wildhorse probe has very good repeatability.
It repeats to less then .001 in testing on my mill. The trick is to make sure that you indicate it is as close as possible with a good dial indicator. I use a .0001 dial indicator to set mine up.

I also use Himmykabibble's probing macro's in a custom screen set. It is so cool to push one button and have the machine find the center of a hole or the edge of your part. MSM also has some very nice probing function built in.

I use the G203V on my router and they make a big difference in how fast you can spin a stepper under load. Should do wonders to drive the knee.

If you don't mind, what state are you in? I am in CT.

Looks like you are going to need a second pport to run the mill with all the I/O. Make sure you get on that is a real Pport and not some weird usb implementation.
Search the forum to see what other people have had luck with. I have one that I think works. If I verify its functionality I will post the make and model it i can.

Good luck with both builds. If you do a build log post the link here so we can follow along.


We never have the time or money to do it right the first time, but we somehow manage to do it twice and then spend the money to get it right.