Clausing 8520 CNC - Gecko G540 - Mach 3
Posted by
pmpcaddy
on 2011-04-26 05:29:22 UTC
Hi there, new to the group and have decided to CNC my old Clausing 8520 mini-mill with an adapted BP M-head. The mill was bought out of 30yrs of storage by the previous owner, therefore the ways are in really good condition and the table is unscarred. Last week I bought a 3 axis Anilam DRO from the ENCO clearance sale, but the more I thought about it, and started looking around on DIY CNC sites at the pricing of components, I found I could CNC it for not much more money. Therefore I am trying to determine the best plan of action, while maintaining manual capabilty.
After a lot of reading over the last couple days I think I have a pretty good handle on it, however still have quite a few questions for the experienced person's of this group regarding the finer points. I decided on a Gecko G540 controller since it is well supported, relatively plug and play, and made just up the road from me. I figured since this is a small mill that the larger Nema 23 stepped motors should be enough, especially with a belt reduction. I plan to power X,Y,Knee and spindle speed since the M-head is also running off a VFD.
On to the questions, thanks to Hvenermo whom has already answered some of them.
The current X-Y leadscrews have .006" lash. My original plan was to replace them with ball screws. If I do what is the best place to purchase relatively inexpensive screws, and what accuracy (C class) would you recommend for a hobbiest machine, I would like it to hold a thousandth. If I choose not to replace them, can Mach3 compensate for the lash, or do I need make a pre-loaded double-nut as I am concerned with chatter.
What are people's experiences with using double ended servos for either handwheels, or for adding encoders to create a quasi-closep loop (from what I've read Mach3 won't do truly closed loop) and allow use as a DRO when running manual. Is the only way to accomplish encoder feedback for DRO by buying the RogerMachine encoder board?
If I replace the Z(knee) leadscrew with a .200"pitch ball screw and want to run it manually by forcing the Gecko into fault do you think it will backdrive. Reason why I am looking into swapping it is because currently the leadscrew has ~.011" lash and due to the rather small knee with weight out at one edge it can stick, thereby not always staying loaded against the nut. Currently as adjusted it has a good feel on the crank an I am afraid to loosen the knee gibs any to help the stiction issue. So I am open to suggestions as to what the best approach is for the knee.
Regarding belts and pulleys, are any better than other's. My current plan is to purchase 3/8"w .200" pitch stuff from Stock Drive.
The plan is to build a small panel/pendant with manual overides, auxiliary inputs, and a jog dial for assisted manual milling. I have looked aroudn and it seems CNC4PC makes a ton of different boards for pendant control, e-stop, keys etc. Is their on you guys would suggest from them or other that will handle a dial encoder as well as 8-12 switches/inputs that interfaces well with Mach3?
Well that should get me started, if anybody has any suggestions on parts, neat accessories, cheap ballscrews, the best Nema23 motrs, etc. I am all ears.
Thanks.
After a lot of reading over the last couple days I think I have a pretty good handle on it, however still have quite a few questions for the experienced person's of this group regarding the finer points. I decided on a Gecko G540 controller since it is well supported, relatively plug and play, and made just up the road from me. I figured since this is a small mill that the larger Nema 23 stepped motors should be enough, especially with a belt reduction. I plan to power X,Y,Knee and spindle speed since the M-head is also running off a VFD.
On to the questions, thanks to Hvenermo whom has already answered some of them.
The current X-Y leadscrews have .006" lash. My original plan was to replace them with ball screws. If I do what is the best place to purchase relatively inexpensive screws, and what accuracy (C class) would you recommend for a hobbiest machine, I would like it to hold a thousandth. If I choose not to replace them, can Mach3 compensate for the lash, or do I need make a pre-loaded double-nut as I am concerned with chatter.
What are people's experiences with using double ended servos for either handwheels, or for adding encoders to create a quasi-closep loop (from what I've read Mach3 won't do truly closed loop) and allow use as a DRO when running manual. Is the only way to accomplish encoder feedback for DRO by buying the RogerMachine encoder board?
If I replace the Z(knee) leadscrew with a .200"pitch ball screw and want to run it manually by forcing the Gecko into fault do you think it will backdrive. Reason why I am looking into swapping it is because currently the leadscrew has ~.011" lash and due to the rather small knee with weight out at one edge it can stick, thereby not always staying loaded against the nut. Currently as adjusted it has a good feel on the crank an I am afraid to loosen the knee gibs any to help the stiction issue. So I am open to suggestions as to what the best approach is for the knee.
Regarding belts and pulleys, are any better than other's. My current plan is to purchase 3/8"w .200" pitch stuff from Stock Drive.
The plan is to build a small panel/pendant with manual overides, auxiliary inputs, and a jog dial for assisted manual milling. I have looked aroudn and it seems CNC4PC makes a ton of different boards for pendant control, e-stop, keys etc. Is their on you guys would suggest from them or other that will handle a dial encoder as well as 8-12 switches/inputs that interfaces well with Mach3?
Well that should get me started, if anybody has any suggestions on parts, neat accessories, cheap ballscrews, the best Nema23 motrs, etc. I am all ears.
Thanks.