Tormach PCNC 770 Series 3 -- Updated 3/26/2020

[briuz]

I really want to have rigid tapping and conversational programming on my Tormach. I investigated upgrading to Mach4 or PathPilot. As I need to install an encoder for rigid tapping I was concerned about what would be involved to add an encoder to either of those options. Since I already got an Acorn running on my portable 5c collet lathe I figured I'd upgrade my Tormach to Acorn. Since this upgrade is rather involved, I am breaking it down into 3 phases.

The first phase is to have basic CNC functionality, the second phase is to add the encoder, the third phase is to restore the operation of the spindle controls on the panel. The first phase only needs a little more work until it is finished. (i.e. Some macro scripting, spindle speed calibration, and testing.) I've also been documenting the changes and have them in an attached document. (I'll update the document as time goes on.) Of interest may be what pins are needed to adapt the Tormach/Leadshine stepper motor drivers to work with Acorn as the connection does not appear to be standard.

So, here are the pics.....

I had to climb mill as this is a modification of the prototype lathe turret and the final turret will have the rocker arc on the other side. The job took about 44 minutes.



Version 0.5 of the configuration document:

Tormach To Acorn Conversion v_0_5.pdf

(94.55 KiB) Downloaded 271 times

2/15/2020:

Machine is almost usable and already working better than it was under Mach3. I just need to check the spindle speed calibration to see if it's close. The configuration file is now at version 0.2.

2/17/2020:

Version 0.3 of the configuration document uploaded. VFD configuration added as well as document cleanup.

3/5/2020:

Version 0.4 of the configuration document uploaded. Changes include changes to VFD configuration as well as spindle/encoder related changes and additions.

3/18/2020:

Version 0.5 of the configuration document uploaded. Changes include updates to the VFD configuration, addition of control panel ribbon cable information, document cleanup, etc.

[Dave_C]

The PCNC1100MX now comes with a spindle encoder. You might look at how they mounted the ring type encoder to the bottom of the spindle pulley and see if you can do something like that. If you can, then the two pulley speeds are no longer a problem.

Spindle has to be 1:1 with the encoder in order to do thread milling of threading.

It really should not be all that hard.... What you have done so far is looking good.

Dave C.

[briuz]

I just checked both the PCNC 1100MX and PCNC 770MX manuals. They use a magnetic disk on the spindle and have a pickup for it. Most likely it's a hall effect sensor. That wouldn't be too hard to do, however, it wouldn't be incremental as required by Acorn. (I made a Hall effect sensor module for my turret lathe so it can home.)

I was also interested to see that the PCNC 770 and PCNC 770MX are drastically different. I figured they'd be pretty close to the and just have updated motors and electronics.

I am planning on making or buying another pulley that is the same size as the high speed pulley then mounting the encoder next to it and use a belt. I don't use the high speed pulley ever since the machine was new. After I bought the machine, I did a lot of milling at 10k RPM and the spindle cartridge died while still under warranty. After that, I've limited it to 3K RPM just to be on the safe side.

The PCNC1100MX now comes with a spindle encoder. You might look at how they mounted the ring type encoder to the bottom of the spindle pulley and see if you can do something like that. If you can, then the two pulley speeds are no longer a problem.

Spindle has to be 1:1 with the encoder in order to do thread milling of threading.

It really should not be all that hard.... What you have done so far is looking good.

Dave C.

[Dave_C]

I just checked both the PCNC 1100MX and PCNC 770MX manuals. They use a magnetic disk on the spindle and have a pickup for it. Most likely it's a hall effect sensor. That wouldn't be too hard to do, however, it wouldn't be incremental as required by Acorn. (I made a Hall effect sensor module for my turret lathe so it can home.

Check the wiring diagram on the 1100MX because it shows it as a 9 pin encoder and is able to do spindle orientation for the BT30 tool holders when you install the tool changer.

If you use a belt to run your encoder it will have to be a toothed belt and not a Vee belt so it does not get out of sync. Unless you don't ever plan on needing to go back into the same hole with the same tap.

Lots of ways to do things,

Dave C.

[tblough]

Just my $0.02 worth here. It's a little more work to make sure there is one and only one encoder pulse per spindle rev, and that it repeats in the exact same spot every time, but the ability to peck tap is extremely useful for "problem" materials.

[briuz]

I agree and this is one thing I want this machine to be able to do. Finding the right encoder may take some time. I am looking into the magnetic ring type. A first glance looks like there aren't many suppliers.

Just my $0.02 worth here. It's a little more work to make sure there is one and only one encoder pulse per spindle rev, and that it repeats in the exact same spot every time, but the ability to peck tap is extremely useful for "problem" materials.

[tblough]

Check out RLS in Slovenia. They are a Renishaw company and ship quickly to the US.

[briuz]

Thanks! I wish I knew about these when I was adding the encoder to the lathe. I need to read everything but if an axial ring will work it's only 2mm high and is attached with an adhesive. This is great!

Check out RLS in Slovenia. They are a Renishaw company and ship quickly to the US.

[tblough]

I used one on my Bridgeport spindle and was really happy with it. viewtopic.php?f=64&t=1944

[briuz]

I am unsure as to the required specs of the encoder and have a couple questions. You posted:

The encoder ring and read head were less than $200 including DHL shipping from Eastern Europe. The read head was an RLC2IC with RS422 5V interface, 6-Bit (06B) interpolation, 1µs edge separation (C), no connector, with reference mark, and no special requirements. Actual part number was RLC2ICA06BC00A00. The encoder ring was an MR axial magnetic ring, 50mm OD, 2mm height, 40mm ID, with reference mark, 72 poles, stainless steel with back adhesion tape. Part number MR050C040A072B02.

The 6-Bit (06B) interpolation on the read head is 64 and the ring has 72 poles. I am unsure as to how this equates to the "Spindle Encoder Counts" in Acorn: Would this be 4608 (64 x 72) Spindle Encoder Counts or something else?

Also, what is the "reference mark" and is it needed?

Thanks!

I used one on my Bridgeport spindle and was really happy with it. viewtopic.php?f=64&t=1944