Logan lathe CNC conversion

[DocsMachine]

Other obligations have kept me from being able to do much on this build since the encoder install, but today I finally had a few minutes to do a preliminary assembly of the Acorn and attendant electronics.

Please keep in kind this is ONLY FOR TESTING. I'm not that great with wiring, and don't yet have a suitable enclosure, so for the time being I just screwed everything to a spare scrap of plywood.



Again, it's very temporary! Note the makeshift E-stop button taped to the lathe controls.

I'm reasonably certain I have the wiring correct, but I'll be double-checking in the morning, and re-reviewing the videos on startup and calibration.

Keeping in mind the lathe itself is not quite complete- I still need some left-end covers, an X-axis leadscrew support, to hook up the VFD to the Acorn, add oilers to the new cross-slide and saddle, and a handful of other little things as well. So we're getting there, but there's still work to be done.

Doc.

[DICKEYBIRD]

...so for the time being I just screwed everything to a spare scrap of plywood.

Naah, ya' just have to describe things in a more accurate, technical manner: "...so for the time being I mounted the control components on a sheet of high-strength organic composite-fiber insulating substrate with their locations determined strategically for best service access and optimum convective cooling."

(Lookin' good...more lathe stuff; I love it! )

[martyscncgarage]

Other obligations have kept me from being able to do much on this build since the encoder install, but today I finally had a few minutes to do a preliminary assembly of the Acorn and attendant electronics.

Please keep in kind this is ONLY FOR TESTING. I'm not that great with wiring, and don't yet have a suitable enclosure, so for the time being I just screwed everything to a spare scrap of plywood.



Again, it's very temporary! Note the makeshift E-stop button taped to the lathe controls.

I'm reasonably certain I have the wiring correct, but I'll be double-checking in the morning, and re-reviewing the videos on startup and calibration.

Keeping in mind the lathe itself is not quite complete- I still need some left-end covers, an X-axis leadscrew support, to hook up the VFD to the Acorn, add oilers to the new cross-slide and saddle, and a handful of other little things as well. So we're getting there, but there's still work to be done.

Doc.

He that's awesome Doc. I get the temporary thing. Look at this on my Emcoturn 120 hanging on the side:

Hope you get it moving soon. Be sure to do a video clip!
Marty

[DocsMachine]

One of the original issues I was having with the old M3/XP setup, was a motor that wouldn't "lock"- IE, it didn't get any harder to turn when energized.

We thought for a while that was due to the controller- they were well used when I got them, so who knows what might have been wrong with it. I eventually bought a new driver board (MicroKinetics) and that appeared to solve the issue.

But today, I tried to power up the system, and immediately upon applying power to the drivers, that same motor (570 oz-in stepper) started buzzing.

I tried swapping control cables between the two motors, but the other one didn't start buzzing. When I booted up CNC12 and configured the motors and whatnot, only the X-axis would move when jogged. If I swapped the cables back (so the axis that did move would go back to being connected to the motor that "buzzed" originally) the motor simply started immediately buzzing again.

Which, since this time I have an entirely new setup- new drivers, new controller, new power supplies, new computer, etc.- I'm thinking this stepper might be bad. It HAS worked in the past. I never put much time on this machine, mainly due to my limited knowledge of M3, but I did execute at least a couple of very simple handwritten programs.

I'm in the middle of swapping the 570 with a 270 I have on hand- which I'd been thinking of anyway since I thought the 570s might be a little too powerful. (I'd rather the thing skip some steps if i crash it, than start shearing keys or stripping pulley setscrews.)

cbckeith- how big are the steppers on that "test mule" lathe you showed in the recent in-house video?

Doc.

[DocsMachine]

Nope, looks like I got a bad driver.

Two Leadshines, one works, the other doesn't. If I swap motor connections on the working driver, both motors work. if I swap outputs from the Acorn between the two drivers, only the one always works. I've double-checked the wiring, checked for power from the driver supply (good 5V) from the stepper power supply (good 36V) checked for continuity through the leads, even tried a third, brand-new stepper.

Everything works great, except for the one driver. No motor connected to it will operate. It'll energize, in that it "locks", the shaft becomes harder to turn, but nothing I do appears to be able to get a step or direction signal through it, in order to make it actually do anything.

I suppose I'll have to contact the seller and see about a replacement...

Doc.

[DICKEYBIRD]

Double, no, triple-checked the dip-switch settings on the non working driver?

[DocsMachine]

The settings are identical between the two. 400 steps per rev, and I think I set it for something like 3.2 amp. Admittedly I haven't tried switching to a different setting...

Is there some other setting or control I need to know about? Even if I had the thing set for 25K pulses per rev, I'd eventually be able to see some movement- the Centroid DRO can read 6+ inches moved, and the pulley hasn't budged a single degree.

Doc.

[martyscncgarage]

Doc,
I just took a look at your write up of your Logan lathe conversion. Very nicely done!
Here is a link to Doc's Logan write up:
http://docsmachine.com/cnc/logan/logan01.html

And docs other machine projects:
http://www.docsmachine.com/projects/machine.html

[andyolney]

Doc-
I have a couple of questions about your Logan conversion, which looks great!

I am on the same road with an 8x14 lathe.

Why use a pair of duplex angular contact bearings? Wouldn't single bearings have the same effect?

The Koyo Automation direct light duty encoder I am looking at (TRDA-2E2500VD) has a radial load capacity of 4.5 lbs and I am under the impression that the timing belt does not need a lot of tension. I found some data at Stock Drive Products (http://www.sdp-si.com/PDFS/Technical-Section-Timing.pdf) that calls for 2 lbs tension for a 2mm pitch 6 mm wide GT3 belt. I completely understand being conservative in designing this mount, but I would love to keep it simple with a direct drive on the encoder. Any thoughts?

Andy Olney

[martyscncgarage]

Doc-
I have a couple of questions about your Logan conversion, which looks great!

I am on the same road with an 8x14 lathe.

Why use a pair of duplex angular contact bearings? Wouldn't single bearings have the same effect?

The Koyo Automation direct light duty encoder I am looking at (TRDA-2E2500VD) has a radial load capacity of 4.5 lbs and I am under the impression that the timing belt does not need a lot of tension. I found some data at Stock Drive Products (http://www.sdp-si.com/PDFS/Technical-Section-Timing.pdf) that calls for 2 lbs tension for a 2mm pitch 6 mm wide GT3 belt. I completely understand being conservative in designing this mount, but I would love to keep it simple with a direct drive on the encoder. Any thoughts?

Andy Olney

I wouldn't advise using a light duty encoder with a timing pulley directly mounted. Jackshaft arrangement(like Doc's) is typical and what is called for.
BUT if you are intent on trying it....you've been warned.