New Build - 'Audit' CNC - Lathe Attachment

[suntravel]

Position mode and speed mode are two pairs of shoes...

Axis with Acorn is position mode only and spindle with 0-10V speed mode.

For spindle use a snubber, twisted pair cable with the shield to GND and dial in zero drift on the servo drive

Uwe

[Chaz]

Position mode and speed mode are two pairs of shoes...

Axis with Acorn is position mode only and spindle with 0-10V speed mode.

For spindle use a snubber, twisted pair cable with the shield to GND and dial in zero drift on the servo drive

Uwe

Yep, aware velocity mode, my point was that it offers fine tuning and a pity there doesnt seem to be for position mode. Ive got a few things to try later.

[Chaz]

I've rewired the panel and the noise is reduced but not gone. I then took the steel sheathing around the premade cables and earthed them and noise is currently gone. Did some testing cutting, looking a lot better. Progress.

Next will be more mechanical work to strengthen the frame but I need to sort the tool turret as I'm manually changing tools as I need to make a part for someone that bought a Denford Orac from me but it needs a new backplate made. Fairly comfortable at the moment that I can do it, albeit with manually changing tools in the turret location. Ive done a bit of cutting on mild steel, machine is happy. I did however flip the tool around so I'm cutting in reverse and forcing the turret down. Doing it the other way is creating some oscillations in the setup which I can solve once I strengthen a frame around the unit.

[suntravel]

Zero Drift in speed mode is normal, you can eliminate this in the servo parameters.

Better servos have an autotune feature for this.

But hey, your post is in Acorn forum, speed mode is here only for spindle drive, not for axis drive...

Uwe

[Chaz]

Made good progress making a part for a friend. Was holding 0.01mm fairly easily. Doing a chuck backplate and when I wanted to take another 0.01mm off, I saw that I had lost position and no idea why. I cant see any source of noise etc and ran some test movements which repeated well.

I'm going to upgrade the 750W servos to something more substantial to match the DC motors that were on there, so looking at 1.5 or 1.8KW size. Any recommendations of brands that are available in the EU etc that wont break the bank that work well with Acorn?

[Chaz]

Anyone know this generic make? I've seen them loads. Anyone used them on Acorn?

https://www.ebay.co.uk/itm/256190693514 ... 6559629355

[Chaz]

This looks to be the manual, based on looking up the larger driver's model number.

https://www.paycnc.com/u_file/2402/file/2fb2cc3233.pdf

[suntravel]

Made good progress making a part for a friend. Was holding 0.01mm fairly easily. Doing a chuck backplate and when I wanted to take another 0.01mm off, I saw that I had lost position and no idea why. I cant see any source of noise etc and ran some test movements which repeated well.

I'm going to upgrade the 750W servos to something more substantial to match the DC motors that were on there, so looking at 1.5 or 1.8KW size. Any recommendations of brands that are available in the EU etc that wont break the bank that work well with Acorn?

JMC is ok.

https://shop.cnc-technics.de/public/det ... 88bfefb399

Uwe

[Chaz]

Thanks. Almost double the price. I might try the ones I linked and get a bunch of those diff drivers to ease some of the challenges with the single ended approach.

[suntravel]

I would never buy a super cheap servo from a Chinese retailer with a 100 page manual half in Chinese for a CNC axis drive.

Even Lichuan is not my choice for axis, this starts with Stepperonline, JMC, Leadshine on the low end.

Local retailers are more expensive than direct order, or Ali, but hey local service is not free...

Uwe