Brother TC-225 / TC-229 adventure!

the machine runs perfectly smooth under the stock control. so, jerk control smooths it out?

im not sure. many other converted machines run fine with bad backlash, however, i know most of them dont have near the same acceleration and the brother..

Sure they run fine with backslash, but who knows what servo bandwidth they run with and what overshoot or oscillations they have. While tuning the motor you see just the motor encoder velocity but not the table movement. For example, in the bode plot above there is -30dB @ 72Hz i.e. ~1/30 of the amplitude compared to 20Hz (plots show power, divide by 2 for amplitudes). If you put your hand on the table you can feel, that it is vibrating as hell. Probably much more than at 20Hz.

Maybe I am putting too much effort in this, but if I can solve the problem for 6$ (for a pack of 10 disks) I'll give it a try. It won't hurt.
Speaking about jerk control. I should have measured the velocity ramp of the stock control, when I had the oscilloscope in the workshop..

so ill probalble stick these in storage for a bit, while i seek out a new shop. im sending the housings to be powder coated, and i will pull the tc225 ball screws to re pack them with new balls.

i think what i may do it take my computer and mesa gear, and my bekhoff system, the servos for size reference, and some other bits, and play with them offline in an attempt create a stable system to apply later.

the only thing that definitely works fine is the spindle motor / drive on the tc225, so we will just leave that in the machine.

we have a few options for new servos:

1 is to keep the sanyo servos, and give them new drives. this im told isnt always smooth if you want to keep the high end performance.the delta asd a2r is a drive we could use, at about $600us each.

2 we just buy new delta drives and motors. $3000ish, analogue and pulse and direction. they make a 750w and 1kw model to fit, but they only run at 3000rpm, which would lower the speeds on both machines.

3 we buy different sized 750w and 1kw servos from delta or yaskawa and make them fit with adapters and new couplings. these would be 5000-6000rpm, and increase the rapids. these motors dont have the low end or intermittent performance of the sanyos though.

4 we buy the brand new equivelant sanyo motor and drive kit, at a cost of around $1800-$2400 per axis. basically whats in a brand new brother speedio, designed to work in this machine. as you may have read earlier, i do in fact have 3 newer-ish sanyo rs1 drives that take analogue or step with incremental encoders which could be used with brand new motors.

hmmmm... any other ideas?

Oh, maybe this could work for someone. i have a TOS FNK25 manual mill, kinda like a bridgeport, but bigger. its a good cnc conversion candidate. i cant take it with me when i move out of the shop, i have no room. maybe someone here would like it, either to buy, or to trade for some ac servos and such that could be used in my brothers.

alright, i got some new used drives coming tomorrow. gonna take the long weekend to try this all again. drives are ultra 3000 from allen bradley

going to first try one on the tc229 x motor to get it set up. then hook it to the actual x axis and try to tune it analogue mode. if it still behaves badly, we will try step and direction mode. i actually know this works already as the guy bringing me the drives has them on his tc229. he never got them to move very fast though while tracking precisely, but they are smooth. kinda the exact opposite of my issues with the stock drives, doh!

anyhow, once we have some solution that seems like it will work, we will move it to the tc225, bypassing the stock drives, but still using the original motors.

so, likely scenarios....

1: analogue mode simply doesnt work well with these motors / drives / linuxcnc but step and dir mode are fine
2; the tc229 motors are fine in analogue, but the tc225 motors do not work well.
3: the new drives fix everything and it all works with good performance in analogue on the tc225.... (im not holding my breath)

should be fun anyway.

Looking forward to what you will report back.
These drives and motors in my 215 are still a big mystery to me. The manual is very imprecise to what they are and how they are wired. The motors in the drawings and wiring diagrams are 2-phase servos, which is different from what I have measured (3 phases, or at least 3 symmetric braking resistors..not sure). I am also unsure if they are resolver or encoder based servos. At the end there is a digital quadrature encoder signal coming out of the drive, but that could also be an A/D converted version of the resolver signal. The manual mentions both encoder and resolver on different pages.