Return of the POS

[MrFluffy]

Phew, that was a interesting struggle with such a low celing, but the motor/head is back on. I even have a small amount of clearance.

[MrFluffy]

Little bump, ignore the touch screen, I ordered the wrong size digitizer so its a temporary thing until the right size arrives and I can neaten it all up.
First, joysticks wired in, they are attached to the circuit board of a broken usb keyboard as keys, so moving the z joystick up and down makes the computer think you are mashing keys on the second keyboard.
I've used xmodmap to change the keycode to the linuxcnc defaults for that axis, I'll use a alternative keymap later on when i get the syntax figured out so I can have a normal keyboard and only map the joystick input one. For some reason my Y axis is much much faster than the X, when I bump the rate up on the X it misses steps, so I have some investigation to do. I have the centre button in series with the joystick wiring so you have to depress the button as well as move the joystick to act as a failsafe against bumped joysticks.

https://www.youtube.com/watch?v=DBL6uRCuQ44

And, the first really fun thing its done, although that clack is annoying, its from the coupler on the X axis handwheel as its not locked up electrically. I should throw it out of mesh and reshoot but I'll save that for when the axis can move faster for a better pitch.

https://www.youtube.com/watch?v=J8Qlb_PRMt8

Time to start making it draw things with a sharpie to test code and axis movement after some air cutting that is.

Edit, fixed the slow X, tone is much better now its 3 times as fast!
I don't know if to laugh or cry at the root cause though, suffice to say that the handwheel mechanism electromagnet engagement mechanism is nothing of the sort, in fact, its a electromagnetic BRAKE. A very worn one so it can still move with reluctance, but even so.
Yes, indeed, the brake has been stuck on the whole time. Redfaces all round.

[MrFluffy]

I have been busy "tuning" my steppers, theyre E# now

https://www.youtube.com/watch?v=pLFVHN67na0

I'm done playing with noises now, had to get that out my system, though my kids love it. I was just monitoriing stepper heatsink levels while testing, honest guv'nor!

[chrsbrbnk]

I was trying to figure out what size steppers and torque and gear reduction you are using. I have a similar size enco mill and I am trying to select the motor driver set. thanks, Chris

[MrFluffy]

I'll post you a definite link to the motor specs later when I can make a note of them again as I don't have them to hand right now. Memory says theyre 1100oz/inch units.
Drive ratio is 2:1 as per standard bridgeport with a 5mm pitch leadscrew, this model of bridgeport came with either 5mm pitch metric version or 5tp pitch ballscrews. The drive gearing and belts are all the original components.
Driving those steppers are 3 * DM860A stepper drivers, and a homemade psu which is capable of a lot of amps at 70v or so. I'm microstepping them in 1/8ths of a unit at the moment and can do steps of 0.01mm in the z or about 0.0004" per step.
I have some vfd control issues to sort then I can make it make chips and see how it all performs under load. I've given up on the chinese bob with vfd circuit incorporated I got from ebay (not the one earlier in this thread, that's still on controlling steppers and e-stop and limit switches) as I've found some blown components already before I start and it arrived with literally *no* documentation and silkscreen in chinese so I'm just going to roll my own.

[MrFluffy]

Ok I checked the labels and they are AC851505042M hybrid stepper motors which are 650N/cm 4.2A/phase. The 650N/cm converts to 920oz/inch but Im not sure how stepper ratings are calculated with regards to them being two phase motors. They are certainly heavier and larger than the 1100oz I bought for the 4th axis part.

[chrsbrbnk]

Thanks ! I have been vacillating between the leadshine easy servo or http://www.automationtechnologiesinc...t-110vac220vac or http://www.automationtechnologiesinc...x-gecko-driver
all the things I've read on driver failures and over rated motors have me second guessing

[raceneer]

I have BPCNC envy

[jonesturf]

I'm interested to see the belt conversion in the head. I want to do the same to mine.

Sent from my SAMSUNG-SGH-I317 using Tapatalk 2

[legendboy]

Thanks ! I have been vacillating between the leadshine easy servo or http://www.automationtechnologiesinc...t-110vac220vac or http://www.automationtechnologiesinc...x-gecko-driver
all the things I've read on driver failures and over rated motors have me second guessing

I would highly recommend looking at a DMM system. Closed loop tuning is handled in real time. Just set a few parameters on how you want the system to respond and your running.
Even with the default drive settings your machine will run nicely!

http://www.dmm-tech.com

[John Stevenson]

Thanks ! I have been vacillating between the leadshine easy servo or http://www.automationtechnologiesinc...t-110vac220vac or http://www.automationtechnologiesinc...x-gecko-driver
all the things I've read on driver failures and over rated motors have me second guessing

Forget the Gecko servo system, it's a very old system, not particularly good in it's day but now way outdated.

The Leadshine closed stepper is very good as is the one linked to by Legend boy.
A bit horses for courses though. The closed loop stepper is ideal for slower machines hogging with direct motor to ball screw drives.
The DMM system is ideal for higher speed machining and requires a usually 3:1 reduction to the ball screws to get torque.

This is just the way steppers and servo's work

[MrFluffy]

Well, to update a bit, I havent got any pictures of the head conversion, but it literally is two pulleys with taper lock hubs to match the shafts, a drive belt, the main shaft cut down an appropriate amount and the brake modified to a disc arrangement inside. Most of the work was because I managed to break the original casting disassembling it so I had to repair my handiwork also.
Ill try to find the post I used as a basis for the conversion on cnc zone and post a link if needed. I can find the belt dimensions from my notes, but its a simple 1:1 drive.

But now I have the oiler hooked up, and its cut its first test piece. Two problems, firstly one of the limit switches is bad and its throwing a error because of it randomly, I have to investigate which is the root cause and replace it, as Ive inherited a legacy bad switch problem. And secondly it seems I have the pitch wrong in the Y. Good news is the vfd is working under control of the linuxcnc software with a add on board from diycnc.co.uk doing frequency to reference voltage duties and using its two relays to control the start and direction relays. :-

http://www.diycnc.co.uk/html/spindle_boards.html

Feeling more confident with this setup than the chinese bob with no documentation. Now to eliminate my gremlins from the wiring and get to the root cause of the Y error. Used the same smiley logo I used for my 3d printer and wire edm testing, but with a suitable POST for the toolchain for the mill control.


Its about 2inch across, and the gouge is because I ran the .ngc code twice because of the limit switch error. The inner edge of the circle looks lumpy because it errored out before doing the inner contour cut too. But still, happy.

[MrFluffy]

Last post, its all working, despite having crappy terrible outdated unfashionable steppers that do seem to have enough power to snap a 3/4 end mill traversing into a table clamp with the spindle off, even if the entire electronics and motors in the mill cost less than a single used exchange yaskawa drive pack for the servo drive on the sodick edm :-)
Y axis error turned out to be a drive ratio issue on the X after checking screw pitches and other areas, somewhere along the way one of the pulleys isnt the correct one for this model and it is no longer 2:1 between the nut and stepper.
Spindle vfd needed step pin drive with a generator adding to hal manually, rather than pwm. Its working now though and I understand hal a lot better for the extra bells and whistles getting added in future.
Two seperate gcode programs with touch offs between them to align, just a old piece of laqueered wood to test things on. And a satisfying blob of oil from the spindle being slightly overoiled while I order a replacement bjur metering valve for the head as I had to drill one out it was so blocked.