emco pc mill 50 & similar

[yvesdupre]

RCREDD, i think you are right... the 1 pulse per rev wouldn´t have changed anything! I think i have now found out the real reason for loosing the steps... there was too much friction in the guides of the x-axis ( and i only lost steps in the x-axis), i forgot to put lubricant there and maybe the owner before too... for some years but now when i have pulled everything apart i will change the steppers anyway but i think it could have worked with the old ones... if the mechanics would have been alright.
Ok i have to admit that this was not very smart but we never stop learning

[yvesdupre]

My pulleys were held on with roll pins that were easy to tap out with a narrow punch.

I meant the pulleys on the ball screw. is it possible to remove it?

[Chip Chester]

Moved... wrong place.
Chip

[CNC support]

as i wrote before i connected the original 5 phase emco stepper board to a csmio ip/m. it worked really well and accurate as long as i didnt mill anything. but the problem is this: in several milling tests i have found out that this leads to a very big coordinate mismatch after a while of milling because many steps are lost under load. i think emco has put the syncs on the axes for good reason but unfortunaly it is not possible to connect them to the csmio ip/m.

Steps loss is a common problem when STEP signal is in a wrong polarization. Have you checked it?
If the STEP signal is in wrong polarization then one step is losing on every direction change.

Andrew

[RCREDD]

TYo remove a pulley from the lead screw, first remove the setscrew in the center of the pulley. The pulley should then unthread from the screw.
Be careful not to damage the components. The setscrewe and the pulley were bothe set with locktite. Be shure to use red loctite when reassembling.

[cncatbkb]

Help me! Im serching for the pinout of the emco pc mill 50 stepper board. I would like to use linuxcnc over this "http://www.ebay.de/itm/300664130725?ssPageName=STRK:MEWAX:IT&_trksid=p398 4.m1423.l2649" board and some simple Logic like this "http://www.stmental.net/~dfoster/emco/". If you can pass me the pinout and your setings it would make me very happy...

[cncatbkb]

Hi,

Im new here too. Im looking out for some pinouts from the stepper driver of the pc mill 50. I would like to use linuxcnc over paralell port and simple optocoupler. Found articles like this "http://www.stmental.net/~dfoster/emco/", wiht simple logic. Is there anybody out there with schematics of the driver card or pinouts of the conectors?

We use the sinumeric 820 software at the moment and it is not what I think is a modern surface...

[cncatbkb]

I have not seen the first post, so i posted it again. Sorry....

[UUU]

New question on spindle speed:

Up until now I've been running my PC mill 50 with a VFD that could go up to 120Hz. I think there's a 19 to 11 relationship between the motor and the spindle (just by counting turns, I've not had it apart - is this right?), and the motor shows 1660rpm at 60Hz, so by my maths the maximum spindle speed I could get was 1920rpm.

I've got a new VFD that can go up to 400Hz. I'm not going to try at this speed, but I'd like to go up to the originally rated top speed knowing that the motor and spindle should handle it. But what was the original speed range, please (and by extension the frequency range of the original inverter board)?

In its F1 guise, I believe the spindle could go up to 4000 rpm - but that was with a different motor configuration. Am I right here - and if so, could I safely run the PC Mill 50 motor at a higher frequency than originally rated? How much higher?

[cncatbkb]

I Got the electrical diagrams from yves (thanks again!), but his diagrams show a f1 and my machine is older. So I asked EMCO and they send me the the inside circuit diagrams. Tomorow I would have a look at them and try some things with a osziloscope. The SR Signals are connected to a ERR Pin of the Driver over a diode. I do not Know what this would mean. But I found a SE Pin that could be jumpered to 24V. I would measure it, but it looks like some kind of enable.

[RCREDD]

I think the ratio is like 60% or 70% of motor rpm is spindle rpm. I don't remember right off.
I installed a prox on the head and am reading the exact spindle speed on my machine.
I have a TECO inverter tha I have set at 200Hz and my top spindle speed is 3400RPM
I have ran the machine at this speed many times without any ill effects.
I have checked the temperature of the spindle and it has not run what I would call hot

[UUU]

That's really useful - I shall set my inverter at 200Hz - and work my way up to there.

My spindle gets warm but never hot at my lower speeds, so we'll see. I have some F1 documentation that suggests max spindle temerature is 60 degress (C) after 45 mins running (15mins at 2000, 15 at 3000 and 15 at 4000). That's hot!

I'm looking forward to going faster so I can get the feed rate up a bit and shorten some of my run times.

[yvesdupre]

i run the spindle at 200 Hz too, tried to go even faster but it didn´t work, at around 220Hz it got slower again. Now i use it with the inverter in sensorless vector control and it works really good.

Would it work to put a 3000 rpm rated Motor on the spindle and run that one at maybe 150-200 Hz?
One like that:
Drehstrommotor, 0,55kW, 3000n, K21R 71G2, B 14 k | eBay

[yvesdupre]

here I present my Retrofit:



comments welcome!

[UUU]

I really like it.

Your components in the back cabinet are nicely arranged - it's good to try and keep things as neat as the original set up.

I'm interested to see you have used the network connection rather than the parallel port approach. This is clearly the way to go. And not using the Smoothstepper but the CSMIO IP/M approach.

You are getting faster G0 rapids than me - but I'm still using the original 24V supply system. I might still be able to get up to 750mm/min, but I've settled at 400mm/min for the moment.

Schöne kleine maschine indeed!

[UUU]

Would it work to put a 3000 rpm rated Motor on the spindle and run that one at maybe 150-200 Hz?
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This might work with your sensorless vector control. I find with my standard inverter that I lose out on torque at low revs. Although I want more speed for the small 3mm and 4mm cutters, I like to run a 16mm inserted-tip tool that can take a bit of effort in steel. I also have a 50mm shell mill that I'd like to run, when I can find holder for it.

[yvesdupre]

Right now i have set the feed to max 1460 mm/min . Before when i had the steppers connected in parallel bipolar (full coil ) max 700 were possible.
The limiting factor now is the 100khz of mach3 . does anyone know where to change the limit. because the csmio ip/m could do 125khz.

And true... the slvc gives really good torque at low revs!

[daus300b]

Hi Everyone,

I am new here and got a PC Mill 50 that has already been converted with stepper motors and a gecko g540. I would like to start setting it up and was wondering if anyone knew the ball screw thread type? It seems that this machine was lightly used. Are there any ball screw adjustments that I would need to make?

Thanks!
Daus

[UUU]

I don't think you'll need to adjust anything. Give it a shot of oil in each of the oiling points. and see if she'll fly!

I have mine set at 1600 steps per unit, metric. I'm assuming they all had the same ballscrew pitch, you might like to see if that works for you.

I've just come from the workshop having used mine for some precision drilling in steel. 8 components, 4 left hand and 4 right hand. Three holes in each, spot drill, drill thorugh and countersink.

[yvesdupre]

The Pitch of the ball screw is 2.5mm per rev and it has a 1:2 ratio to the stepper.
If you have bipolar steppers it is 160 full steps per mm or 320 in half step.
I guess Uuu has the stepper in 1/10 microstepping mode.