Messages

311

General Mach Discussion / Re: Mach 3 tool offset question

« on: April 27, 2006, 11:54:30 AM »

I use tool diameter offsets a lot in my enviroment which is production.

But I agree that for a start let your cam package handle it just to get used to running a machine.

The reason Use them is I dont want to have to re-post the whole prog when I find a cutter is cutting under or oversize beacuse of wear/regrind etc etc.

On the other hand all 3D work I do is compensated in cam.   Comp is rarely applicable for this type of toolpath.

Also no matter what type of work I'm doing tool length offsets ALWAYS apply.

Wayne...

312

General Mach Discussion / Re: MOTOR LOCK-UP ON RAPID MOVEMENT

« on: April 25, 2006, 11:18:51 AM »

Steve..

You should be able to!   They should go faster than the speed at which they stalled on the bench.

If they dont, then I'd expect that they are not seeing enough load.  Or if they stall at a lower speed you got some serious friction, but I very much doubt that will happen.

I still reckon you might be better off at 1:1.    You have some big motors there.

What are you intending to cut?

Wayne...

313

General Mach Discussion / Re: MOTOR LOCK-UP ON RAPID MOVEMENT

« on: April 25, 2006, 09:34:14 AM »

Steve....

Just had an idea for something you can try..

Take the motors off the machine, and run them one at a time on the bench.

Increase your max velocity in mach until they will stall on the bench, the motor will just stop turning an squeal.

They probably wont all behave the same, but that soesnt matter.

Now lower velocity until they no longer stall on long rapids.

Now the figure you get will be LOWER than what you SHOULD be able to achieve loaded by the machine.

In my case I was able to increase max velocity by over 50% when loaded by the machines mass and friction..

Let us know what you find..

Wayne....

314

General Mach Discussion / Re: MOTOR LOCK-UP ON RAPID MOVEMENT

« on: April 25, 2006, 09:08:25 AM »

I believe that the package I bought has Prodrive 2000 drives but they don't advertize or publish this in their documentation.  They stated that the power supply is a 48V DC 13.8 amp unit.  They recommended using a 2:1 ratio based on their past experience with this combination on larger routers.  My router has a fairly large working area of 48" x 96" x 24".  To remove the gear redcution I would need to buy some more parts. Your speeds are much higher than anything I have ever seen with my machine.  That might be because of the gear ratio setup requiring the motors to spin faster to turn the screw.

Steve.   Well if it does have Prodrives in there, they are ripoff's of the Gecko G201.  The Gecko's at least are rated to 80v.

Re: reductions.   It's all about tradeoff's, with 2:1 reduction you probably more than half the torque at your target rapid speeds, as the stepper looses torque most at higher speeds.  I dont quite get their logic!   If it's a wood router then it needs much less torque than my machine cutting metals.  You will be wanting to cut at higher speeds than me.   If you were using servo's I'd understand it.

My vmc yesterday was cutting Al-alloy during testing at 1000mm/min (40"/min) 3/4" endmill 40% stepover and 3mm (1/8") deep cuts, no problem with it at all.  and thats direct drive steppers with lower holding torque than yours.  No idea of their torque when actually moving though.  These are chinese square body motors.

Steppers can be  a pain to get right, but very possible!  Doesnt help that there's so much duff information out there!

315

General Mach Discussion / Re: MOTOR LOCK-UP ON RAPID MOVEMENT

« on: April 25, 2006, 07:50:43 AM »

I attached the specs on the stepper motors. I have size 34 P/N PF4913A-05 on all three axis.

Steve...

Looking at that there are two 1280 oz/in motors.   Looks like you have been wise and bought the lower inductance one.   Although they dont mention it at all.   But my guess is the lower current version 34 P/N PF4913A-11 is the higher inductance versoin.

It may be that you are just not driving them with enough voltage.   I know nothing of the drives you are using..

I personally wouldnt of had the 2:1 reduction with steppers.   It generally makes matters worse, and they need to spin faster with it.

I'm currently retrofitting a small vertical machining centre and have 920oz/in steppers driving 5mm pitch ballscrews 1:1 through compliant couplings.   I get over 5000mm/min rapids with no stalling.  I'm using 72v supply through Parker drives.  Motors rated at 4.2A.

The same motors struggled to spin at an equivilent of 3000mm/min on the bench.

Anyway you can try it without the reduction?

I really dont think this is a signal jitter problem..


Wayne...

316

General Mach Discussion / Re: MOTOR LOCK-UP ON RAPID MOVEMENT

« on: April 24, 2006, 07:02:30 PM »

It will run fine for long periods but then all of a sudden a motor freezes and makes awful sounds.  I have had it happen individually on all three axis on separate occasions. Can anyone provide suggestions or offer advice on how to trouble shoot this?

Steve

That is a classic step motor Stall.   You are probably trying to run them faster than they are able to.

Tell us about your setup.   Are the motors on the machine and driving a load?   Steppers on the bench unloaded will nearly always stall at a lower rpm than when under load.

Also steppers prefer to have some damping between them and the load.   Never use rigid couplings.   I tend to use fenner couplings with a nitrile insert acting as a damper.

Wayne....

317

Show"N"Tell ( Your Machines) / Re: Got My mill running :)

« on: April 24, 2006, 12:48:36 PM »

I think it is time to finish wire it and get making chips.... the pen is fun but chips are so much cooler

Not if they are blue ;-)   

318

General Mach Discussion / Re: Can I connect my stepper motors to the COM port?

« on: April 22, 2006, 06:38:10 PM »

No you can't.   Mach3 handles the motion control directly.    If you want to go this route with an external step/dir controller, then it's either the Camsoft product and their software.  Or Mach IV and Gecko's G100 which is similar to the Camsoft controller, but connected via ethernet.

The latter is more likely to have the level of support we are acustomed to with Arts products ;-)

Wayne...

319

Show"N"Tell ( Your Machines) / Re: Got My mill running :)

« on: April 20, 2006, 02:08:39 PM »

I made my own cables... the breakout is to big and nasty to put in my mill

You should post some pics of the installation Brian ;-)    I wonder if Automationdirect will supply outside of the us.

320

Show"N"Tell ( Your Machines) / Re: Got My mill running :)

« on: April 20, 2006, 09:48:55 AM »

Yes they are 

Yes I vaguely recalled you said you had some to try...   I'm very interested in them myself as Servo systems seem to be very expnsive in comparison here in the UK. (We do tend to pay £1 per $ on some imported stuff)

Did you have rto buy all the items listed? ie leads, breakout, etc etc.

Wayne...