Thread: Lost steps on A/X axis

Hi, bob is it the motor which took a swim or the new motor you added that is causing a problem? or does it alternate between the 2?

Has the PSU got enough grunt to drive all the motors?

Hi Chris

It seems to be mainly the newer motor that is stalling.
I must have wired it up correctly because it is actually moving along OK.

The power supply I use is an AnTek torroidal PSU that puts out 70Volts DC at 11 amps

This should be able to handle the ...hmmmmmmm just checked on your site, and the 1200 oz motors draw a maximum of 6 amps each, so that is 12 amps even without the other two smaller motors which also draw about 3 amps each.

Damn

What to do now?

Well. I could buy another one of these to go with the one I already have.

Or


I could go for a larger one that handles up to 19 amps. If I go this way then it would cost another $225 plus postage,, but I would then be able to sell the old power supply for about $120 or so.

Bob Willson

Originally Posted by Bob Willson

Hi Chris

What to do now?

I'd disconnect the other 2 motors/drivers from the psu and then check performance and see at what point it looses steps, keeping acceleration the same, if it is a problem with the PSU you should see some gains I'd think by removing the 2 motors.

Good suggestion Chris

I did that and I can get the speed back up to 4000 again.

I ran it through about 20 iterations of
G0
X0
X1550
and it ran fine. Even got a bit too much whip on the screws due to the speed.

I'm just going downstairs again to try it at 5000.

Nope, that didn't work, but then again I didn't expect it to.

Bad thing is that definitely means that I need to spend more money on this pale elephant.

Bob Willson

It might be worthwhile looking into a 2:1 increase with those massive motors and 5mm ballscrews, it should give you better performance.

About the PSU if you dont want to spend too much money a seperate switchmode PSU would probably be the cheapest option.

Originally Posted by Ch4iS

It might be worthwhile looking into a 2:1 increase with those massive motors and 5mm ballscrews, it should give you better performance.

About the PSU if you dont want to spend too much money a seperate switchmode PSU would probably be the cheapest option.

I had thought of making up a belt drive for them, except I was going to look at 4:1. Not that I would expect to drive at those speeds but the gearing would be a good thing.

The only problem with switch mode PSU is that they generally only go up to about 48V.

Bob

I ordered a PS-10N70R5R12 power supply from AnTek. which supplies 14.3 amps at 70 V at a cost of (US$180) plus (US$44)

I had originally intended to order their PS-15N73R5R12 power supply. This would have given me 19.5 amps at 73V, but not only was the price for the supply a fair bit higher (US$ 240)but the delivery was almost 5 times as much as well at US$200

Bob Willson

Ok, I got the new power supply and the wired it all up to the motor drivers and then sat back to wonder why the motors weren't holding or turning at all.

Can you spell dlckhead? I had wired it all up back to front and blown the fuses in the Geckos. Two days later when the new fuses arrived and I had wired it all up properly using colour coded wires this time, and the motors turn on and hold.

Start testing and F@#$. It didn't make any difference at all to the way the machine behaved. Still lost steps in one motor or the other.

I re-ran the driver test and it said that all was OK.

Is it likely to be the BOB? I have had trouble in past with same board.

Bob Willson

Originally Posted by Bob Willson

Is it likely to be the BOB?

Bob Willson

Left yourself wide open on that one.

Bob
What sort of B.O.B. are you running?
I have had some issues with CNC C10's in the past.
Presently running dual motor machine '(i.e. Y and A axis) and initially had somewhat similar issues with racking when reffing but cured the problem by chaning out the B.O.B.
Cheers
Noel

Originally Posted by rodm

Left yourself wide open on that one.

You are beneath my notice Rodney.

Bob

Whoops, forgot the smiley

Originally Posted by PsychoPig7

Bob
What sort of B.O.B. are you running?
I have had some issues with CNC C10's in the past.
Presently running dual motor machine '(i.e. Y and A axis) and initially had somewhat similar issues with racking when reffing but cured the problem by changing out the B.O.B.
Cheers
Noel

Hi Noel
Yes, it is a C10.
I have set the steps to 400, the velocity to 1000 and the acceleration to 80 and it is still losing steps.
What B.O.B. (Thanks again Rodney) did you use instead Noel?

Bob Willson

Solved the problem. It was all because I had set the steps too high at 400. Apparently this should have been 138.68285.
Using this number I can now set the acceleration to 1000 and velocity to 4000. this was of course brought about by my having put a 44 tooth pulley on the motor and a 15 tooth pulley on the shaft. No doubt I could make it a lot faster, but that is fast enough for now. At least it is all going again.

Now, ????? what to make? Hmmm.

Bob Willson