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cncadmin
03-30-2003, 12:10 PM
any one using this drivers?

HomeCNC
05-26-2003, 01:21 PM
I built one of the 2 amp board kits that Dan sells. It went together fine and works fine too. It is now sitting in a box with three 118 oz 1.5 amp .9 deg stepper motors. The 2 amp board from Camtronics works great. The maximum voltage the board will handle is 18VDC. I was going to do something with this stepper system but I have now moved on to servos.

cncadmin
05-26-2003, 02:48 PM
I put one together and it was missing allot of parts to complete it. :(

HomeCNC
05-26-2003, 08:35 PM
Mine too was missing parts but if you tell him he will send them.

dakenskys
06-15-2003, 03:14 PM
Hi Everyone,

I also built a 2A 3 axis system with camtronics and am using Desknc and Deskam.

I'm having a problem in that the stepper motors slip, and my cutting is way off...sometimes as much as 1/8" or more.
I also noticed that circles are not very round.

Any ideas how to correct this?

I am quite upset after spending a lot of time building the whole system, and am considering changing to a servo drive system.

Can anyone suggest a site where I can buy the driver and servo motors at a good price?

Thanks,

Ken

HomeCNC
06-16-2003, 12:07 AM
Give us more information. How big are your stepper motors and the amps and volts of them. What voltage are you running the motors at? You are loosing steps because you are running them at a rate that is too great. Slow down your step rate (in/min) until you get a stable run of the motors.

dakenskys
06-16-2003, 05:25 PM
Hi Jeff,

Not sure of the size of the motors....they are Pacific Scientific types. The label says .76A(DC) Bipolar
I believe that the driver is set to run them at 18 volts.
As to the program....Desknc, it is set at the following:

Max steps/sec - 500
Start velocity (sps) 300
Acceleration (sps*s) 10000

It seems to be jumping, or skipping when changing from an X axis cut to a Y axis direction and vice-versa.
Thanks for any help.

Ken

dakenskys
06-30-2003, 09:22 AM
As a followup to my last post....I think I may have solved my own problems.

I looks like the steppers don't have the power I need as I can grab the ball screws and stop them with my hand.

My thought to correct this is to add a gear train in the ratio of 1:3 so as to increase the torque of each motor.

I would guess that I also have to make some changes to the program to increase the steps per inch to account for the change in speed and turns per inch.

Has anyone else had this problem...and do you think this is a correct way to go?

HomeCNC
06-30-2003, 12:57 PM
You do know that with a stepper motor the faster you turn them the weaker they are. A stepper motor is strongest when it is not moving. If you want to make them stronger you must spin them slower. If you gear them and then run them faster you are defeating your gearing.

dakenskys
06-30-2003, 01:00 PM
Hi Jeff,

Thanks for that info.

Is there a rule-of-thumb as to the proper speed to run these motors?

Ken

HomeCNC
06-30-2003, 01:30 PM
If you can't increase the voltage anymore then you must find the maximum IN/MIM by trial and error. Start with a slow feed rate of say "4" in/min. I don't know 'DeskNC' so you will need to figure out how to set this speed. Move the axis 20" so it will move for awhile. Can you stop the screw with your fingers? If not then set the feed rate to "8" in/min and do the same. Do this untill you can stop the screw or your stepper motors start to jump and miss steps. Back off a few in/min setting and this will be a good maximum speed of your setup.

dakenskys
06-30-2003, 01:59 PM
Thanks Jeff,

I'll try what you recommend tonight.

If it looks like the speed is too slow to get decent production, would you recommend changing to a servo system?

Ken

HomeCNC
06-30-2003, 05:09 PM
A servo system is not cheap. You would need new drives and power supply as well as new motors. You would be talking over $1000 for all the electronics.

Why don't you get one of these motors to test with your setup. If it works then you can get two more.

http://www.herbach.com/Merchant2/merchant.mv?Screen=PROD&Store_Code=HAR&Product_Code=TM02MTR4572&Category_Code=STEPPING

dakenskys
06-30-2003, 07:58 PM
Jeff,

I looked up the torque of the motors I have and they are rated at 77 to 116 oz/in.

The one you suggested at 187 oz/in is about 60% more.

Will consider giving it a try.


Ken

Kookaburra
07-09-2003, 03:19 AM
With the powermax motors there is usually two ways you can wire the plug at the motor end (that is if it is not a flying lead type). One is a series configuration the other is a parallel configuration, you will get much more out of them if you wire them in the parallel configuration. I you look up the powermax cattledog it will show you both ways of doing it, we had a similar problem and changing the config fixed it for us. Also grabbing the shaft to stop the motors is easy in most cases when you are testing the torque, the best way to test the mechanical advantage/motor power is to set the axis moving and try pushing the end of the table in the opposite direction.

We have dans stuff and are happy with it. :D

dakenskys
07-09-2003, 07:40 AM
Thanks Dave,

I'm not quite sure how the motors are hooked up...but will see if that makes a difference.

Kookaburra
07-09-2003, 05:01 PM
No Probs,

If you can't find the specs you need I can fax them to you as we use these motors all the time for our cnc retrofits. Just pm me your fax no.

rob2424
07-10-2003, 07:53 PM
Hi Kb
the powermax steppers with the flying leads
how are they wired in series or parallel?
thanks
rob

Kookaburra
07-10-2003, 10:26 PM
Rob,

I will look it up for you, I'll get back to you as soon as I can, I will have to find out what colors correspond to what pins in the plug type that we get in, once I get that info I will email you a diagram.

I will keep in touch.

Best

jimini
07-30-2003, 02:49 AM
Ken
I just verified with Dan that you can run higher voltages on that board if you run a seperate 5v supply.
I intend to run 24v and Dan said it was possible, but you'd require a larger heat sink...........Jim

dakenskys
07-30-2003, 06:29 AM
Thanks Jimini....will look into that.

In the meantime, I added a 3 to 1 gear train, and the torque has increased quite a bit, where I can't stop the leadscrews with my hand anymore.