Camtronics driver questions

[CNCadmin]

any one using this drivers?

[HomeCNC]

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]

I put one together and it was missing allot of parts to complete it.

[HomeCNC]

Mine too was missing parts but if you tell him he will send them.

[dakenskys]

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]

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]

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]

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]

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]

Hi Jeff,

Thanks for that info.

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

Ken

[HomeCNC]

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]

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