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Author Topic: help with motor torque  (Read 7189 times)

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help with motor torque
« on: September 15, 2010, 06:30:30 AM »
hi all,
I'm new to cnc so still very wet behind the ears so please forgive me if I'm not making any sense i will try to explain as best i can.
i bought a cnc router with the intention to use the motors and board on my mill i put the z axis on the fine feed as i didn't think the motor would be strong enough to lift the whole head (i think the motors are about 400oz)but there was to much play in the spindle unless it was locked off every time,so i made a rough coupling and with the motor held by hand tried it on the column and to my surprise it moved the head up no problem at all.
then while trying to make a bracket i had bother with cambam and mach i couldn't get a circle cut, then my pc went down when i got it back up and running i had lost all the settings for the board and the whole thing was dead in the water.
so i bought a new board (TB6560AHQ) and every thing was ok i got cambam to work with mach and made the bracket for the z axis but now the motor will not lift the head it just makes a clicking sound its as if i have lost some power from the motors, i did notice with the old board when the power was on and the motors lock up it was hard to turn the mill handles but with the new board it seems easier to turn them, i have tried adjusting the motor velocity and acceleration so its just going slow but this never made any difference.
any help would be great thank you.
john

Offline Hood

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Re: help with motor torque
« Reply #1 on: September 15, 2010, 06:58:56 AM »
Have you got the motore wired up the same? Other things to check is you have the correct current setting for the motor as current gives you torque but dont set to high as it will cause too much heat.
Hood

Online Tweakie.CNC

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Re: help with motor torque
« Reply #2 on: September 15, 2010, 07:02:11 AM »
Hi John,

Sounds like you are not supplying enough current to the stepper. Most boards have some form of current adjust, check the max current specified for your motor and adjust the board current accordingly. Although the motor voltage can be exceeded by many times the motor's rated current should never be exceeded so it is a careful adjustment.

Hope this helps,

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.

Offline stirling

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Re: help with motor torque
« Reply #3 on: September 15, 2010, 07:59:05 AM »
Did I miss something? - what was wrong with your old board?
Re: help with motor torque
« Reply #4 on: September 15, 2010, 08:25:07 AM »
hi thanks for the replays I'm not to sure about the specified motor current for my motors they dint have anything on them but i will take a look at the board to see if there is some adjustment and take it slowly. this is the ebay number for the new board i got  250682276810 if you can see any adjustment please let me know

as for the old board there is nothing wrong with it after my pc went down i had to reinstall mach3 and i never had the board settings so it worked on screen but the motors never went around knowing nothing about cnc i thought it would be best to go for a new board with the settings .the old board and motors were bought about four year ago.
john

Online Tweakie.CNC

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Re: help with motor torque
« Reply #5 on: September 15, 2010, 09:03:58 AM »
Your current settings are dip switches 1 & 2 as follows :-


setting      1          2

100%       on       on
75%         on       off
50%         off       off


You would be wise to look up your motors maximum current rating as specified by the manufacturer.

Tweakie.
 
« Last Edit: September 15, 2010, 09:07:41 AM by Tweakie.CNC »
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: help with motor torque
« Reply #6 on: September 15, 2010, 09:26:52 AM »
hi,
thanks for getting back my settings are 1 on 2 off so if I'm right I'm running at 75% so if i set them both to on i should be at 100%
told you i was new to all of this, the motors have no names or markings on them so i will just have to take the chance they will be OK, there a good size motor and like i say they were alto harder to turn with the old board so must have been getting more juice.
thank you again for your help
john

Online Tweakie.CNC

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Re: help with motor torque
« Reply #7 on: September 15, 2010, 09:46:08 AM »
Good luck, hope it works OK.

As Hood said too high a current will cause too much heat in the motors so keep checking they are not running too hot to comfortably hold your hand on.

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: help with motor torque
« Reply #8 on: September 15, 2010, 09:55:52 AM »
ok mate thanks again I'm off to give it a try

Offline RICH

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Re: help with motor torque
« Reply #9 on: September 16, 2010, 06:37:22 AM »
skanner,
Simple intial test would be to be to select the lowest current setting and see how warn / hot it gets to the feel in say 5 - 10 minutes.
Work your way up. If the current setting is to high the motor will get hot rather quickly and then drop down by one setting.
 With that setting see if you can move the Z, if not, then you may be able to change the wiring. Go through the currrent testing again if you wire the stepper differently. Go to the Geco site as they have explainations on stepper wiring and how it affects speed and torque.
With the current setting right, now you can test for velocity and acceleration  settings. Too high a current and the stepper may not run correctly
ie; like having it set right on the max.

RICH