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Author Topic: Bad BOB???  (Read 6546 times)

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Bad BOB???
« on: February 17, 2011, 07:42:52 PM »
 ???   First of all I'm a real beginner in building a CNC.  I built a Router, which was a real blast.  Problem being that I think I purchased a real inexpensive break out board.  Toshiba  board.
I'm having a fit trying to figure out the problem with my Y axis. The other 2 axis cooperate rather well.   At any motor setting or speed, the Y wants to stall out for only a millisecond now and then?  Which pretty much messes up my projects.  I've checked all the wiring, changed stepper motors, and no change.  I've even switched axis.  And in doing so my problem is with the axis that I've changed to. So to me this pretty much tells me the problem is with the board???  In looking into purchasing a new board, I'm really confused as to what to look at or look for?  I don't mind spending money on a quality product, on the other hand I don't want to break the bank (I'm retired) and this is suppose to be a hobby.  Anyway, any suggestions on a new board or possibly might be the problem if not the board.  I would be really appreciate input. Please keep it simple. 
Re: Bad BOB???
« Reply #1 on: February 17, 2011, 08:08:24 PM »

You haven't provided information about what stepper drivers and other components you are using.  A bit more info whould be helpful.

I sell, a robust and simple to use breakout board.



Homann Designs
email: peter at homanndesigns.com
Re: Bad BOB???
« Reply #2 on: February 17, 2011, 08:34:24 PM »
Ok, I'm using (3) KL23H2100-30-4B   382 oz-in Stepper motors, TB6560 Driver Board (4 axis) but only use 3.  Ball and screws acme drive.  And of coarse Mach3
Re: Bad BOB???
« Reply #3 on: February 17, 2011, 08:52:07 PM »
You could try to rotate the screw by hand on the Y axis, seems like a mechanical problem.

Verify if it is easy to rotate the screw all the way from one side to the other

Re: Bad BOB???
« Reply #4 on: February 17, 2011, 10:03:30 PM »
I've done that, in fact when I power jog the Y axis it works really good, it's only noticeable when I run a X Y combined move?   The Y axis stops and the X continues and then the Y starts moving again, and that happens anyplace on the table, so I doubt that it's mechanical. 
Re: Bad BOB???
« Reply #5 on: February 17, 2011, 10:55:02 PM »
You might monitor the power supply output voltage while making combined axis moves. A significant drop due to an undersized PS can produce symptoms similar to what you are seeing.
Re: Bad BOB???
« Reply #6 on: February 18, 2011, 09:04:43 AM »
have you got a capacitor on each driver as well as a main one in the power supply. If not maybe there isnt enough power to run both motors at the same time
Re: Bad BOB???
« Reply #7 on: February 18, 2011, 01:36:47 PM »
Each one has it's own capacitor, my power supply is a HS 300-4  24 volt 12.5 amps.  Not quite sure what the voltage at each motor is suppose to be (4 wire stepper motors)?    In playing around a lot more, I've found out that the machine seems to run X Y combination moves without hesitation, but when you run arcs, is when it appears that the Y Stalls???? Frustrated, but retired and have lots of time.  I have no doubt that it's electronics and not mechanical. 
Re: Bad BOB???
« Reply #8 on: February 18, 2011, 09:59:09 PM »
the voltage should be around 10 to 20  times the motor voltage if the voltage per coil is 2.5 volts at 1 amp for example you could use any thing from 24 volts to 50 volts dont forget when you take for example 20 volts ac and convert it to DC with your compacitor in line the voltage will increase 1.5 per cent so now you have 21.5 volts this is all aproxamite but all within  a volt. look on a forum called   mechmate.com    they have all the formulas and infermation that you need to check machine build problems . They were out of south africa now it it run out of the U.S.

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Re: Bad BOB???
« Reply #9 on: February 19, 2011, 06:17:02 AM »
the DC voltage will be 1.4 times approx the AC volatge so 20vAC would be approx 28vDC.

It seems you are using an all in one 4 axis driver with inbuilt bob? You mentioned swapping motors around and the problem stayed with the actual outputs I think? Have you tried putting the motor on the spare drive outputs?