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Author Topic: Roatery Table addition questions  (Read 2819 times)

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Roatery Table addition questions
« on: December 14, 2009, 10:26:53 AM »
As the title mentions I am adding a Sherline rotary table and have a few questions.  I have read several posts on running the rotary table in degrees or linear, but what would be the easliest/most common to use?  I am using Bobcad v23, but pretty new to it and really new to 3d/4th axis aspects of bobcad.

Its currently set up as 3 axis, so the entire 4th axis addition will be new to me.  Any other tips or guides that have already been writtten for adding a 4th axis and/or a rotary table would be appreciated.  My basic setup is;

Smoothstepper
CNC4PC C23 BOB
CNC4PC C3 Index Pulse Card
CNC4PC C16 Photo Limit & Home board
KBMG 212D spindle drive
5v2a power supply
Homeade linear power supply of 28v8a.
Xylotex 4 axis stepper driver

Offline mr.c

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Re: Roatery Table addition questions
« Reply #1 on: December 14, 2009, 11:10:59 AM »
This may not be the best approach,but I configured my 12" Cushman so that 36" equals one revolution. So it is easy for me to convert to degrees. I just need to remember to add a zero. nine inches would be ninety degrees.  .1" would be one degree.

Offline Graham Waterworth

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Re: Roatery Table addition questions
« Reply #2 on: December 14, 2009, 11:23:35 AM »
All industrial rotary tables are set up in degrees, work out how many steps it takes to rotate 1 degree and that way any program from any system can be used.

Graham
America gave us powered flight, England the steam train and Germany the car.  Who invented the first boat?
Re: Roatery Table addition questions
« Reply #3 on: December 14, 2009, 11:30:09 AM »
Thanks for the comments.  This question maybe best asked in the bobcad forum but, would degrees be harder to work with than linear in bobcad?
Re: Roatery Table addition questions
« Reply #4 on: December 15, 2009, 12:44:19 PM »
I've just added a 4th axis and asked myself the same question. I decided to setup both ways on separate profiles. With the Rot 360 Rollover checked in Mach config the axis is configured as a 360 degree axis with positive values to rotate in one direction and negative moves in the other. I quickly found that if programming only in positive values, several rotations of the axis later there was a large error in position. This is because there must be a small error between my "steps per" and the gearing which culmalative.

I have found it better to uncheck the Rot 360 Rollover and set my steps per so that 360 on the dro correspondes to one complete revolution of the axis. Working in degrees is ok for the work I do but I can see if I want to do some engraving later it would be better to set the axis up linear.

Setting up separate startup profiles makes choosing which to use easy.