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Author Topic: Wooden CNC Router -- Pillow Block Set Screws  (Read 1113 times)

AtomicProf

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Wooden CNC Router -- Pillow Block Set Screws
« on: April 07, 2013, 12:12:42 AM »
Hi ALL --


The drive belt came off on me on the LEFT-RIGHT axis..  (X)...  First we thought that maybe the two drive motors on the FRONT-BACK axis (Y) were getting out of synch.  So I lined them up..  Put the belt back on..  And went ahead and did some cutting..  The drive belt came off again.


Now -- An interesting thing happens when this drive belt comes off..  The X axis stops moving, but the Y axis is happy to continue on..  This means that I ended up with a wandering cut through my work piece..  GRRRRR....


SIDE NOTE -- Should something like this happen..  STOP the LINUC CNC program..  don't worry about turning off the router..  SEE -- if the router is turned off and then you turn off the LINIX CNC -- well not instead of cutting through the material.. the machine will PUSH it.. and it is very strong..  AND it will crack the wood that the CNC router is made of.. and maybe bend the bit.  So STOP the LINEX CNC (i wonder how to spell linux)


OK -- SO back to the belt coming off..


The culprit was the SET SCREW.  There is one set screw on the motor end of each drive screw.  This set screw fixes the drive screw so it will not move linearly in its own axis.  With a tight set screw, the drive screw will turn, and then the cutter will move.  However with a LOOSE SET SCREW..  the motor will turn, and then the force of cutting into the stock will push back on the drive screw and it will move linearly and it will move enough that the belt will come off.


SOLUTION -- There is an allen wrench on the right leg of the machine.  This is used to tighten these set screws.  I tightened them.  It probably should be checked once a week.  This would be a good thing to list on the STATUS STAKE, the last time the set screw were checked.


See photos. 
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tomlong74

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Re: Wooden CNC Router -- Pillow Block Set Screws
« Reply #1 on: April 09, 2013, 12:36:26 AM »
Actually, this also happened to me and I had to put the pulley back on align and re-belt it.

I loosened the stop screwto 'snug fit' for safety reasons.

When the system is powered off it discharges the left over power into one of the motors and can cause the the CNC's wooden shuttle to break (as it already shows breakage). The idea is that it is better that the pulley pop off than the stop screw cause the unused power to torque and further damage the shuttle.