Wednesday, February 23, 2022

Ganesh CNC Mill

Hello Everyone,

As I mentioned in the last blog update, there was not a lot going on in the Prowler world during late 2020 and early 2021.  So, I took advantage of the time to get some machine fixing done. 

CAUTION ! - This blog update does not contain any Prowler related material.  If you don't care to see me talk a lot about repairing old machines, you might want to skip ahead to the next blog update.

One project that has been nagging at me for years was my Ganesh CNC mill.  From the time that I bought the machine, it had damage on the top of the spindle motor.  You can see it here:
It appears that during a previous move, it was run into a door overhead or something.  All of the bolts holding the plate on top had been sheared off and was just sitting loose on top of the motor frame.  That slotted circular plate holds the cooling fan for the spindle motor.  So, I have always wanted to repair the damage and get the spindle motor cooling fan re-mounted properly.  First step was to remove the top of the motor frame:
You can see more of the damage better here.  I checked on just buying a new motor frame, but it was going to be over $400.  I didn't think that was an acceptable cost.  So, I set out to fix it, or make a new motor top frame.  If I had the missing pieces, I might have tried to weld the frame back together.  But without those, it was going to be a lot of work.  If I tried to fabricate a whole new piece, I would have to design something with the webbing and bearing pockets that are integral to this part.  The last option was to try to re-make just the cylindrical portion that actually had the damage.

This option would require keeping the webbed part of the frame that holds the upper motor bearing and centers the motor shaft, and then fit and attach a new cylinder to the webbed plate.  That might work!  I thought I remembered having a large diameter aluminum tube from an auction a while back.  I dug it out of the storage shed and, sure enough, it was the right size!
Cool!  I cut a piece off the right length:
Looks good!
Next, I had to true it up in the Bridgeport mill to make sure the cylinder was square.  I did that in the Bridgeport mill by fixturing the cylinder in the super spacer (set vertically) and then rotate it 360 degrees against an end mill (on both ends):
The next step was to remove the cylinder portion to be replaced off  of the motor frame and leave just the webbed plate.  Some cut-off wheel work with an angle grinder got it started:
So far, so good:
Now, back to the Bridgeport mill to clean up and true-up the webbed plate for the new cylinder.  Here is the webbed portion of the motor frame fixtured in the Bridgeport mill.  I ran an endmill around the perimeter of the part to get it flat and true so that the new cylinder could be bolted to it:
Then, I flipped it over and drilled a proper hole pattern for mounting the new cylinder.  In this pic (below) you can see the bearing pocket and the centering shoulder that keeps the spindle motor armature aligned.  You can also see the counter sunk holes I put into the frame to use to mount the new cylinder:
Then, I drilled the same hole pattern in the bottom end of the new cylinder.  On the top end of it, I drilled the correct hole pattern needed for the fan plate on the top.  Then, I bolted the webbed plate to the new cylinder.  Here it is put together:
After that, it could be fitted back onto the spindle motor:
It worked perfectly!  A quick test run of the spindle ensured that the motor was working properly.

Next, I was going to need to fabricate a new slotted plate for the spindle motor cooling fan to mount onto.  Here is the old part placed on top of the new aluminum plate stock to make sure it would be big enough to cover the new cylinder top:
Since the spindle motor on the CNC mill could now be used,  I mounted the new fan motor plate stock into the CNC mill, wrote a program, and cut it out:
Here is the whole unit put back together:
All that was left was a coat of matching paint.....well, close to matching:
Oh, and put the data plate back on:
Happy to have this repair project done!!

Thanks for checking out this repair job.  Next up, more of the work I've done on the never ending Hardinge CHNC lathe project.

1 comment:

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