Large Grinding Machine

The 32" F/4 mirror requires a large machine to grind and polish.  John Pratte wanted a machine for himself, so we decided to scale it up just enough to handle the 32".  The machine was built by John in his shop with help from Bob, and the turntable was used to dewedge the blank.  After this, the machine was disassembled, painted, and brought to my house, where it was reassembled in my basment where the work will be done.  Here is a photo of the parts in the van parked in my driveway (with Bob Holmes and John looking on), and a photo of all the bolts that had to be installed to put the machine back together.

Parts in the van Bolts!

The frame was assembled without too many incidents in the basement.  It is shown below at the left.  Bob Holmes is standing on the left, John Pratte is on the right.  The rest of the assembly of the shafts, bearings, pulleys, gearboxes and other parts went mostly without incident, but a little "under the chassis" debugging was required to quiet a noisy coupling, and this work is shown in the next photo.

Frame assembled Debugging

Finally, below is a photo of the completed machine, complete with turntable, wooden drip pan, and the 32" mirror sitting on the turntable for completeness.

Machine assembled

Lastly, here are some photos of the drive shafts, belts, and gearboxes, and the drive arm and eccentric.

Belts, shafts, gearboxes, etc.

Drive arm

Bob also built a nice tilting test stand out of steel tubing so that the mirror can simply be slid off the turntable onto the stand and tilted nearly vertical for testing.

Now it is up to me to finish the mirror so Bob can finally get his scope operational and doing research.  It is long overdue (due to no fault of ours), and I can't wait to see it producing images.  It will be fun to work on a big mirror again!

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