This is true. Very well said.wa2crk wrote:You said that the drilling speed was about 1700 RPM.
Does the condition very when the speed is raised or lowered?
Does the chattering frequency increase or decrease as the quill is extended?
Is the chattering/vibration obvious when the headstock is horizontal?
Does the chattering get worse as the quill is extended?
Can you measure the diameter of the two quill housings at several points along the length of the housing to detect any variance between the old and the new?
Did you closely inspect the casting to see if there any cracks?
Can you change the chattering if you try to push laterally on the quill housing ( left/right or in/out ) when it is chattering?
It is now time to go through the entire problem in a methodical and predictable manner and record the results.
Come back here with a summary of the results and maybe we can figure something out.
Bill V
P.S. I just re-read your post from 1815 hrs and the reference to out of round holes. The only way to drill out of round holes is to have the drill bit running off center. My feeling at this time is that something is being held in place when the quill housing is fully retracted but picks up some play when the the quill is extended. Improperly installed bearings in the quill housing and/or play between the casting and the quill housing. I used to work in a QA lab and I love trying to get to the root cause of a problem.
This is a machine, it is fixable. I have learned the hard way that you usually need to do things yourself when the going gets rough. You (we) need to just get some parameters, apply some engineering and technical processes and get this fixed. I personally think you have bearing problems, but it certainly could be the quill itself as has been pointed out. These machines are not that complicated, so let's just get it fixed!

I am disappointed in Shopsmith, and a little disturbed by this and hopefully there is a good explanation .... :/
Just trying to help ....
