# Microbore Devlieg boring bar head repair.



## Tim9 (Sep 18, 2018)

I actually am just getting around to posting this today. I have a Microbore Devlieg boring bar head that had a 1" shaft on it. So I wanted to make a 3/4" shaft to use with a 3/4" R-8 collet. This makes it much more usable for me.


	

		
			
		

		
	
Turning some 1-1/2" stock to size.

I didn't take a lot of pics, but I was shooting for 1" -20tpi threads with a outer register of 1-1/2" which would snug up to the boring head housing when tightened. Sadly, my SB Model C is a little worn and it's tough holding tolerances. Bottom line is that I ended up with a register a couple of thousands shy.
   So...Plan b. Since the threads came out great I decided to take about 1/8" off the register diameter... Make a Bronze bushing a bit over 1-1/2".... And silver braze it on the shaft. After brazing, I turned it on the lathe a little oversized.
It came out great. A nice snug fit after sneaking up on the machining and final filing to fit the boring head. FWIW, the Devlieg Microbore boring heads are works of engineering art IMO. Just wonderful designed machine tools. American work of art.


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