[TowerTalk] Cutting Large Holes in Aluminum

[KB7WW Art Moe]

Mike,

You don't say what size your lathe is, so I will take a stab at it.  

Guessing you have a 10 inch I would start by putting on the 4 jaw chuck,
centering the work then drill the largest hole that you have a bit for.
Then using the largest boring bar you have start in boring. Depending
on how rigid your machine and boring bare you should be able to take 
out .100 or more, on our 18 inch at work I have bored aluminum at .500
per pass with large inserted boring bar. Watch your feeds and speeds
don't turn to slow I would start at about 250 SFM (not rpm) at .005 feed
and go from there. If your set up is rigid enough go to 300 350 SFM and
up the feed rate.  Use your power feed to keep an even load on the cut.


Another thing you could try is taking the cutting tool out of your fly
cutter and and mounting it on your tool post cut half way then turn
the part around and finish. Then you could bore to finish size.

Art
KB7WW




Mike Wetzel wrote:
> 
> I have aluminum rectangular blocks (4"x4"x1") that I need to cut a 3"
> diameter hole in (using them instead of muffler clamps).  I tried a bi-metal
> hole saw and also a circle cutter with not much success since I need to make
> about blocks altogether.  I have a metal lathe that I can bore the finish
> diameter on but I would like to get a big chunk of the material out of the
> way (to save some time).  I have also thought of using a smaller drill bit
> (1/2") and drilling a series of holes around the diameter and may do this
> but there seems like there has to be a better (less labor intensive) way.
> 
> Thanks
> 
> Mike W9RE
> 
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