I'll second the non-use of reamers here. Just drill 'em, and remember
you have the choice of numbered, lettered and metric drills to get the
size hole you need. Temperature also seems to play a big part in how
much spring back you get drilling holes in this kind of material.
Experiment :-)
==================
Leon McAtee

Bob Upp wrote:
You can reference standard drill size "probable oversize" which would
apply to holes in metals but I work with black polyethylene parts a lot
in my ultra-lights and helicopters and if I used it for your purpose I
would just use a 1/32 or 1/64 oversize drill. From my experience a .6250
drill will leave an undersize hole in polyethylene and a reamer would
just push polyethylene aside unless the edge is ground and relieved
especially for pliable material. Instead of wasting money for reamers I
would just drill test holes and then check for the clearances you need.
My guess is that a 41/64 drill will give you a probable hole of .6407
inches in aluminum and somewhat less in polyethylene, maybe .630 or so.
I suspect the drill speed will effect finish hole size as well and you
could experiment for finish hole size this way too.
Again, in metals and hole sizes of around 1/2" to 3/4" will be roughly
.004 oversize and in plastic probably less. I say drill some test holes
and try them out.




"DonMorrisey" wrote in message
oups.com...
I'm trying to figure out how and where to buy reamers. I need to
create some 5/8" and 1/2" holes in ultra high molecular weight
polyethylene blocks for my control system. The aileron push tubes
slide thorugh the blocks and the aileron actuators mount in the blocks
as well. The mounting component of my aileron actuator is 5/8", so
when buying the .6250" reamer is that already slightly oversized? I
have been told the holes should be oversized by .002". I have looked
for reamers on line but don't know if what I'm buying is the right
size, there is little or no description for them.

Can someone tell me what I should look for in buying these tools and
where may be the best place to do so?

Thanks. Don