[TowerTalk] Machining Fiberglass

[Bill Aycock]

When I was active in the Aerospace industry- machining filled plastics was
a real Bear- the problem is that, unlike metal machining, the material
being cut is a very good heat insulator, and does not carry the heat away
from the very small active cutting area on the bit. The chips are a poor
heatsink.

One thing that helps a little is to use an air-blast on the tool tip- this
is dusty, so be carefull.

There is an obvious difference, also, in the effect of machining
thermosetting plastics and the ones softened by heat- I have seen some
plastics build a flange ahead of the tool, as they softened and lost
resistance needed to cut.

Bill 

At 06:03 AM 5/12/00 -0500, you wrote:
>
>Can't say about safety issues, but use common sense.
>Yes the stuff is real hard on tools, and they have to use solid carbide in
>the PC industry to get reasonable life. I have successfully turned bar and
>rodstock on the lathe using normal tool steel cutters. Use a slow feed and
>speed, and watch for dulling. You have to reshape/resharp the tool several
>times during the operation. Also the smoothness of the cut can depend a lot
>on the grain of the fibers.
>One project I did recently was to machine some 2" dia. donuts from 1.2 inch
>flat stock. The stuff looks like G-10 but 1/2 inch thick. 4 of these were
>used  to transition from the ends of a 16 ft long,2" ID fiberglas tube down
>to 1-1/4 solid barstock. That project was for the portable EME array.
>I used some more of the barstock as the insulating elements on a 48'
>aluminum tower base,  which is part of a 75M folded unipole.
>
>Geo>K0FF
>-----Original Message-----
>From: Tom Wagner <tomwagner@mindspring.com>
>To: towertalk <towertalk@contesting.com>
>Date: Friday, May 12, 2000 3:56 AM
>Subject: [TowerTalk] Machining Fiberglass
>
>
>>
>>I have access to some inexpensive fibeglass rods.
>>Are there safety issues in machining fiberglass?
>>Is fiberglass hard on tools?
>>
>>Thanks,
>>Tom - N1MM
>>
>>
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>
>
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-
Bill Aycock   ---   Persimmon Hill 
 Woodville, Alabama, US 35776
 (in the N.E. corner of the State)
      W4BSG   --   Grid EM64vr
        baycock@HiWAAY.net
             w4bsg@arrl.net

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