Cutting Thermal Ply

[bob_anderson]

I have been approached concerning cutting parts from Thermal Ply which is similar to hard board but not as thick approximately 1/8" thick. When I tried to cut this material using 1/4" downcut spiral and straight cut bits the cut quality was fuzzy and quite rough. Has anyone tried this before and what kind of bit did you use as well as feeds and speeds.

[Brady Watson]

Robert,
You are going to get fuzz nomatter what cutter geometry you use...a quick pass with some 220 on an orbital sander (just on the top surface) cleans the edges up perfectly.

-Brady

[paco]

Compression bits?

[billp]

Paco,
Most compression bits wouldn't work because the lower segment of the bit is usually deeper than the 1/8" that Robert wants to cut. In effect it wouldn't be much different than running an upcut spiral...
Robert,
It might be worth trying a spiral "O" flute (one flute) bit which is still an upcut configuration but they are usually SO sharp that they minimize the fuzzies...And it would minimize the sanding which you might have to do anyway..

[paco]

Oups... answered too fast...

What about Onsrud 60-102 (1/8" CED, 3/8" CEL w 1/4" upcut, compression) cutting say 3/16" into the spoilboard... assuming the order justify this... migtht worth to consider.

I remember Bill Young telling me he acheived clean cut in birch ply by cutting it once paint... maybe just some sort of "sealer" would hold the fuzz down...

[mziegler]

Robert what is Thermal Ply? What do you use it for? When I Google Thermal Ply, it gives information about Radiant Barrier, paper rolls for credit cards, dog and cat insulation and all kinds stuff. I also Google Thermal Ply hardboard still don't know what Thermal Ply is. Thanks Mark

[bob_anderson]

I didn't spell it correctly it is Thermo Ply and is used in new construction as wall sheathing prior to applying house wrap and exterior siding. The way I'm planning on cutting this stuff is to lay up 8-10 sheets and then cut out the parts that my customer wants. The fuzzy parts are the top and bottom pieces. But the fuzzy parts are more than some minor tearout it is quite pronounced. An upcut bit causes a lot more than a down cut. I was wondering if a stagger tooth bit might work. My customer makes consoles for antique cars and he applys vinyl over the thermo ply parts so a little bit of fuzz doesn't matter. Mark you can find out more on google.

[billp]

Robert,
If it's only the top and bottom sheets which have the tear out/fuzzies, could you try to place a backing piece of some sort of ply/MDF on both the top and bottom to see if it doesn't then transfer the fuzzies to the sacrificial pieces?

[beacon14]

1/8" thick wall sheathing? I thought I had heard of everything

[bob_anderson]

Well sometimes I can't see the forrest for the trees. I had tried to mannualy sand the rough edges with 80 grit and decided it wasn't worth it. The best and most obvious solution is to use 320 grit sandpaper and my ros to knock off the tearout, which worked great. My thanks to all who responded. Bob