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Taper Cuts on Light Ply

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Old 02-15-2012, 03:12 PM
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AA5BY
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Default Taper Cuts on Light Ply

When repairing or scratch building, most planes have a few taper cuts. On balsa, such cuts were easy, just lay a straight edge on the taper and knife cut it. That doesn't work on light ply however. If one has a table saw, a very simply way is shown below. Pick a scrap of plywood a little larger than the largest part that will be taper cut.and thick enough to accept screws through a couple of cleats. Rip it to near its width and leave the rip guide set. Now, fasten the piece to the top with cleats aligning the taper cut marks to the edge of the board. Run through the saw.

It is that easy.
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Old 02-15-2012, 03:24 PM
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Default RE: Taper Cuts on Light Ply

Excellent
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Old 02-15-2012, 05:12 PM
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Default RE: Taper Cuts on Light Ply

If its something like a fuse bottom on a box fuse, I usually rough cut'em glue everything up, then use a router table with a trim bit. The fuse box sides guiding the trim bit will make a flush cut.
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Old 02-15-2012, 05:59 PM
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Default RE: Taper Cuts on Light Ply

Yep... and the advantage to that method, it that it deals with a curve.
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Old 02-15-2012, 07:46 PM
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Default RE: Taper Cuts on Light Ply

Micro mark makes an excellent little table saw, and a taper cutting jig.

It comes in handy.
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Old 03-17-2012, 09:45 AM
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Default RE: Taper Cuts on Light Ply

I cut lite ply with a razor knife and a metal straight edge.

After a light scoring pass I usually put the straight edge aside and go with a couple full weight passes [that follow the previously scored line] to cut all the way through.
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Old 03-17-2012, 05:24 PM
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Default RE: Taper Cuts on Light Ply

Has anybody done a scarf (spelling) joint with light ply, or balsa for that matter? If you have, what is your technique?

Ken
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Old 03-17-2012, 05:45 PM
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Default RE: Taper Cuts on Light Ply

Make male / female "V" shaped cuts in the mated pieces of liteply. Just use a heavy duty razor knife to mark your cuts and do your cuts. Fill any slight gaps with fine saw dust and thin CA.
Mist 2 oz FG cloth with 3M77 to cover the splice joint, smooth the cloth out over the wood and saturate the cloth with medium or thick CA, wiping off the excess with a credit card. The glassing is optional, but doesn't add much weight or time to do.
Balsa can be done with similar technique, or just a single plane, low angle cut. Pack any gaps with fine sawdust and thin CA and glass the splice if you like.
A razor saw and home made miter box are good tools for this type of work.
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Old 03-17-2012, 06:31 PM
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Default RE: Taper Cuts on Light Ply

IMHO, a taper jig is too complicated. To start with, the cut requires holding three points. The piece has to rest against a stop, it has to stay tight to the jig and the jig has to stay tight to the fence. Second, a taper jig has significant limitations. Third, they work far better on large cabinet grade table saws than small saws like would be used for airplane construction.

Cleating the piece being cut onto a slider is faster, easier and more versatile than setting up a taper jig. The biggest plus for me however, is there is no testing that the taper jig is going to produce the necessary cut. The slider board technique produces a perfect taper cut without any testing. All that is needed is the taper line be on the piece being cut.
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