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Band saw to cut foam/glass


aviator_edb

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Getting close to start. I almost have the workshop finished.

I haev a question about the different techniques used to build the bulkheads.

Someone mentioned the cutting and glassing the foam oversized then cutting to dimension with a band saw works well. With this method is there any chance of the glass being pulled up from the foam at the cut?

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I'm in the middle of my bulkheads (chapter 4, step 4), and only used a bandsaw for cutting out the hardpoint shapes. I didn't have a Fein tool when I started, but would highly recommend it at start for anyone convinced they're going to make the long haul with this project. I could have cut the hardpoints with the Fein, but the bandsaw worked great in that case.

 

You don't have to worry about using a bandsaw or not for many of the bulkheads anyway, as there are quite a few internal cuts that prevent you from using it altogether.

Jon Matcho :busy:
Builder & Canard Zone Admin
Now:  Rebuilding Quickie Tri-Q200 N479E
Next:  Resume building a Cozy Mark IV

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Bandsaw is plans recommended, but not for the oversize methods some use. You're supposed to cut the foam to match the templates, then layup one side & either knife trim the excess when still soft or bandsaw it when cured. It is hard on the blade, but I haven't heard of resulting delamination. A jigsaw, with its reciprocating action, would most likely do some damage.

 

In the archive you will find posts from "Dust" (now migrated to the "dark side") who made his bulkheads oversize, then trimmed twice with a router to a ply template to make bulkheads that are probably more accurate than the plan templates... This extra gibber may have been worth it as he is building two Cozy and the jigs & templates have gone to others and will probably make plenty more. I am in no way convinced it will save you any effort if you have to make the ply templates yourself and use them once, the plans methods work fine.

 

I've used a Fein, (in my one and only layup so far) and concur they are brilliant. Bit pricey but.

Mark Spedding - Spodman
Darraweit Guim - Australia
Cozy IV #1331 -  Chapter 09
www.mykitlog.com/Spodman
www.sites.google.com/site/thespodplane/the-spodplane

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Someone mentioned the cutting and glassing the foam oversized then cutting to dimension with a band saw works well. With this method is there any chance of the glass being pulled up from the foam at the cut?

aviator, summarizing a KISS approach...

  • Get yourself a Fein Multimaster. I got the 'start' model because I didn't think the variable speed option was required or worth the extra $ (I still feel that way).
  • Cut the foam however you feel is best. I used a 'razor saw' for the low density foam, and a Dremel with a cut-off wheel for the high-density foam (along with other Dremel bits). I suppose I could have used the Fein as well for the high-density, and could also have used a bandsaw or jig saw -- up to you.
  • Without testing cutting glassed foam in a bandsaw, I'd be very careful. It seems to me that it would delaminate, or worse yet, do so without you being able to tell.
  • Use the Fein tool to cut the glass close to the foam, but not butt up against it. To finish the edges, just sand. Sanding glass edges is relatively easy and painless. I have found the Permagrit line of sanding tools to be excellent (not the rotary tool bits).
  • I mentioned I used a bandsaw to cut out the hardpoint material as traced in the attached image. There was no foam to delaminate from, and the bandsaw made quick work of this. However, notice the rectangular shape of the bulk material. That was cut using the Fein tool. Neither approach will assure you of straight edges -- use a long Permagrit sanding block for that.
Templates for bulkheads have been used by others in addition to dust. However, I'm not convinced what value they really add considering you need to invest time into the creation of the templates themselves.

post-386-141090152499_thumb.jpg

Jon Matcho :busy:
Builder & Canard Zone Admin
Now:  Rebuilding Quickie Tri-Q200 N479E
Next:  Resume building a Cozy Mark IV

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The easiest way is simply use a sharp knife or razor knife to cut the foam to "very close" to the template, a light sand with appropriate sandpaper (36-60 grit) to the proper size, then apply the glass.

 

A much earlier post of mine describes the curing process of fiberglass and resin, which is a good place to experiment too. I did!

 

A bandsaw pushing the glass into the foam (glass on top, foam below) will not delaminate it even in "brittle" stage, and after full cure, won't delaminate it.

 

The fein is great, and while the glass is brittle, can delaminate quite easily. The big difference is the fein blade will last a lot longer. I was replacing bandsaw blades every week when I used it for glass.

 

Knife trim to the foam or cut with the fein to the foam. Close enough for government work!

 

I have the variable speed Fein, and while it changes the sound a little, I find I run it on high almost all the time to get a peoper cutting rate, so it's not a real benefit right now. For detail sanding I can see the speed control helping, but that's next week!

/dan

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