Using an air saw to cut fiberglass?

[sgtmac1]

Looking through the builders threads, I have seen various people recommending Dremel diamond blades and cut off wheels to slice the fiber glass hulls up-removing the top half for easy access-and was wondering if anyone had used an air saw to make the cuts? It will zip through thin sheet metal pretty quick when I am working on my car and thought that it would make short work of separating the deck of my SSY 1/48th scale fleet boat. The blades come in coarse and fine and are probably no thicker than a Dremel cut off disk.

[Guest]

Re: Using an air saw to cut fiberglass?

It will cut, for a while, but the blades will soon lose their edge, as the glass blunts out the HSS blade.

When cutting laminates, abrasive wheels, tungsten carbide cutter and diamond wheels are the best tools for the job.

[JWLaRue]

Re: Using an air saw to cut fiberglass?

I would definitely recommend using a Dremel tool (or equivalent) with an abrasive cutoff disc. You will have much better control over where it cuts.

-Jeff

[bwi]

Re: Using an air saw to cut fiberglass?

.......and it will result in a thin kerf so you need lesser touchup afterwards.

grtz,
Bart

[bigdave]

Re: Using an air saw to cut fiberglass?

Fiberglass loves HHS blades.
Eats them like candy.
You would be amazed how fast it can turn a razor sharp new blade into a butter cutter.
BD.

[thor]

Re: Using an air saw to cut fiberglass?

A reciprocating type saw should NEVER be used cut fiberglass laminates. The action of the blades has a nasty tendency to delaminate the layers of glass and can quickly destroy your part. Rotary type blades only should be used.

[mucklestone]

Re: Using an air saw to cut fiberglass?

The air saw cuts fibreglass fine they use it for kit cars all the time for much longer and bigger cuts that you will do in a model sub. They also use these to cut holes in full size boats for fitting hatches etc!!

The blades can blunt quickly but a cheap way round this is to use a full size 12" hacksaw blade. Just make sure it is a Bi-Metal blade so it does not shatter. The base of the air saw blade is the same size as the full size blade so they fit in fine and you will get three blades out of one 12" hacksaw blade, just cut them with tin-snips. Keep the thin blade for those special jobs when you need a small blade.

If you get any problems with de-lamination then it is probably rubbish fibreglass to start with. Decent fibreglass should not de-laminate easily. If it is a home-brew molded item then maybe, the resin may not be mixed perfectly, wrong temperature or too long between layer etc may cause problems but anything professionally molded should be absolutely fine.

[thor]

Re: Using an air saw to cut fiberglass?

Rubbish fiberglass? The U.S. Military will not allow the use of reciprocating saws on any of its composite components due to the use can cause delaminations which can lead to structural failure.

[mucklestone]

Re: Using an air saw to cut fiberglass?

I am always happy to admit if I am wrong - I did not know that and it is the first I have heard of it.

I know the use of these saws is very common in the kit car and boat industry for cutting fibreglass - it seems like the done thing, and that is where I was coming from. Also a quick google search show manufacturers recommending the blades for fibreglass in this type of saw.

Are you sure it is not included by a 'blanket rule'? I believe because of the type of matting used that carbon fibre/kevlar composites can be more likely to de-laminate than a fibreglass one, perhaps it is more aimed at those composites?

Does anyone member have any stories (successful or otherwise) of de-lamination caused be a reciprocating saw?

[thor]

Re: Using an air saw to cut fiberglass?

I spent many years as a design engineer on the B-2 and YF-22. Reciprocating saws were not allowed on the premises in the composites production areas.. I have personally seen tests of various laminate types utilizing many different processes to complete and trim the components in industry and college. All laminates have their strengths and weaknesses. It may certainly be the case that some industries or manufacturers use those practices. I, personally, have not seen them used with great success. From my experience, I just would not recommend the practice.

It may not be that big of a deal for what we are doing here with our models, as you pointed out. I guess I'm just insanely particular and probably get a lot carried away.

[salmon]

Re: Using an air saw to cut fiberglass?

Matt,
You are also insanely qualified to give your advice. I would follow Matt's suggestion. Have you seen his subs that he manufactured?
Peace,
Tom

[sgtmac1]

Re: Using an air saw to cut fiberglass?

Lots of good discussion. I was going to use the air saw on my Scale Ship Yard 1/48th scale fleet boat hull. Any one have difficulties cutting Lee's stuff with any kind of tool?