Multitool saw blades for composites

Hi all,

Is been a real pain to find a decent saw blade to cut fiberglass and especially on some parts that are round (rims on a kayak).
The only saw blade that I found that works in terms of shape is this one:
https://m.media-amazon.com/images/I/71X0stK9T8L._AC_SL1500_.jpg

But is a painful slow in cutting plus it lasts so little.
Any recommendations about a tool/accessory that I can trim round edges 0.5mm-1cm more or less that works good?

Thanks a lot

 

Are these flat flanges with a curve? A photo would help. A grinder with a cut-off wheel would work much faster.

 

Hi @gonzo ,

See attached picture. I want to make smooth the round in order to fit properly the rim afterwards.

 

I would make a plywood jig to guide a router. A carbride or diamond bit will work well..

 

I use carbides on the multi tools. For longer straight cuts, I use a 4" carbide circ saw. For round holes, I use amthe right sized hole cutter and then fill the pilot a/o the raw core with thixo.

 

To make that hole in the picture smooth, I would template it with hotglue. So, assuming you cannot make it perfect to start, you cut a template with a hole saw that is the precise final i.d. Use something hard. Then, if possible, size the template so it can be set above, and then use a flush carbide bit on a router (as Gonzo said) to fly the edge off even. May require some effort to make the cutting template..if you want to do multiple hits on the template; even more work so it doesn't wear out, etc

2-3 Spot it with hotglue; then cut; then warm the template up from above so the glue releases..

or template underneath for less risk to finish and oversize the template for a router with a bearing, etc..I'd still probably make something to run the router on from above..

 

I can see two ways to do the job; a router with guide bush and a pattern with a suitable offset on the top surface.With a carbide or diamond cutting bit like this one.



Alternatively,get hold of a saw like this.



You need to use metal cutting blades and given the very short stroke of the saw,you can make several from one ordinary hacksaw blade.

 

go to harbor freight and get a drum sander attachment for your drill, of course a wood template adhered the the surface with carpet tape would be nice if you wanted to router with a flush trim bit for a quick and smooth operation

 

Unfortunately, there is no Harborfreight in the UK>

 

Very true,but we do have Machine Mart,which seems to be very similar.Not that it matters too much to the OP in Greece.

 

I've chopped up a few glass boats, built one glass boat and for some reason ended up in a tyvek suit cutting up a new glass pilot house that had been royally screwed up in layup recently.

I've come to the conclusion that glass kill everything, so now I mostly rock consumables or blades I don't mind treating like consumables.

On oscillator bits, they last ok as long as you keep them cool, but they heat quick and then fall to pieces quick. They work, but I burn through them waaay faster than reciprocating and circular. I like rotary with thin blades cleaned up with rotary abrasives.


Unless we're talking chopping up boats, the chainsaws and cement saws with lots of blades.

 

Make a duplicate of the opening, trim, bond, finish,

 

I've found that these diamond blades are the best thing for straight cuts,if you just need to slice up a moulding.




Oscillating tools come into their own where access is restricted,but are a lot slower.None of which really matters to the OP since he has a round opening to trim,in fact he should have done it by now.

 

I use this one. Does not clog up. Won't cut tight radius. For trimming tight radius, I use carbide diamond cut tool bit.

 

They work well too,both types are more heavily coated with diamond grit than the ceramic tile cutting blades.I favour the continuous rim as it tends to survive longer.For cutting curves,I think we all tend to use something like this: