Afternoon all

A quick question for the collective knowledge of LCB. I want to cut two straight lines in my fibreglass side panel which is fitted to the car. The cuts will be horizontal and I want them flush with the top face of the bottom chassis rail and bottom face of the top rail.

Firstly, which is the best tool for producing a neat straight cut, and any techniques involved, and secondly any ideas as to an easy FOOL proof way to ensure the cuts end up level with the rail faces? I will eventually be removing the materical from between the two cuts if that helps.

Any ideas to make this neater and easier much appreciated. I dont want to be post a NOOOOOO!! post after trying to get this right.

Can you use the rail as a cutting guide? Ie, clamp a batten to the rail and run a jigsaw or 'cut-off tool'? fibreglass isn't tricky to cut, but doing it without chipping the surface can be tricky. Always tape the surface with masking tape to avoid chips, and cut on the good side (the backside of your cut is most likely to chip).

You want one of these, fantstic bits of kit. Just hold it against the fibreglass and it's vibration cuts through.

http://www. diy.com/diy/jsp/bq/nav.jsp?action=detail&fh_secondid=11867962&fh_location=//catalog01/en_GB/categories%3C{9992017}

[Edited on 28/10/11 by Tiger Super Six]

Tape up the panel and cut roughly to size with an electric jigsaw (with a very fine toothed blade...) Don't inhale the dust, and finish to size with sandpaper on a block. That should do the trick. Just take it steady and you'll be allright.

Many thanks for the prompt advice, just need to summon up the nerve now to wield a jigsaw near my side panel.

Nigel

I made cuts in a GRP side panel in situ when I made flared front sections.

Masking tape and a pen line then used a hacksaw blade (removed from the saw handle) and positioned so the blade cut on the push stroke as not to chip the gelcoat.

Was done very slowly and produced a clean straight cut.

Ash

Two things.

MAke sure the blade is fine weather a jigsaw, hand or what ever and have the teeth pointing towards the gelcoat on top. In other words the teeth point through hitting the gelcoat first not pushing the gelcoat outwards after the cut.

Also would a router with a follower cutter do this?

High speed (same as fine blade) and will follow the metal rail with the ball bearing. I recently did this to cut laminate topped wood for my kitchen. Its like tracing and very easy to do.

Good luck, be brave!

I believe you can buy jigsaw blades that the teeth go downwards instead of up so it cuts on the down stroke
If that helps
Jacko

Well i have just had a look on google and cant find any so i must be wrong
sorry

[Edited on 28/10/11 by jacko]

I found the dremel better for cutting fibreglass panels than the jigsaw as it does move the panel (back and forth) as you cut. You need the right discs and not the useless one that they supply that shatter if you breath on them.

I think it was these I used previously.
linky

You should be able to put a thin sheet of metal on top of your rail and then run the cutter along /very close without damaging the rail.

regards pete

Dremel blade was better for me too

I used a grinding disc on my arches. Worked a lot better than the jigsaw for me, but potentially more dangerous if you don't hold on to it pretty tightly.

The best tool, if you have a substancial cut to make, is the diamond/ceramic angle grinder discs sold for cutting tiles/bricks.

As said above, you do have to be carefull if doing delicate work.

If you want nicely rounded corners to a square or rectangular cut out, mark it out and use a hole saw to cut the corners first, then slot out with the grinder from hole to hole. Finish to the lines with a file/sandpaper.

Cheers

Fred W B

[Edited on 30/10/11 by Fred W B]

Using any type of abrasive cutting disc on GRP is dicing with death.

You need very good masks and breathing protection, and extraction gear. The fine dust gets in your lungs and never leaves. End result is similar to asbestosis. The dust gets in your skin and pores, and itches like crazy for a day or three. (Carbon/kevlar/& similar are multitudes worse, particularly carbon.)

After near 50 years of using this stuff, the best and safest way of cutting GRP is a jigsaw at slowish speed, using a blade with reverse to normal teeth, cuts on the downstroke.

Whatever you use, it should cut like a saw, and make granules and not fine powdery dust.

You can't say you weren't warned, in 40 years time when you are coughing and wheezing.

Cheers,
Nev.

down cut jigsaw blades are readly available for cutting laminate worktops
4 BLACK & DECKER A5193 DOWN CUT JIGSAW BLADES WORKTOPS | eBay

I got my downcut blades from toolstation. screwfix do them to.

Many thanks for all the advice especially the health realted warning, it's only a hobby and isn't worth my health.

Thanks again all for taking the time to assist

I swear by a dremmel for small cuts, tight spots etc, a metal cutting wheel in a minigrinder for longer straaight cuts and a powerfile for the tight bits, radiuses etc

I use one of these in a Dremel or similar. Makes a very neat job. The same company also sell really nice clog free files both flat and curved that are great for dealing with GRP.

And I think 'dicing with death' is a tad on the strong side. By all means be careful and use a mask and some glasses but most of us who have been using these tools on GRP are more than likely to die of something else