MontyMariner
Active member
Lidl / Aldi 20v Multi tool / Angle grinder for the thick bits, but on a dinghy, you may well be able to cut a lot of it with Tinman's snips or even long handled garden tree branch loppers.
Best tool or blade for cutting thick fibreglass
- Thread starter StefanSG
- Start date
dancrane
Well-known member
A manual snipper is a neat idea for dust-free cutting, thanks! I reckon I'll be in for some cost regardless, whether I spend on something like a branch lopper that I'd never need again, or a multi-tool, or just a fully protective respirator for the specific purpose of using the grinder I already have.
The multi-tool in the vid below looks very effective, but I'd rather buy Bosch as I have their 18v batteries. Are other brands likely to be equally good?
The multi-tool in the vid below looks very effective, but I'd rather buy Bosch as I have their 18v batteries. Are other brands likely to be equally good?
MADRIGAL
Active member
afterpegassus
Active member
Passive dust masks are also pointless unless you're clean shaven.
SvenH
Active member
No one has mentioned a circular saw yet... Probably needs teeth with negative tooth angle and is not for the faint of heart.
Angle grinder is probably the best option for speed, jig saw keeps the mess most local.
A vacuum cleaner is not ppe.
Angle grinder is probably the best option for speed, jig saw keeps the mess most local.
A vacuum cleaner is not ppe.
Refueler
Well-known member
I remember cutting the hole for speed log in my 1970's boat ... 50mm solid GRP ..... took 3 good hole saws to get through .... GRP just wore out the teeth as though they were butter !!
GRP repair guy doing my bilge keel joint - has used grinder for 99% of the work and a reciprocating hand saw for rough stuff ... I now have a devils job to clean up inside the boat !!!
GRP repair guy doing my bilge keel joint - has used grinder for 99% of the work and a reciprocating hand saw for rough stuff ... I now have a devils job to clean up inside the boat !!!
bigwow
Well-known member
CFS Fibreglass - Diamond Blades - GRP Supplies
I use one of these, at first glance looks expensive but I've been using the same one for the last 30yrs
I use one of these, at first glance looks expensive but I've been using the same one for the last 30yrs
B27
Well-known member
I would consider a circular saw with a blade intended to cope with nails etc.
Advantage being the waste is chips more than dust, and my circular saw has a fitting for dust extraction.
I get 'a vacuum cleaner is not PPE', but if you can trap the majority of the fallout at source, that can only be good.
I have a reciprocating saw, imitation 'sawzall' which is ultraviolently effective and the blades are cheap.
What you need to know, is how small must you chop it up?
I've seen videos of whole Laser hulls going in the skip at the recycling centre.
The other possibility is to talk to a 'down to earth boat yard'. They get rid of boats from time to time and may make space in their skip for a fee.
Or you could ask a commercial waste company, they will just drop a skip on it a few times and sweep it up, then invoice you...
Other possibilities include cutting useful panels out of it, re-purpose bits of it into a garden compost bin or something!
When you want a fairly flat bit of GRP for a bodgery project, there's never a scrap dinghy handy!
Advantage being the waste is chips more than dust, and my circular saw has a fitting for dust extraction.
I get 'a vacuum cleaner is not PPE', but if you can trap the majority of the fallout at source, that can only be good.
I have a reciprocating saw, imitation 'sawzall' which is ultraviolently effective and the blades are cheap.
What you need to know, is how small must you chop it up?
I've seen videos of whole Laser hulls going in the skip at the recycling centre.
The other possibility is to talk to a 'down to earth boat yard'. They get rid of boats from time to time and may make space in their skip for a fee.
Or you could ask a commercial waste company, they will just drop a skip on it a few times and sweep it up, then invoice you...
Other possibilities include cutting useful panels out of it, re-purpose bits of it into a garden compost bin or something!
When you want a fairly flat bit of GRP for a bodgery project, there's never a scrap dinghy handy!
Geoff A
Member
4 inch diamond tip angle grinder blade with a face mask and eye protection
geem
Well-known member
I had to drill new holes through my deck to fit new genoa tracks. The genoa tracks have aluminium plate glassed into the deck for reinforcement. With brand new drill bits, the drilling process of first going through grp then into the aluminium was shocking. By the time I had drilled the grp, the drill was blunt. There was no way I could then drill the aluminium. Any drill bit or mutiltool blade, jig saw blade will suffer the same fate. Grp is terrible for blunting steel.
I would suggest, as other have done, to use 1mm angle grider cutting disks.
I would suggest, as other have done, to use 1mm angle grider cutting disks.
MontyMariner
Active member
Cheaper makes are equally as good for hobby use, it's the blade that does the work, so buy good blades.
As you have Bosch battery then there is a good argument for buying Bosch as the battery plus charger is a fair percentage of the price.
Don't you have any DIY mates / acquaintances that could lend you a tool or two?
requiem
Active member
From my forays into woodworking I like the "chips vs dust" distinction. If you can see it in the air, it's too large to be a problem for your lungs. It's all the tiny particles too small to see that are 1) getting flung everywhere, 2) the long-term health hazard, and 3) not adequately picked up by most dust-collection methods. (I also happen to have a relative who worked with fiberglass in his younger days and is now paying the price.)
Thus, I'd second the idea of taping up a sheet of plastic to guard the interior and using disposable coveralls so you don't contaminate belowdecks. A vacuum is certainly good for tidiness, and a good breeze can take care of what it doesn't catch.
PCUK
Well-known member
Multitool with bi-metal blades. Safe and effective.
PetiteFleur
Well-known member
I've used a jigsaw blade which is specifically for grp - not cheap from memory but it works well, from local builders merchant. Not sure if you can get a similar blade for reciprocating saw.
dancrane
Well-known member
Thanks for so many good suggestions - whether they relate to the OP's question or my own.
Given how ineradicable (and barely detectable) the airborne product of fibreglass cutting or grinding is likely to be, I can see it's crazy to attempt the job (whatever the tool) without full recommended respirator, eyewear and some sort of chuck-away overalls to ensure the dust isn't transferred into the car and home. I'd rather be careful than regretful...
...so as long as I'm going to cover up thoroughly, and since the work will all be outdoors, I might as well use the grinder I already have.
We'll see, I may only be busy for 20 seconds before I decide I'd rather shell out on something tamer than the grinder.
I read somewhere else (sorry if it was somewhere here!) that a tungsten carbide scoring knife is effective - neatly scoring a line in the fibreglass which then cracks easily and cleanly if given a swift kick. It sounds basic but it may be ideal for reducing mess.
Of course, I'd still gladly give the boat away, whole...much happier all round.
.
Given how ineradicable (and barely detectable) the airborne product of fibreglass cutting or grinding is likely to be, I can see it's crazy to attempt the job (whatever the tool) without full recommended respirator, eyewear and some sort of chuck-away overalls to ensure the dust isn't transferred into the car and home. I'd rather be careful than regretful...
...so as long as I'm going to cover up thoroughly, and since the work will all be outdoors, I might as well use the grinder I already have.
We'll see, I may only be busy for 20 seconds before I decide I'd rather shell out on something tamer than the grinder.
I read somewhere else (sorry if it was somewhere here!) that a tungsten carbide scoring knife is effective - neatly scoring a line in the fibreglass which then cracks easily and cleanly if given a swift kick. It sounds basic but it may be ideal for reducing mess.
Of course, I'd still gladly give the boat away, whole...much happier all round.
.
Refueler
Well-known member
Not so positive about 'chips rather than dust' ... gives me thoughts of 'blade' ripping and splintering the cut line ...
GRP has a terrible habit of not clean cut line if cut coarsely .... thats one of the reasons that its best if possible to cut from the 'underside' so any Gelcoat is not splintered by action of blade 'lifting it' ...
Same idea as cutting ply / wood etc .... have saw enter at the hidden side - not waht will be the face ... to avoid those missing ripped out chips !!
GRP has a terrible habit of not clean cut line if cut coarsely .... thats one of the reasons that its best if possible to cut from the 'underside' so any Gelcoat is not splintered by action of blade 'lifting it' ...
Same idea as cutting ply / wood etc .... have saw enter at the hidden side - not waht will be the face ... to avoid those missing ripped out chips !!
MisterBaxter
Well-known member
There's a company called Perma Grit who sell very high quality TCT cutting and sanding tools, made for use with exotic laminates. They do really excellent jigsaw and hole saw blades that will cut a nice smooth line through GRP.
Refueler
Well-known member
We use all sorts of Perma Grit products when building models ... excellent.