Grinding fibreglass

[Weyalan]

Well, folks, this weekend should be my last weekend of significant grinding fibreglass for a month or so. After this I get the (relative) pleasure of laying glass...whoohoo! Chopped strand first, then Bi-ax. And then, if I'm really lucky...flowcoat!

[phorvati]

There's a guy next to me in the yard repairing severe osmosis on a nonsuch. He actually used a planar to level off the newely cured glass layers. Then he uses the grinder and at the end orbital plam sander.
Petar

[zac]

What are the best discs to use on an angle grinder for fiberglass in polyester resin? I bought a 50 grit fiber disc to use, is it supposed to be that slow?

I actually got a plastic backing plate for it but I thought I was supposed to use a rubber one so it forms to the surface better. I couldn't find a rubber one, any truth or difference?

[w42]

Originally Posted by zac

What are the best discs to use on an angle grinder for fiberglass in polyester resin? I bought a 50 grit fiber disc to use, is it supposed to be that slow?

I actually got a plastic backing plate for it but I thought I was supposed to use a rubber one so it forms to the surface better. I couldn't find a rubber one, any truth or difference?

3M Green Corps Production Cut with a soft pad works great. Available in 24 and 36 grit. 5 and 6 inch. Great for surface grinding.

I also have some 24 grit "flap discs" that works well grinding fiberglass on edge (not surface).

[Roy M]

Folks, You really ought to investigate a Festool for grinding fiberglass. Normally, it is absolutely verboten to do so in our local boatyards unless the entire area is tented to eliminate dust from contaminating the environment, as well as other boats. I started grinding on my boat, and the manager hot-footed over to read me the riot act. Then he stopped and watched. Then he sent over all of his supervisors to watch. Then they smiled and told me to have a good day. The attached photo shows my friend, Jeff Allen, sanding overhead on the underwing, without mask, goggles or dust on his black teeshirt. 'nuff said.

[w42]

Originally Posted by Roy M

Folks, You really ought to investigate a Festool for grinding fiberglass. Normally, it is absolutely verboten to do so in our local boatyards unless the entire area is tented to eliminate dust from contaminating the environment, as well as other boats. I started grinding on my boat, and the manager hot-footed over to read me the riot act. Then he stopped and watched. Then he sent over all of his supervisors to watch. Then they smiled and told me to have a good day. The attached photo shows my friend, Jeff Allen, sanding overhead on the underwing, without mask, goggles or dust on his black teeshirt. 'nuff said.

YES! their air powered integral dust collection R/O sanders are way cool. I dont have one, but as soon as my Porter-Cable dies an "accidental" death, I can justify it to the Admiral.

[Whimsical]

Roy
How long will he be your best mate after giving him that job.

Rupes also make a similar tool with a forced rotation and boy can it remove material, fabulous

Mike

[Mathil]

I grind fibreglass daily at my work. I never itch, aside from the times I don't adhere to the following rules :

1) NEVER TOUCH YOUR SKIN WHILST THE DUST IS ON IT. Blow off all dust with an air gun before you THINK of touching any exposed skin. This counts for clothing flopping around as well. If your wrists get glass on them while you're reaching up, or over, and then your sleeves slide back down that will do it.

2) LEARN TO TAKE COLD SHOWERS. Take a cold one, rinse yourself off, lather if you must, then you can warm it up and make yourself comfy.

3) AIM THE DUST CLOUD AWAY. Duh.


If you're really paranoid you should wear work gloves over long sleeved clothing and then duct tape around where the gloves meet your sleeves. Nothin gettin in that way. Don't forget proper respirators and eyewear.

[zac]

What is the best eyewear for grinding? I keep getting dust into my regular safety goggles. The kind that go completely over your eyes but have little vent holes around it.

[Roy M]

Nothing, absolutely nothing beats not getting the dust on you in the first place. If you are grinding glass regularly, you are taking a big risk for silicosis and other tasty workplace hazards. I still use a mask and goggles, but then, I have survived to be older and smarter and healthier than those who were "tougher". Get a Festool.

[hellosailor]

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SandingGrindingPaintingWelding


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For really good eye protection, you'll need something like a hood with filtered air, because keeping the dust out means blocking airflow, catch-22. But they make "protection" in all sorts of degrees and prices, and for some reason the big box hardware stores just don't carry much of it.

[kellyp08]

There are some great suggestions on restoring Gelcoat. Could i have some opinions on polishing awlgrip (flag blue) topsides using a polisher. Forgive me if this is a dumb question but can you use a 110V electric rotary polisher (e.g. Makita) run by the onboard generator while working on the topsides from the dinghy? (I recall on shipboard in the Navy that all powertools ran on compressed air but rotary polishers need a compressor with output of 8.5 to 15 CFM - something I don't have or want). Thanks.

[johnar]

While doing the bottom of Dutch there was a man in the yard stripping the bottom of a boat with spray, he told me the cost was around $9 a foot. It looked ever nice right down to gel.

John

[Talbot]

Originally Posted by kellyp08

Forgive me if this is a dumb question but can you use a 110V electric rotary polisher (e.g. Makita) run by the onboard generator while working on the topsides from the dinghy? (I recall on shipboard in the Navy that all powertools ran on compressed air but rotary polishers need a compressor with output of 8.5 to 15 CFM - something I don't have or want). Thanks.

You are right - it is a dumb question, and if enacted will probably lead to a darwin award. Thats why the navy used air tools (and they are a lot lighter to handle).

If you want to do it afloat, do it be hand or hire the larger compressor (but you then need a big genny to run it!)

[kellyp08]

Thanks, Talbot

I KNEW it was a dumb question - sorry I asked (Perhaps I should also shoot my kids to remove them from the gene pool).