Best type of grinder and discs

[Lwarden]

I'm getting ready to start grinding my hull and transom in prep for new stringers and transom. Whats the best type of grinder and disc's to use? I have a 4 1/4" electric, and I have acces to air just wonder if an automotive air grinder would work better?

 

[GWPSR]

Re: Best type of grinder and discs

One advantage to an air-powered grinder is that, as long as you keep it oiled, it's way less likely to get dust in critical places and burn up. Many on this forum can tell tales of electric tools that have succumbed to 'white lung'. Even when I use my electric angle grinder, the airhose is close by to blow out the vents frequently and reduce the risk of dust seizing up bushings.

That said, the air tools often have less torque than an electric tool, and you can't bear down quite as much before stalling the disk.

 

[mwe-maxxowner]

Re: Best type of grinder and discs

It might, but I think most of us have used 4.5" electric angle grinders. I have and its been great. I think 24 and 36 grit resin coated sanding discs with a rubber backer are the best to grind the hull with. I also used a metal grinding disc for some tricky places. The flap discs are overrated, IMO. For me they wore out quickly, and they have a small contact patch. Coupled with their expense, I don't like them. But you might try a 36 grit flap disc too, some seem to really like em.

 

[zool]

Re: Best type of grinder and discs

Its good to have both, a flapper on the electric, and a smaller sanding disc on the air grinder for tight spots....

But the best grinder I find..is the one in my friends hand...while Im having a smoke..:couch2:

 

[Woodonglass]

Re: Best type of grinder and discs

I think the Back UP Pad with resin Coated discs are more aggressive and last longer. Cheaper too! An Old Tennis Shoe will Clean the built up resin OFF of them and make em last a bit longer. Just grind the rubber shoe sole to clean the resin off.

 

[gm280]

Re: Best type of grinder and discs

Unless you have access to a really big air compressor to keep up with the huge demands of a good DA pneumatic disk sander, you'd be way better off with an electric angle grinder and some 24 or 36 grit disks. I've used both and can tell you the electric angle grinder will plow through the work faster... Whatever you choose make sure you use a good respirator and NOT just a dust mask to save your lungs too... That dust is not very healthy for anybody to be breathing in. The saying is still true, If you can smell the dust or fumes, your respirator isn’t working...period!!! And of course some good safety glasses too...

 

[Woodonglass]

Re: Best type of grinder and discs

Hooded Tyvek Suit, rubber Band the ankles and wrists. Wet towel around your neck Coat your entire body with Baby powder before suiting up. Full Face respirator Gloves. I'm just sayin....

 

[Sea Stomper]

Re: Best type of grinder and discs

When I did my deck and transom, I settled on a 90 degree hand die grinder with Roloc style 3 inch disks. 36 grit disks are my favorite. I'd like to try 24. I went to this because these disks are made for grinding steel. They can run at twenty thousand rpm which is nice. They last way longer than anything I found for my electric 90 degree sander type grinder. The disks never fold or deteriorate, they just wear down over quite a long time. 20 bucks for the grinder at harbor freight and the disks and arbor can be gotten there too. I can't speak for the rolocs that are at harbor freight, I use scotch rolocs. I also use this setup for hand shaping any wood curves or whatever as it makes quick work of it.

Having said that, I can understand why other folks have different choices for different reasons. My air compressor is a 4 horse craftsman, belt driven. When I was really getting into heavy grinding however, I used my service truck air compressor which is hydraulically driven by the propulsion engine of the vehicle so this is the drawback to using air grinders like the other gentleman said.

 

[chriscraft254]

Re: Best type of grinder and discs

If looking at electric, I prefer Hitachi with the pad type trigger. It doesn't wear your trigger finger out. Have yet to burn a hitachi grinder up either. I use the flap disks 36 grit for most heavy grinding.

 

[gm280]

Re: Best type of grinder and discs

When I did my deck and transom, I settled on a 90 degree hand die grinder with Roloc style 3 inch disks. 36 grit disks are my favorite. I'd like to try 24. I went to this because these disks are made for grinding steel. They can run at twenty thousand rpm which is nice. They last way longer than anything I found for my electric 90 degree sander type grinder. The disks never fold or deteriorate, they just wear down over quite a long time. 20 bucks for the grinder at harbor freight and the disks and arbor can be gotten there too. I can't speak for the rolocs that are at harbor freight, I use scotch rolocs. I also use this setup for hand shaping any wood curves or whatever as it makes quick work of it.

Having said that, I can understand why other folks have different choices for different reasons. My air compressor is a 4 horse craftsman, belt driven. When I was really getting into heavy grinding however, I used my service truck air compressor which is hydraulically driven by the propulsion engine of the vehicle so this is the drawback to using air grinders like the other gentleman said.

I actually use both types of grinders myself. I like those Roloc type R disks in so many different grits, but I live in a very high humidity area and like any compressor will, i get a lot of water both in the compressor tank and the lines to the die grinders too... So that is why I like the electric angle grinder better for the larger areas. I use a Dewalt angle grinder and have yet to burn one up myself. Of course I do blow air through every now and then during usage and after finished for the day and clean it out so there is no grinding grit in it. I use the 90 degree die grinders with the Roloc type R disks in the corners as areas that I can't get the larger grinder in to...

 

[ondarvr]

Re: Best type of grinder and discs

Hooded Tyvek Suit, rubber Band the ankles and wrists. Wet towel around your neck Coat your entire body with Baby powder before suiting up. Full Face respirator Gloves. I'm just sayin....

This is the best setup for a typical DIY job if you want to keep the cost of purchasing supplies down, it will do just about everything well and quickly. The flap discs tend to be slow due to the design, they are rarely seen in shops for grinding F/G

Air tools have there place, and the small one pictured works well, but is limited by its size and power.

 

[Duramaxgreg]

Re: Best type of grinder and discs

Where's the best place to buy the full face respirator

 

[zool]

Re: Best type of grinder and discs

This is the least expensive one ive found, free shipping too....the bottom end 3m ones are not much more tho

Sperian Survivair? Opti-Fit

 

[Duramaxgreg]

Re: Best type of grinder and discs

Thanks zool

 

[JASinIL2006]

Re: Best type of grinder and discs

I regretted not popping for a full-face model. It would have been so much more comfortable than goggles and a half-face model.

 

[Nickypoo]

Re: Best type of grinder and discs

If looking at electric, I prefer Hitachi with the pad type trigger. It doesn't wear your trigger finger out. Have yet to burn a hitachi grinder up either. I use the flap disks 36 grit for most heavy grinding.

I second the use of a hitachi. Mine's still going strong after being subjected to a fair amount of fiberglass dust and heat.

One thing I found is that cutting and grinding wheels were getting pretty expensive. Then I found a diamond masonry blade I had floating around (like this one) and tried that. It cut through fiberglass like butter and never wore out. It would probably never wear out on fiberglass. It's also pretty safe because the blade won't cut you if it contacts your hands.

I would stay away from pneumatic grinders. They're useless if you don't have a huge compressor.

 

[StevenT]

Re: Best type of grinder and discs

I just wanted to share a good source for flap disc and resin fiber disc. Lehigh Valley Abrasives - Premium abrasives and tools at value prices
4-1/2 Zirconia flap wheels $1.89
4-1/2 Resin fiber disc aluminum oxide $.50
4-1/2 Resin fiber disc Zirconia $.57

 

[Lwarden]

Re: Best type of grinder and discs

Where's the best place to buy the full face respirator

I just ordered mine from amazon, I got the full face mask, filter cartridges, prefilters and prefilter adapters all for $111.00 with shipping.

 

[Lwarden]

Re: Best type of grinder and discs

Im finding even just cutting the transom and floor out I was getting really itchie! SoI started wearing my tyvec suit. Seems to help.

 

[JASinIL2006]

Re: Best type of grinder and discs

Yeah, I was amazed at how little fiberglass dust I could create and still get itchy. Tyvek suits are the bomb!