School Me on Abrasive Wheels

[Ridge Runner]

Earlier today, someone was kind enough to post a link to Lehigh Valley Abrasives. I'm not used to having so many grit options for sanding wheels. They have 24, 40, 60, 80, and 120 flap wheels and I admit that I'm lost as far as knowing which ones I need. I'm doing miscellaneous metal work - anything from sanding welds down flush to sanding off surface rust to stripping paint.

Also, they carry both type 1 and type 27 4 1/2" cut-off wheels. What is the difference between the two types?

 

[Cypherian]

http://www.nortonindustrial.com/upl...s/Documents/Toolroom Selection Chart 7505.pdf

http://multimedia.3m.com/mws/media/...es-flap-disc-selection-guide-brochure-pdf.pdf

http://www.carborundumindustrial.co...ives/documents/catalogca1000-toolroomwhls.pdf

 

[Ridge Runner]

Thank you.

 

[terryo1965]

I have tried just about every type of flap wheel made, all the shapes, sizes, grits etc. I have found I mostly use a 36/40 grit for weld grinding and general metal removal. I sometimes run a 60 grit for more intricate grinding but not very often. Personally I just haven't had much use for the finer grit wheels.

The 3M black "Clean & Strip" wheels work really well for removing rust and other coatings, they now have a purple heavy duty version but I still like the original one. This is a great product for cleaning surfaces without removing any metal or tearing up your part.

The cutoff wheels for 4-1/2" grinders are available in 2 styles, type 1 and type 27. The type 1 wheel is flat, while the type 27 has a raised hub around the center hole. This allows you to mount the wheel and the locking nut is recessed up into the wheel. This gives you a little extra clearance if you are cutting things off flush and you have to keep the grinder flat to the workpiece. The downside is the T.27 wheels are usually a little more money.

 

[Ridge Runner]

Ok, so they're not specific to your grinder - you can run either one. That's one thing I wasn't sure about since my Porter Cable came with a 27.

Thanks again.

 

[CGT80]

I use the LV flap wheels. 40 grit for general use to prep for welding and to grind down welds and 60 grit to finish the part. You can go finer if needed, but the fine grit wheels are slow and seem to wear out quickly (I have only used 40/60 in the LV brand).

After the 60 grit, I used a surfacing disc to smooth out the grind marks a bit and get an even finish on mild steel for some gates I built. The finish was a patina and clear lacquer.

I bought a flap style surfacing disc for about 20 bucks from the local steel supplier. It worked very fast and left a nice finish. It also wore out fairly quick and was way too expensive. LV has the same discs, but I haven't tried the couple that I bought, yet. I also got the LV 5" backer for my angle grinder and used the hook and loop style surfacing discs. They are around 2 bucks each for the 5" and they work well for the price. They are not as fast as the flap style, but I will continue to use them.

I used that process to clean up the welds on this gate:

I took the next photo after I used the surfacing disc on part of the gate. The roll/weld marks showed through on the steel tube when I tested the patina, so I had to make the surface uniform (no mill scale or weld residue as all that effects how the patina reacts on the steel). You can see that the lock box hadn't been surfaced yet.

 

[AbbySomeone]

Don't buy type 27 slicers. If you don't know what you are doing they can fly apart. Stick with type 1s. Also don't buy chinese specials. Stick with name brands where you can see the fiberglass reinforcement in the wheel

Don't us a flap disc for paint removal. Inefficient and a huge waste of money. Use a coarse nonwoven disc with a backing pad.

40 and 60 grit will satisfy 99% of your needs with regard to metal fabrication.

 

[Nele]

All I know if you buy cheap stuff you'll spend more money in long run, they wear much faster and don't do as fast of a job removing material

 

[AbbySomeone]

As for general "school me on abrasives" type commentary...

There are two types of metalworking abrasives. Coated and bonded. Bonded are wheels such as slicers and traditional "rocks". Coated includes abrasive material that is adhered to a cloth, to include products such as flap discs and fiber resin discs.

By the way, a flap wheel is something different entirely from a flap disc. I think the folks in here using the word flap wheel actually mean flap disc. Big difference, if you order some flap wheels for your 4 1/2" grinder I can guarantee you disappointment. Flap disc.

There are typically three types of abrasive material.
Aluminum oxide- ubiquitous, decent cost, decent removal, decent life.
Zirc- less common. Higher cost, better removal, better life (typically)
Ceramic- less common. Highest cost. Best removal, best life. I.e. Norton norzon, DeWalt xp ceramic, or 3m cubitron II

The "type" of wheel is simply the shape. Type 1 is flat. Type 27 is depressed center. Those are by far your most common but there are several others.

 

[MJD1]

Zirconia in 40 grit will suit your needs well. As the disc wears it will cut similar to a 60 or 80 grit disc. I haven't had much luck with 24 grit as it seems to wear out really quick due to the abrasive material flying off the disc.