Angle grinder (air) - 2 inch mini flapper disc?

[Gusb]

Any opinions on air angle grinders - Sears ($70), Ingersoll Rand 3102 ($120) through Snap-on/3M ($300+) - quality issues/noise, etc.?

Anyone know who makes the current Sears line (Ingeroll Rand, etc.)?

I only have a small (DeWalt/15 Gallon/SCFM 5.4 @ 90) compressor so a grinder is probably questionable anyway?

And lastly you can get 2 inch flapper discs for use with a Roloc setup for hard-to-reach areas - anyone tried these out?

Thanks for any feedback.

 

[Ebag333]

I have a fairly similar sized compressor and haven't had much luck using any air tools which require consistent streams of air (as opposed to something like an impact wrench which you tend to use for short bursts).

IMHO it's hard to beat the Harbor Freight grinders. Get the orange one (one step up from the cheaper blue). With the blue some disks rub against the guard, no big deal but kinda annoying. I have two that I've abused, and if I break one the cost is minimal. Plus I can afford to have several of them and don't have to swap disks, just grinders.

 

[Trollhole]

I have the IR. Works great. Plan on waiting every 1 min or so to let the compressor keep up. Use a good quality air hose. You will be fine. I use the 3 inch disks. Flapper disks are okay. I prefer the straight sandpaper disks.

 

[MOfj40]

I use CP and IR. Both are very good quality. We go through a lot of 2" disks in 36 and 80 grit, as well as the coarse, med, and fine scotch-brite disks. All work great. I used to buy 3M but MSC's TruMaxx and BriteStar brands last almost as long for less money.

I've also bought from Abrasives4sale.com - Purchase industrial grade abrasives factory direct with good results. They have very good prices if you're paying retail.

Flap wheels have their place, but the Roloc style disks are better in most applications.

 

[Gusb]

Picked up the Craftsman, which I'll try out for a week and return if it doesn't work out. This should also be a good test for the DeWalt compressor to see just how usable it is with a die grinder.

I still may jump to something like Snap-on later ...

 

[Gusb]

Flap wheels have their place, but the Roloc style disks are better in most applications.

I see your point - these 3M Green Corps 2" disks I've picked up are great on the pneumatic grinder. Much better for the final finish/blend grind than trying to control a larger flapper. And great for getting into tight spots.

Update:
The Craftsman angle grinder seems fine so far, bearings in the angle head seem good, etc. - but I'm not pushing it too hard.

The little Dewalt is doing better than I thought but it's pretty easy to run the tank low and the pump motor runs most of the time. But it works ok - not what you would want in a real shop concerned about getting lots of work done

 

[MOfj40]

The only time I prefer a flap wheel is when opening up a round bore. If you don't need high precision it's much easier to maintain relative roundness with a flapper and much faster than a hone.

 

[Layonnn]

I just bought a 4.5" electric grinder this weekend to tackle some rust on the 80. Can i buy the smaller mini disk and remove the guard on the grinder to reach smaller areas? Or am i limited to the 4" sized disks?

 

[Ebag333]

Removing the guard adds a certain amount of risk. Additonally, some of the 4 or 4.5 inch grinders spin way too fast for some disks.

If you remove the guard, be extremely careful.

 

[Layonnn]

Removing the guard adds a certain amount of risk. Additonally, some of the 4 or 4.5 inch grinders spin way too fast for some disks.

If you remove the guard, be extremely careful.

Thanks for the advice!

The only other option i was thinking of was using my Dremel. Do they make any wire brush style attachements that would be good for rust removal in areas where the 4" disk is too big for.

 

[Ebag333]

You mean like this...or this...or this?

dremel wire brush - Google Search


Personally, I hate wire brushes. They always poke you, tend to rust badly, can fling wires at you at high speed, make tons of dust......

I'd much rather use a grinding disk, flap disk, heavy grit sandpaper, etc.

Or this stuff is amazing.

 

[Gusb]

I just bought a 4.5" electric grinder this weekend to tackle some rust on the 80. Can i buy the smaller mini disk and remove the guard on the grinder to reach smaller areas? Or am i limited to the 4" sized disks?

I was thinking along the same lines but never seem to find the right adapters, etc. I think the speed would not be an issue because the disk would be getting smaller. The "Tiger" brand people make a flapper that can be "cut down" in diameter.

Removing the guard adds a certain amount of risk. Additonally, some of the 4 or 4.5 inch grinders spin way too fast for some disks.

If you remove the guard, be extremely careful.

Some people will tell you to take the guard off. I only remove it the few times it seems necessary. Safety aside, I think the guard helps more that hurts most of the time. In the right situation it can support the grinder a bit and can also keep you from grinding where you don't want to by accident.

 

[Ebag333]

I think the speed would not be an issue because the disk would be getting smaller.

The disk size doesn't matter for the speed. The speed will be the same whether it's a 1" disk, 2" disk, or 20" disk, since it's all revolutions per minute.

Some of the smaller disks I've seen have ratings that are rather small, only a few thousand RPM. If your grinder spins at say 6k RPM, and is not adjustable, then you can shatter the disk (which is obviously bad).

Just check the rating on the disk and make sure it's going to work with your grinder.

 

[MOfj40]

most of the 2-3" disks are rated for 20,000+ rpm since they are designed for use in pneumatic angle/die grinders

 

[Gusb]

The disk size doesn't matter for the speed. The speed will be the same whether it's a 1" disk, 2" disk, or 20" disk, since it's all revolutions per minute.

Some of the smaller disks I've seen have ratings that are rather small, only a few thousand RPM. If your grinder spins at say 6k RPM, and is not adjustable, then you can shatter the disk (which is obviously bad).

Just check the rating on the disk and make sure it's going to work with your grinder.

Most smaller disks I've seen usually have a higher speed rating - and I would think size does matter. Spin your 20" disc example at 20,000 rpm (die-grinder speed) and there's something radically different work-relative speed wise on the larger diameter of the disc - not to mention the additional mass, etc.

And the size of a grinder (disc size) is all about speed:
- 9" Large Angle Grinder - no load speed 6,000 rpm
- 4-1/2" Angle Grinder - no load speed 11,000 rpm
- Die Grinder - no load speed 27,000 rpm

my .02

 

[Ebag333]

most of the 2-3" disks are rated for 20,000+ rpm since they are designed for use in pneumatic angle/die grinders

Most smaller disks I've seen usually have a higher speed rating

Most small discs do have a higher rating. But I've seen some with a low rating (designed to work on corded/cordless drills, etc). Bottom line is, just check.

and I would think size does matter. Spin your 20" disc example at 20,000 rpm (die-grinder speed) and there's something radically different work-relative speed wise on the larger diameter of the disc - not to mention the additional mass, etc.

And the size of grinder (disc size) is all about speed:
- 9" Large Angle Grinder - no load speed 6,000 rpm
- 4-1/2" Angle Grinder - no load speed 11,000 rpm
- Die Grinder - no load speed 27,000 rpm

my .02

It's true that a 20" disc feels and reacts differently than a 4" disc. But when you get down to it, 20k RPM is 20k RPM no matter what the disk size. If you slap on a 20" disk rated at 2k RPM, and spin it at 20k RPM, it'll fail just like a 4" disk rated at 2k RPM would. Not saying that there are disks out there with that particular rating, just an example.

Plus the RPM rating should be specific to that disk, not the size of another disk. You don't see warnings that say "This disk is only rated at 2k RPM....unless you also purchased our 20" disk, in which case spin it as fast as you'd like!"

Again, the bottom line is to check the RPM rating on the disk and make sure you're not exceeding that with whatever tool you're using. Simple as that.