Noobie question! (bout grinding wheels)

[redi-arc]

ok so im newish to this stuff but i have a fair idea of metal working. Anyways im looking to buy a cutting disk for my angle grinder. My angle grinder arbor is 5/8 -11. I was wondering what the -11 means because it doesnt say and if i type it in on google it just does math (5 divided by 8 minus 11)

Thanks in advance!

[cafyrman]

I'm pretty sure it's the threads per inch of the arbor.

[WyoRoy]

Yep, thread per inch.

[fredschrom]

Yep, 5/8 inch diameter shaft, 11 threads per inch. Standard here in the US, in Europe and metric counties they use M14. I am pretty sure they are NOT interchangable.

[tbone550]

Originally Posted by fredschrom

Yep, 5/8 inch diameter shaft, 11 threads per inch. Standard here in the US, in Europe and metric counties they use M14. I am pretty sure they are NOT interchangable.

Correct - 14mm is it's own animal - closest to 9/16" in common bolt sizes but it won't interchange.

[redi-arc]

Welll when I was looking at them online they had a 5/8 and a 5/8 -11 My guess is that they are not interchangable ro else they would not have the -11...

[tbone550]

No, they're the same. 5/8-11 is standard coarse thread. They may have specified thread count on the ones that the nut was made into the wheel - the others may have been the clamp-on type that required arbors. They will all work with your grinder. The ones with nuts built in will not require your arbors - just the bare threaded spindle.

You will pay a lot more for grinding wheels with nuts built into them. I only use that type for my 9" grinder.

You did say you were looking for cutting wheels - which are not the same as grinding wheels. I have never seen a cutoff wheel that had a nut incorporated into it, so maybe I'm wrong.

[fredschrom]

If its a name brand grinder and they say 5/8' they have just left out the pitch (11) on the advert.

Brand X, harbor fright I don't know, but Dewalt, Milwakee, Makita, Bocsh, Metabo all have 5/8-11arbors

[fredschrom]

" You will pay a lot more for grinding wheels with nuts built into them. I only use that type for my 9 grinder"

Come on T Bone.......wire wheels.

I keep some on my truck for in a hurry, so I have both, but I am like you I would rather have 3 disks than 2 which it works out to be cost wise.

[tbone550]

Originally Posted by fredschrom

" You will pay a lot more for grinding wheels with nuts built into them. I only use that type for my 9 grinder"

Come on T Bone.......wire wheels.

I keep some on my truck for in a hurry, so I have both, but I am like you I would rather have 3 disks than 2 which it works out to be cost wise.

Yeah, yeah, you're right. Here, let me give you a dollar. Whoops - I dropped it on the floor and I'm too tired to pick it up.

Thinking a little more about it, the ones that aren't threaded do fit the arbors for 5/8" grinders, but if I'm not mistaken the pilot holes in those wheels are actually 7/8" - and sometimes the wheel is advertised that way. So it could be confusing if you're new to it.

[redi-arc]

So basically a 5/8 wheel is just a hole no threads whereas 5/8 -11 is a threaded hole? And tbone your right it explains why I just wasted 10 min looking for 5/8 -11 cutting wheel...

[redi-arc]

Also does it matter if I put a 4in disk in my grinder if its size is a 4 1/2in. My local store doesn't have any 4 1/2's that meet my specifications. I just need it to cut 1in d pipe...

I see a lot of the 7/8 disks... Does anyone know for sure if they are equal to 5/8?

Thank You to all those who helped!

[fredschrom]

Yes smaller wheels fit on bigger grinders, and there is a flange nut that adapts grinders to the 7/8 wheels.

If you local store doesn't carry 4 1/2" wheels look somewhere else, thats about the most common grinding wheel size, go to a welder supply store.

[redi-arc]

Does aynone know for sure whether a 7/8 arbor wheel will work on my 5/8 arbor angle grinder SAFELY... Everytime i look it seems like the majority of the wheels are 7/8 I have read that you can use the 7/8 to protect the threads on your grinder. Wouldnt it being 2/8 larger casue problems if its not centered on or if it moves while cutting? Or will it be ok if i tighten down my spindle enough so there is no chance of it moving.

[fredschrom]

" there is a flange nut that adapts grinders to the 7/8 wheels."

Nut threads to the 5/8 and adapts... I got 7 grinders they all work the same, quit thinking this out buy a grinder and play with it for 10 minutes, its simple and your making it way to complicated. Smarter guys than you have it all figured out so you don't have to.

[tbone550]

Redi-arc, you're not understanding how the arbors work. It is true that the arbors have holes that are 5/8" diameter - the inner one is smooth so it slips on, and the outer one is threaded so that it tightens up the whole assembly. However, the arbors are designed to work with wheels that have a 7/8" pilot hole.

The inner arbor might be 1.5" or 2" in diameter, but it has a raised flange of maybe .040" thickness that is 7/8" o.d., which is a snug fit in the grinding or cutoff wheel's 7/8" pilot hole.

The outer arbor is two-sided and about the same overall diameter as the inner arbor. It is also threaded as I mentioned before. One side will have a 7/8" flange just like the inner arbor, and you put this side against a grinding wheel so it's pilot hole is laterally supported by both arbors. The other side of the outer arbor is a smooth face, and you use this side against a cutoff wheel. The reason is that a cutoff wheel may only be .045" thick, so it is completely supported by the thickness of the flange on the inner arbor alone. All the outer arbor does is clamp down on it - it doesn't offer any additional lateral support.

This is kind of hard to explain, but if you take our word for it and go out and buy a cutoff wheel, then look at your two arbors closely it will be self-evident as to how it works.

[redi-arc]

I took my disk off and it was 4 1/2 x 1/4 x 7/8 Thanks to all those who replied im getting a 7/8 cutting disk

[redi-arc]

Got the 7/8 disk and it fitted (as you all said lol) your right tbone as soon as I took it off I figured out how it goes....

Thanks to all those who helped