4.5" discs for HSS

[PeterT]

I've got a Makita mini disk grinder, think its 5" but uses 4.5" dia cutoff discs. It seems to have enough oomph but whatever cutoff wheels I'm using are pathetic on HSS blanks. Just want to lop off 3/8-1/2" HSS cutters, bits etc. I'm using 60 grit, 3/64" wide (.045") wheel, its generic dark brown fiberboard embedded grit style. Not sure what brand. They seem to cut mild steel so-so but HSS is just really slow going. Lots of sparks, but not much progress. I don't use this a lot so I don't know what is normal. Is HSS just tough material or maybe coarser grit yet?

 

[Bofobo]

its tough stuff .... i have a chunk in my drawer that i acquired, it looks like the piece was scoured on all sides then broken. What kind of disk? picture?

 

[GrayTech]

Brown cutoff wheels I'm familiar with in that size are for masonry. The steel ones are grey. Check you have the right disk. A steel cutting disk on a small angle grinder zipps through hss bits pretty quick.

 

[PeterT]

Here is what I was using. Turns out the label does say for steel & also stainless steel. Maybe just worn out or poorer quality? I don't think brown distinguishes their use just based on color, seems like masonry & steel both are brown? Even my Dremel fiber wheels are brown.

Anyway, it was my one & only so I bought a different brand off Amazon with decent reviews, see how they work. I do think thinner width is better in this application because the thicker disk basically just sat there & made sparks due to wider kerf. Maybe HSS tool steel is just plain tough stuff.

 

[Alexander]

Dont cut all the way through. You just score all the way around and hit one end with a hammer while the other end is in the vice.