Recommendation? Billet grinding questions

A

Aidenag

Joined
Apr 16, 2009
Messages
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Gettin tired of usin a 4 inch angle grinder for damascus billets. And am lookin to move up to a 7 using the snagging/cupping stones.. couple questions im running into during my hunt though.

• anyone got recommendations on what brand/model of abrasive stones works best for this task? Sooo many options and variables that i figure someone here knows whats what and can point me in right direction.

• i keep seeing a lot of different rpm limits on the stones, ALL of which seem to be below the rpm of pretty much every 7 inch angle grinder ive seen (dewalt, makita etc). Most these grinders seem to be doin 8k+rpm. With the stones, ones ive found at least, being 6k-7400rpm Am i lookin at the wrong angle grinders for these stones? Wrong stones for the grinder?

Any tips/suggestions much appreciated!
 
Look at a smaller stone, like 4.5 or 5 inch the 7 inch grinder.
 
I have a 4.5" Dewalt with a 4" Norton Gemini wheel on it and a 7" Makita with a 6" Norton Gemini. I have to look, the 4" is coarser grit than the 6" by at least one step. The Makita is 6600 RPM (10,367 SFM) and the Dewalt is 11,000 RPM (11,519 SFM).

I bought that big Makita thinking what you are, but it's slower than the Dewalt at removing scale and metal. Whether that's due to the grit difference or the surface speed difference or a combination of both, I generally use the Dewalt for snagging scale off then the Makita with a flap wheel to touch up the surfaces a bit before restacking.

The other thing is the vise I use to hold billets when grinding is rather high for that task and it's much easier to handle the Dewalt for longer periods. If it was down at waist level I might change my mind since the bit Makita absorbs the vibration much better and the weight means you don't have to put much force on it. The Dewalt at 11,000 RPM with a 4" cup wheel will shake your hands numb if you hold it too tightly :confused:
 
That Makita was one i was lookin at. its RPM is 10% over the max rpm of the 6 inch cups though. Seems all the 7 inch angle grinders are over those Norton gemini max rpm unless you put a 4 inch on a 7 inch angle grinder. Rest of the 7 inchers ive seen are 8k+rpm too
 
I apparently remembered wrong. The 4" I'm using is a Bluefire (16 grit), not a Gemini. I have a pile of these. More than I can use in a lifetime. I assumed my Dewalt was the more common 11,000 RPM but I see they have everything from 9,000 to 12,000 in 4.5" grinders, so I'll have to check. Here's the thing, it's never going max RPM when you're using it. Only when it's free spinning. I've used the heck out of my first cup, from grinding with the edge to make ladder patterns to just plowing off the surface for the next restack. It's not caused me any problems. As out of balance as these things are I would believe it would have by now.

Anyway, if you want one to try I'll send you one. I got a bunch of them for practically nothing at an asset sale. Let me know.

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That would be awesome! thanks Kuraki. I'll contact ya via your website to arrange everything and get your paypal for shipping.
 
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