expander wheels, any experiences?

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kungfucowboy

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Oct 27, 2008
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Hi has any one here ever used 8 or 10inch expander wheels to hollow ground knives? Do they work ok? I think I saw one person do a file knife tutorial on one a while back, he did a good job with .

They seem really inexpensive over here in china. Aluminium oxide belts/sleeves seem to cost about what a 2 sheets of regular sand paper or 1 sheet of premium sand paper does and custom made ceramic ones seem to be available from multiple sellers. Are these things they worth while or a waste of time. As an aside, I can't get a 2x72, it wouldn't fit in my appartment.

example of the most common large wheel I can find here 250mmx40mm (~10x1.5 in)with a 32mm mounting hole
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They are common in the farrier industry. I have one. On a 3450 rpm motor, they are VERY fast for knife stuff. Great for hogging on horseshoes. The other thing, here there are limited grits of belts. Great for hogging, not so great for fine work.
 
They work well, but the belts wear quickly.
If you snag a belt and rip it off, this type wheel can literally explode at high RPM.
 
They are great for working wood and smaller metal objects. They are best at 1750RPM. While it probably will do the job, I would not hollow grind on one.
 
Thanks for the feed back so far.

So if I do it definitely Lower RPMs and safety gear.

Stacy:Would you be willing to expand more, when you say "While it probably will do the job, I would not hollow grind on one." do you mean because you have better equipment you wouldn't or that in my position you would use another option for hollow grinding or in my position you would stick with flat grinds or something else?
 
They are a bit soft in use for getting a consistent hollow grind unless being run at high speed. Most contact wheels are 70-90 durometer. The belts wear fast, so the first side may not end up the same as the second side. And, as said by others, you have a limited belt supply in most places. Getting a good metal cutting belt similar to the ones we use on a 2X72 is unlikely. Splices are critical ... or the "bump" may show on the blade.
 
Many years ago I bought one from a rock shop and mounted it on my 3650 bench grinder.
It was rated for 1700 RPM, but I didn't bother to read that.
It worked great until I snagged a belt.
When it exploded, it really sounded like a shotgun going off. Pieces hit my chest, and I was sure I was going to die.
No real harm was done, but I was very lucky.
I still use one (a very good one!) on a low speed grinder for sanding 6" contours.
 
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