The Armour Archive

I just got an expander wheel for grinding, but the site I bought if from forgot to mention it's max rpm is 2800 and my 6" grinder is 3400.

I went looking around at other grinders/buffers, and I'm actually surprised to find almost none that run under 3000 rpm unless they are wet. I found a couple 1800 rpm buffers that were around $250, but that's a but much to just use an expander wheel...

Is there any way to slow mine down? Or is there a better solution?

One possible solution is to set up a pulley system to an alternate housing that is geared down, yo could even keep the grinding wheel on, and just put the pulley on when you need to do any expanding. That's just an idea... One of the major benefits to this idea it that the expander will have much more power, and the pulley belt would slip on the grinder rather that rip the piece out of your hand. I have never tried this particular set-up before, but I have used ones similar to this and they have always worked great. Either way, good luck and if you want me to draw some plans up for you, just send me a pm and I'll shoot them to ya!!

Well, if you've already got it i say give it a go. so long as its not made for a different size arbor or anything i can't see there being too much of an issue.

Lowe's and probably others are selling a variable speed Delta bench grinder that will run slow enough for the expanding wheel.
I think it's about $100 unless you catch a sale.

hope that helps

I've never blown mine up at 3400 but people say it's a really bad idea. Haven't used mine a whole lot though.

You can buy a router speed controll. Cost you about $15. It'll let you adjust the speed of your grinder and is supposed to keep the full horsepower but I'm skeptical about that one.

No fancy wiring necessary just plug the speed controll in to the wall and plug your grinder into the speed controll.

If it is an AC motor rather than a DC motor, it can wear it out sooner. There may be other problems as well.

I have a 3200 or more rpm buffer motor I have used my Eastwood expanding wheel on.
It worried the crap out of me, going over the manufactures rated rpm.
However I ground a sword and matching dagger with it.

Would not recommend it.
I now use my expanding wheel on the 1200 something rpm Grizzly knife 2" by 72" belt sander.
It has a long extra shaft on the other side...
It fits right up.

Be safe.

Hal

I know you probably aren't keen on throwing more money at this issue, but...

I had found the expander wheel system before getting the bench grinder, so I was on the lookout for a slower grinder system. I found a Delta double-grinder with variable-speed, 2000 thru 3000 rpm. Cost about $100. I've been using it to great effect on almost every project I've done in the past 4 years.

One thing I've noticed is that different manufacturers' belts for the expander wheel have different fits- some are slightly tighter, and won't tolerate anything but the bench grinder's lowest speed. The Trizact belts I get from Eastwoodco.com, on the other hand, are loose enough that I can crank them almost all the way up.

Hope this helps.

Kase

Ya know that's probably exactly why I wasn't happy with the results from the expanding wheel. It was spinning too fast making it too hard.

Gonna go find my wheel and try it out on a slower speed I've got an extra router speed controll that I bought for my hammer but didn't need.

I noticed McMaster-Carr and Eastwood belts were a little bit different.
I don't use my expander wheel very much anymore.
I find the big wheel on the Grizzly to do almost everything.

Has any one ever cut the guard off on the top of the Grizzly to get at the small wheel.
Perhaps for tight radius it might be useful.
I am temped to cut my top guard off with the plasma torch next time I drag it out.

Hal

What Mad Matt mentioned earlier is this. http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=43060 Im curious how well it works.

I do not think that will work on an AC motor. AC motors need a change in frequency to change speed, and a cheap variable frequency unit is about $100.

It works but the whole range you get out of it is between 9 and 10. Just tried it out. Didn't stick anything in it to see if it was easier to stall or not.