Gonna build me a belt grinder

Post by **KurtHuhn** » Sat Jun 09, 2007 8:37 pm

I've decided that I'm going to get off my duff and build myself a KMG clone. The original can be seen here:
http://www.beaumontmetalworks.com/

I've priced out all the pieces, and it looks like I can get off fairly inexpensively. I'll build mine out of 6061-T6 aluminum so that I can easily drill/tap/machine the metal. Even ordering custom cuts from onlinemetals.com, the materials come out to about $150. On top of that, I need some drive and idler wheels, as well as some pulleys, and that looks like less than $125 from McMaster-Carr. I've got a Baldor 3/4 HP motor I can use, though I suspect I'll want a 1.5 or 2 HP motor one day.

The benefit to building one of those, is that I can also use it for metal grinding, and start dabbling in making knives again - the failure that brought me to pipe making to begin with.

If anyone is interested, I can document the process with pics and descriptions of the various mistakes I will surely make.

For everyone looking for pulleys for their electric motors, McMaster-Carr has every kind imaginable - and they're *cheap*.

Frank · Post by **Frank** » Sun Jun 10, 2007 2:18 am

Go for it Kurt. I'm interested to see your progress.

I don't think you'll need more than a 1 hp motor. I've found it to have enough torque for grinding steel, even tempered steel. For quicker stock removal, you just use coarser belts. Your 3/4 hp motor should do fine for most of the time.

I know it would cost somewhat more, but if you could manage variable speed, constant torque it would make a big difference.

magruder · Post by **magruder** » Sun Jun 10, 2007 2:52 am

I've heard of belt sanders in pipe making studios in Europe that have rounded pulleys that bow the belt to help avoid digging in on the edges - very cool.

Heinz_D · Post by **Heinz_D** » Sun Jun 10, 2007 7:12 am

Hi Kurth and all,

I'm going to build a belt sander like Rainer Barbi's. Here some asorted pics:

For me it's important, that the belt is rather long and ductile to get into any corner, as example the bowl/shank junktion... In the last pic you can see how it should work. Leading the belt with the fingers you're able to form it in any shape you want to use - but yes, it'll take some time to learn it very well!

It may be necessary to use different belts with 120, 180, 240 and/or 320 grit.

The motor should run with 800 to 1000 rpm (higher speed will burn the fingers!) and it is variable by exchanging the v-belt pulley. Because ther is no need of much tourque the motor only needs 0.5 to 1 HP, I think.

My father in law will build me the needed frame with the possibility to bend the v-belt by changing the position of the motor.

An important point is, that one of the wheels wher the belt runs over should be out of metal or electroconductive material to prevent electrostatics!

This one is easy to build by oneselfe and the material - except the belts (?) - should be rather cheap.

If anyone has some more ideas, it would be nice to read some comments.

ScoJo · Post by **ScoJo** » Sun Jun 10, 2007 8:12 am

Where do you get belts for something like this?

geigerpipes · Post by **geigerpipes** » Sun Jun 10, 2007 9:21 am

Cool Pics Heinz..

I dont know if you remember but a while back i posted pics of my homebuilt bandsander with parts from an old sweing mashine...this summer I will rebuild it to feature a motor that is frequency controlled..Also I will not bolt the upper weel to the seiling or wall like my current one (or Reiners) but go to the junkyard and find some kind of metal thing that fits my needs to hold the motor and weels so it can be portable and moved around the shop if desired..

The belts are easely made but getting cloth backed sandpaper rollls and super glueing them with some fiber backed tape on the backside

Heres a picture of toms sander

Frank · Post by **Frank** » Sun Jun 10, 2007 1:08 pm

ScoJo, here's one source: http://www.trugrit.com/
You might need to have them custom cut & joined for extra long ones as seen in the above pics. You can also find places that sell the cloth backed in rolls to make your own.

For this type of application, where you want to be able to guide & bend the belt by hand, you need "J" weight (very flexible) belts.

Don't buy generic, no-name belts, they're a waste of money. Get Klingspor or Norton or Hermes or 3M. Buy your belts from a reputable supplier that sells the quality belts from these manufacturers. I know for a fact that Norton also make cheap shit abrasives to supply to places like Home Depot.

achduliebe · Post by **achduliebe** » Mon Jun 11, 2007 11:34 am

Kurt,

I would definately love to see a documented step by step. That would be awesome.

mchain · Post by **mchain** » Mon Jun 11, 2007 1:46 pm

achduliebe wrote:Kurt,

I would definately love to see a documented step by step. That would be awesome.

ditto that.

Nick · Post by **Nick** » Mon Jun 11, 2007 3:00 pm

Can you just build one for me? And, can you come to my house and assemble it? And then, as long as you're there, can you teach me all your tricks?

I'll pay in beer?

Heinz_D · Post by **Heinz_D** » Mon Jun 11, 2007 5:54 pm

geigerpipes wrote:Cool Pics Heinz..

I dont know if you remember but a while back i posted pics of my homebuilt bandsander with parts from an old sweing mashine...this summer I will rebuild it to feature a motor that is frequency controlled..Also I will not bolt the upper weel to the seiling or wall like my current one (or Reiners) but go to the junkyard and find some kind of metal thing that fits my needs to hold the motor and weels so it can be portable and moved around the shop if desired..

The belts are easely made but getting cloth backed sandpaper rollls and super glueing them with some fiber backed tape on the backside

Heres a picture of toms sander

Hi Love,

yes I remember your former post... That and what I saw by Rainer was the reason, why I now decided to build one by myself...

But, as you mentioned, my will also be a "portable" one. My father in law is a retierd blacksmith and he'll make the rack for me.

I also thought about a frequency regulated motor, but that'll be always changing the tourqge of the motor. So I want to try a v-belt pulley or, if it's to difficult, a strong, frequency controlled motor...

I'm just waiting on the mainparts - than we'll see, how it could be managed.

Frank · Post by **Frank** » Mon Jun 11, 2007 6:51 pm

Heinz_D wrote: I also thought about a frequency regulated motor, but that'll be always changing the tourqge of the motor.

Actually, you can get variable frequency speed controllers (VFD) that supply constant torque.

I'm not sure of the physics, but it's my understanding that to get constant torque with variable speed you either need a DC motor or a 3 phase motor.

I've spent years trying to figure out a way to speed control my single phase, 120 volt AC buffer & belt grinder electronically. Sadly I have to accept the fact that I am unable to change the laws of physics. (Where is Einstein when I need him most?? LOL).

geigerpipes · Post by **geigerpipes** » Tue Jun 12, 2007 3:52 am

Like frank mentioned a 3 phase frequency modulated motor will not loose torque but is rather expensive... around here they usually go for 200€ used...I was lucky enough to be gifted 2 frequency modulators from our neibour who happens to be an engeneer at a large factory where they replace their modulators every 4th year, some of them never used, and just trow them in the trash!!

Frank · Post by **Frank** » Tue Jun 12, 2007 2:04 pm

geigerpipes wrote:...I was lucky enough to be gifted 2 frequency modulators from our neibour who happens to be an engeneer at a large factory where they replace their modulators every 4th year, some of them never used, and just trow them in the trash!!

They're just as expensive here in the States.
Throw them in the trash? OMG! What a waste. You're a lucky guy, Heinz.