Update on 2 x 72 Belt Grinder Project

[Tmate]

In an earlier thread in this forum, I mentioned a 2" x 72" belt grinder I was planning on putting together from a kit sold by Brian House (www.housemade.us).

I have finished fabricating the frame assembly as shown by the photos. Pretty easy so far except for the always challenging task of making one piece of square tubing telescope inside a slightly larger piece. I will be using a 3,400 rpm 2 hp Baldor 3 phase motor along with a variable speed, reversing VFD. I'll post more pictures as things progress.

 

[Janderso]

That motor should do the trick!
I”ll be curious to see how you like the kit/build when you are finished.
He does a great job on his videos.

 

[Watchwatch]

Lucky. The USPS might get around to delivering my kit this week. It’s not that big of deal because I have zero welding experience and need a lot of practice before I assemble the kit.

Did you do any milling on the critical pieces? I’ve thought about kissing the tubes with an end mill to true them up.

I found a NIB 3hp 3450 rpm Baldor off EBay for $300 and could not resist. Still torn on a VFD. I’ll probably bite the bullet on KB 29D.

What route are you taking for pulleys? I’ve thought about making my own but a 7inch chunk of aluminum ain’t cheap.

 

[Tmate]

After removing the internal welding seams on the two larger pieces of square tubing, I ran all sides of the smaller tubes lightly along my bench disk sander to expose bare metal. Then I put Dykem Blue on the areas I thought were causing interference. Inserting the tubes then produced scratches which helped to find the areas that needed to be taken down a bit.

If none of an inner tube will pass through the outer tube, the problem is the weld seam. If some will pass through, but not all, the problem is with the inner tube. Both the inner surfaces of the outer tubes and outer surfaces of the inner tube have irregularities. Since it isn't possible to remove the irregularities inside the outer tube, it is necessary to fix those on the inner tube. The extent to which the tubing requires this is the luck of the draw!

Make sure the motor you are using is TEFC (Totally Enclosed, Fan-Cooled) to keep out the metal dust, etc. Try www.electricmotorwholesale.com for your VFD.

Haven't decided on the pulleys yet. If there is a weak link in the design, it may be in the pivot for the tensioning arm. Depending on how it works I may try to add some bearings there. I am going to use the $29.00 tracking mechanism sold by Origin Blade Makers (https://ebay.to/30b39Dv).

 

[Tmate]

Just about done!

 

[Tmate]

All wired up for 230V and tested! Just waiting for the pulleys and belts to arrive.

 

[Tmate]

Finally finished. Tested it at about 3,000 sfpm (surface feet per minute) and with a 36 grit belt it really ate some steel. With the 7" drive wheel, the top speed is around 6,500 sfpm.

 

[Tmate]

I threw together a plywood cover for the grinder, which I hope will partially contain the debris and soften the noise a bit. It lifts off in seconds for belt changes, etc.

Motor is a TEFC unit so I don't think it will be affected as long as there is plenty of air circulation around it. It should also provide some protection in case a belt disintegrates.

 

[jwmelvin]

That looks really nice. It may be the motivation I need to finish mine. I’m tempted to get the tilt-hinge pieces cut somewhere; it does seem the best way. I bought inner tube with ample clearance to the outer tube, thinking I’d take up the gap with bolts through the outer tube. But perhaps a rudimentary gib would be better. And I’ve considered a flexure for the tracking adjustment. I have a hard time committing but I suppose the point is to start with something and consider other options once it’s working.

 

[slodat]

How much do you have in the grinder project?