DIY 2x72 Belt Grinder For Knife Grinding

[capitalcrew]

This is going to be my project thread for the belt grinder I am making. As most of you know from my other thread I've decided to try to make a few knives and after looking for a suitable grinder to start with I decided I didn't like the prices or the options and set out to build my own. After a lot of research I found this design here DIY Knifemaker's Info Center: BG272 - DIY 2 x 72" Belt Grinder and decided this is what I was going to go with, at least for a starting point.

Main differences between mine and his are a non tilt adjustable platen and fixed speed. I did read in the comments on that page that he rarely adjusts the angle of the platen anyways so I decided to skip it entirely. Fixed speed is just a cost saving option, I may upgrade to a VFD control for the motor in the future so I have speed adjustment, but for now this will do.

Parts / Supplies list:

• 60" 2x2 steel square tube, 3/16 wall
• 60" 1.5x1.5 square tube, 3/16 wall (any wall thickness will work here really)
• 24" 2.5x2.5 angle, .25 thick
• 24"x12" flat bar, .25 thick
• 30lb/in 3.5" free length, .9" diameter spring https://www.amazon.com/gp/product/B005KVAM48
  
• 5" caster (drive wheel) https://www.amazon.com/gp/product/B004071SZU
• Idler and tracking wheel set Belt Grinder wheel 2x72 set for knife grinders
• A suitable motor, I have a 2hp 3p motor I will be using.
• Assorted nuts and Bolts

A few notes.. I order excess of all of the different steels. I figure I'll have extra if I make any mistakes and it never hurts to have some extra around. You'll want a chop saw to cut things square, I've been using an angle grinder with a cut off wheel and it isn't ideal but it is workable. If anyone needs a spring I had to order ten, but I only need one, so I'll have 9 available if you decide to make one of these. The 2hp motor I have is actually something I bought for my lathe but I decided to use it for the grinder after the motor I bought for this project turned out to be more suitable for the lathe due to shaft diameter. I will be using the cost of the motor I bought initially for this project when I figure the total cost though. If you don't have three phase power you'll have to find a single phase.

Cost so far:

Motor - 20 on CL. (SCORE)
Steel - 75.87 (cut fees included)
Caster / Driver Wheel - 13.80
Springs - 25.65
Idlers / Tracking Wheel - 41.75

Total - 177.07

I still need to purchase the nuts, bolts, and washers so they're not figured into the cost. I also don't have any belts yet.

To get started you cut your 2x2 square into the proper sizes. You will need three 10" pieces, one 4" piece, one 3.5" piece. Leave a little extra to square up the ends, especially if you're using an angle grinder. Find the one 10" with the squarest end and set that aside, that will be your vertical / upright piece that houses the tensioner and holds the tracking wheel. The other two you can put on a flat surface and butt up against the third piece, tack and then weld the two pieces together. Don't weld anything to the third piece yet, that upright will be welded later. You only used it here as a reference to keep the ends that touch it square.

I will update this more as I go, this is as far as I have gotten so far. I would be working on it tonight but there's a bit too much going on in the shop right now for that. I expect this weekend to get the frame welded to the plate so I can start working on the moving piece of the upright and the platen.

Edit - I accidentally posted this before I was ready lol. Pictures will all be in subsequent posts.. I can't add any now that I'm editing the original.

 

[cgrutt]

Cool project. How are you running the 3p motor without the VFD? RPC?

 

[capitalcrew]

Yup, I have an RPC to run my lathe and bridgeport so I have 3p available. If anyone wants to build one of these it would be easy to swap out a single phase motor though

 

[capitalcrew]

You can see here the pulleys and spring. You'll notice in the one picture that the black tracking wheel is tapered slightly from the middle out to the sides, this is what allows you to adjust the tracking of your belt.

 

[capitalcrew]

This is how it will look when you're finished, as well as a drawing of the basic frame that i am working on from that page.

 

[capitalcrew]

This is where I'm at now. Working on getting the short support in front ground more level before I weld the horizontal pieces. The horizontal pieces being straight and square is essential

 

[capitalcrew]

Current progress. The main frame is all Welded and done, working on the rest of the pieces now. Unfortunately I just ran out of wire so I have to get more before I can do much else. You can see the tracking adjustment with the holes all drilled clamped to the upright / tensioner here. It'll be taller than it looks here, I haven't put the spring in yet.

Happy with the progress so far. I'll have that finished tomorrow and I'll start on the platen attachment. I'll do the motor last I think, but that's still under consideration.

 

[capitalcrew]

I haven't been able to work on this at all. Someone has their RV/camper in our shop and it's pretty tight in there, and I don't really like working on things when other people are around. Hopefully I'll be able to focus on this over the weekend.

I did pick up all of my hardware and some more wire so I'm all ready to go.

 

[wizrd]

Looking good - and it looks like you've done your homework. There are also some good plans in Wayne Goddard's book - "The $ 50 Knife Shop". Please keep us posted on your progress.

 

[capitalcrew]

Testing out motor placement. None of the pulleys are ready to be Tightened down, I have to get everything aligned still but everything is coming together nicely!

I just realized when I pulled the 1.5x1.5 tube for the platen out, and put it back in I forgot to clock out correctly. Now I have to grind the seam out of that inside piece. Damn.

 

[capitalcrew]

Also, don't ask me why I'm working off of a garbage can. I really don't have a good answer for that. There is a perfectly good bench 20 feet away

 

[wizrd]

Springs from old oven doors can be used to your advantage. A foot switch should be used, blade grinding should start with the blade against the belt - and the grinding pass should be ended with the blade still resting on the belt -- while the belt stops. With a moving belt, it is easy to damage an edge applying or removing a blade...just saying. Foot switch makes this much easier.

 

[capitalcrew]

This definitely won't be that fancy. Knife making was the spark that prompted me to start this project but a belt grinder is a tool I've always wanted so knives won't be its sole purpose. I may make a more refined one in the future though

 

[Robin]

Damn Cool!!!!
Robin

 

[S&W Fan]

This IS coming along nicely. The finished product should get the job done just fine. Great build along.

 

[capitalcrew]

Motor placement marked out and a bushing was made for inside of the blue castor / drive pulley. I filed a keyway into the bushing and it is now mounted on the motor shaft. It's a nice interference fit so no set screw needed. Still more to do but here's how it looks with a belt on it...

 

[capitalcrew]

Motor is mounted for real now, everything you see is finalized. Only thing left is wiring. The holes for the electrical box are done, everything is ready to go. Really. One more day of work!

 

[capitalcrew]

It lives.

If anyone has any questions feel free to ask, if you want to see anything close up I'll get any pictures you want. Total investment is well below 400 dollars, and i could add variable speed for another couple hundred. I did use some things I had laying around like the empty breaker box and a magnetic starter I already had, but if i had to buy everything I think I would come out right around 400.

 

[Robin]

Awesome job Cap!!!! How does it track with a load on?
Robin

 

[capitalcrew]

Thanks Robin. Tracking is excellent, I was actually surprised to be honest. Spinning free and with a load it tracks identically, and I only tweaked the adjuster from spinning by hand to actually under power. I have a short video, I'll have to upload it to youtube or make a slightly longer / better video.

I still need to make a rest for the platen and get a contact wheel and make an attachment for it, but to have it turn on and go is great!

 

[capitalcrew]

Also, now that it runs I'll be working on the details. I want to add a cap to the top of the vertical post so it looks neater, plus a handle there. I want to add handles to the lock down bolts so I don't need a wrench, round off some hard corners etc etc.

Once it is warm I'll be sand blasting the whole thing and painting it so it looks nicer.

Now I just need to built a nice steel top bench with a spot for this on the side. That'll be my next project.