Grinder frame design.

[Natlek]

Yeah 20” wheel was what I wanted to do but there is so little area for an idler/tracking. With a 20” wheel the best way is to have it be the driving wheel.

Something like this one , but with two wheel not like this

 

[mike-E]

You could use a 5 1/2-6" drive wheel with a 20" machine. Use the weight of the motor for tension by hinging it a bit forward of center.
Make the hinge/motor mount swivel for tracking.
As for your 12" wheel, I would just build a standard 1 1/2" tool arm grinder that would accommodate at least a 14" wheel.

 

[coldsteelburns]

I was recently watching this, which I thought was a pretty brilliant idea for tracking a two wheel grinder, which uses the motor and drive wheel as mike-e mentioned above. I'm sure it could be made in a more crude/easier manner if you wanted.

(For what it's worth, I recommend watching the entire 6-part build series, not only for all the clever construction and machining techniques, but because it's just plain fun lol)

Video showing the finished grinder:

Here's the video specifically dealing with building the motor tracking system:

~Paul
My Youtube Channel
... (Some older vids of some of the older knives I made)

 

[JTknives]

You could use a 5 1/2-6" drive wheel with a 20" machine. Use the weight of the motor for tension by hinging it a bit forward of center.
Make the hinge/motor mount swivel for tracking.
As for your 12" wheel, I would just build a standard 1 1/2" tool arm grinder that would accommodate at least a 14" wheel.

My original belt grinder had the motor weight as the tension and when I wound load up the belt the motor wound climb up the belt and slack the belt. Now this was the drive belt of a stepped pulley set up but it was very problematic.

 

[ashwinearl]

There is the open source grinder project with plans.

 

[REK Knives]

Jt, I think you should make some production grinders ... You not only have all the equipment to do it but you are a very knowledgeable knife maker so you know what works and what doesn't, and what would be innovative...

 

[Scaniaman]

Yeah 20” wheel was what I wanted to do but there is so little area for an idler/tracking. With a 20” wheel the best way is to have it be the driving wheel.

Yes, like on the BBA20 by Burrking. Excellent solution, and maximizing contact wheel size.

 

[Scaniaman]

Something like this one , but with two wheel not like this

Bruce Bumps 24" machine! I really want a 24" machine as well. Posted about it some time back. I did put an order for one shortly after but the whole deal collapsed since the maker's wheel supplier could not make that size anymore. Since then I did find another supplier but I'm more and more leaning towards a 20" one since I'll be able to use standard belts that goes on my current grinder, but the jury is still out on it..

 

[Stacy E. Apelt - Bladesmith]

To run a very large wheel on a standard grinder, just make a longer tool arm and use a longer belt. You will need a 1.5" or 2" tool arm.