jason, I am familiar with the glass grinders, as I had one when I did lapidary work.
But, I don't want a large belt grinder, I want to build a grinding wheel stimulant. I have a 36" radius platen for my 2X72 grinder already. There is a huge difference in how a large radius wheel grinds cuts vs a platen. The water spray will lubricate the belt and cool the blade at the same time. This should be an affordable version of a kaiten toishi for a fraction of the cost. The ability to easily change the grit will make it really versatile.
javand - I allowed for the cloth, that is why I dropped the resin amount to 20-30 gallons from the cylinder volume of 40 gallons.
More on the build:
I plan on building this as a unit with a straddle type bench seat...so I can grind sitting down. A kaiten toishi is normally fully enclosed and there is a 4"X10" exposed area of the wheel. Some are just a fully exposed wheel like the old Sheffield units, with a or the person grinding to lean on. Normally the smith stands up and leans over the wheel. Mine will have a flip down cover that mimics the Japanese versions, and I can straddle the bench seat while I grind. One reason I may go with a smaller diameter ( 30" -36") is to avoid having to reach out over the wheel diameter to grind...another is that 36 and 48 inch tires are hard to come by in any width near 6".
On the tire . It won't really matter if it isn't a perfect cylinder, as the belt will ride on it. The slow speed will not make a bumpy grind. I plan on doing a post grinder thing when the tire is in place and taking down the tread until I get a near perfect radius. I could even take the tire to a tire shop and have it lathe turned. If the tire is wider than I want, I may grind the tread down on both sides of the 4" area that I will track the belt on. There is a lot of thickness in a tire that I don't need if it isn't on the road. I even considered filling the tire with oil, but decided that air will be fine.
One huge advantage of using an automotive wheel and axle is that it leaves one side unobstructed. The build will be basically like an enormous KMG. I can change a belt in less than a minute. I am really thinking of using the 12" drive wheel system for two reasons ( contact wheel - tracking wheel - drive wheel). One - I already have it. Two - It will be easier to gear down, since it runs on belts and pulleys already. I haven't looked at the gear ratio that is on it, but it may already be low enough without changing a pulley. Another advantage is that I can make the belt size the same as the tire, as the tracking and drive wheels are for 12" belts - 6" or 8" will be fine ( but overkill).
When I start this build next year, I will fully document it and make a tutorial, as I believe this is an unexplored grinding technique for most knife makers. Grinding on a large wheel will create a low angle hollow grind that is hard to match by any other method. Straight razors could be ground in one pass. Japanese chisel grinds will be a simple task, and have the proper shallow hollow grind on the back. Few makers of Japanese style knives actually have the proper geometry ( myself included). Who knows, I may even attempt a hollow ground katana.
As to the cost???/ I think I can build it for about $1000. That is because I lucked into so many of the parts at pennies on the dollar.
