DIY 42" grinder

[changeofseasons]

I'm looking into building a custom 42" grinder. Has anyone here done this or know of someone who has? I need to make something better and more precise than a belt sander, but lighter and less powerful that a 72" kmg or the like.

 

[McAhron]

Check out British Blades.They have many smaller grinders made by their members.

 

[Peter Milner]

My first grinder was a 1" x 42" with a 1/3 hp motor. I just put on a drive wheel and idler from a local hardware supply, mounted it to a wood board and away I went. Made my first five knives with it. Once I got my salvaged Burr King off and running, I set it aside. I brought it back to do final shaping with a slack belt and fine belts. It still serves me well as a final step between my production machine and hand sanding.

 

[Matt Browning]

McAhron, would you be any chance have advice on where to look on BB? I've been spending some time searching the site and haven't come up with anything.

I just made my first knife on a Grizzly 1 x 42. I'm happy with it, but i'm going to need to built a stiffer platen for it soon. Eventually, I'd love to build my own 1 x 42 from the ground up, as I plan on primarily making small slipjoints, and don't know that I have a need for a large KMG or similar either. I also just really like small yet powerful and well built tools.

 

[12345678910]

http://www.practicalmachinist.com/vb/general-archive/diy-belt-sander-77689/

http://www.projectsinmetal.com/free-metalworking-project-plans-2-x-42-belt-sander/

no idea how to resize this huge pic
http://www.projectsinmetal.com/wp-content/uploads/2009/03/franciscos-sander-01.jpg

 

[jawilder]

If all you want is a 2x42 then why not go with a Craftsman 2x42. It has all the precision and power you would need unless you want to slow it down or really hog off steel.

 

[ernestrome]

I think there is some confusion here between speed and power. The craftsman 2x42 is fast at 3450rpm, but low powered at around 1/2 hp. So it is both hard to control (especially for a beginner, as I found) and yet easy to stall if any pressure is applied: the worst of both worlds. I'd much rather have a 1+ hp 1725 or even 1150 RPM motor than a 3450 if I only got to have one speed (which I do).

If your budget stretches to 3 step pulley system or better still a VFD and 3Phase motor you can adjust speed and at slow speed it gives you the precision you are looking for, and the ability to ramp it up for hogging.

If you have the ability to make a custom, you could make it so that the 2 wheels types shown above were adjustable so it could run 42 and 48 maybe even 72" inch belts. With a rear idler you could also extend it to take 72" belts. There are some great belts that are available in 72" lengths and not in the others.

I put a slower (1725RPM) but more powerful motor (1.5hp) on an old 3 wheel craftsman 2x42 and it works great. I would love more speed control if funds allowed. I have some pictures http://sites.google.com/site/alexnharvey/home/knifemaking/craftsman-2x42-grinder

 

[Stacy E. Apelt - Bladesmith]

An important thing to consider is that except for 15" more steel in the arm, there is no difference between a 2X42 and a 2X72. I would make it the longer size.

Power is not a big issue, and any motor 3/4HP to 1HP will work fine. Use three-step pulleys and it is speed adjustable. If you come up with a VS motor online later , you will only have to switch out the motor. There are many low price DC motors available in the 3/4HP range.

My only other piece of advise is to overbuild it by at least 50% over what you think is plenty ( twice would be better). What looks thick enough in planning may flex under load.

 

[Matt Browning]

1-10, thank for the links and images. Very cool looking little grinders.

I can't speak for everyone, but for me, I'm interested in potentially building a 1 x 42 (not a 2 x 42) over a 2 x 72 for several reasons (in order of importance):

1. I make very small folding knives, and doubt I'll ever be grinding a blade over 3 inches.
2. I have a small workspace, but even more importantly, I just like smaller, more portable tools. I see some of these KMG clones that look like they weigh 250lbs. My little grizzly 1 x 42 probably weighs 30lbs.
3. If I plan on making very small blades, and really never hogging off lots of metal, I would rather have a compact machine with a thinner belt that makes detail work easier.
4. There is some money, a small amount, saved in making a smaller machine.
5. There is some money, a small amount, saved in buying smaller belts. Norton Blaze and a lot of the good ones do come in 1 x 42.

I get the RPM vs. horsepower argument, and would definitely go for a 1hp motor even on a 1 x 42, most likely on a step pulley system. Thank again for the plans and images, these are great.

 

[Atlas Knife Company]

I would agree about the 2x42 grinder. A fine choice used by many.

However, I made a DIY 2x72 grinder conversion thread. You can build one for about $150. It is definitely lighter and cheaper than a KMG or even a GIB kit, but still enough to use 2x72 belts. The only inconvenience is the lack of variable speed with it. definitely a step up from the stock 4x36 or some other belt sander designed for wood. If you look around, Menards might still have some 4x36 grinders for $69.99 left over from their Christmas specials.

http://www.bladeforums.com/forums/showthread.php?t=803811&highlight=diy+conversion

 

[ernestrome]

You can run 1" belts on 2" wheels but not vice versa. Unlikely to regret building in flexibility. Good luck whatever you build.

 

[james terrio]

You can run 1" belts on 2" wheels but not vice versa. Unlikely to regret building in flexibility. Good luck whatever you build.

Absolutely right. If you're going to build from the ground up, go for 2x72". It shouldn't cost much more to build and you'll have far more choices in good belts, room for contact wheels, different platens etc.