Multi Use Tool Arm Build (Pic Heavy)

Big Smitty

Big Smitty

Joined
Aug 30, 2007
Messages
509
Here are some pics of a tool arm that I designed for the grinder I just built. It is modeled after others that I have seen, but I tried to take it up a notch.

This tool arm will work with an 8" or 10" contact wheel on one end and up to a 4" contact wheel on the other end. The platen is 7" long and is made to be adjustable to the varying angles that different size wheels will present. There is a slack belt grinding area on the back that is nice and deep due to the arched design of the arm.

The pictures show it set up with an 8" wheel and a 2" wheel. Positioning is accomplished by loosening the nut and rotating the arm and then re-tightening the nut. This thing is really sweet and runs smooth. Saves a lot of time in switching tool arms.

Comments and feedback welcome. Also, I am considering doing a production run of these if there is any interest, let me know.

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I am just wondering, how well does the bolt hold it? If I made this, I would probably drill 4 holes in the thing around the bolt hole, and then put one hole in the arm slot, and then put a pin in there to add extra strength. If you don't understand what I am saying, I can try to draw a picture.
 
Mike,
No pic needed :D, I get just what you are saying. The bolt you see holds fine, but is not optimal. Not to worry, I have the answer to your comment at my machine guys shop being made.

Notice the hole in the arm is 3/4". I am having a bolt machined that is 1/2" diameter and then there is a flange and it bumps out to a 3/4" ferrule and then to a 3/4" thread with a 3/4" bolt. The 1/2 inch end goes into the tool arm that comes with your grinder and is snugged tight. The multi use tool arm mounts on the 3/4" side of the ferrule and then the 3/4" nut tightens against the multi use tool arm and the flange. LOL if you need a pic I can post one :confused: :eek: . Anyway, once I get one back from the machine shop I'll post it. This 1/2" to 3/4" set up will hold the arm and allow quick loosening and retightening with one wrench and only a 1/4 turn of the 3/4" bolt to move the arm.
 
Yeah, a pic would really help. I got the 1/2" diameter, and then the flange and then it all got lost in a series of fractions :p
 
Hi Friend,

Thanks for posting this! It looks fantastic. I too look forward to seeing pics of the bolt solution you described. Can you weld a handle of some sort on the bolt head and dispense with the wrench?

Just wondering...can you think of a way to do something like this with a third arm so there can be 8", 4", 2" contacts plus platen and slack belt? :eek: Seems like if anyone could figure it out it might be you! :D

All the best, Phil
 
Farmer Phil said:
Hi Friend,

Thanks for posting this! It looks fantastic. I too look forward to seeing pics of the bolt solution you described. Can you weld a handle of some sort on the bolt head and dispense with the wrench?

Just wondering...can you think of a way to do something like this with a third arm so there can be 8", 4", 2" contacts plus platen and slack belt? :eek: Seems like if anyone could figure it out it might be you! :D

All the best, Phil
Click to expand...

It is a very nice build and thanks to Big Smitty for sharing pics.

I've been thinking about the 3 wheel multi position arm as well. It shouldn't be that difficult, the only real consideration is that to gain effective radius on the smaller wheels you lose effective radius on the big wheel. For a knife maker it probably won't be an issue, as you can see from the drawing.

Disregard the belt drawn in, as there isn't a drive pulley drawn in yet. :)


3wheel.jpg
 
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Man, it looks GREAT to me. I'm kinda jealous really!
 
Terry,
I went with 1 1/2 hp @ 115VAC for now. Just easier for me now, plus I am moving up from a Craftsman 2X42, so I kinda feel like I went from a bicycle to a race car.

Phil,
I am not sure that an additional wheel would work but I can try. the reason I say this is that it would reduce belt contact on the smaller wheels which would effect grinding into smaller radius spots. Look at my last picture and envision another wheel added in and it would tak the belt away from the smaller wheels. I really had to work with the geometry of the multi arm you see to get it as good as possible. 69 knives hit it right with his comments.

As far as welding an arm on the bolt, no problem, just have to watch for clearance issues, but I can work on that one. I am also considering some typ of a knurled knob that would eliminate a wrench all together.

Thanks for all the comments everyone!
 
Big Smitty

The receiver tube (? 2x2) on top of the large tube (?4x4) it's purpose?

Maybe a tool rest receiver? If so where are you going or have you gone with a tool rest.

Your design is so neat and I am in love with tool arm

Let me say thanks for the excellent photo's

Sincerely

Rupert Lucius
here in Louisiana
 
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