DIY Grinder design

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kirch93

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Aug 18, 2015
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Hi guys!

I am designing my 2x72 grinder, so I thought some may be interested in having a look. This is my second grinder design. The first was a spring less design that I learned a lot from. (without actually making it)

I have spent waaay too long on the design so far. Going back and forth several times, being too picky. But hey, its a fun project and I will get there eventually.

After looking around at all the different grinders, I really liked the DSM toolworks grinder, but it seems they never carried on with selling it or anything.

The design will be laser cut and bolt together, for those of us without a decent welder.

There are actually two designs I am working on and keep going back and forth between, one will be a fixed flat platen, nice and simple, the other will be for use with a tooling arm, but both will be similar in style and function.

Here is my old design:

KB-MK1.11.jpg


KB-MK1.10.jpg


This is the dsm toolworks grinder that looks awesome.

dsm-toolworks-grinder.jpg


Here are the current designs:

Mk2-1.jpg


mk3-1.jpg


Cheers!
 
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I'd seen the DSM grinder some time ago. There are a few things I like about it, and a few I don't. The main issue I saw with it is that it didn't really allow for a larger contact wheel. The tension seemed just a bit light as well, with just a small tension spring. The mechanism he used looked really cool and simple to actuate, but the belt tension seemed awful light.

If using for knife making, I like to have options, but for general fab shop use/deburring parts, a flat platen and a small wheel are probably fine. For the most part, it seemed like a pretty neat and thought out design.

Between your two designs, I'd probably lean towards the top one for versatility sake.
 
All the cut outs are cool and all, but just more places to catch dust IMHO. I'd have to lean towards the to one as well. Looks more functional.
 
Changing out tooling arms is the reason we build our grinders the way we do. The first design looks to accommodate this feature while the second looks to just be a flat platen grinder?
 
Are you looking at producing this to sell, or just building it as your own personal grinder?

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The first design looks to be just about perfect in my opinion. Secondary tool arm, direct drive, swivel base, ratcheting tension. Much more versatile than the secondary design. Just my opinion. :thumbup:

Blessings,
Joshua
 
My only concern with the first design is the way you are clamping the tool arm in. I'm not an engineer or anything, but I am not sure that type of lock will pinch tight enough. It works on bike seats because the round tube is in contact with the entire surface of the clamp. In this case, it is only contacting the two sides of the square tube and primary at the top corners of the tube. I really like the idea of the outer material clamping the tube. Maybe a bolt with a lockwasher would allow you to get it tighter?
 
If I had mine to do all over again, I would add a third slot for tooling. When go to convert from my DC treadmill motor and pulley set up to a direct drive AC motor set up and have to cut off some parts and weld on a new motor plate, I may just add it then.
 
Thanks for the input guys!

So most of you would prefer to use a tooling arm over a fixed flat platen? I really liked the simplicity of just a fixed flat platen, for someone who doesnt use contact wheels I think it would be great, but obviously you guys do. Thats kind of why I went with two designs, one with and one without. Maybe I should focus on the tooling arm version. hmmm.

I probably need to clarify, the red version at the top is a finished design I did a while ago, the bottom two pics are of what I am working on now.
 
kirch93 said:
Thanks for the input guys!

So most of you would prefer to use a tooling arm over a fixed flat platen? I really liked the simplicity of just a fixed flat platen, for someone who doesnt use contact wheels I think it would be great, but obviously you guys do. Thats kind of why I went with two designs, one with and one without. Maybe I should focus on the tooling arm version. hmmm.

I probably need to clarify, the red version at the top is a finished design I did a while ago, the bottom two pics are of what I am working on now.
Click to expand...

Way back in the day of machines like the Wilton Square wheel, swapping out tool arms and work rests was not on the top of anybody's radar. In a fab shop where you're just using the machine to knock a burr off or put a quick chamfer on something, you really don't need much more than a flat platen. That's kind of what I envision the DSM style machines to be geared towards. Then on his, you have a small wheel option for notching tube and things like that.

In a knife making shop, on the other hand, versatility is king. One minute I may be flat grinding a chef knife, the next I may be hollow grinding another blade, and then I may throw on a small wheel to contour a handle. Then I might want to tilt the platen or a tool table to work out a swedge or grind a tool bit for my lathe.

For a fab shop, a belt grinder may be almost more of an afterthought, and I'm sure many don't even use them. For knife makers, it's probably the #1 tool in the shop. The more features the better, I say, as long as you're not sacrificing one for the other.
 
I just finished building my grinder a few weeks ago that looks almost identical to your top design aside from the ratcheting arm. I gotta admit, the bike clamp mechanism worked much better than what I was expecting.

b9b9ff6659f754a25936b31e65aba424.jpg



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I agree with Andrew on what he has said, I would try and mod to accommodate 3 tooling arms. You definitely want to be able to remove the flat platen easily and put a different tool in place. I would also design my flat platen assembly where you could actually remove the platen and allow slack grinding between the two wheels for the platen attachment. I actually like the later design and the multiple cutouts wouldn't bother me that much--I've got an air compressor and a nozzle so I could blow off any dust that gathers on my grinder. I think if you asked a lot of knife makers it would be pretty consistent that folks wanted multiple tool arm options. I would also make sure you could put on a strong gas shock to ensure tight belt tension, and even possibly offer a ratcheting tensioning option like North Ridge does. Good luck, and also try to keep the cost as low as possible.

Good luck--Don
 
tommywoh said:
I just finished building my grinder a few weeks ago that looks almost identical to your top design aside from the ratcheting arm. I gotta admit, the bike clamp mechanism worked much better than what I was expecting.
Click to expand...


Well, I stand corrected on the bike clamp. It certainly would make it a bunch faster and easier to swap out tooling! Thank you for the picture Tommywoh.
 
It really is much faster and it eliminates the scoring and indentation caused by traditional adjustable threaded handles


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the red one is a much better design, but a couple things. 1. move the horizontal pivot closer to the side. it will be easier to swing. 2. the design as-is will still require welding in a couple places. 3. you show ledges that the top of the tool arms slide into, that will be a pain to do and keep the pocket square.
 
Thanks for all the input guys, you have convinced me to work off the old design.

I may pick the others back up at a later date.

So is 3 tooling arm slots necessary? What do you use the third for? I may do two versions, one with 2 slots and one with 3.
I am simplifying the tracking to the "standard" design everyone uses. I wanted it to be .25in plate but it just isnt viable. Will be using .5
Other changes are I will be going to a sprung tension, if I produce plans for people (kind of the plan) I wanted it to be as simple as possible, thats why the original didn't have springs. However I have come up with something clever (I think its clever haha) to accommodate many different springs.
It is also going to be completely bolt together so you don't have to have a welder to put it together. It may have a couple of straight bent parts for the mount. But most places that will do laser cutting have a folding brake of some sort.

Here is progress, didn't have too much time today to work on it but I am happy so far.

Mk4-1.jpg
 
I suggest to only have the slots on the left side plate so that when the bike clamps together it will push the tool arm flat against the motor plate instead of having both side clamp towards the arm which can cause a very slight amount of misalignment


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i agree with tommywoh. no slots on the motor mounting plate. 3/8's plate will be plenty heavy, 1/2'' will work but it might be a pain to compress the left side. if you use 1/2'' there that will put you at least 3/4'' thick counting the thin rails. i still dont see how you can maintain the squareness of the ''pockets'' when the two halves are only connected by the clamp handle bolts in the front. tommywoh has a total of 7 bolts and spacers holding the two halves together. much better design, but i cant figure out what he's using to tension the belt.
 
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