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I Forge Iron

Homebuilt belt grinders

Rich Hale

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Lot of folks on here wish to ,,and do build their own belt grinders. Keep in mind that I am a knife maker and want a grinder for that..different uses may alter the build. 

For knife grinding you need several things that are really not options if you want one that is worth building

If you wish to hollow grind knives you need a cushioned faced contact wheel the correct size for the thickness and width of the blades you will grind. A metal faced wheel will not work for this. The coating on contact wheels is measured by a durometer. Too soft or too hard will not work well. You can contact some of the well known knife grinder makers and see wot they spec for durometer ratings for their wheels. Then when you find a wheel you need to see how it stacks up to wot we know works. For idler wheels you can use steel or aluminum. Remember one of them needs to be crowned for belts to track well. If you are going to flat grind you need a platen the width of the belt and sufficient length to work. Look at pics of commercial grinders for an eyeball guess on length. The plated need to be thick enough to not bend and warp with the pressure and heat of grinding. If I were build a grinder now I would use half inch thick steel and high enough carbon to heat treat. 

The tracking mechanism has to be really right. If the wheels are out of line the grinder will give you problems..Tracking is a fine adjustment to move belt from side to side or take care of an inconsistency in a belt. If you use cheap belts you will not get good grinds. 

All wheels must have a pair of good quality bearings to run on and nicely fit to the axles. The drive wheel must be firmly fixed to the drive shaft. The frame of the machine needs to be really solid..Grinders work hard and put a lot of stresses on the frame. 

Some steels and some belts require different belt speeds,,as well as different handle materials. To work well with all of that a grinder needs to be changed easily for belt speeds. That can be with different pulleys that let you move belts easily, or with variable speed motors, Or you can make do like I do with my milling machine,,,I need high spindle speed for tiny bits and low for large cutters..It is tough to change,,I leave it on lowest speed setting which makes me take too long with the small cutters....some day it will get a new motor and a speed knob...

My knife grinder has an adjustable height setting...seems like fluff but quite often I prefer to raise or lower it a bit. 

And let us not leave out a solid stand to hold all of this fine machinery on. 

If you read between the lines I just spent time on you may figure out that a cheap grinder is not worth the time it takes unless you keep a lot of things in mind. And if you take half a year to build one that is even passable for alright knife work,,would that be a deal?,,,

Or would you be better off to work a part time job and buy something that you can begin to learn on the day you get it?







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Thanks for your thoughts Rich.


I have a hand belt sander that sits idle and every now and then it whispers to me to build it a box and stand it upright. I need to either do as it wishes or wait it out and buy a commercially made one. 


I may want to start dabbling in bladesmithing once I get my hands on some book that I heard a couple of guys wrote.



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I started building a belt sander/grinder about 8 months ago but apart from the frame and a view bibs and bobs it's still in pieces awaiting a few components to be turned up. It's designed to be used more for wood than metal so it's current design is for a two roller with 48 x 6 belt, but I was thinking of adding a 3rd outboard  belt roller so I could put a  longer narrower belt on it. Speed control wise I bought a never used used 3phase 2HP motor for $35 and a new VFD so it can run on single phase and provide a comfortably  X5 speed range. I plan to get back onto it in the new year. I'll post some pics

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Rich......very well said and very much agree with you.

One point that you mentioned I would like to stress the importance of, that being the
rigidity of the grinder itself and the rigidity of the stand/table as to which it is mounted.
The more mass any given piece of equipment has the less prone it is to the evidence
of vibration waves affecting the surface finish on the work piece. This also holds true
In the use of sloppy inexpensive bearings, which can add to unnecessary vibration
related surface finish problems.
So when planning to build a grinder or purchasing one.........weight of the machine
and the mounting system play important roles in its overall performance.
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We have got a little saying in the workshop: "When you buy a machine you pay for the things you cannot see."


These things are the little tweeks that the manufacturer did to make the machine good. It may not be much, but it makes a big difference in the final performance.


If I could afford, I would buy new. Until then, I've got this idea for a belt grinder that has been knocking around my skull for a while......

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Bob L,,,if you do decide to retrofit for longer narrower belts keep in mind that 2" x 72" are  real user friendly..You can shop around and find a lot of sellers for that size and belts suited to almost any task you may wish to do. The length helps a lot with making a belt last. The width has a lot to do with how much work you can do with a given horsepower drive. Wide belts take more power. 

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Wayne I hope that anyone wanting to build takes advantage of wot you offer...Tips from someone that has been there may help direct away from a build that may fail. I say fail as if it would just not function as a grinder should..However maybe even worse is one that does grind...but not well at all. poor tracking..incorrect belt speed, wobbly wheels etc. may not even be noticed by someone using a belt grinder for the very first time. If and when they get a chance to use a real well built grinder a lot of things change...all of them I can think of are for the better. 

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  • 10 months later...

Here is the one I built Brother Rich . Yes it is a Beast ( Built with Much thicker material then it Originally Required) and Quite a few Mods for my own spec's & needs. It was Built from the spec's of a KMG and I added a few other things from other Machines to help me out also .


1'st set has 8 photos of parts and extras with a platen and Lg wheel adapter.




2nd shows 7 photos of some of the details of a bit of the Custom work built Wheels, Platen, Handles, Lock pin for tench arm, 6 inch direct drive wheel , and some of the Pretty work with the machine screws instillation/build.




3rd shows 5 photos of the Finished Build , and the Heart of the power & Controler used.




I hope Y'all like the photos and build I have shown here .


Blessings & Best Regards


Ret, Sgt. Yates

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:DHey Robert, guys were talking about grinders and you come along and post picks of some bit of an aircraft?


Nice job! :)


I have No Idea what you are looking at All Three links are of A KMG Clone Grinder parts, the Build & Finished  of the "Grinder" I built NOT bits of Any aircraft  Ian !

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