home built grinder 20 bucks

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vikingGoalie

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i dunno why this site doesn't have google as an allowable source for media but here's a link a picture...

photos.app.goo.gl

New item by Carl Christianson

photos.app.goo.gl photos.app.goo.gl

I used a treadmill motor, skateboard wheels, pvc end cap as the drive wheel bolted onto the flywheel of the treadmill motor.
Spring is from a trampoline, work table is from the deck of the treadmill and the lumber was scrap I had laying around, only real outlay was on bolts, in truth this probably cost me closer to 10 the 20 dollars ;)
The good.
It eats metal like crazy, the belt tracks well the frame is *very* stiff and doesn't vibrate or anything like that.
I felt it amusing to just use the treadmill controls so I have a slider for speed of the motor, I love the variable speed even at low speeds it's impossible to stop the motor dead.

The bad.
The swing arm with the wheel for tracking, I should make the arm longer on the spring attachment side. That will give more tension and will help reduce sideway yaw forces on the bolt.
It has enough tension now that it tracks well and does what it should but I would like just a bit more, that's phase two of the project ;) For now i just want to use it.

Some on this forum posted that a treadmill motor is not suited for this purpose. Well I'm here to tell ya you can't bog this down it's a 7.5K rpm 2.5 Chp motor. I only ever really run it at half speed at most, mainly because i don't want to eat metal to fast (don't trust my skills to not completely screw up a piece of steel). I talked to someone else who has done this and their motor is still going strong after 2 years, these motors are free every week if you look in facebook marketplace, I made this with a cradle for the motor so it's stupid easy to thread the flywheel with drive wheel bolted on off, put on a new motor and clamp it back down. In fact I have a second motor on the shelf already. I'll see how long it lasts but so far so good.
 
Looks like some creative work there. Good luck with the grinding - you gonna have fun.
 
You Little Rascal the hell out of that.

That motor will work until the steel dust kills it.
 
We have seen a lot of wooden Frankengrinders over the years. It is a fun way to get into knifemaking. It won't last a long time, but will be fun while it lasts.

YouTube video links are allowed. The only restriction is sites that have sales info or prices posted.
 
polish avenger said:
Don't ignore the whiffs of campfire!
Click to expand...
number one concern was sparks, wood, and fire. i'll keep an eye on it, the platen takes most of the heat and it's steel. I have metal tape on standby to apply as needed.

The only downer is I had a couple of jigs I made that I used with my 1x42 (that i killed) but due to how the frame is very close to the table on the one side messes with it, so gonna craft another jig that works for consistent profiling on this, right now doing it by hand and that's definitely not optimal.
 
You really want to do something to close up that control board from the treadmill and move it to another location beside the grinder. Besides a shock risk, it will attract metal dust and fry the board pretty easily sitting behind the grinder like that.

Your project reminds me of how a simple and not technically perfect project that was fun to build can lead to learning how to do more complex things.
I built my first "race car" at age 6. It was nailed together from three 2X4s with baby buggy wheels nailed on with 40p nails as axles. It was gravity powered down a steep driveway and you steered with your feet on the front axle. It crashed when you tried to turn into the street and would fall apart easily. I nailed it back together many times before I figured that screws and bolts would work better than nails. Of course, I had to teach myself how to drill holes and put in screws, but the next one was much better. I followed up by building all sorts of soap box derby cars over the next 6 or 7 years. Around age 13 I figured how to add a motor and every kid in the neighborhood had a go-kart. I lost a fingertip in a chain on one of those. 10 years after that first primitive 2X4 death trap I built a welded metal frame midget racer with a 20HP motor that did well over 100mph (talk about a death trap!). The principles were the same, just each ideation more refined and technologically sound.

Same with knifemaking. That knife I made in my grandfather's garage 62 years ago using a propane torch, a ball peen hammer, and a scrap of mild steel was exciting ... I had made a KNIFE! What I make today is the same thing with more refinement and better technology. I still have that knife and am still proud of it.
 
AIL4fc9Lw59xki6ivlknxjlYA3ToERdXSuB1GGJzos7AHSVgBZ7LwDC_Q7fPYkliDpXbwDT82ngqLVAOSgLkz8IPGcFMkqs8COY7YKP7IiwFT860YiHBszHLC8SaFWeWC---AhRnQtpSzoVNg14DW4-znbziDw=w1648-h927-s-no
 
oh don't worry i'm enclosing all that, this was just a hey I got it all working kinda pic. since then i've mounted it to a table on wheels and I'm putting a drywall filter bag (for a shopvac) around the components, figure it stops drywall dust it'll stop metal dust.
Oh and I've already got a few improvements I want to do to this design, and the next one built from scratch will be just a little different
 
Reminds me of the grinder someone in a discord server I'm in made/uses.

Screenshot_20230723-234724~2.pngScreenshot_20230723-234731~2.png

Its made of wood, with skateboard wheel, a wooden drive wheel he made. He runs it off of a bench grinder, with a drive belt he made out of duct tape.
 
vikingGoalie said:
i dunno why this site doesn't have google as an allowable source for media but here's a link a picture...

photos.app.goo.gl

New item by Carl Christianson

photos.app.goo.gl photos.app.goo.gl

I used a treadmill motor, skateboard wheels, pvc end cap as the drive wheel bolted onto the flywheel of the treadmill motor.
Spring is from a trampoline, work table is from the deck of the treadmill and the lumber was scrap I had laying around, only real outlay was on bolts, in truth this probably cost me closer to 10 the 20 dollars ;)
The good.
It eats metal like crazy, the belt tracks well the frame is *very* stiff and doesn't vibrate or anything like that.
I felt it amusing to just use the treadmill controls so I have a slider for speed of the motor, I love the variable speed even at low speeds it's impossible to stop the motor dead.

The bad.
The swing arm with the wheel for tracking, I should make the arm longer on the spring attachment side. That will give more tension and will help reduce sideway yaw forces on the bolt.
It has enough tension now that it tracks well and does what it should but I would like just a bit more, that's phase two of the project ;) For now i just want to use it.

Some on this forum posted that a treadmill motor is not suited for this purpose. Well I'm here to tell ya you can't bog this down it's a 7.5K rpm 2.5 Chp motor. I only ever really run it at half speed at most, mainly because i don't want to eat metal to fast (don't trust my skills to not completely screw up a piece of steel). I talked to someone else who has done this and their motor is still going strong after 2 years, these motors are free every week if you look in facebook marketplace, I made this with a cradle for the motor so it's stupid easy to thread the flywheel with drive wheel bolted on off, put on a new motor and clamp it back down. In fact I have a second motor on the shelf already. I'll see how long it lasts but so far so good.
Click to expand...
Hi. I am a newbie here and to knife making. I have made 3 knives with hand tools and a 1x30 grinder. I am now finally building my own 2x72 grinder. Would you be so kind and explain how you built/attached the drive wheel (looks like a PVC pipe) to the flywheel of the motor. I would be much obliged. Thanks so much
 
Welcome dmon1234. Fill out your profile so we know where you live and something about you.

The OP hasn't been on the forum in a year.
He said it was a treadmill motor and he bolted the PVC pipe cap on the flywheel.
"I used a treadmill motor, skateboard wheels, pvc end cap as the drive wheel bolted onto the flywheel of the treadmill motor."


I will say that the methods and parts the OP used don't look like they would last long. The drive wheel should be metal and fit concentric on the motor shaft. If not, you can expect the thing to shake the nails out of the walls. Use a 56C face motor and a standard drive wheel with a 5/8" bore. These can be found online pretty reasonably. If we know where you live, someone may have parts and a motor they will give you.
 
Hi Stacy. Thanks for the reply.

Yes, I agree. Without making the "wheel" concentric with the flywheel, it will vibrate like hell... Thus my question :)
I have seen some YouTube videos of folks welding a pipe to the flywheel...

I have 2 treadmill motors (1.0 and 1.5 HP) which I was hoping to re-purpose. I have a nice little Chinese speed controller for the 180v motors. I have been reading about the metal "dust" getting into the motors and screwing them up after a few months.

It seems to me that the consensus is to buy a 2 HP ac motor and drive it with a VFD. The cost here would be around £250 ($320) which I was hoping to avoid. But I might just bite the bullet and get it done right... Will also have to buy a drive wheel to match the motor shaft.

I bought some lovely aluminum idler and tracking wheels and was looking to improvise with the drive wheel :)

Thanks again for the response.
 
Treadmill motors work. The open frame is the problem. Wrapping with a layer of fiberglass filter material and putting a plastic bin cut to fit over the motor will also help keep stray metal dust out. Vacuum often.

You might be able to get a drive wheel with a bore to match the treadmill motor. A machinist could make one, or rebore one, if one isn't a stock item. If the treadmill shaft is a good bit smaller, a sleeve may work.
 
Agreed. A filtering system. To make a custom wheel or machining one is just so expensive here. I don't know any amateur machinists... For that money I would just go to AC/VFD.

What are your thoughts on:

1) Making a wooden wheel to fit the protruding part of the flywheels and then screwing it onto the flywheel ... Not hard to do with my wood lathe.
2) Just using the flywheel (it is almost 6 inches in diameter) to drive the belt...

Cheers
 
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