Thread: An idea for a contact grinder.

So as part of my plan to make razors, I got myself a harbor freight mini metal lathe. I've spent the last couple of days cleaning it up and doing a bunch of little tweaks for performance.

I was there in my workshop, cuttin' up metal rod when I realized this lathe, while probably technically a bit underpowered for the job, does have a PWM motor in it and it would be stupidly easy to make a cart for it that includes a 2x72 grinder powered by the lathe.

Has anyone else done anything like this? I don't think it even really counts as a modification when the mod is to just make a custom 'tool' to stick in it that drives the sanding belt.

There are a lot of wild belt grinder conversions on "Pinterest." Many home made 2x72s and assorted others. from around the world.
Have fun!
~Richard

How much oomph does the motor have? I've heard that 1hp is more or less a minimum for a 2x72. Mine is a 1.5hp and I don't think I'd want to go lower than that.

The other thing that came to mind is what kind of enclosure the motor has. Grinder dust will kill a motor right quick in a hurry if it isn't protected.

Cool idea - I hope it works out!

If you're on FB, there's a home built belt grinder group that might have members who have tried this before.

Enteresting. I like the idea of having two tools on one motor. Keep us informed if you build this. Ive been eyeballing the HF lathe. Wasnt sure if it could knock out pens or brush handles. So i will be watching on how you go about this.

Originally Posted by Cangooner

How much oomph does the motor have? I've heard that 1hp is more or less a minimum for a 2x72. Mine is a 1.5hp and I don't think I'd want to go lower than that.

The other thing that came to mind is what kind of enclosure the motor has. Grinder dust will kill a motor right quick in a hurry if it isn't protected.

Cool idea - I hope it works out!

If you're on FB, there's a home built belt grinder group that might have members who have tried this before.

It's 3/4 horse, and I'm not sure about the motor. If I build this, it will include dust control.

Dust control in this case will be a backing between contact wheel and lathe made of peg board on one side and particle board on the other with about 1" between them inside a hot-glue sealed wooden frame ported at the bottom for a shopvac or bigger dust collection system.

I have intermediate-plans to make a serious dust collector using a box fan and one of those 'make your own' venturi vacuums that goes on top of a Home Depot bucket.

https://www.youtube.com/watch?v=4-hNfX7OKwU

As long as you don't hog down too awful hard on it, that just might work.

Will you be using it for woodworking too? If so, be careful with the dust collection. One of the guys on the FB group recently had a nice little shop fire thanks to grinding some high carbon steel after wood. The sparks and sawdust in his dust collection system made for a bit more excitement than he bargained for.

Originally Posted by Cangooner

As long as you don't hog down too awful hard on it, that just might work.

Will you be using it for woodworking too? If so, be careful with the dust collection. One of the guys on the FB group recently had a nice little shop fire thanks to grinding some high carbon steel after wood. The sparks and sawdust in his dust collection system made for a bit more excitement than he bargained for.

If it doesn't have enough power, I'll hunt down a treadmill and yank its motor out. Those are typically 2-3hp and PWM controllable too.

Essentially, having used a gizmo with continuously variable speed instead of changing belts or gears, I would like to move forward using just that and nothing else. I mean, even on this lathe, I get different results at the same speeds on two different pieces of mystery steel rod, and it's very nice to be able to just fine tune it.

That said, I'm putting a tach on here so I can more easily repeat results than just looking at the nob and maybe using a sharpie.

And no, I don't plan on mixing steel & wood. I've got a tiny 1x30 I use for any wood I need to shape, but also scales (which are usually horn, but I've got some bone and synthetic ivory I want to play with). That has its own small shop vac which I also use to clean up my work area when the metal gets deep enough to need a snow shovel.

Thank you for this thread, and those who posted ideas!
I'll be referring to this when I build my own, and regardless of when that happens, I like to plan far ahead.
Good luck with your endeavor! I look forward to seeing your process.
Much appreciated!

There’s home built 2x72 on CL right now in Albany. His asking price is a little high imho but may be worth a call to talk him down if you’re interested.

Originally Posted by jfk742

There’s home built 2x72 on CL right now in Albany. His asking price is a little high imho but may be worth a call to talk him down if you’re interested.

That replicates enough stuff I've already got that I think it doesn't quite make sense for me, but it lead me to his website and videos on his new contact grinder. Oh my is it nice.

https://www.youtube.com/watch?v=y-llG4ZG-7I