New belt grinder, some questions

O

Ofek O.

Joined
Jul 15, 2019
Messages
6
Hello, I'm planning on building myself a belt grinder soon, and I have some questions:
1. Will a 500W DC motor (equal to about 3/4 HP I think) be good enough to run a 2x72? I live in Israel and so getting anything stronger than that is gonna cost me an arm and a leg.
2. I'm planning on using a 100N (about 22 pounds) gas spring to tension the grinder. Is this too strong? Too weak? Should I change it?
3. I don't have access to a welder, so I'm planning to make my grinder out of wood and some reinforced 3D printed parts. Can wood withstand the stress?
Thanks!
 
I have seen a couple wood grinders, I think as long as you make it sturdier than you think you need to you’ll be good.
As far as the tensioning system goes, you want as strong a spring/gas shock as you can reasonably get. The one I got when I made mine is 40lbs, and it could probably be stronger.
The 3/4 horse motor is a bit on the weak side, but if that’s all you can get, it’s better than pedaling it with your feet!
 
A.McPherson said:
I have seen a couple wood grinders, I think as long as you make it sturdier than you think you need to you’ll be good.
As far as the tensioning system goes, you want as strong a spring/gas shock as you can reasonably get. The one I got when I made mine is 40lbs, and it could probably be stronger.
The 3/4 horse motor is a bit on the weak side, but if that’s all you can get, it’s better than pedaling it with your feet!
Click to expand...

Thanks! Do you think 3D printed parts will hold up? I'll reinforce them with steel dowels, so I think they have a good chance.
 
I know nothing about 3D printing so I wouldn’t be able to give any reasonable advise about that. Sorry!
 
Ofek O. said:
Thanks! Do you think 3D printed parts will hold up? I'll reinforce them with steel dowels, so I think they have a good chance.
Click to expand...
That will all depend on the amount of stress applied to the part, and how strong you make the part. 3D for tension arm? I doubt it. 3D part for none loaded part - most likely.
 
Many grinders are made from metal only using bolts. No welding.
 
I would forget the 3-D printed parts.

Whatever motor you used will need to be TEFC. Using an open frame motor is just wasting money, because it won't last long.
500W is only a theoretical .76HP. In actual use it is likely to develop only a tad over 1/2HP.
You should be able to get any size motor you want in Israel. 500W will work if the wheels and bearings are good, but the grinder will be very underpowered.

Wood grinder frames will work for the frame and arms if that is all you can get, but the mechanical parts will need to be metal. There are plans for wood grinders on the internet for guidance. Make it heavy duty and it will work for general light knifemaking. You really don't want wood wheels unless you have some serious woodworking equipment and skills.

Have you considered ordering a pre-cut grinder kit like the GIB, or a lower cost assembled grinder like the Origin Blade maker or similar. Shipping may cost a bit, but the grinder will be better.
http://www.polarbearforge.com/grinder_kit_order.html
https://originblademaker.com/product/belt-grinder-2x72-complete-chassis/
 
Stacy E. Apelt - Bladesmith said:
I would forget the 3-D printed parts.

Whatever motor you used will need to be TEFC. Using an open frame motor is just wasting money, because it won't last long.
500W is only a theoretical .76HP. In actual use it is likely to develop only a tad over 1/2HP.
You should be able to get any size motor you want in Israel. 500W will work if the wheels and bearings are good, but the grinder will be very underpowered.

Wood grinder frames will work for the frame and arms if that is all you can get, but the mechanical parts will need to be metal. There are plans for wood grinders on the internet for guidance. Make it heavy duty and it will work for general light knifemaking. You really don't want wood wheels unless you have some serious woodworking equipment and skills.

Have you considered ordering a pre-cut grinder kit like the GIB, or a lower cost assembled grinder like the Origin Blade maker or similar. Shipping may cost a bit, but the grinder will be better.
http://www.polarbearforge.com/grinder_kit_order.html
https://originblademaker.com/product/belt-grinder-2x72-complete-chassis/
Click to expand...

I'm trying to make this grinder with a small budget of around $300, so I wanted to use 3D printed parts to lower costs since I own a 3D printer. Since I already have the 3D models for the parts, I'll call a place that does CNC and check how much it'll cost me to just get the parts machined.
About the wood, I found a way to replace my wooden parts with 6063 aluminum for cheap from a friend, is it better than wood?
I'll have to look for a stronger motor for a good price. My problem is that anything stronger generally costs about my entire budget. I might be able to get a second hand one, or yank the motor out of an old lawn mower.
 
Aluminum is fine ... as long as it is thick enough to be strong. Many of the top grinders on the market are all aluminum.
 
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