Machine belt grinder build

[garageguy]

I am looking into building a belt sander/grinder. I've done a bit of research but have not found any advice as to how many ft/min. to run the belt at. It would be used almost always on metal. I have a DC 100v treadmill motor and an AC 1/2 horse motor that I can use . I think the DC motor is just over 2 HP. I need to figure out what size drive wheel I would need for each etc. but aprox. what fpm should I be shooting for on the belt? Any help or tips would be appreciated! Oh, and looking at using a 2x72 belt as this seems common.

 

[whydontu]

all else fails, cheat. We’ve been running one of these in our shop for about 15 years, almost 100% for shaping 316 stainless steel. It runs at 3900 sfm

3" x 79" 2-Wheel Metal Belt Grinder/Sander - Grizzly Industrial

<h1>G0489 3" x 79" 2-Wheel Metal Belt Grinder/Sander</h1> <h2>A belt grinder/sander designed to give you versatility and performance.</h2> <p>The Grizzly G0489 3" x 79" 2-Wheel Metal Belt Grinder/Sander is made specially for metal workers.</p> <p>It uses 79" sanding belts that resist heating up...

www.grizzly.com

 

[combustable herbage]

This is a good place to start.

2x72 sander

I should have added some photos for those into....photos....:D

canadianhobbymetalworkers.com

 

[garageguy]

Great! thanks for the link, wish I had seen that earlier.

 

[Art M]

I’m looking at the same thing. After an excessive amount of internet research I’ve narrowed it down to either a basic KMG design or the Sayber open source grinder. The Kmg is rock solid easy build but no tilt. The Sayber is tilting and can be bolt together or some welding. Only thing with the Sayber is paying to waterjet or laser the parts. I tried plasma table at work but the files would need rework as the kerf is to wide and my guy couldn’t figure it out.
Art

 

[Art M]

Note
I also collected square tubing to make one as they seem to work well too. But with the development of no more welding. I decided to go with a little more elegant design. Also we have an actual KMG at work and I really like it.

 

[Former Member]

I built one about 2-3 years ago and love it. Belt speed I forget what I calculated so it is what it is. Intent was to build it as cheap as possible and upgrade, truth be told works great, so why mess with it.

My general feeling is that belt speed may help in certain circumstances, but overall no matter what it is, correct grit and pressure results in the fastest removal, best finishes with the least amount of heating experienced in other methods.

Go for it.

Beeswax help can help in keeping the belt from clogging or alternatively use a crape stick and clean the belt on occasion.

 

[phaxtris]

ive built two, the current one is 3800sfpm, the last one was a similar speed, iirc in the 3500-4500 sfpm range was considered kind of a good general use speed

 

[garageguy]

Did you guys use an AC 110v motor or a DC ? The 1/2 hp motor I mentioned earlier is 1073 rpm, out of a wheel balancer, seems slow and also I am wondering if it will be underpowered. Thoughts? The DC motor I have is 2.25hp.

 

[phaxtris]

both of mine were with ac motors, 1/2hp ac would probably be pretty underpowered , you could make up the sf with a bigger drive wheel, or a jackshaft, but you would still be under powered imo

i would should for the min of a 3/4hp motor if using an ac motor, and a 3650 motor makes life easy for direct drive without a massive drive wheel

dc i cant really comment, they have some funky rating methods, what is the rated rpm of that motor ? might be easier to figure what an equivalent ac hp is if you know the wattage of the motor

 

[garageguy]

The tag on the DC motor doesn't give much info, no rpm rating, wattage, nothing. just HP and voltage. I don't even know what max rpm would be, maybe 3000 or more? I believe max volts is around 100-110. This is what makes it so hard to figure out drive wheel size. I am guessing that I will get more HP by increasing voltage/rpm?

 

[garageguy]

I went to the KMG site and all their kits use 1 hp or more so the 1/2 hp is out. I have a 220v motor that was on a pump out in the garage, I'll check the hp on that one.

 

[garageguy]

my othermotor is 3/4 hp 110/230v , 3450 rpm, A10/5 , SFA 12/6 , SF 1.25 . Marginal, I would say.

 

[phaxtris]

i just checked, the one i have currently is a 3/4hp open frame 3450rpm jet pump motor, that does fine for what i use the grinder for (just general metal working)

im sure i might be able stall it out if i was trying to grind 3 or 4 square inches at a time, like trying to make a big knife...but that's not what i use mine for, i tried it, grinding at work and then coming home and doing more grinding wasnt for me

overall the 3/4hp works for me, i dont know what you plan to use yours for, if its just general metal working, rounding corners, chamfering, flattening edges, etc, the 3/4 will probably do you just fine

if the motor you have is a c face motor just give it a shot, if you find it underpowered find a bigger c face motor later on, really if you already have it you dont have anything to loose by trying it

 

[TorontoBuilder]

Okay, time for my two cents... because why not.

While researching surface feet per minute speeds for materials to include in my machining calculator I was able to find the following general guidelines for belt grinders. The usual caveats apply in the event that your results don't turn out as expected because speeds for belt grinding depend on the type of material being ground, the type of abrasive belt being used, and the size and type of the grinder.

1. Metal Grinding:

• General purpose grinding: 3,000-4,000 SFPM
• Heavy-duty grinding: 4,000-6,000 SFPM
• Finishing and polishing: 2,000-3,000 SFPM

1. Plastic Grinding:

• Soft plastics: 1,500-2,500 SFPM
• Hard plastics: 2,500-3,500 SFPM

1. Wood Grinding:

• Roughing and shaping: 3,000-4,000 SFPM
• Finishing: 2,000-3,000 SFPM

As a general rule, a 3400 rpm motor and 5" drive wheel will deliver about 4500 surface feet per minute. A variable speed drive and minimum 2 HP are typically recommended for 2 x 48 and 2 x 72 belt grinders. the only functional difference between the two sizes is the 48" belt will load up faster and require replacement sooner.

 

[garageguy]

good info, Thanks guys! I'm doing all mystery metal, no wood or plastic . No knifemaking or real heavy grinding. I may go with the 3/4 AC. Probably the same motor as what @phaxtris has.