Will W.

Upgrading a belt sander to a belt grinder

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Will W.   

Good day everyone. 

I bought a belt sander very similar to the one pictured below. 4x36" 1/2 horse Harbor freight special! Lol. It works fantasticly well for wood, but for steel, it is a little underpowered, it will cut it, but it's slow to do so. I want to upgrade it.

I was thinking about hooking it up to a 1 hp motor that I have, or changing the drive pulley to a larger one, to increase the ratio, or both even. Do you think these upgrades will be enough to make it work for steel a little bit better?

Currently the pulley ratio is 1:1, its simply a 1-1/2" connected to a 1-1/2". I was thinking of putting a 3" on, to double the speed of the belt. The single hire motor I have actually already has a 3" on it. 

I don't expect it to ever work like a Bader, mind you. Lol.

Thanks in advance for any advice. 

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Frosty   

Probably more practical to cut the belts narrower so there isn't as much load on the motor. I'd try ripping 2" off a belt and trying it. Tracking might take a little tweaking but it should be doable. Try different widths till you get one that works or it proves a failure. That will only cost a few sanding belts rather than a 1hp motor and possible destruction of the machine you have. You just never know what doubling the HP of a machine will do.

Frosty The Lucky.

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Will W.   

Boy, youre fast, Frosty (Frosty the Quickdraw?) I'll try cutting the belts down. Thanks for the tip. 

What is your opinion about changing the pulley? No increase in power, just sending it forward differently. 

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Frosty   

Which pully, more speed or more torque? More pertinent would be how much modification do you have to do to the machine to a change?

I forgot to mention why I wouldn't put a bigger motor on one of these, they're made to the minimum possible safety cushion so doubling HP. could cause it to self destruct. Changing the pully might not be in the same category but it's still trying to get more out of something the maker didn't put any more into than they absolutely had to.

A 2" x 72" belt grinder is darned easy to build. I can just imagine how sweet these babies would've turned out if we had a couple few professional fabricators in the club.

Frosty The Lucky.

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Will W.   

I've considered building a 2x72, but I really don't have time for it at the moment. It's on the to do list though, once I finish up the laundry list of commissions I have (on top of working 50-60 hours at my day job.)

As for the first set of questions, the drive pulley, and more speed is what i had in mind. 

I understand the safety precautions that youre speaking of. This is by no means a high quality machine.

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Will W.

As Frosty mentioned, changing pulleys will trade speed for torque.  While your machine might be slow for heavy hogging operations, it's probably closer to ideal for finishing work.  It took a while for it to dawn on me, but the higher grit's have more surface contact than lower grits.  The heat from friction is going to be a function of surface area (contact area), time,  pressure, and belt speed. 

I have a fixed speed belt grinder and a 400 grit belt will heat the steel much, much, faster than a 40 grit belt.  If I could slow it down for the finer belts, It'd cut faster because I could make contact longer.  I have a Trizact A30 (800 grit) belt that heats the stock so fast that in some cases, I can only make contact for 2 or 3 seconds between cooling dunks. 

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I have the same exact harbor freight machine.... i agree it works decent for wood but real.... make that extremely slow going on metal. Don't get me wrong I love harbor freight it is great when you're on a budget and they have some good stuff but just remember the old addage you get what you pay for. I don't know how to post a link but maybe someone here can help there is a thread called NWG no weld grinder. I plan to build one also, check it out it may give you some ideas. I understand about the time crunch I'm working 80+ hours a week... but if you really want it you will find some time. Have your wife come out there with you while you work then you can spend some time with her and maybe she will get bit by the bug also!:D

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Will W.   
On 9/11/2017 at 3:55 PM, rockstar.esq said:

While your machine might be slow for heavy hogging operations, it's probably closer to ideal for finishing work.

This is true. It works decently well for finishing blades. It barely works for flattening and taking out hammer marks though, and that's mainly what I wanted it for. Looks like I should just build a 2x72 for that. 

On 9/11/2017 at 4:29 PM, Charles R. Stevens said:

Beter quality belts make a big difference. I use mine to dress hammers and to sharpen chisels and axes. 

I'm using some decent quality ones (can't remember the name right now) but I know what you are saying. Those aluminum oxide ones that come with the machine are garbage. 

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Will,

It might sound too rustic, but an angle grinder with a sanding disk backer can achieve admirable results for flattening out hammer marks.  The sandpaper disks can be had in aggressive grits that hog off material pretty rapidly.  The main limitation is the diameter of the wheel.  Most angle grinders have higher RPM's that work well with coarse grits.  In my opinion, the sandpaper disks are superior to stone wheels because the backer keeps them cutting flat. 

Just for clarity's sake, I'm not referring to the sandpaper flap disks.  Those are great for blending curves, but they don't cut a flat. 

 

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Yep, I have a stack of sanding disks between two plates with bolt to keep them flat. Dang things want to curl on 100f days

Don't forget the lowly file, a corse bastard file like the back side of a farriers east will remove a lot of stock! But make sure you get the scale off first, it's hard on files. Wire brush hot, hit it with a angle grinder or pickle it. Then file your blade flat. Remember before the bridge port mill all machined serfaces wer files and scraped to achieve dead flat. 

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