Belt grinder.

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toglhot
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Belt grinder.

Post by toglhot » Wed Jun 27, 2018 2:49 am

Here's a belt grinder I made up, it takes 730x25 belts, which I chose because the grits available vary from 80 od to 1000. Originally the design was a three wheeler and there were two belts but the motor didn't have enough power to spin them, so I came up with this two wheel design. It's used for sharpening drills and lathe bits. When I come across a more powerful motor I'll ad another belt rub.
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Harold_V
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Re: Belt grinder.

Post by Harold_V » Wed Jun 27, 2018 3:11 am

Nice grinder, but I'd like to make mention of the problem that is common for sharpening any type of cutter with a belt--and it doesn't really matter what kind of belt grinder/sander is involved.
When a belt has pressure applied (like when you use it), it tends to "bunch up" in front of the load. What that does for you is to slightly round the upper edge of the part (your cutting tool), which can result in no relief at the cutting point. For that reason, it's a good idea to not use a belt, but a wheel instead, which doesn't yield the same problem.

Please note that I didn't say it doesn't work. I'm simply suggesting that you'll achieve better results by not using a belt, aside from roughing.

H
Wise people talk because they have something to say. Fools talk because they have to say something.

stevec
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Re: Belt grinder.

Post by stevec » Wed Jun 27, 2018 6:05 am

What would happen if one were to point the "trailing" edge of the tool into the oncoming belt?

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Bill Shields
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Re: Belt grinder.

Post by Bill Shields » Wed Jun 27, 2018 6:43 am

There is an entire industry created around 'linishing'

if you are not aware of the term / technology, it might be a good read....

from my shop experience, belts are good for many things, but I have never really had success sharpening much beyond lawn mower blades..and yes I have invested / built several tool / cutter grinders to get to what I need.

I do find the belts handy to 'rough out' broken drills and what not to get them to the stage where they are ready to be put into the grinder
Too many things going on to bother listing them.

RMinMN
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Re: Belt grinder.

Post by RMinMN » Wed Jun 27, 2018 6:58 am

stevec wrote:
Wed Jun 27, 2018 6:05 am
What would happen if one were to point the "trailing" edge of the tool into the oncoming belt?
You would then pull out a fine burr that would need to be removed before use or else it can fold over and leave you with a very dull edge. There is no free lunch.

John Hasler
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Re: Belt grinder.

Post by John Hasler » Wed Jun 27, 2018 8:31 am

RMinMN wrote:
Wed Jun 27, 2018 6:58 am
stevec wrote:
Wed Jun 27, 2018 6:05 am
What would happen if one were to point the "trailing" edge of the tool into the oncoming belt?
You would then pull out a fine burr that would need to be removed before use or else it can fold over and leave you with a very dull edge. There is no free lunch.
You can take that burr off quickly with a hand stone. I prefer to grind cutters on a wheel, though. A belt leaves the faces flat or even slightly convex, making honing difficult. With a wheel I can make most faces concave, making honing much quicker.

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NP317
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Re: Belt grinder.

Post by NP317 » Wed Jun 27, 2018 9:17 am

Very creative belt grinder.
Judging from the arrows on the back of the belt, either the belt is on backwards,
or the direction of belt motion at the part-rest is upwards.
?
~RN

toglhot
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Re: Belt grinder.

Post by toglhot » Fri Jun 29, 2018 2:00 am

Interesting comments! Belt bunching up? I don't know about you, but I tend to have my belts under pressure to stop the belt 'bunching up. Just how hard do you force the work onto the belt???

As for the burr, you're kidding right??? Remove it, it's not rocket fuel science.

Harold_V
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Re: Belt grinder.

Post by Harold_V » Fri Jun 29, 2018 2:04 am

How hard doesn't matter. This is an issue that has been well addressed on many occasions, and I've experimented with it myself. If you have the means to examine a sanded surface critically, you'll see what I'm talking about. For cutting tools, the slight alteration of the surface isn't acceptable, although if you have little to no experience in machining, you likely can't and won't see the difference.

Look at it this way. If belts were acceptable for grinding on cutting tools (excepting knives), they'd be used in lieu of wheels, as they cut faster.

The point about the hollow grind with a wheel is very conducive to successful honing of ground tools. Makes it a lot faster, with far less risk of rounding the edge, much like a belt does.

H
Wise people talk because they have something to say. Fools talk because they have to say something.

toglhot
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Joined: Mon Nov 26, 2012 6:03 pm

Re: Belt grinder.

Post by toglhot » Fri Jun 29, 2018 7:38 pm

Another interesting comment. Funny, how some will think others have little experience if they don't agree with them. Funny indeed! Perhaps you should take note of your own quote at the bottom of your posts.

John Hasler
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Re: Belt grinder.

Post by John Hasler » Fri Jun 29, 2018 8:32 pm

Do you use steel belts? Any non-metal belt will compress slightly under the pressure of the work no matter how taut it is.

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wlw-19958
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Re: Belt grinder.

Post by wlw-19958 » Fri Jun 29, 2018 8:48 pm

Hi There,
John Hasler wrote:
Fri Jun 29, 2018 8:32 pm
Do you use steel belts?
Are there steel abrasive belts? If so, where does one get them?

Good Luck!
-Blue Chips-
Webb

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