Ultrasonic mold polishers as a hand sanding alternative?

Drew Riley

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Anybody using these things? Looks like jewelers use them for detail polishing, as well as tool and die makers. They’re normally pretty pricey, though the pneumatic import brands are significantly more cost effective. I know you’re probably not gonna want to polish a broad sword with it, but seems like it might be good for folder blades, or smaller details like plunge lines and whatnot.

Thoughts? I may pick one up just to try.

Pneumatic Grinder Ultrasonic Vibration Grinding Polishing Machine Reciprocating File Air Grinder 1/8 Inch https://www.amazon.com/dp/B07CZWM7T2/ref=cm_sw_r_cp_api_fabc_Z9rYFbJFEFZS8
 
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I did try an die air grinder before when I started out the only reason so is because my grandfather owns a body shop and I have access to a bunch of them. However I found out that it’s useless to me and I would say the same about this thing you are showing us except for fine detail work maybe but I don’t see a purpose and never heard anyone using one, but as far as plunge lines I say no.
 

Stacy E. Apelt - Bladesmith

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Using a 1/8" to 1/4" wide file or sanding pad isn't going to work well for even hand sanding. Also, you would have to change the paper every 30 seconds on a knife.
 

Drew Riley

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Using a 1/8" to 1/4" wide file or sanding pad isn't going to work well for even hand sanding. Also, you would have to change the paper every 30 seconds on a knife.
They use edm style stones, ceramic or sintered diamond files.
 
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They use edm style stones, ceramic or sintered diamond files.
But wouldn’t it leave scratches on the blade that doesn’t match the existing scratch pattern that sandpaper leaves on the rest of the blade finish? Plus why go through the trouble of buying this device and the accessories for it? I’m a fan of having tools but In this case I don’t see it necessary.
 

CasePeanut

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With a 1/8" collet and 28K RPM its a very similar feature set to a Dremel. Curious how this would be different than a Dremel or foredom?

For roughly the same price, Grizzly (and I'm sure lots of other importers) have a variable speed rotary tool built into a mini buffer. I was looking at this last night as a cheaper version of the mini foredom buffer that was being discussed on another thread:
https://www.grizzly.com/products/gr...chtop-grinder-buffer-with-rotary-shaft/t32002

They also have a nice looking VS mini buffer that supports a larger wheel but doesn't include the rotary tool.
https://www.grizzly.com/products/grizzly-1-4-hp-variable-speed-mini-benchtop-polisher/t32003
 

Drew Riley

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But wouldn’t it leave scratches on the blade that doesn’t match the existing scratch pattern that sandpaper leaves on the rest of the blade finish? Plus why go through the trouble of buying this device and the accessories for it? I’m a fan of having tools but In this case I don’t see it necessary.
The idea would be to take it past your final finish and then finish with a few swipes of 600 or 800 grit.
 

Nathan the Machinist

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It’s not a rotary tool, but it reciprocates/vibrates.

Right? It's maddening the lack of comprehension...

Folks, this isn't like using a rotary tool with a tiny surface area that will lead to trouble nor does it leave a rough finish. It automates the back and forth scrubbing used with die makers stones and saves you time and elbow grease. If you've never used diemakers stones you may not have a good frame of reference. They're commonly used to finish tool marks from molds and a mold maker that I know who is also a knife maker swears by his. That said, the real deal is considerably more expensive so I'm a little skeptical about this unit just because it's so inexpensive. I think it's an interesting idea.

I use N grade die makers stones from Falcon tool here for scrubbing tool marks from my work. It doesn't dull or round over details like paper. The stone doesn't cut as much as the slurry it forms cuts so technique is important. It's a fast and precise way to shape steel without causing undulations like you'd get from a rotary tool.


Carothers_dagger.jpg


This mirror finish was done with stones. I didn't have the best milling machines back then and the tool marks were substantial. I stoned them out to 800 grit and went back to either 400 or 600 grit paper through to mirror finish. I don't think I could have done it very well without the stones. These ultrasonic die profilers are what is used in industry rather than just sawing back and forth with a stone. You'd develop an accumulative stress disorder without something like that if you did it every day.

I'm not sure, because I haven't personally tried it, but I would think a tool like that would have application in our field.
 

Stacy E. Apelt - Bladesmith

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I am aware that this is a reciprocating tool. The one I have ( somewhere in a box of things I don't use because they are pretty useless) is similar to this one. It is basically an impact tool with a collet to hold a 1/8" round attachment. It does not hold any flat or square things. It was OK with micro-files for getting inside castings and tight spots on jewelry, and could be used with very small stones for smoothing. The stroke was very short - only a few mm. I tried it with Cratex cylinders that I flattened on one side and didn't like how it polished. I don't see any way it would hold an EDM stone. Even if it could, there is no "float" of the stone because it would be a rigid extension of the tool. Any angular error would show horribly on a large flat surface you want to end up mirror polished. When using EDM stones by hand you let the stone level flat to the surface and use your fingers to guide it across the surface.
 

Drew Riley

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I'm a little skeptical about this unit just because it's so inexpensive.

That's my reservation as well, but I suppose it's cheap enough to be worth a try. I have a range of 1/2" x 6" die polishing stones that I really like using before my paper, so that's what got me thinking about this, though obviously the stones for it are much smaller.
 

Drew Riley

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I am aware that this is a reciprocating tool. The one I have ( somewhere in a box of things I don't use because they are pretty useless) is similar to this one. It is basically an impact tool with a collet to hold a 1/8" round attachment. It does not hold any flat or square things. It was OK with micro-files for getting inside castings and tight spots on jewelry, and could be used with very small stones for smoothing. The stroke was very short - only a few mm. I tried it with Cratex cylinders that I flattened on one side and didn't like how it polished. I don't see any way it would hold an EDM stone. Even if it could, there is no "float" of the stone because it would be a rigid extension of the tool. Any angular error would show horribly on a large flat surface you want to end up mirror polished. When using EDM stones by hand you let the stone level flat to the surface and use your fingers to guide it across the surface.

I thought it had a 2nd collet pictured that might hold a round OR flat stone, but it's hard to tell from the pics. I imagine I could modify fairly easily to hold a stone like the die filer in this video:

It shouldn't need much of a stroke if any as long as it oscillates/vibrates fast enough. You still have to scrub back and forth, of course, but it's like using an electric toothbrush. Would it be any better of different than just hand stoning the blade? With this cheap one, who knows. Probably not. That's why I'm asking though.

I've asked other makers about the die maker's stones in the past, and people looked at me like I had something growing out of my forehead, or they had no idea what I was even talking about. Now I'm starting to see more and more makers who use and swear by them, but it's still a largely unused/unexplored method from what I can see.
 

Stacy E. Apelt - Bladesmith

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The extra piece shown is the file clamp. It is inserted in the tool and the file is inserted in the clamp. If you use a pointed tip for writing on things or texturing metal, it is inserted directly in the tool. The whole thing is just held together with Allen screws. Go ahead and buy one if you want to play with it, but it is almost surely going to be a pretty flimsy piece of Chinese junk, IMHO.

Oh, and you will need a foot pedal air controller to use it. It requires about 90PSI and a 3-4 CFM as I recall.
 

Drew Riley

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The timing on this is pretty funny, but I just saw somebody else asking about "air lappers" in another knife making forum, and they actually had a video of somebody already using one:

Fast forward to about 10:30. Looks like he also uses an oscillating multi-tool before that, which I also find interesting.

Concerning the "air lapper" however, it looks like he's using a pretty good sized stone on it. I wonder if it's similar to the tool I linked above, or a slightly larger model? I messaged the creator of the video, so hopefully I can get some further clarification. I figured I'd share the video for anybody who wanted to see a similar tool in practice.
 

Stacy E. Apelt - Bladesmith

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Yes, he is using something 1000 times stronger/bigger/more powerful than the little tool in the OP.
 
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The timing on this is pretty funny, but I just saw somebody else asking about "air lappers" in another knife making forum, and they actually had a video of somebody already using one:

Fast forward to about 10:30. Looks like he also uses an oscillating multi-tool before that, which I also find interesting.

Concerning the "air lapper" however, it looks like he's using a pretty good sized stone on it. I wonder if it's similar to the tool I linked above, or a slightly larger model? I messaged the creator of the video, so hopefully I can get some further clarification. I figured I'd share the video for anybody who wanted to see a similar tool in practice.

What is that liquid he use with oscillating tool? Some kind of polish? Maybe i can try , I would never thought about that it can be used that way :D Some years ago i used it on handles but I stop long time ago ,grinders do better and faster .

ArJtZj2.jpg
 

Drew Riley

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Looks like he’s using something like these “turbo laps” found here:
https://www.argofile.co.jp/en/products/industry/airgrinder/turbolap

Looks like they make them with varying “rpm” and an option of “linear” or “swing” which I assume is back and forth vs oscillating. I’m not sure they’re bigger or much different than the first one I posted, but they seem to get the job done either way.
 
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