Sharpening Rasps. Is it possible?

[IanW]

.......It seems to me that the level of precision required for that abrasive blasting process would be extraordinarily high. Realistically, would you not blast away any part of the teeth within range and not just the bits you wanted to remove?

Graeme, what I visualise is blasting the back, or "bevel of the teeth to remove some metal & thus 'sharpen" them - just as you sharpen a chisel by abrading the bevel. The angle would need to be right, of course, and yes, it would have to be done carefully. But we're talking about removing minute amounts of metal, and the degree of unevenness you might create would be neither here nor there, no more (in fact probably a good deal less), than the variation in hand-stitched teeth.

But I stress this is theory, & my theories are occasionally (frequently!? ) well off the mark.....

Cheers,

[D.W.]

The boggs tool page says they use steam and abrasive to take material from the back side of edges, so it seems like a pretty good guess so far.

[Bushmiller]

I took the last of the rasps out of the various solutions this afternoon. Although some had been soaking for up to 96 hours, none of them made a better impression on the test piece of Spotty. I did take the ten swipes with each of the five rasps and I will post a pic of that tomorrow (don't stay up late in anticipation as there is literally almost nothing to see). I did not trouble to even identify which was which as there was no difference in their dismal performance.

Having had to report a dismal performance, I have placed one of the rasps in the Citric acid solution and will leave it there for, say, a week. I have also placed a large used rasp, that I mentioned in an earlier post, into the tall tube with a vinegar solution. That too will be left in for at least a week. There was some crud in the teeth which a wire brush was unable to move. I picked at this with a steel pointer, but still not all the debris was removed. I will take it out after a couple of days, attempt to clean out any remaining crud and give it a fresh vinegar solution. It too will have a lengthy soak.

Regards
Paul

[Skew ChiDAMN!!]

I wonder if there's any common item one could use to 'fill' the teeth before dipping to mask the front edge.

Sorta like chalking a file to apply and as easy to clean out. Obviously not chalk... not in acid.

Waxes'd be too hit'n'miss in application, maybe a potters clay?

[GraemeCook]

... I did not trouble to even identify which was which as there was no difference in their dismal performance. ...

Or you have eliminated a number of false leads?

Reminds me of an apocryphal story about Thomas Edison. As you know, he was a very prolific inventor, but he did not work alone, he headed quite a large research laboratory. He employed engineers, pattern makers, craftmen, etc, whose job was to transfer his ideas into reality.

Allegedly he invented the electric light globe on a blackboard and then handed it to his engineers to build the prototypes. Initially, they failed repeatedly (or eliminated false leads) and Edison then had to report to his shareholders at an Annual General Meeting. He announced that he had invented 10,000 light globes that did not work. None of his shareholders knew what an electric light globe was, so the comment went through to the keeper.

Prototype #10,001 became known as the incandescent light bulb and 100+ years later it is now being phased out.

PS: If this is not true, then it should be!

[IanW]

....PS: If this is not true, then it should be!

I don't know if it's true or not Graeme but it's consistent with what I've read about the bloke. One of Edison's sayings was "Invention is 99% perspiration & 1% inspiration". Which would fit with your story....

[Bushmiller]

To recap, the test piece of wood was Spotted Gum (old power pole) and just ten, firm full length strokes were made along the flat surface with the file held deliberately horizontal to the timber:

Five rasps soaked.jpg

Staring on the right, the first mark was from one of the untreated rasps.

The second mark was from the Liogier, which admittedly, although the same grain (8g), is a narrower profile and arguably could be considered more aggressive.

The next five marks are from the files that have been subjected to the "treatment". As I stated before, my original intention was to identify each one, but as there was no perceivable difference between them I did not trouble to identify which was which. As you can see I did drop the rasps down onto the edge to see how they performed there. Once the sharp edge had been removed there was less cutting action happening. It certainly did not feel as if the rasps were cutting.

If anything, the marks on the timber show up more prominently in the pix than they did with the naked eye. My take is that the rasps just damaged what was a perfectly good surface.

Regards
Paul

[Bushmiller]

Something that did come out of this test was a closer examination of some of the other rasps I have:

This is one of the five test rasps, which were 200mm next to the 300mm rasp I now have soaking:

300 and 200 mm rasps.JPG

Close ups of the teeth. 200mm on the left and 300mm on the right.

300mm rasp close up.jpg300mm close up detail.jpg

This was the result of ten strokes of the 300mm file on the Spotty sample.

300mm rasp untreated.jpg
These were two rasps I bought just to try them. Bahco on the left (flat rasp) and HART on the right which was again half round.

bahco flat and HRRT.JPGBahco flat and HART close up.jpg

I did try them out on the same test piece and both cut: A little bit. It was a little unfair on the Bahco, being a flat file.
Bahco flat and HART test cut.jpg

The following are two hand stitched rasps: On the left is a Tomé Fetiera and the Liogier on the right that was the original comparison rasp

Handstiched fetiera and liogier.JPGTome Fetiera and Liogier hand stitched.jpg

The Tomé Fetiera is a much shallower profile and a finer grain.

What I have taken from these different styles is that the hand stitched rasps tend to be made in a spiraling pattern while the machine made version are cut straight across. What this does mean is that hand stitched rasps have a little more versatility and can be produced in left or right hand patterns. It has so far also confirmed that hand stitched versions are better performers, which is something of a relief considering how expensive they are. Also having watched how they are made, I can understand why they would be expensive, but that doesn't help pay for them.

Regards
Paul

[IanW]

The surprising thing to me is just how useless those rasp-like things are. I would have expected they might not cut as well as a Liogier, but to barely cut wood at all is quite something. If you'd bought them from a regular retail store, you'd certainly be entitled to a refund as 'not fit for purpose' or false advertising (whatever they are, they aren't rasps! }.

I would venture you have proved one rule, Paul, the one about 'you can polish a piece of faecal matter but it's still a piece of faecal matter.....

Cheers,

[IanW]

Deleted duplicate...

[NeilS]

Paul

Thanks for sharing your findings with this experiment.

If the long dip doesn't improve anything with the other rasp, perhaps it is worth doing what some farriers do with their worn rasps...

Keep Your Rasps Sharp And Save

This method may have already been discussed here somewhere, but if not DW is an exponent of using this technique on chisel and plane blades and I'm sure would be willing to share his expertise. If so, perhaps a separate thread could be run on how effective his unicorn method is on rehabbing rasps.

I expect the effectiveness of the technique would depend on the tooth geometry. Sufficiently offset teeth patterns would work best so the rag wheel could come into contact with the back of all of the teeth.

I use the technique for raising a micro burr on my turning scrapers and also for keeping a high polish on the flutes of my turning gouges. It's very quick and the cost of a rag wheel and compound is relatively cheap.

From my experience with the turning scrapers, I expect that a fragile micro-burr would form on the front of each rasp tooth that came in contact with the rag wheel, which would give a fine cut for awhile but then need to be refreshed on the rag wheel to keep cutting.

One issue for woodworkers would be cleaning out the abrasive compound from the tooth 'gullets' before using the rasp on wood, which I expect isn't an issue for farriers.

[D.W.]

Unfortunately, I don't know what would solve the issue with these teeth because they need to be more upright instead of hooked forward. I kind of wonder how they actually got the marks as deep as they did, and the teeth less "tombstone" sticking up. mine look like little tombstones and so do most of the rasps that I have, which leaves the thinnest part of the tooth wearing.

This creates the smallest low clearance contact point when the rasp wears and allows the rap to work in soft and hardwoods alike.

I think there may be no way to remove the backs of the teeth here without compromising the tips, and because of that, I don't know of a solution.

I would be surprised if they aren't made of good fine grained plain steel, though, and would keep them on hand because having that kind of steel is sometimes useful.

[GraemeCook]

... 'you can polish a piece of faecal matter but it's still a piece of faecal matter.....

Cheers,

Or the cruder version ... : "You cannot polish a faeces" ... unless you are Martin.

My mate Martin the eccentric scientist has a coprolite - litterally a fossilised dinosaur faeces- only from a small dinosaur - which he has polished to a deep sheen. It looks like semi-opaque amber, quite nice, and few realise the source, although the shape is a giveaway.

[Explanation: Faeces is a word which, in these political correct times, is acceptable to Big Brother the auto-editor, rather than that subversively common terd. I kid you not.]

[Bushmiller]

Never say die: I mentioned before that I had two old files I would like to subject to the restoration process. The first I have already pictured in post #23

This is the second one, which I suspect is actually a horse rasp (not just a coarse rasp ), but either way I thought I would give it a go while I am not totally demoralised. One side is a double ended file:

P1080844.jpg

While the other is a double ended rasp.

P1080845.jpg

I expect the eagle eyed among you have already spotted the Wiltshire brand: My favourite, although I had not noticed this before I began to wire brush to clear the teeth. A quick buff on the fibre wheel unequivocally revealed the ownership.

P1080846.jpg

The teeth were very clogged and wire brushing would not remove all the crud. I will revisit it after a couple of days.

P1080847.jpgP1080848.jpg

The reason I have only just got to this rasp is that it was too wide to fit in the other 40mm tubes. However, I had anticipated this and had a 50mm tube with a cap to suit.

P1080849 (2).JPG

Without any means of easily attaching a handle, I just plonked it in and it rests on the bottom. The solution is citric acid.

P1080850.jpg

Now we hurry up and wait again.

Regards
Paul

[Simplicity]

Never say die: I mentioned before that I had two old files I would like to subject to the restoration process. The first I have already pictured in post#

This is the second one, which I suspect is actually a horse rasp (not just a coarse rasp ), but either way I thought I would give it a go while I am not totally demoralised. One side is a double ended file:

P1080844.jpg

While the other is a double ended rasp.

P1080845.jpg

I expect the eagle eyed among you have already spotted the Wiltshire brand: My favourite, although I had not noticed this before I began to wire brush to clear the teeth. A quick buff on the fibre wheel unequivocally revealed the ownership.

P1080846.jpg

The teeth were very clogged and wire brushing would not remove all the crud. I will revisit it after a couple of days.

P1080847.jpgP1080848.jpg

The reason I have only just got to this rasp is that it was too wide to fit in the other 40mm tubes. However, I had anticipated this and had a 50mm tube with a cap to suit.

P1080849 (2).JPG

Without any means of easily attaching a handle, I just plonked it in and it rests on the bottom. The solution is citric acid.

P1080850.jpg

Now we hurry up and wait again.

Regards
Paul

Paul,

It may be what’s called I think a four in one(I’ve only just learned this tho).

While watching a live clip by Wood By Wright,
Can’t seem to find a link tho, so unfortunately my evidence is zero, an you may just have to go on my excellent character, o come on give me a break.[emoji849].

An possibly not a Farriers rasp, tho I possibly could be wrong there as well.

Cheers Matt.

I’ve just re deemed my self

How to cut Make Organic shapes. - YouTube
[emoji849]


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