Thread: Sharpening Rasps. Is it possible?

Originally Posted by Simplicity

Thought some might find this an interesting read,

Hand making files.


Also I wonder if a rasp could be be “Repaired” sharpened by re punching it ?.

http://www.hawleytoolcollection.com/...0-%20Files.pdf


Cheers Matt

Matt

Thanks for the link. It's a good'un.

To re-punch the teeth, you would need to anneal the file first and then after re-punching heat treat it. I have annealed triangular files easily in an open wood fire. After I was able to bend them in a "U" shape without breaking them so absolutely soft. The question is whether they can be successfully hardened again and indeed whether it is worth this level of intensive attention. You may remember that in an early post Graeme queried whether this whole endeavour was worthwhile. I think I can see him raising his hand for an objection.

I had thought somebody mentioned the Ken Hawley videos, but I couldn't see them so it must have been on another thread. In fact I thought it was you. Here are some links :

Making Files by Hand - YouTube

Why Files Aren't Used Anymore - YouTube

File Making and How Children Used to Help - YouTube



Regards
Paul

Originally Posted by Simplicity

Thought some might find this an interesting read,

Hand making files.


Also I wonder if a rasp could be be “Repaired” sharpened by re punching it ?.

http://www.hawleytoolcollection.com/...0-%20Files.pdf


Cheers Matt

I've been told several times that files were case hardened steel, implying that the centers are lower carbon steel. I've never seen real evidence of this in any good files as they all break easily, and if the steel was lower carbon, they wouldn't. Grain looks uniform to me.

However, I've also failed to reharden some to an acceptable level, and I don't know why that is. Maybe they are actually water hardening steel or alloyed so that they fully harden at a warmer temp than room temperature (convert to martensite) so that they can be bent and straightened without breaking.

As for the rasp question, if the steel is uniform, the answer is yes. However, you will be surprised how deep the front divot is ahead of the teeth, and you'll which you bought a bar of something like 1084 and toothed it.

To truly anneal to a very soft state takes more than just heating and air cooling - it takes heating, and very slow descended cooling, or holding at subcritical temperature for a long time and then cooling, and it may even be a little bit gamed by manufacturers to overheat steel a bit to grow the grain and then let it partially cool and slow cool.

This may be a lot of detail, but in faffing with rasps, it's the one thing so far that I am pretty sure I'm coming up short at - getting the steel to look like it punches as softly as the french rasp makers' videos.

never tried to tooth a file.

The fun of the rasp thing is wearing off quick enough that once I've made the rasps I want to have, I'll be done with it - i recall the same thing for saws. Happy to make my own, but wouldn't want to make any more - it's just not that stimulating for me. Rasps require fixtures to hold the rasp still - i'm beginning to think that the fixtures should be sprung in the middle to ensure contact and support (mine's not, it's flat - at least until this evening).

And punching teeth, I can't say how easy it will be with truly soft steel, but raw bar stock that's any softer than what I've managed to "sandwich anneal" in vermiculite is noticeably better.

I will try files at some point, though - not so much to save anything, money or whatever, but to see if a file with slightly irregular spaced teeth leaves a smoother surface. If it does, the slightly irregular height may cancel out the benefit.

Originally Posted by Bushmiller

... I will have a look at those diamond wheels. I only have the fibre mini cut off discs for the dremel style tools.

Something that springs to mind following your endeavours is to freshen the face with a cutting/diamond mini wheel and use the buffing method on the backs.

Paul

I found the mini fibre cut off discs for the dremel style tools a bit fragile, but if you have those on hand then definitely give them a try.

The advantage of the buffing method is it is so quick. So much so that there is a risk of over dubbing the teeth edges. Working on the curved side of the small rasp I tested this method on I did just one slow pass on the left side and the same again up the right side at which point I could see bright metal teeth tips, which is close to where I reckon I would get the the optimum benefit.

Originally Posted by Bushmiller

Even if my testing with vinegar and citric does not produce any sharpness benefit, it certainly removes the crud that a wire brush fails to dislodge

Along similar lines, I've been using Citristrip to clean the crud off the circular saw blades at the local men's shed before I re-sharpen them. It's a sticky gel that clings to the teeth and gullets, which I leave on for five to ten minutes and then brush and wash off in warm water. It does the job quite well, so I might also add a few files and rasps now while doing that...

Originally Posted by Bushmiller

... You may remember that in an early post Graeme queried whether this whole endeavour was worthwhile. I think I can see him raising his hand for an objection.

No, Paul; I remain a passive observer - hopeful, but not optimistic. But then my grandfather probably thought the Wright Brothers were wasting their time.

Becuause of the pervasive decline in rasp quality, I cannot help but wonder if the woodworking fraternity is approaching the end of the "rasp era", after 200 years? Possibly being superceded by "porous tools" such as the variants of the Stanley surform and the Shinto rasps?

Hi all,

Went to my reuse shop today and picked up
two Nicholson USA rasps just to add to the thread.
Paid next to nothing for them and both are in good nick.
One 12" and one 9" . Were Nicholson rasps good.

Martin.

Originally Posted by D.W.

To truly anneal to a very soft state takes more than just heating and air cooling - it takes heating, and very slow descended cooling, or holding at subcritical temperature for a long time and then cooling, and it may even be a little bit gamed by manufacturers to overheat steel a bit to grow the grain and then let it partially cool and slow cool.

.

David

The saw files I annealed were placed in a simple outdoor wood fire (in a chimenea). I stoked the fire as hard as it would go and threw the files in. I could see they reached a bright red. Then I left them in the fire so they cooled relatively slowly in the ash. Ash actually holds it's heat very well.

I have used the same technique on a larger scale when I have annealed old leaf springs. On that occasion we were out in a paddock at a neighbour's property. They used to drag an old fallen or dead tree and build a fire around it. One of them was American and they used to do this for Thanksgiving. It wasn't a religous thing: Just an excuse for a party. I took the opportunity to throw the leaf spring in and collected them a couple of days later. It worked very well. The party was good too. Again the slow cooling in the ash was the key.

Regards
Paul

PS can't find the pix. I will post them later if I find them.

This might be of interest on file making. I can't claim the credit as it was originally posted by Forum member Pagie.

Antikythera Fragment #3 - Ancient Tool Technology - Hand Cut Precision Files - YouTube

Anything this guy does is pretty amazing and I know at least one participant on this thread will be impressed.

Regards
Paul

Originally Posted by Bushmiller

David

The saw files I annealed were placed in a simple outdoor wood fire (in a chimenea). I stoked the fire as hard as it would go and threw the files in. I could see they reached a bright red. Then I left them in the fire so they cooled relatively slowly in the ash. Ash actually holds it's heat very well.

I have used the same technique on a larger scale when I have annealed old leaf springs. On that occasion we were out in a paddock at a neighbour's property. They used to drag an old fallen or dead tree and build a fire around it. One of them was American and they used to do this for Thanksgiving. It wasn't a religous thing: Just an excuse for a party. I took the opportunity to throw the leaf spring in and collected them a couple of days later. It worked very well. The party was good too. Again the slow cooling in the ash was the key.

Regards
Paul

PS can't find the pix. I will post them later if I find them.

Thanks, paul. This is what they do at williamsburg for various things, or at least used to. In the gunsmith video, wallace gusler anneals the flat stock for the barrel before it's rolled and welded, and he does it by leaving the barrel in a high-ash cooler fire that burns out.

I have fine vermiculite, which is about as good as wood ash and probably better, but it doesn't start with the benefit of a slowly dying fire.

It could also be an issue at this point that I'm just not using the right steel in the blanks.

It's possible that the fire as you describe it spheroidizes the steel (causing carbides to become circular and attract more and more carbon leaving the matrix with less carbon in it and softer). The outcome is more important than the terminology.

Originally Posted by D.W.

Thanks, paul. This is what they do at williamsburg for various things, or at least used to. In the gunsmith video, wallace gusler anneals the flat stock for the barrel before it's rolled and welded, and he does it by leaving the barrel in a high-ash cooler fire that burns out.

I have fine vermiculite, which is about as good as wood ash and probably better, but it doesn't start with the benefit of a slowly dying fire.

It could also be an issue at this point that I'm just not using the right steel in the blanks.

It's possible that the fire as you describe it spheroidizes the steel (causing carbides to become circular and attract more and more carbon leaving the matrix with less carbon in it and softer). The outcome is more important than the terminology.

Actually David, there is potentially an issue of carbon migration in the wood fire I have described, which I take to be a diminishing or loss of carbon. However, at my level of expertise this is probably not too important. Having said that, a file I suspect needs to have superior hardening properties.

Regards
Paul

Originally Posted by old workshop

Hi all,

Went to my reuse shop today and picked up
two Nicholson USA rasps just to add to the thread.
Paid next to nothing for them and both are in good nick.
One 12" and one 9" . Were Nicholson rasps good.

Martin.

Martin

Coincidentally, the 300mm rasp I am currently soaking in citric acid I pulled out today to have a quick look at how it was coming along. I can now see it is a Nicholson.

Regards
Paul

Originally Posted by Bushmiller

Actually David, there is potentially an issue of carbon migration in the wood fire I have described, which I take to be a diminishing or loss of carbon. However, at my level of expertise this is probably not too important. Having said that, a file I suspect needs to have superior hardening properties.

Regards
Paul

I had the same thought about decarb. If case hardening was done in the old days, it would sort of cancel that out. I thought decarb happened above critical, but we found out last week on here that it starts around 1300F, just a very slow rate.

Critical in the fire situation is determining where to put a file so that it doesn't get so hot that it decarbs, and even that, I believe is a process of migration, like soaking water out of something with a dry rag. You can soak water from the surface of something, but if there is more water behind it, it will migrate to the dry area.

Spheroidizing in an electric furnace is an option, but I just don't have enough need for an electric furnace (or desire to have one cycling for a day or days) to chase that.

In a coal forge, you can find the fuel surplus part of the fire pretty easily and avoid oxidation, but I'm not sure if the lower part of a wood fire has the same effect- it could be that you didn't experience trouble with decarb/oxidation because of some effect like that. I don't have the option, at least not a good one, to make a long lasting fire and leave it unattended due to where I live (suburban lot), though I do have a fire pit and some fallen wood to burn so I could use that as an excuse to just dump some older files at the bottom of the fire.

Originally Posted by Bushmiller

This might be of interest on file making. I can't claim the credit as it was originally posted by Forum member Pagie.

Antikythera Fragment #3 - Ancient Tool Technology - Hand Cut Precision Files - YouTube

Anything this guy does is pretty amazing and I know at least one participant on this thread will be impressed.

Regards
Paul

This guy is clearly far better at producing and monetizing his trials in making old tools!

Unless he's starting with low carbon steel, I don't think the case hardening is doing much (especially when he think grinds the graver/tooth chisel in a pretty healthy way), but that does lead to a question. I doubt modern files are case hardened, but I'll have to find a video that "how it's made" or someone else has done.

It's probably true that there wasn't much 1.25% carbon steel in solid rolling around 200 years ago because it's really intolerant of impurities at that carbon level.

Last night I took the rasps out of the acids for a look. I had not inspected them for a couple of days as I have been pre-occupied with another more urgent task, if you believe SWMBO's perception. (It's only a kitchen. )

As I walked up to the tubes I was a little apprehensive"

P1080851.jpg

Holy moley, I thought. I expected that the rasp had disintegrated and wondered how I was going to explain it to the readers of this thread, but it turned out all was well.

P1080854 (2).JPG

I think it must have been a reaction to crud embedded in the teeth. As you can see in the next two pix, it cleaned up just fine. The "blunt from new" rasps clean up well too. The vinegar soaked rasp is on the left and the rasp soaked in citric on the right. They all look decidely better with the dark grey magnetite look

P1080860 (2).JPGP1080861 (2).JPG

The 4 in 1 rasp cleaned well too. Although I agree with Matt's finding of what this rasp is, I think a 2 in 1 would be a better description as I can see no difference on each side between the teeth other than they face the opposite way.

P1080862 (2).JPGP1080863 (2).JPG

So how did they perform? Actually I have had no real opportunity to test them properly.They did feel a little more prickly to my hand touch, but the brief test showed they still would not cut the hard Spotty when used on a flat surface. When put on an edge my impression was that they bit a little more than before, but I don't really know whether that was me wanting them to perform better. When I get a moment away from kitchen reno duties, I will try them out a little further.

Regards
Paul