Turn a scalpel blade into a saw

[bruce d]

I found this trick buried in a YouTube video. After trying it out, I was pleasantly gobsmacked to find just how well it worked. 

 

Clamp a curved scalpel/craft blade in a vice, curved edge uppermost and exposed.

Rock a file, not too worn, along the whole length of the exposed edge while pressing firmly but not too hard. 

Place the blade flat against a sharpening stone and make a single swipe on each side.

You now have a saw.

 

When pulling the saw across a test piece of wood it was surprising how much 'drag' I could feel as it cut compared to the same blade and same piece of wood before the saw-teeth were installed. It doesn't seem to matter if the blade is worn or new, so I know what I will do with tired blades in the future.

It works best on curved blades used with a rocking motion but will also work with straight blade used for shorter strokes. 

The kerf is quite narrow and a saw made this way seems especially well suited for scoring straight lines in wood since the toothed edge resists following the grain.

 

Maybe others already know this trick but hopefully someone will find this useful.

 

Bruce

[allanyed]

Thanks Bruce! 

Can you share the link to the video?
 

[bruce d]

 

1 hour ago, allanyed said:

Thanks Bruce! 

Can you share the link to the video?
 

 

From 20:45. I did a few experiments and found that I preferred the results obtained by using firm hand pressure (he uses a small hammer) and not going over the same spot twice. I am certain everyone will find their own style.

Also, a straight blade converted to a saw will act completely differently from a curved one, at least in my hands.

 

 

[mtaylor]

Thanks Bruce for the post and link.  I'm going to have to give this a try.

[bruce d]

5 minutes ago, mtaylor said:

  I'm going to have to give this a try.

Mark, I'm interested to know what others find when they try this trick. I have already found how the blades perform differently with different woods. 

[mtaylor]

8 minutes ago, bruce d said:

Mark, I'm interested to know what others find when they try this trick. I have already found how the blades perform differently with different woods. 

I'll try to get to it this weekend.   Things are bit hectic here for me at this time.

[allanyed]

Great video Bruce!   Just before the making of the saw he explains about using bees wax for tempering and hardening his home made stabbing and carving tools which was a new one for me.   

The saw blade making looks like a great idea to try!

Thanks for posting the video, it is very much appreciated.

Allan

[bruce d]

11 hours ago, allanyed said:

using bees wax for tempering and hardening his home made stabbing and carving tools

I don't know the advantage gained by using beeswax instead of water or oil but it seems to have been the standard way for jewelers to anneal gravers 'back in the day'. Possibly a metallurgist among us can shed some light?

Having now watched a couple of his other videos I can see Paul Hamler, the guy behind it all, is quite a character. He has made a gazillion different things and can make you laugh.

[Charter33]

Another vote of thanks for posting the link to the scalpel/saw modification, I will be giving this a try for certain. I also watched the rest of this episode - love watching a craftsman who clearly enjoys his work and takes the trouble to share his skills.

I too was intrigued by the heat treatment alluded to for the jewellers graver tools using beeswax. This was the first time I've come across 'hardening and tempering' being carried out together at the same time. I was always under the impression that high carbon steel had to be heated and then quenched to harden it ( the carbon going into solution and being trapped within the structure resulting in an extremely hard but very brittle material) followed by a separate re-heating (tempering) to a lower temperature that enabled some of the carbon to come out of solution - a lower temperature for tempering giving a harder material suitable for a tool such as a scriber, a slightly higher temperature for tools that are subjected to impact and therefore needed a degree of flexibility such as a cold chisel. Annealing is heat treating a metal to make it as soft as possible so that it can be more easily worked. Metallurgy is one heck of a science with so many variables. The specific carbon content, and the presence of other alloying metals in some cases, results in a vast range of possible physical properties that can be fine tuned to meet a requirement. All this is achieved using different temperatures, holding at this temperature for different periods, and the rate of cooling. I can only assume that the process described in the video 

has been found to produce the properties needed for a graver tool, ie. the ability to retain a hard and sharp edge to enable it to remove metal skilfully and accurately in the hands of a talented artisan.

I'll be giving this method a go too!

Cheers,

Graham.

[mtaylor]

Well, I tried it with an old blade and it works very well on the scarp wood.   Well worth the effort.  Thanks for sharing this Bruce.

[wefalck]

Sounds like an interesting idea, indeed, and I have to give it a try. I can see uses for it to make small incisions and slots.

 

I don't know about the relativ hardness of ordinary razor-blades and files, but that could be another application of the idea.

 

I haven't heard of jewellers using beeswax for hardening/tempering and have to check on this. Normally, one controls the hardness through the tempering temperature, which is indicated by the oxidation colour. Have to watch the video tonight in order to see what the guy actually does.