making-titanium-saw-frames

Even though the machine development was stopped, I still liked the idea of a forward tightening mechanism like all commercial hacksaws use.
I never understood why that method was not used in the jewelry trade.
Instead we had a frame that had to be compressed against the chest and bench peg to tighten the blade.
I tried other methods of tightening the blade, though.
This one version had an over complicated tightening mechanism.

It was rather clunky and rightly discarded.

This model was made out of stainless steel, because at the time I didn't have a Tig welder, so using hard silver solder worked after a fashion.

Then I made this model, which actually was on the right track.
I used 5 mm square stainless steel as the cross arms, and that was eventually found to be too springy.
The Delrin handle was also uncomfortable and heavy.
But I used it for a month or two and it was quite OK.

This model was actually not a bad saw at all, and I used it for several months in my day to day work.
The entire frame was made out of aluminium, all screwed together, because of no Tig welder.
But it was still a bit clunky even though it was light to the touch.

My next model was made completely out of stainless steel with a brass tensioning knob and a white Delrin handle.
It also worked well but soldering stainless steel is tricky and definitely would become a drag if I had to make more than one.
Nevertheless, it also worked well and I also used it for some months in my day to day work.

I wanted to see if I could make a clamping system for the blade that was the same as a normal saw frame, so I built this model.

It used a square sliding nut and a Delrin tensioning nut.

But is was a drag to make, far to many pieces to solder together.
I used this saw for many months and then, in a quirk of amnesia, I forgot about my orginal blade tightening method and concentrated my efforts on flat clamping methods.
The reason for this is that making a square hole ( so the top does not spin) is beyond the machinery I had at the time.
This was a long and laborious mistake.

Then I made a (wait for it) saw that had the top cross arm loose.

As in, not joined to the spine.

This one was not successful from the start.
Except for the tensioning method by which the Delrin tensioning knob was at the back of the saw.
So if it is tightened down, it moves the two cross arms apart thus tensioning the blade.
This method of tensioning a blade was a rabbit hole that I jumped in with both feet.

Then I soldered up an iron frame to test out my new tensioning method.
I became hung up on tensioning my saws this way, and coupled to the flat clamping method, I walked for many miles down a rocky and cold path.

It worked OK but the tightening nut was a bit tough to tighten and I was worried that female goldsmiths would have trouble getting it tight enough.
No point having a saw that needs gladiator strength to tighten.

And because the frame was made out of 6 mm square stock, the clamping area was a bit small, so the thumb screws had to be tightened down quite hard, otherwise the blade would slip.

I also made a deep throated version, but is did not work well, to much bounce and wobble.

Here are three versions I made.
On the left, a 5 mm square deep throat version.
In the middle a normal 6 mm version and on the right a 6 mm deep version.
All of them were rejected.

And then I bought a Tig welder, finally.
After I had taught myself how to use it, it changed everything.
Now I could weld titanium and aluminium, something that I had wanted to have the ability to do for many years. This is the first model I made out of 6 mm titanium rod.

For a long while I messed around with round titanium bar, trying to get it stable enough to use.

The problem was that 6 mm rod does not leave much area for clamping the blade.
Also, titanium is inherently a 'slippery' metal, so I needs to be tightened far harder than say steel, which again brought the saw out of the strength level of the average female hobbyist.
I used my wife as a gold standard for strength and if she was able to tighten it easily, it would be OK for the general public.

So eventually, after some months of working round titanium rod, I came to the conclusion that it would not be up to standard.
Too weak, too difficult to work and not enough clamping area.
The giant problem was to source square titanium rod.
Very difficult to buy in small quantities for testing purposes.

Eventually I sourced some in Germany.

I think it was used for some chemical applications and so the surface needed extensive finishing of to bring up to standard.
No matter, the material was good enough for further development.

And then I decided that I was going in completely the wrong direction with my rear tensioning design and also with my flat clamping method.
I think I made enough proto types to be sure of that decision.

I went back to my original method of clamping the blade, with a tensile screw on the one side and a hardened thump screw on the other side.

The blade holder went through the top arm and had a flat side machined into it.
Then the set screw visible in the front would hold the top clamp from turning.
After working this method for some time it proved not to be stable enough.
The fit would become loose over time, needing constant adjustment with the set screw to keep the top clamp aligned.

Also, I first made titanium tension nuts but these did not screw smoothly enough, so I changed to brass, which not only works better, but looks nicer too.
I'm not worried about the nut wearing out, because each saw has a lifetime warranty, so if it wore out I would simply replace it free of charge.

The square hole in the front was always the big problem.
I made a round tube and drilled a hole for the set screw ( on the right) but that did not work any better.
Then a tube that was machined in half.
The theory was that the flat side of the arm would give the stability, but it seemed that the inner round sides of the tube caused the sliding rod to be either too tight, and thus not move up or down, or to loose, giving a slack fit.

I finally solved the problem by machining the end of the arm like this with an end mill.

Then a 2 mm piece of titanium is welded onto the end.
This took many attempts before I was able to achieve a consistent result.

I made a special jig so that the welding can be precisely controlled.

This allows me to weld using a head magnifier ( Optivisor) so that I can see precisely where the weld must take place.

I want each and every handle to be unique to each saw.
So I made the bottom blade holder out of titanium with a M6 thread so the handles can be easily screwed on.
That way people can choose a handle for themselves when they buy a saw frame.

I like the brass top.
It is clean and simple and easy to turn.( it passed with flying colours when my wife used it)

So here is the basic frame. I have used this model extensively and it works well.
No bounce, wobble or wander. This is where I wanted to be.
A stable platform which I can expand it any artistic direction, be that with handles or metal work.

And with that in mind, here follow a few pictures of the frames I have built so far.

Laminated Beech and Teak wood.

Heat forged titanium

Details of the titanium frame.