Matilda re design.

[swagman]

Most will remember my 1st Matilda Bow Saw.

Well I have started work on a new design.



The following changes will be included:


Remove the requirement to have a wooden stretcher between the 2 frame arms;

Double the compression resistance by using 2 steel bands;

Use longer steel bands to increase the depth of cut to 1.5 inches below the twisting cord;


Will it work! In theory there is a very good chance it will.


Feedback appreciated.


Regards Swagman.

 

[Racers]

Hi,

I am interested and seeing what you come up with, I do think you might be re-inventing the wheel, but you might just have something good.


Pete

 

[pedder]

Hi Swagmann,

I see a big chance of twisting without the stretcher.

Cheers Pedder

 

[eoinsgaff]

All I have to say is that is one very fine looking bow saw...

Eoin

Actually, does the steel band ever get in contact with the work piece?

 

[swagman]

Hi,

I am interested and seeing what you come up with, I do think you might be re-inventing the wheel, but you might just have something good.


Pete

Hi Pete. I will take a photo of the design layout. It should give you a clearer idea on what I intend to do.

Regards Swagman.

 

[swagman]

Hi Swagmann,

I see a big chance of twisting without the stretcher.

Cheers Pedder

Hi Pedder. I am hoping the the upper tensioner cord and the lower tensioned blade will prevent any misalignment or twisting of the 2 frame arms. The steel band will be pinned to the inside edge of the arms, and should also help. Well that's the plan anyway.

Cheers Swagman.

 

[swagman]

All I have to say is that is one very fine looking bow saw...

Eoin

Actually, does the steel band ever get in contact with the work piece?

Hi Eoin. If the depth or curvature of cut is likely to foul on the steel band, the blade can be adjusted up to 90 degrees either side of normal set, to give you additional clearance. I have used this bow saw to cut out other bow saw frames, without any problems.

Regards Swagman.

 

[Benchwayze]

I like the design of the frame.

I think if I wanted to dispense with the 'Spanish-Windlass', I'd have modified the saw with a brass rod right across the top of the frame. With enough thread at one end to take a knurled screw, tightening the screw would pull the uprights together. Thus doing the same job as the windlass.

I can't say if this would work of course, but it might. Thinking on, you might need a knurled screw at each end of the rod?

Just 'noodling' a few ideas!

regards
John

 

[woodbloke]

I like the design of the frame.

I think if I wanted to dispense with the 'Spanish-Windlass', I'd have modified the saw with a brass rod right across the top of the frame. With enough thread at one end to take a knurled screw, tightening the screw would pull the uprights together. Thus doing the same job as the windlass.

I can't say if this would work of course, but it might. Thinking on, you might need a knurled screw at each end of the rod?

Just 'noodling' a few ideas!

regards
John

It does work John and has already been done :wink: - Rob

 

[Benchwayze]

.

I can't say if this would work of course, but it might. Thinking on, you might need a knurled screw at each end of the rod?

Just 'noodling' a few ideas!

regards
John

It does work John and has already been done :wink: - Rob

Well there I am again. Late as usual!

I like my old lightweight 'bow-saw'. Although I had to replace the windlass, with some nylon cord!

Apart from that, it's a good 'un!'

John

 

[Harbo]

I may be missing something here, but frankly I cannot see the point of the steel bands?
As well as interfering with the depth of cut, sufficient tension should be provided by the top mechanism be it string or even better a metal rod?

Rod

 

[Aled Dafis]

I may be missing something here, but frankly I cannot see the point of the steel bands?
As well as interfering with the depth of cut, sufficient tension should be provided by the top mechanism be it string or even better a metal rod?

Rod

I've also been thinking that, but didn't want to pee on any body's parade. Seeing as Rod has asked the question, I'll do the same

WHY??

I also have questions about whether your proposed design will actually work. Surely the wooden stretcher is the only component in compression, and is essential in keeping both the windlass and the blade in tension. Removing the stretcher would result in a floppy mess surely?

In the words of my old physics teacher "Every action must have an equal and opposite reaction...."

Cheers

Aled

 

[Vann]

Removing the stretcher would result in a floppy mess surely?

A springy mess maybe? I think the spring is supposed to provide the tension instead. It'll be interesting to see how well that works.

Cheers, Vann.

 

[swagman]

I like the design of the frame.

I think if I wanted to dispense with the 'Spanish-Windlass', I'd have modified the saw with a brass rod right across the top of the frame. With enough thread at one end to take a knurled screw, tightening the screw would pull the uprights together. Thus doing the same job as the windlass.

I can't say if this would work of course, but it might. Thinking on, you might need a knurled screw at each end of the rod?

Just 'noodling' a few ideas!

regards
John

Hi John. Thanks for the feedback. Will keep your ideas in mind.

Regards Swagman.

 

[swagman]

I may be missing something here, but frankly I cannot see the point of the steel bands?
As well as interfering with the depth of cut, sufficient tension should be provided by the top mechanism be it string or even better a metal rod?

Rod

Hi Rod. Thanks for the feedback. What the steel band provides is a greater degree of tension to the blade than would normally occur with the traditional frame. The greater tension provides a more accurate cut as the blade is less likely to stray off line. The depth of cut can be increased by turning the blade up to 90 degree's either side of the standard set up. This was the 1st design I built, and was to prove that the steel band concept would work.

Regards Swagman.

 

[swagman]

I may be missing something here, but frankly I cannot see the point of the steel bands?
As well as interfering with the depth of cut, sufficient tension should be provided by the top mechanism be it string or even better a metal rod?

Rod

I've also been thinking that, but didn't want to pee on any body's parade. Seeing as Rod has asked the question, I'll do the same

WHY??

I also have questions about whether your proposed design will actually work. Surely the wooden stretcher is the only component in compression, and is essential in keeping both the windlass and the blade in tension. Removing the stretcher would result in a floppy mess surely?

In the words of my old physics teacher "Every action must have an equal and opposite reaction...."

Cheers

Aled

Hi Aled. Thanks for the feedback. I have enjoyed viewing the work your doing. Very nice !

Your physics teacher was spot on with his statement " Every action must have an equal and opposite reaction...." and that was the basis behind using the spring steel band.

If you bend a spring steel band into a U shape , you will also feel an opposite reaction near the ends of the band as it wants to return to its original flat form.

If you then capture this energy by securing this bent form within a bow saw frame, you can use this energy to tension the bow saw blade.

If you then add some additional compression to the upper part of the spring steel band, more tension is given to the bow saw blade.

The tensioned windlass and bow saw blade should keep provide secure alignment to both of the bow saw frame arms.

This of course is all theory, and can only be confirmed by completing the new bow saw and trialing it.

Thanks again.

Regards Swagman.

 

[swagman]

The following images show progress I have made so far with the new bow saw design.

Regards Swagman.

 

[Mcluma]

I like that design

are you building for selling??

 

[AndyT]

I've been wondering about the grip you are going to use. Having the steel band quite close to the handle means, I think, that you are expecting to use a single handed grip only. (If you were to use the two-handed grip, you would be wrapping your second hand around the steel, which would be uncomfortable.)
If you are planning single handed grip only, you might want to include a comfortable curve for an extended forefinger to rest on.

There's an interesting discussion on this point (and much more about design of similar saws) on the Tools for Working Wood site here:

http://www.toolsforworkingwood.com/...e=toolstore&nextpage=/extra/bowsawdesign.html

 

[Harbo]

It looks very nice - but my only concern would be the further away from the Fulcrum the less force from the top tension arrangement will be applied to the blade? It is acting as a lever.

As you say the "proof of the pudding is in the eating"?
Hope it works.

Rod