New Matilda Bow Saw

[swagman]

Hi all. Attached are images of the newly designed Matilda Bow Saw.

Template design. The fasteners shown for the top spreader were replaced with M6 X 35 High Tensile Cap Head Screws.

Completed bow saw. Matchbox on the left hand side of photo.

Photo showing spring steel tension plates fitted to the inside of the frame arms.


Total weight is 1.05 lbs (0.54kg).

Depth of cut = 8 inches.

Individual components including threaded inserts,washers,ferules,screws, and frame = 62



Although heavier than a Gramercy, the Matilda Bow Saw is still very well balanced.


To tension the blade, you wind the threaded handles in until the blade connecting screws lock into the inside of the frame arms.


The additional 3rd handle is very handy inclusion when using the bow saw with the blade set off vertical.


I am extremely happy with this design. Its performance, weight and balance, as well as ease of dismantling, is what I have been striving for.



Swagman.

 

[Philly]

Nice one Stewie! Looks great,
Philly

 

[Chris Knight]

I admire your persistence and your execution although I still don't care for the design.

If I wanted a saw like that, I think I would be focused on looking at ways of getting rid of the steel strapping which I presume is there in this latest model to strengthen the wood limbs.

An obvious approach - pardon the implicit pun, would be to laminate suitable woods such as those used for bow-making like Osage Orange, Lemon wood and the like in a shape I liked. I reckon you could build in enough strength with a tapered lamination to do away with the metal and the heavy cross piece.

 

[Mcluma]

If I wanted a saw like that, I think I would be focused on looking at ways of getting rid of the steel strapping which I presume is there in this latest model to strengthen the wood limbs.

.

I adisagree with you completely

the introduction of steel just ads more oempf to the design, i really like it, maybe you could do some work on the steel, like black or so, or blue steel

also if you could line up the screw heads please, and maybe have the steel strip routed into the design, rather then added on top, or if you go laminated, have a strip of steel laminated inbetween the wood.

I really like it =D>

 

[bugbear]

Hi all. Attached are images of the newly designed Matilda Bow Saw.

I am now very confused. You started trying to reduce the tension (and chance of breakage) in the wooden arms, due to concern over possible breakage.

Yet this latest design appears to use steel springs to increase the tension, but has removed the "self contained" nature of the spring in your first design. The steel spring is now increasing the loading on the very part whose fragility first concerned you (indicated).

BugBear

 

[dannykaye]

I am with BugBear on this one, The 'original' without the steel seems elegant to me, the addition of the spring steel, while making the whole thing more predictable I assume, is just ugly, again to me.

 

[swagman]

Nice one Stewie! Looks great,
Philly

Thanks Philly. Appreciate the feedback.

 

[swagman]

I admire your persistence and your execution although I still don't care for the design.

If I wanted a saw like that, I think I would be focused on looking at ways of getting rid of the steel strapping which I presume is there in this latest model to strengthen the wood limbs.

An obvious approach - pardon the implicit pun, would be to laminate suitable woods such as those used for bow-making like Osage Orange, Lemon wood and the like in a shape I liked. I reckon you could build in enough strength with a tapered lamination to do away with the metal and the heavy cross piece.

Thanks for the feedback Chris.

 

[swagman]

If I wanted a saw like that, I think I would be focused on looking at ways of getting rid of the steel strapping which I presume is there in this latest model to strengthen the wood limbs.

.

I adisagree with you completely

the introduction of steel just ads more oempf to the design, i really like it, maybe you could do some work on the steel, like black or so, or blue steel

also if you could line up the screw heads please, and maybe have the steel strip routed into the design, rather then added on top, or if you go laminated, have a strip of steel laminated inbetween the wood.

I really like it =D>

Thanks for the feedback McLuma. Will work on the screw alignments for the new lot of bow saws I make. The steel is high grade spring steel used on hand saws. The type of steel, the way it is fitted, and its location serve an important part of the bow saws design. Laminating is not an option.

Thanks.

Swagman.

 

[swagman]

Hi all. Attached are images of the newly designed Matilda Bow Saw.

I am now very confused. You started trying to reduce the tension (and chance of breakage) in the wooden arms, due to concern over possible breakage.

Yet this latest design appears to use steel springs to increase the tension, but has removed the "self contained" nature of the spring in your first design. The steel spring is now increasing the loading on the very part whose fragility first concerned you (indicated).

BugBear

Hi Bugbear. Nice to hear from you.

The reason began looking at a better design for the wooden framed bow saw, was to find a way of overcoming the level of frame failures that resulted from overtensioning on traditional style frames.

If you did a search on tools that utilize effective mechanical advantage to there advantage I doubt very much if the traditional style bow saw would be given any merits Its a complete design disaster.

Starting off with a mechanical advantage of no more than 1 - 1. This is reduced even further by the fact that the leverage joint is also being put under compression due to resistance between the 2 wood surfaces.

Feedback from users of the highly regarded Gramercy also battle with the same problem. How do tension the blade effectively and not chance breaking the frame.!!

My earlier designs looked at trying to increase this mechanical advantage by including the use of a steel tension band. This did a very good job in this respect, but there was still room for improvement.

This latest design works on a slightly different strategy. When initially put together, the inside span on the bottom of the frame arms is 25mm above the final tensioned span. This design relies on the resistance of the arms to inward movement. The spring steel plates work to build this resistance even higher.

Does it work. Sure does. And far superior in all aspects to the previous designs I built. On top of that, I have also increased the depth of cut to 8 inches. That is 2/3 of the frame height.



Thanks again.


Swagman.

 

[swagman]

I am with BugBear on this one, The 'original' without the steel seems elegant to me, the addition of the spring steel, while making the whole thing more predictable I assume, is just ugly, again to me.

Thanks for the feedback Danny.

 

[aesmith]

Swagman, what blade do you use?

 

[swagman]

Swagman, what blade do you use?

Hi aesmith. The blade is a 12" old stock traditional bow saw blade purchased through ebay-UK. Seller is gandmtoolsales. They are sold in lots of 5 for GB 6.50.

Swagman.

 

[Chris Knight]

Swagman,

I am interested as to why you say a bent lamination wouldn't work. I have made quite a few now for furniture and also for a longbow and based on my admittedly unscientific testing of their strength, I'd be very surprised if you couldn't get a hell of a lot of tension on a blade with something like the crude drawing below.

 

[swagman]

Swagman,

I am interested as to why you say a bent lamination wouldn't work. I have made quite a few now for furniture and also for a longbow and based on my admittedly unscientific testing of their strength, I'd be very surprised if you couldn't get a hell of a lot of tension on a blade with something like the crude drawing below.

Hi Chris. Got an even better idea. You make up the laminated bow saw frame. I would like to view your final work.

Cheers.


Swagman.

 

[PeterBassett]

Game, set and match. :lol: :lol:

 

[bugbear]

Hi all. Attached are images of the newly designed Matilda Bow Saw.

I am now very confused. You started trying to reduce the tension (and chance of breakage) in the wooden arms, due to concern over possible breakage.

Yet this latest design appears to use steel springs to increase the tension, but has removed the "self contained" nature of the spring in your first design. The steel spring is now increasing the loading on the very part whose fragility first concerned you (indicated).

BugBear

My earlier designs looked at trying to increase this mechanical advantage by including the use of a steel tension band. This did a very good job in this respect, but there was still room for improvement.

This latest design works on a slightly different strategy. When initially put together, the inside span on the bottom of the frame arms is 25mm above the final tensioned span. This design relies on the resistance of the arms to inward movement. The spring steel plates work to build this resistance even higher.

Does it work. Sure does. And far superior in all aspects to the previous designs I built. On top of that, I have also increased the depth of cut to 8 inches. That is 2/3 of the frame height.

But it appears to me that the tension at the blade is multiplied UP w.r.t to the wooden part indicated by the red arrow - the ratio is the length of the arm contacting the middle "pivot" piece to the lower arm length.

BugBear

 

[Chris Knight]

Game, set and match. :lol: :lol:

I don't think so..

I had a crappy old partial prototype for a table leg (in maple) I made a year or so ago and have just taken a few minutes to slice a bit off it to make the saw shown below. The bow is rectangular in section, 20mmx 30mm the blade length is 600mm and the max depth (arc height) is 380 mm. All together it weighs 695 grams.

I am cutting 20mm thick hard maple in the pic. The blade is from an old 1/4 inch bandsaw blade.

Plainly the dimensions are very different from a normal small bow saw but I think it proves my point about strength and the practicality of the method. To tension the blade, I compressed the bow about one inch only which was ample to tension the blade sufficiently for cutting.

Hi Chris. Got an even better idea. You make up the laminated bow saw frame. I would like to view your final work.

I am afraid this is as final as it will get , I just don't need a bow saw. Although every time I see Frank Klausz using one to cut dovetails, I am a little bit tempted to be truthful. :wink:

 

[PeterBassett]

Boom! And he's back in the game.

Do these saw cut on the pull stroke? Surely all the issues with tension would disappear if the blade was turned so that it cut on the pull stroke?

 

[Chris Knight]

Boom! And he's back in the game.

Do these saw cut on the pull stroke? Surely all the issues with tension would disappear if the blade was turned so that it cut on the pull stroke?

Peter, I think it's up to the user. I found this thing cuts much more smoothly by pushing. It has a tendency to bounce on the return stroke using it the other way.