Monday, December 30, 2013

Bow Saws Begin

Another set of projects in the woodworking adventure.  A saw.  Yes, every carpenter or wood worker needs a saw.  What kind of saw?  How many saws?

  

I started with the idea of making one big saw and a smaller detail saw.  I try and do a lot of work without power tools.  When it comes to saws I get away with basically three saws.  
1) A crosscut saw with very aggressive teeth
2) A smaller detail saw with more teeth per inch, but much smaller.  
3) Coping saw for scroll work.

I thought that was a good place to start.  Replace my modern tools with period looking ones.  While doing some antiquing I came across some deals on used and some vintage tools that I couldn't pass up.

After some research and work I decided that the list would have to grow to 4 saws.  I will be making two versions of the first saw.  One with large aggressive teeth for cutting greenwood and one with smaller teeth for cutting well dried wood.

I decided to sacrifice the following saws in my endevour.
  

I planned on taking off the handles and cutting the saw blades down to a more period looking ribbon to be attached to a bow saw.

I started working on the smallest saw first.  I took this branch of what I think is ASH and split it.


Using my favorite axe I cut it down to shape.  Rather than simply cutting it, I wanted to choose a piece of wood with straight grain which I could split.  Never having made a saw like this I wasn't sure, but my theory is that the arms of the saw must be rather flexible.  I wanted to make sure that the grain ran straight along the arms.


Roughed and flatted with the ax I moved on.


 Here you can get a basic idea of the size of the blade.  This will be used to make the first saw which will be the second smallest.  I will eventually make another "fret saw" using a bandsaw blade, but I decided to finish these three first.


The basic anatomy of a bow saw contains a stretcher separating two cheeks to make a basic capital letter H.  The blade then crosses the bottom of while a cord is attached across the tops of the cheeks.  The cord is tensioned using a turnbuckle or tensioned cord wound up.  The following picture is the first attempt at the toggle which will be inserted to secure the twisted cord once it has been tensioned.

The first picture was after rough shaping with an axe and the second picture is after it has been cleaned up with a draw knife.

 

Here is the basic layout I was planning.  While it would probably have been beneficial, I had no measured plans.  I often have an image in my head and just play with the materials until I get what I want.  I have never made one of these and so my first images I had in my head turned out to be a bit chunkier than I needed.


I planned on doing a basic mortise and tenon style joint for the stretcher and the cheeks.  The fit will be very loose and allow for some movement.  The twisted line needs to tension the saw while unwinding it should reduce the tension on the blade.


I didn't like the first toggle I made.  I kept it and will use it for one of the larger saws.  I replaced it with a smaller version cut more sleekly out of the orange colored ash.


Initially I had planned using only square stock but later I toyed with adding a little embellishment.  I sketched the following on the cheeks of the smallest saw.

 

I roughed out the cheeks with my trusty axe once again.  I would finish the details up later with a carving knife.  You can see here the updated toggle is more to the proper scale.  Time to set this aside and make a blade.


I removed the handles from the blades and toyed with using a cold chisel to cut it to shape.  

Here you can see I was able to cut the corner off using only a chisel on my steel railroad track as an anvil.


I used a cold chisel to follow along a line of tape I applied.



No need to cut all the way through with the chisel.  Hitting twice on each spot caused a weakness and brittleness to the blade.

 

After scoring the entire line I placed the blade in a vice and used a hammer to crack the weakened blade free.



Rusted and dirty blades all cut roughly to shape.



I broke down and used some power tools here.  I used my angle grinder with a wire wheel on it to clean off most of the rust.  I also used a bench grinder to clean up the sharp edges from the cut I made.  Using a chisel leaves a lot of small and very sharp slivers of metal hanging along the edge.  I used a quick zip along the grinder to smooth out the edge.


Looking more and more like the saw I had in my brain.  This will be the only saw with a fixed blade.  This saw will replace the small saw which I used for doing small detail work like dove tails and mortises.  I don't have any need to have a rotating blade.  The two larger saws will have a larger rotating blade to allow for larger stock to be cut.  The smallest of saws (which hasn't been started during this post) will have a rotating blade as well as it will be used for doing small scroll work.

 

Larger saw layout. 


That is a heck of a blade.  I think I love this saw already!  To make the stretcher I took a piece of the cleanest rough cut oak I had from my old pallets.  The oak I had was about 3 inches by 3.75 inches.  I decided to rip it into three pieces.  Two of the cleanest pieces would be used as the stretchers for the two bigger saws.


A rip cut is made parallel to the wood grain.  As the saw runs the length of the grain the teeth seem to bite a lot less vigorously than when cross cutting.  I have never ripped an oak timber with an hand saw.  I imagined that it would take some work, but it was far more laborious than I imaged just to get two good pieces to use.


Three roughly cut pieces were the result of the rip cuts.

 

I cleaned up the two stretchers with a jack plane to determine if there was any inherent twist in the grain. The finished pieces seem usable.  After the rip cuts and planing I was wiped and the next steps will wait for another day.