Saw sharpening... a balance between rake, fleam, and set.

At the Perth Wood Show last weekend, I picked up a lovely Canadian-made Disston tenon saw from the second hand tool stand run by the Hand Tool Preservation Society of Western Australia. It's a beauty! However it just needed sharpening...

Yep, a very nice Disston tenon saw, with the handle in very good condition.

I have a few odd Disstons made in Canada. This is a new addition to my Canadian bunch. 

With a three day gig this week at a primary school doing woodwork with the K - 2 students, I needed another sharp saw on hand. I also had another tenon saw needing sharpening for the event -an older Disston saw. So it seemed a golden opportunity to get them both done during a window of opportunity I had on the day before the school program commenced.

The older Disston tenon saw, made in Philadelphia USA.

About the variables in saw filing - rake, fleam, and set.
In a nutshell, RAKE is the vertical angle of the face of the tooth, which also determines the aggressiveness of the cut. If the rake was 0 degrees, the face of each tooth would be straight up and down. FLEAM is the angle of the face of the tooth in relation to the line of the teeth. If the fleam was 0 degrees, the teeth would be filed straight across. Rip saws are commonly filed like this, so that the teeth work like little chisels. Crosscut saws are filed with fleam up to as much as 30 degrees, which makes the teeth like little knives as they slice through the fibres of the wood. Set is the applied by bending alternating teeth either side of the tooth line. Increasing the set widens the kerf cut by the saw, which stops the sawplate from binding in the wood. However, the wider the set the harder it is to push the saw, and the less accurate the cut. Dovetail saws typically have minimal set, which enables greater accuracy.  

These saws are going to be used mostly by small kids. I am still experimenting with filing angles and the amount of set which works best for the little people (age 4 up) who have short arms, limited muscle, and who are often using saws for the first time in their lives. This means that they are yet to get the hang of moving their saws in a dead straight line. The wobbling wrist and arm will tend to make the saw plate bind in the kerf, so a bit more set in the teeth than usual will help to prevent this. The trade off is that they have to remove more material to have a wider kerf, meaning more energy is required. It's a balancing act, and my experimentation is yet to achieve the optimum saw configuration for the little kids. The other ingredient in the equation is the type of material being cut. With the kids, I almost exclusively use softwoods and plywoods. With softwoods you would normally use a greater fleam angle than you would for hardwoods. So, I continue to experiment...

The new saw in the saw vise, ready for sharpening.

After jointing, shaping and setting the teeth, I filed the teeth with a rake of 30 degrees and a fleam of 20 degrees - hence the angles. The kids will be mostly crosscutting in softwoods.

Teeth being filed for cross-cutting, with a rake of  30 degrees and a fleam of 20 degrees. 

Two nice Disston saws, sharpened and ready for action.

I would have between 4 and 6 tenon saws in operation at the school. The picture below shows my standard "sawing station" set up. This 4 saw station is a bit like having 4 bench hooks set up on a pair of sawhorses. It also works really well, for right and left handed students.

The sawing station set up at the school ready for use. 

As I finish this post, I have completed the 3 day gig at the school. Eight classes of students had a great time  making stuff - using hammers, nails, saws, and a  pile of wood pieces. The saws worked flat out for much of that time. Amid all those cutting their pieces of wood to size, there are always a few kids who just love sawing! They might not make much, but they do create piles of little pieces! It's great seeing kids enjoying using tools for the first time. So empowering.

The verdict? For the really little kids, the 4 and 5 year olds, I reckon we might need just a little more set in the teeth...    I'm still looking for the right balance...

The right amount of SET...

In line with my New Year's Resolution - for 2013 to be the year I become proficient in saw sharpening - I have been at it again. Filing and setting lots of saws, that is.

Using a saw set takes some concentration! You've gotta be careful to set every second tooth.

Putting set on the teeth means bending each alternate tooth outwards. When this is done from each side of the saw, each tooth points the opposite direction to it's neighbours. A Saw Set is a special tool like a form of pliers designed for applying set to the teeth, pictured above. Squeezing the handle pushes a pin which bends the tooth against an anvil. The angle of the bend is determined by the adjustable anvil. You dial in the tooth spacing (in Points Per Inch) on the anvil's dial and set every second tooth. You then turn the saw around and come down the other side to set the remaining alternate teeth.

The reason for giving the teeth set is to increase the size of the kerf - the width of the wood material removed by the teeth. There are many variables here. There is a lot of science in saw construction, tooth geometry, and sharpening! However, as a general rule of thumb, a saw with no set will be inclined to jam in the wood. Too much set and the saw will easily wander all over the place and it is harder to do more accurate cuts (eg joint cutting). More set is needed with green softwoods, and less set is required for seasoned hardwoods.

Amongst the saws I have been sharpening recently, the dovetail saws need minimal set. This helps make very accurate cuts with it's very fine teeth. However I also had to sharpen the "tenon saws" (technically Sash saws) I use for kids and others in my workshops. I was preparing for another day in a school with about 110 kids, and 5 of the saws "needed a birthday". I'd noticed at the last gig that some of the saws were getting a bit dull. I remember when someone was cutting through a nail in the wood they were cutting. I heard it from across the room and went straight over. Too late! Anyway, I filed the saws sharper, but felt that not all of them required re-setting.

My two favourite saws, 14 inches long with very heavy brass backs. English made: BUCK.

Interestingly, while watching the kids at work, I noticed that my two favourite (freshly sharpened) saws were offering a little more resistance to the 5 year old kids than I like. They were good for me, as I have a nice straight relaxed sawing action. However for kids learning and sawing for the first time, it was clear that a tad more set would've been good!

Yep, it's all about the right amount of set for the array of variables on hand at the time!
Mmm ...the right amount of SET...  

Saw sharpening day.

Today was a saw sharpening day. I have a couple of teaching workshops coming up where I will be teaching the pleasures of hand cutting dovetail joints. It was time to get more dovetail saws organised for the bigger groups.
Much of my dovetail saw collection has been amassed (like the rest of my saw collection) over the last few years from antique tool sales, garage sales and flea markets. I am not a Tool Collector, incidentally, for my purpose is to put tools back into service, not into glass cabinets. Many of the priority saws have been piling up in a box awaiting for a sharpening day. That day arrived today.

A few of the saws awaiting cleaning up and sharpening...

Some of the saws needed to be "given a birthday" first: Many needed surface rust removed, some needed a bit of straightening of their saw plate, the odd bit of nut tightening, and a bit of nourishment for the handles. The cleaning up of the saw plate was done with the wire wheel in the bench grinder, wet and dry paper, WD40, steel wool, etc.

When the saws were ready, I donned my magnifying head gear, sharpening equipment, saw vice, and got onto the next phase of the task. Sharpening day was well under way.

What a beautiful array of dovetail saws!! Several of them are well over 100 years old. The brands represented include Sheffield companies like Robert Sorby, Marples, Sanderson Brothers & Newbould, Bowden and then of course Disston from the USA. There are a bunch of other unknown brands present in the pile too, including the inevitable "Warranted Superior"which many companies seemed to use.

The dovetail saws in the pile are a mixture of open handled models, gents saws, and a few closed handled models. I had a few other saws waiting in that pile too, including a couple of old panel saws and small carcass/tenon saws. I'd do them if I had time. Such a beautiful array of saws and all oozing with history.

One of the Gents Saws in the saw vice.

The Gent's Saw. What's in the name? In the 19th century, upper class recreational woodworking gentlemen did not want to appear like the lower class tradesmen, so I understand. Gentlemen required a different style of handle to the tradesmen's saws. Hence the Gent's Saw was born. This style still bears the name to this day.

Sharpening a Gent's Saw using the new Veritas filing guide.

What makes saw a Dovetail Saw? Ideally, they will have a thin saw plate for minimal kerf, minimal set of the teeth, be only 8 to 10 inches long, and be filed with ripping teeth.  Saws are generally filed for ripping (cutting along the grain) or for cross cutting (cutting across the grain). It is the various angles of the teeth which makes the difference. Dovetailing involves cutting along the grain, so the best dovetail saws are filed for ripping - that is, filed straight across. This creates a chiseling action by the teeth - the most efficient and clean way to cut along the grain. Crosscutting teeth are filed on a different angle to create a slicing action on the fibres of the wood. Whatever the style and size of the saws in my pile awaiting sharpening, I was setting them up to be used almost exclusively for dovetailing, so they would all be filed for ripping.  There is a science to getting the shape of the teeth right - but I will save a discourse on that for another post.

In the past I have used a block of wood driven onto the far end of the file as the guide for consistent filing. This was the first time I have used the new Veritas filing guide... and I like it very much.

Looking good. Another saw done. The test cut was good too.

While the filing generally went well, there was one sad story. One of the really old open handled saws had a couple of bad patches of corrosion on the saw plate. There were almost no teeth left on it - I'm sure the previous owner must've been cutting bricks with it! I was having to re-form the teeth on the saw plate. Sadly, while filing a corroded section a small piece blew out. At least the beautiful handle and nuts can be used on another saw.

Bummer. Too much corrosion, so filing caused a blow out. This saw now in the spare parts box.

Keeping the saws sharp.
Some hours later, I had finished filing assorted 10 dovetail saws.

Ten beautiful dovetail saws all cleaned up, freshly sharpened and ready for action

However, the saws would need some protection on their edges to ensure they don't knock against other or against other metal objects, as this bluntens them. I commonly use a piece of 1/2" trickle irrigation tubing slit along much of its length, and held onto the saw with rubber bands made from cross-sections of a bicycle tube. The recycler's solution to protecting the saws' edges.

Protection in place. A pile of ten sharpened dovetail saws.

A good day's work.
It can do your head in, staring hard through your magnifying head gear for hours on end while filing and setting saw teeth. By the time I called it a day, I had filed 14 saws. Ten dovetail saws filed for ripping, three small tenon/carcass saws filed for cross cutting, and a panel saw filed for cross cutting. Sensitive finger tips from too many pin pricks from the sharp teeth, tiredness from concentrating hard for so many hours, and a sore back from so much stooping over the saw vice.

Despite all that, I was very satisfied with the day's achievement. I have never filed so many saws in one day, and I was a few steps closer to getting enough saws ready for the dovetailing workshops coming up in June. It was a good day's work.

At the start of the year, I had resolved that 2013 would be the year that I become very competent at saw sharpening. I reckon things are going according to plan... my skills are improving.

All in a day's work.

Saw sharpening day was a lot of work but very successful. However, I need to do many more such days if I am to make a dent in the huge pile of saws awaiting similar treatment!!  Hopefully my skills will keep improving as I go...  


 

Saws, saws, saws...

Decision made. 
This year I am going to seriously improve my saw sharpening skills.

I have a lot of saws. Many dozens in fact ... most awaiting cleaning up and sharpening.

Sure, I do sharpen the occasional saw - but mostly I pay someone else to sharpen them for me. Saw sharpening is not what I would call one of my strengths. However that is all going to change. I have commenced my upskilling process.

Q: Why bother mastering saw sharpening?
A: It's the smart thing to do! It's about sustainability, self-reliance, flexibility and independence.
It's also about respect. Respect for a quality saw and respect for the people who have used, owned, and valued the saw before me.

Q: Why fix up old saws when it is cheaper and easier to buy new hardpoint saws for under $10?
A: It's about being a responsible global citizen. Hardpoint saws are "disposable" saws of low grade steel with hardened teeth and nasty plastic handles. They cannot be sharpened. There is a cost to the planet when these bluntened hardpoint saws are thrown into the bin. However an good quality old saw can be re-sharpened until there is almost nothing left - which may be decades or even centuries.  I regularly use my great-grandfather's Disston carcass saw, which is over 100 years old. It is a beauty, and there is no reason why my own great-grandchildren can't be using the same saw in years to come.

Q: Which are the best saws to clean up, sharpen, and bring back to life?
A: The handle is often a good indicator. After the Second World War, modern mass production brought about saws with increasingly chunkier handles. In contrast, look at a good quality saw from before WWII. The handle will have a more ornate shape. Saws made earlier, before WWI will commonly have an even more ornate shape. The more ornate handles have longer horns, which help the saw hang nicely in the hand. They are shaped to fit better in the hand than the chunkier more modern saws. These more ornate shaped handled saws can be used all day and are a joy to hold. The chunky handles are not moulded to fit the hand and will become increasingly uncomfortable as the day goes by. Saws made in the late 19th century were also mass produced, but there was a convergence of excellent technology and the concept that tools would be owned and used for life. Watch for the more ornate handles. The other issue is the state of the sawplate. Is it badly rusty or pitted? Is the blade badly bent, dented or damaged? The less damage to the sawplate the better the saw will be when resuscitated.   

Now that's a beautiful dovetail saw. English made. Marples. A joy to use.

I found the old dovetail saw pictured above at a flea market. It was worth resuscitating and putting back into service. Shown here at work! Nice comfortable handle, nice thin sawplate. Delicious...

An invitation. As I embark on this journey of saw sharpening, I invite you to travel with me. Every now and then I will post something about saws and how to bring them back to life - including the sharpening process! ...Come share with me in the joy of saws, sawing, and saw sharpening!!