LumberJocks

Saw Talk #11: More Thoughts on Sharpening Backsaws

  • Advertise with us
Blog entry by Brit posted 843 days ago 7315 reads 16 times favorited 56 comments Add to Favorites Watch
« Part 10: Hand Shaping and Sharpening the Teeth on a Backsaw Part 11 of Saw Talk series Part 12: You win some, you lose some »

I’ve been hesitating to post this entry on my Saw Talk blog series, basically because I don’t feel I’ve sharpened enough saws yet to make any recommendations to others. Instead, I thought I would take the opportunity to point you to some websites that I have found helpful. I have read most of the information available on the web on this subject and the links below are what I consider to be the best information for those new to sharpening. If you are serious about finding out about this subject, I highly recommend you read and inwardly digest this material.

From Vintagesaws.com:

Saw Filing – A Beginner’s Primer
The How’s of Setting Saws

From Wenzloffandsons.com:

On Choosing Saws

From Badaxetoolworks.com:

About my (Mark Harell) Saw Filing Technique

From Blackburntools.com:

Saw Tooth Geometry
Practical Cross Cut Saw Tooth Angles

From Matt Cianci on WKFinetools.com:

Rake and Rip Saws

From Toolsforworkingwood.com:

Elements of Saw Tooth Design

I thought it might be helpful if I pointed out some of the things I’ve realised are important when it comes to sharpening saws, so here goes:

You must use the right size saw file for the number of teeth per inch (tpi). The number of teeth is sometimes expressed as points per inch (ppi) and you should know that:

tpi + 1 = ppi (e.g. If it is written that a backsaw is 13ppi, then it is also 12tpi)

Online stores that sell saw files usually have a table that explains which file to buy for each tooth pitch.

It is also important to perform the steps involved in saw sharpening in the right order which is:

  1. Joint
  2. Shape
  3. Set
  4. Joint
  5. Sharpen

However, depending on the condition of the teeth before you start and whether or not you intend to change the tooth geometry, it might not be necessary to perform all of these steps. For example, if the teeth are in good shape and all you want to do is touch them up so they are sharp again, then you only need to perform steps 4 and 5 and 10 minutes should see you done. You can usually sharpen the teeth on a saw 3 or 4 times before it is necessary to re-set the teeth.

One thing I’ve realised as I’ve researched saw sharpening is that there are as many opinions as to the right tooth geometry for a given saw as there are people who file saws. You hear things like:

”I like to add a touch of fleam to rip teeth.”
“A little rake makes ripping easier.”
“Adding slope creates more space for the sawdust and helps move it up the side of the plate.”

Now I’m not saying that these people (who shall remain nameless) don’t know what they’re talking about, because they do. What I would like to point out though, is that the most important aspect of saw sharpening is that the teeth end up SHARP. Sharp teeth will cut wood regardless of whether they have 8 or 10 degrees of rake, 0 or 5 degrees of slope, or 6 or 8 degrees of fleam. After you have filed a few saws you will start to appreciate how rake, fleam and slope influence the cut of a particular saw, and you shouldn’t get too hung up on the optimum degree settings for each of these parameters when you first start out.

On the face of it, a backsaw is a pretty simple piece of kit isn’t it? It consists of a saw plate, a handle, a back or spine and two or three bolts. Whilst that’s true, there are many additional factors that influence how well a backsaw will perform in a given situation. Here are some of them:

  • Sharpness of the teeth
  • Degrees of fleam
  • Degrees of rake
  • Degrees of slope
  • No. of teeth per inch
  • The straightness of the toothline
  • Saw plate thickness
  • Amount of set per side
  • Hang angle of the handle
  • Spine weight
  • The balance of the saw
  • Handle comfort and fit
  • The cant of the saw plate (if present)
  • The angle you approach the cut
  • Your ability to start a saw
  • Your ability to cut to a line
  • The type of wood you’re cutting

After reading the above list, you might be forgiven for thinking that there is more to this saw sharpening lark than you first thought, but let me say it again – SHARP TEETH WILL CUT WOOD. Even if all the teeth are not exactly the same height or if the tooth geometry is less than perfect, SHARP TEETH WILL CUT WOOD. After you have sharpened a few saws, you can start to experiment with some of the other factors that can influence the saw’s effectiveness. I bought the backsaws that I’ve restored in this blog series because I wanted to learn to sharpen and maintain my own saws and play with some of these factors to see firsthand how they affect a saw’s ability to cut. I’m sure you can appreciate now why I bought as many as I did.

So armed with all this information and a good helping of commonsense, I created a spreadsheet. The column headings were:

  • Make and length of saw
  • Filing (i.e. Rip, Crosscut or Combination)
  • Teeth Per Inch
  • Rake angle
  • Fleam angle
  • Slope angle
  • Plate thickness
  • Depth of cut at the toe

I carefully measured these details on each of my backsaws and recorded them on the spreadsheet. Then I inserted a new row for each saw and after much consideration, recorded the details of how I intend to file each saw (shown below in brown text) in order to end up with a versatile set of backsaws that will cater for all my needs.

As I’ve already mentioned, I’m new to sharpening saws. I hope I’ve got it right, but the nice thing about learning how to sharpen your own saws, is that you can always change them again.

Thanks for your support. As always, I welcome your comments, be they good or bad.

Happy sharpening!

-- Andy -- Old Chinese proverb say: If you think something can't be done, don't interrupt man who is doing it.



56 comments so far

View Don W's profile

Don W

14645 posts in 1168 days


#1 posted 843 days ago

another good blog Andy. I still have as many to sharpen as I did 2 months ago. I need some sharpening motivation. Its probably going to take a few rainy days. Thanks for all the information.

SHARP TEETH WILL CUT WOOD
SHARP TEETH WILL CUT WOOD
SHARP TEETH WILL CUT WOOD

:-)

-- Master hand plane hoarder. - http://timetestedtools.com

View Brit's profile

Brit

5107 posts in 1444 days


#2 posted 843 days ago

Don – Glad you got my point if you pardon the pun. Actually I have a huge respect for the likes of Mike Wenzlof, Mark Harell and Matt Cianci, but the skeptic in me wonders whether adding a touch of rake, fleam or slope is more to compensate for people’s inability to saw. Sometimes I think what is really needed is sawing practice and more sawing practice.

-- Andy -- Old Chinese proverb say: If you think something can't be done, don't interrupt man who is doing it.

View Don W's profile

Don W

14645 posts in 1168 days


#3 posted 843 days ago

Sure and I agree, but must add it takes more than sharp teeth, it takes sharp teeth reasonably consistent. If not the saw walks. I know this how? I’ve got a very sharp saw, with a hook worse than my golf swing.

-- Master hand plane hoarder. - http://timetestedtools.com

View Brit's profile

Brit

5107 posts in 1444 days


#4 posted 843 days ago

LOL.

-- Andy -- Old Chinese proverb say: If you think something can't be done, don't interrupt man who is doing it.

View Don W's profile

Don W

14645 posts in 1168 days


#5 posted 843 days ago

I do know with your help, I’ll get it straight (the saw, not my golf swing, I gave up on that a long time ago)

-- Master hand plane hoarder. - http://timetestedtools.com

View Brit's profile

Brit

5107 posts in 1444 days


#6 posted 843 days ago

Full disclosure: Since I sharpened my little dovetail saw, I went back and experimented with it a bit. First I added 5 degrees of fleam and made a lot of cuts in some pine, sapele and hard maple. I couldn’t detect a difference to the 0 degrees I used originally. The back of the cut wasn’t any cleaner and the surface finish on the wood seemed to be the same. Next I added 5 degrees of rake and 5 degrees of fleam. It was easier to start the cut, but it took more strokes to reach full depth. Since I wasn’t having trouble starting the cut with the 0 degrees of rake and fleam that I originally filed, I ended up filing back to how I had it in the first place. IMO, the exercise was well worth the 1/16” of steel I wasted. You’ve got to try these things haven’t you?

-- Andy -- Old Chinese proverb say: If you think something can't be done, don't interrupt man who is doing it.

View Don W's profile

Don W

14645 posts in 1168 days


#7 posted 843 days ago

you just don’t know until you try.

-- Master hand plane hoarder. - http://timetestedtools.com

View Dave's profile

Dave

11142 posts in 1441 days


#8 posted 843 days ago

Andy well detailed blog and the goto to link for the goto info. Thanks.

-- Superdav "No matter where you go - there you are." http://chiselandforge.com

View bandit571's profile

bandit571

6674 posts in 1284 days


#9 posted 843 days ago

I’ve been playing around with my full sized handsaws, lately. Takes a while, there are a lot of teeth in 26” of saw plate. The latest has 12 ppi, and took at least 1/2 an hour to file. WHEW! Looking forward to filing the two rip saws i have. Fewer teeth, since they are in the 5-6ppi range, BIG teeth. High-tech saw vise still works alright, though….

-- A Planer? I'M the planer, this is what I use

View Philip's profile

Philip

1079 posts in 1140 days


#10 posted 843 days ago

Andy, your series is fantastic and informative. Well done friend.

-- If you can dream it, I can do it!

View AnthonyReed's profile

AnthonyReed

4379 posts in 1041 days


#11 posted 843 days ago

Always a pleasure to read your posts.

Thank you Andy.

-- ~Tony

View llwynog's profile

llwynog

282 posts in 1180 days


#12 posted 843 days ago

Andy,
That is a great source for learning how to sharpen.
I love the fact that you did try to file your backsaw with different tooth geometries in order to see for real if it had such a big impact.
Thanks a lot.

-- Fabrice - "On est bien bête mais on sent bien quand on se fait mal" - my grandfather

View Brit's profile

Brit

5107 posts in 1444 days


#13 posted 843 days ago

Dave – Thanks. Just trying to make it easier for beginners. There is a lot of confusing and contradictory information out there and really the best thing a beginner can do is pick up a file and have a go. I learnt more from actually filing a saw than I did spending hours reading all the articles.

Bandit – I know what you mean. It would have been easier to start with the bigger teeth on hand saws than the small teeth on my backsaws, but I like a challenge.

Philip – Glad you’re enjoying the blog. I’ve certainly learnt a lot writing it.

Tony – The pleasure is all mine my friend.

llwynog – Different tooth geometries do make a difference, but all other things being equal, that difference can be small. I just don’t think a beginner should get too hung up on it. I firmly believe that you could sharpen two different backsaws with the same tooth geometry and one might end up cutting better than the other. For instance, if you sharpened both sets of teeth with 0 degrees of rake, but one of the saws had an extra heavy brass back (two of mine do), you might have to compensate for the extra heavy back by adding 5 or 6 degrees of rake to help prevent the saw grabbing. You can’t just look at tooth geometry in isolation without also considering the thickness of the plate, the tpi, the hang angle of the handle and the weight of the spine. IMO all these things must work in harmony and only by filing, trying and tweaking will you find what’s right for a particular saw.

I can totally understand how people get consumed by saw filing though. Whenever you finish filing a saw you are always left wondering whether adding another degree of rake for example would make it even better. :-)

-- Andy -- Old Chinese proverb say: If you think something can't be done, don't interrupt man who is doing it.

View need2boat's profile

need2boat

544 posts in 1293 days


#14 posted 842 days ago

Great post Andy,

Sharpening is something that just takes a lot of practice and I think that everyone has there own leans and pit falls. I’ve been actively chipping away at it for months and still have room to improve. I’ve leaned through the process that getting a saw back to it’s glory, the shaping and sharpening is just one small piece. Things like proper ppi, rake, angle, and even set all play just as big a role and once you start messing around it’s your can start to spin. ;-) as you said one can always start over.. . .

Did you do your chart in Excel or Word? I’d love to get a copy emailed. jfederici(at)limitedbrands.com

cheers

Joe

-- Second Chance Saw Works http://www.secondchancesawworks.com Blog: Positive Rake http://www.positiverake.com

View hhhopks's profile

hhhopks

560 posts in 978 days


#15 posted 842 days ago

Another great post.
I am guity of being too lazy to use the hand saw.

I got a few (well more then a few).
To get to know the tool better I would think think I need to skip the gym and just sawing.
I may not have the time to mess with it for now, your chart will make an excellent reference.

Thanks.

-- I'll be a woodworker when I grow up. HHHOPKS

showing 1 through 15 of 56 comments

Have your say...

You must be signed in to post the comments.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics

HomeRefurbers.com

Latest Projects | Latest Blog Entries | Latest Forum Topics

GardenTenders.com :: gardening showcase