Saw making, Bladeslot and fitting in the spine

[KlausK]

Hi Handtoolers,

in another thread I was asked to share the methodology how Pedder and I fit in the spine. I want to show a few pics that should make it clear. The example shows a saw with a ovally filed and polished spine that is inserted flush to the top of the cheeks.

The first step is the making of the blade slot. I use a horizontally fixed drilling machine with a circular saw blade that is designed to cut metal. It's thickness is 0.5 mm. The handle blank is fixed in a vise that is movable because it is sitting on a cross table. So the adjustment is relatively easy.

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Since the circular blade doesn't have any set, one can do only the initial cut with the depth of about 5 or 6 mm. If you go deeper, the blade will bend and destroy the cut. The rest of the blade slot can be cut easily by hand because the predone 5mm-slot serves well as a guide.

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The same set up will be used for the sides of the mortise for the spine. It can be done in the whole needed depth since the predone bladeslot allows enough movement for the slim piece of wood that the saw blade doesn't bend. Due to the circular shape of the blade, the sides can't be sawed the whole depth and length however.

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The above shown pics are from former times. The following are actual and show therefore another handle. It's one out of Karelian birch, also known as Masur birch. At first a pic of the already ovally filed spine. You will see, that the rear end of the spine is shaped in a unusual way. We do that because we think that this shape with the corresponding shape of the mortise help to keep the top of the spine flush to the handle top.

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As you can see, the sharp edges of the spine are filed dull where the spine sits in the handle. That helps to prevent damages of the crisp shaped edges of the mortise while the spine has to be taken out and reinserted what happens several times while making the saw.

Here's the handle.

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And here you will see the inside shape of the mortise.

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At last 2 pics that show the inserted spine.

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Thanks for looking.
Klaus

[IanW]

Thankyou, Klaus. I sometimes start the slot with a slitting saw, too. If I am doing several handles, I use the slitting saw, but for a single handle, I usually can't be bothered setting up the saw, so I will make the whole slot with a hand-held saw. However, my slitting saw setup is very crude compared with yours, just the saw chucked in my drill-press. (It looks rather scary, too, so I'll not make it public. :;).

One reason I asked how you made the slot was because in one picture I saw, the oval spine appeared to continue in a perfect fit into the handle, but I think it was my eye being tricked, because as you clearly show, the handle part of the spine remains un-shaped, apart from the little step. I like to put a bold chamfer along the bottom edge of the spine, which causes some trouble when fitting. I have tried stopping the chamfer when it reaches the handle, and shaping the bottom of the handle slot to accommodate the chamfer, & it is tricky to get a really seamless fit either way. I have noticed on old saws that the slot for the spine is often quite roughly made. That may not affect performance, but I try to do as good a job of it as I can!

Cheers,

[DSEL74]

Thanks Klaus, a very nice breakdown. We will have all your secrets soon:wink:.

Look forward to part 2, shaping and polishing the spine.:D

[RayG]

Thanks Klaus, nice simple setups, and not too much heavy machinery, just a good use of a drill press and electric drill. :2tsup:... How are you slitting the brass?

You might like to know, that it was one of your saws that inspired Dale to organize the backsaw making workshop, so you can take a bow. :)


Regards
Ray

PS. It was the ebony handled one.

[planemaker]

A very detailed post full of high quality information Klaus. Thank you. A great source of inspiration for our up and coming saw makers to what can be achieved given the right mind set. The mortise fit on your backsaws are the best I have seen by far. We are indeed most fortunate on this forum site to have such experienced saw makers as yourself, Isaac, & Marv, willing to share their knowledge & experience in an effort to assist up an coming saw makers learn this craft. A most generous gift.

Stewie;

[KlausK]

I like to put a bold chamfer along the bottom edge of the spine, which causes some trouble when fitting. I have tried stopping the chamfer when it reaches the handle, and shaping the bottom of the handle slot to accommodate the chamfer, & it is tricky to get a really seamless fit either way. I have noticed on old saws that the slot for the spine is often quite roughly made. That may not affect performance, but I try to do as good a job of it as I can!


Hi Ian,

to me it's less tricky to stop the bottom chamfer of the spine than to shape the slot bottom of the handle according to the chamfer shape. Indeed I agree, that the fitting in of the spine on vintage saws often was made sort of crude. But one thing the former saw makers did always perfectly. That's the parallelism between blade slot and spine mortise. You hardly will see a vintage backsaw with a bow in the blade beneath the cheeks (aside the saw was damaged of course).

I like a proper connection between spine and handle because it shows some of the pride from the maker that went into the tool.

Cheers
Klaus

[KlausK]

Look forward to part 2, shaping and polishing the spine.:D

Hi DSEL,

the shaping of the spine is easy. Just remove all the parts from the brass blank that you don't like with a file. The rest will be the part of the brass that you like:D

Cheers
Klaus

[KlausK]

Thanks Klaus, nice simple setups, and not too much heavy machinery, just a good use of a drill press and electric drill. :2tsup:... How are you slitting the brass?

You might like to know, that it was one of your saws that inspired Dale to organize the backsaw making workshop, so you can take a bow. :)


Regards
Ray

PS. It was the ebony handled one.

Hi Ray,

nice to hear from you.

Our brass backs will be slitted by a machinist on a CNC mill. He uses carbide saw blades in different widths to do that. Since this man makes the slots in this way, we never had one less than perfect spine blank again.

It makes Pedder and me very proud that the dovetail saw we made for you was that inspirational. Wow!

Cheers
Klaus

[KlausK]

A very detailed post full of high quality information Klaus. Thank you. A great source of inspiration for our up and coming saw makers to what can be achieved given the right mind set. The mortise fit on your backsaws are the best I have seen by far. We are indeed most fortunate on this forum site to have such experienced saw makers as yourself, Isaac, & Marv, willing to share their knowledge & experience in an effort to assist up an coming saw makers learn this craft. A most generous gift.

Stewie;

Thank you, Stewie!

Klaus

[IanW]

.....I like a proper connection between spine and handle because it shows some of the pride from the maker that went into the tool....

Absolutely. I could not agree more. With respect to older saws, I sometimes wonder if the loose fitting of the spine wasn't deliberate, so that there would be less chance of distortion after tightening the bolts, caused by mis-match of the respective slots.

I have seen a few old saws with bowed blades caused by less-than-perfect fitting of their handles - there have to be a few that escape QC, I suppose. :;


.....the shaping of the spine is easy. Just remove all the parts from the brass blank that you don't like with a file. The rest will be the part of the brass that you like...

:U Seems like you read the instructions on 'how to make a chair', that I saw somewhere, years ago. It was the same, essentially. "Take several pieces of wood, knock off the bits that don't look like a chair, then stick what is left together until it does..." Probably dates from pre-historic times. :U

Cheers,

[Heavansabove]

Great work Klaus, that is a lot of dedicated file work, and W & D paper, and polishing (I assume on a power polisher). After filing small chamfers, I decided I liked square.

Is the drill press a standard commercial product, or a custom job. I have never seen anything as robust, or flexible, as this for a drill.

Cheers
Peter

[planemaker]

Absolutely. I could not agree more. With respect to older saws, I sometimes wonder if the loose fitting of the spine wasn't deliberate, so that there would be less chance of distortion after tightening the bolts, caused by mis-match of the respective slots.

I have seen a few old saws with bowed blades caused by less-than-perfect fitting of their handles - there have to be a few that escape QC, I suppose. :;



:U Seems like you read the instructions on 'how to make a chair', that I saw somewhere, years ago. It was the same, essentially. "Take several pieces of wood, knock off the bits that don't look like a chair, then stick what is left together until it does..." Probably dates from pre-historic times. :U

Cheers,

Hi Ian. I think Klaus is not quite reflecting the amount of high end work that goes into producing the mirror finish they can achieve with their shaped backs. With less care taken, they can look not so appealing. IMO.

Stewie;

[planemaker]

Hi DSEL,

the shaping of the spine is easy. Just remove all the parts from the brass blank that you don't like with a file. The rest will be the part of the brass that you like:D

Cheers
Klaus

Hi Klaus.. You will pleased to know I have following your lead and have completed a haunched mortise fit to the brass back & handle on the burdekin plum backsaw build. It will also become a dt but differ in that it will have a much lower hang angle so the controlling hand is more behind the stroke. Too early for photo's yet.

Stewie;

[pedder]

The spine filing is easy but time consuming. I work about 3 hours to this point:
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Cheers
Pedder

[planemaker]

The spine filing is easy but time consuming. I work about 3 hours to this point:
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Cheers
Pedder

My apologies Pedder. I have forgotten to mention the important role you have in producing these fine quality backsaws. It looks like I will be spending some hours trying to shape the brass hardback similar to your technique.

Stewie;

[DSEL74]

The spine filing is easy but time consuming. I work about 3 hours to this point:
295941

Cheers
Pedder

Hi Pedder, thanks for dropping in on the thread and sharing.

The little jig your using to hold the end on the spine in the vise is that all that supports it during the shaping??

[pedder]

The little jig your using to hold the end on the spine in the vise is that all that supports it during the shaping??

It was on the first spines I made. Now I support the toe with a beam and 2 clamps and reclamp in every step. But I don't have a picture of this.

Cheers
Pedder

[MarvW]

The spine filing is easy but time consuming. I work about 3 hours to this point:
295941

Cheers
Pedder

Hi Pedder,

Is that a holding jig that you have clamped in the vise so as to not disturb the end of the back that fits into the mortise while you shape the sides of the back?

Have you tried scraping the brass in addition to filing it? A scraper can remove a lot of metal quite fast.

Thanks,
Marv

[pedder]

Is that a holding jig that you have clamped in the vise so as to not disturb the end of the back that fits into the mortise while you shape the sides of the back?

Hi Marv, exactly, I couldn't describe it better


Have you tried scraping the brass in addition to filing it? A scraper can remove a lot of metal quite fast.

Yes I've tried, but it doesn't leave a better finish than the file. It is not the main problem to remove a lot of brass, but to do it as exactly as possible and very clean from the first file stroke. Filing is finished after 15 minutes. After that it is sanding. And sanding and a little more sanding from G 120- G 3000 (don't skip a grain), than a short period of polishing (three minutes) and turning to the other side. You really have to like sanding to do that. Good music and a Coffee helps, too.

Cheers PEdder

[KlausK]

Is the drill press a standard commercial product, or a custom job. I have never seen anything as robust, or flexible, as this for a drill.


Hi Peter,

it's a commercial product that is rather common in Germany. The brand is Wabeco. It's that common because of it's versatility. Many tasks of woodworking will be done rather good by this drill press. For metalwork I wouldn't recommend it because it isn't that sturdy one want's to have while working metal.

As I know since a few days, there's at least one of those down under:U. It was pimped in a very special way. It's done that good and impressive that I want to copy some of those awesome ideas.

http://www.woodworkforums.com/f11/woodworking-drill-press-heavily-customised-158214/

Cheers
Klaus

[Heavansabove]

Hi Peter,

it's a commercial product that is rather common in Germany. The brand is Wabeco. It's that common because of it's versatility. Many tasks of woodworking will be done rather good by this drill press. For metalwork I wouldn't recommend it because it isn't that sturdy one want's to have while working metal.

As I know since a few days, there's at least one of those down under:U. It was pimped in a very special way. It's done that good and impressive that I want to copy some of those awesome ideas.

http://www.woodworkforums.com/f11/woodworking-drill-press-heavily-customised-158214/

Thanks Klaus, I have been in Brett's shed and seen the drill stand. Mea culpa, I did not examine the setup at all! A quick google, and I see this is not a cheap option, even in Germany. Now I wonder if I can get a right angle saw arbor/chuck for my bench top drill press (my only machine tool)? I fear that hand sawing is it for me.

Cheers
Peter

[KlausK]

Thanks Klaus, I have been in Brett's shed and seen the drill stand. Mea culpa, I did not examine the setup at all! A quick google, and I see this is not a cheap option, even in Germany. Now I wonder if I can get a right angle saw arbor/chuck for my bench top drill press (my only machine tool)? I fear that hand sawing is it for me.


Peter,

the hand sawing of the blade slot is tricky but doable. To me it works quite good if I do at first an initial cut around the frontend of the handle with the depth of about 5 or 6 mm with a fine bladed dovetail saw. It's quite the same cut that I do with the drill stand. The following deepening of the cut with a dovetail saw is not that difficult after that.

Cheers
Klaus

[Ron Bontz]

Thanks for posting Klaus. Interesting little jig you have there. I do the same thing with my small mill, but horizontally. Your handles will be a classic someday.

[KlausK]

Thanks for posting Klaus. Interesting little jig you have there. I do the same thing with my small mill, but horizontally. Your handles will be a classic someday.

Hi Ron,

another fellow saw maker here, I'm happy! Looks like these guys here down under become to be a hot spot!

Cheers
Klaus

[KlausK]

Hi Klaus.. You will pleased to know I have following your lead and have completed a haunched mortise fit to the brass back & handle on the burdekin plum backsaw build. It will also become a dt but differ in that it will have a much lower hang angle so the controlling hand is more behind the stroke. Too early for photo's yet.
Stewie;

Hi Stewie,

excuse me please that I nearly have overseen this post. The haunched mortise will do great service for a flush mounted spine. If the spine is mounted proud of the cheeks it doesn't need to have a haunched mortise IMHO. In any case I'm excited to see your next saw however!

Cheers
Klaus

[planemaker]

Hi Stewie,

excuse me please that I nearly have overseen this post. The haunched mortise will do great service for a flush mounted spine. If the spine is mounted proud of the cheeks it doesn't need to have a haunched mortise IMHO. In any case I'm excited to see your next saw however!

Cheers
Klaus

Hi Klaus. A lot of my recent backsaws I have reduced the height of my brass hardbacks from 19mm down to 13mm. This was done in an effort to reduce the overall weight of the saw in front of the handle. IMO its been a most successful experiment. But it seemed the right timing for me to try something new such as it keeps the mind fresh. Trialing a mortice fit such as you and Pedder use with your backsaws seemed most interesting to give a go. To achieve this I am keeping with the 19mm. Using the term Haunched Mortise is quite quite an accurate description from a joinery perspective as sides of the tenon remains flush, not as you would normally see with the rails on a traditional panel door frame. But that's okay. I am also keeping the top line of the spine slightly proud to the top of the mortise, not flush as you prefer. Will see how it all pans out.

Stewie;