Birdsmouth

[mklotz]

In my thread on my improved Panavise hook...

Improved Panavise hook

I mentioned adding a birdsmouth to it but never got around to doing so. Later I reconsidered and decided that a stand-alone birdsmouth would be a better tool so this thread is about making that.

There are undoubtedly a few out there who don't know what a birdsmouth is so I'll explain briefly. It's a tool to assist in sawing out intricate patterns and piercings with a fret saw or a jeweler's saw in the case of metal parts. Basically, it's little more than a wooden plank with a slot or slots that can take many forms although the traditional is a narrow triangular slot which looks a bit like a bird's open mouth/bill, hence the name. The saw blade is set to cut on the pull stroke* and is used vertically through the slot with the work held on the plank. In some cases the plank is attached to a frame held in the bench vise to raise the plank to a more comfortable working position; often it attaches directly to the work table (my case) so it can be used by a seated sawyer.



I used 5/8" plywood for my plank with a traditional birdsmouth. In use it must be right in the center front of the worktable so it needs to be removable when not in use. I had some steel C-channel that just spans the thickness of my indoor worktable and the expendable fiberboard protector on it. This was drilled and tapped for two 3/8-16 setscrews to provide a clamping action. Conventional screws won't work here because if they project one can catch his legs/knees on them. Tightened down, the setscrews hardly project so they're the correct choice. I don't want fasteners projecting through the top of the plank so the channel was epoxied to the bottom of the plank. There's no appreciable strain on the joint so these joints should outlast me.

Clamped in place, the C-channel raises the bottom of the plank by the channel's thickness, 1/8", so, to prevent flopping, a piece of 1/8" aluminum scrap was epoxied to the rear of the plank.

Here's a picture of the birdsmouth in place, ready to work...



Give it some thought. There's limitless latitude here for expansion and modification to fit your particular work environment.

--
*Most Japanese handsaws are arranged to cut on the pull stroke and the Japanese are the hands-down champions of intricate wood joinery. Try it with your saws paying close attention to the motion of your forearm while sawing. I found sufficient improvement that I converted even my hacksaws to pull-cut. [Remember that old bromide about not being able to push a rope ?]

[DIYer]

Thanks mklotz! We've added your Birdsmouth to our Metalworking category,
as well as to your builder page: mklotz's Homemade Tools. Your receipt:

Birdsmouth by mklotz

tags: fixture

[old_toolmaker]

Hi Marv,
I like the “birds mouth” and it is a handy accessory to have.
It was especially interesting that you mentioned pull saws. I own two pull saws. They were a little weird to use at first, but I eventually adjusted to them. They have rather thin blades that flex easily so the pull stroke is a must but they follow a line well and saw strait. I liked your comment on converting your hack saws to pull stroke. I have a 1900 era Union hacksaw that I love. I also have reversed the blade in this as well. With only one hand on the straight round handle it is a “no brainer”. This is my favorite 8” hacksaw.

[greenie]

Marv what you have described there is actually called a "Jewellers Bench Pin ", they been around for centuries.

Instead of using that weak plywood for the bench pin, use any timber that you use for outdoor decking, it's a hell of lot tougher timber/wood they use instead of that ply, so that it can take all sorts of weather before disintegrating.

For those that are too lazy to bother making their own bench pin, then check out the 'evilbay', they have a variety of different shapes and different timbers to choose from as well.


https://www.ebay.com.au/sch/i.html?_...n%2C&_osacat=0

[the harmonious blacksmith]

Being raised in a family of fine custom jewelers of a business started over a hundred years ago by my grandfather, a Guild master, I never heard the bench pin called a birds mouth. Jewelers benches normally have a mortise cut into the front of the top surface - a wide rectangle - and the tenon on the back of bench pin is cut so the top of the pin is level with the top of the bench. They are normally thick at the back, over an inch usually, tapered up toward the front. It is used, of course, for sawing in the center vee cut but it used as a support for many other manual operations like filing, to support a hand held ring for stone setting, etc.

[mklotz]

... I never heard the bench pin called a birds mouth. Jewelers benches normally have a mortise cut into the front of the top surface - a wide rectangle - and the tenon on the back of bench pin is cut so the top of the pin is level with the top of the bench. They are normally thick at the back, over an inch usually, tapered up toward the front. It is used, of course, for sawing in the center vee cut but it used as a support for many other manual operations like filing, to support a hand held ring for stone setting, etc.

AFAIK, "birdsmouth" is not another name for a "bench pin" as used by jewelers. A bench pin is a handy tool for a jeweler but I have no need of one. What I did need was a platform for handsawing small, precise shapes from thin wood and light brass. From what little I know of woodworking, that's called a birdsmouth and hence the name of this thread.

A good technique for fora such as this is to concentrate on the tool, its utility for the purpose built, and its possible applications to other jobs. Contrasting it with what it wasn't meant to be isn't particularly rewarding.

[mklotz]

While my birdsmouth lacks the appearance of a bench pin and its 5/8" plywood doesn't appear to be very flexible, it has turned out to be a very useful tool in the four years since I posted about its construction. However, any tool can be improved and that's what I'll discuss here.

On a number of uses I discovered that my left hand tired holding the work in place while I sawed. Clearly some form of hold down clamp would be very helpful. When I built my finger plate...

More versatile finger plate

I standardized on 1/4-20 threads and made up a variety of clamps (pictured in the thread) to work with that thread. Obviously, if the birdsmouth had those threads I could make use of the finger plate clamps. Amazon supplied ...

https://www.amazon.com/gp/product/B0...e?ie=UTF8&th=1

some handy threaded inserts that were easy to install in the birdsmouth.



One simply drills an appropriate size hole into the wood and then screws the insert into the hole using an Allen wrench in the hex section at the top of the insert.

My steel bench block is another handy tool. It can slide easily though if any side force is applied. Being round, it's difficult to clamp securely in my work table vise. I decided that, now that the birdsmouth had threads, I would use it as a means of securing the block from sliding. To that end, I made a circle of plywood with a diameter equal to that of the block OD. Centered on this is another wooden circle with a diameter equal to the block ID. Small magnets fitted into the lower block prevent the block from slipping off. You can see this wooden cake in front of the birdsmouth in the above picture.

Now it's just a matter of drilling holes in the cake to match the spacing of the thread inserts; add a few machine screws and Bob's your mother's brother. The final result is shown below.

[DIYer]

Thanks mklotz! We've added your Birdsmouth Modification to our Workholding category,
as well as to your builder page: mklotz's Homemade Tools. Your receipt:

Birdsmouth Modification by mklotz

tags: magnet, holding