The saga of the Bird Mouth Bit #1: Setting up the material

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Blog entry by splintergroup posted 01-04-2021 08:51 PM 446 reads 1 time favorited 7 comments Add to Favorites Watch
no previous part Part 1 of The saga of the Bird Mouth Bit series Part 2: Last preps for the cut »

So, as many of you know I like to do/post experiments on new-to-me “things” related to woodworking.

This series mainly shows some of the extra steps I’ll do when making a project but there are a few things to really help with getting success from a new router bit.

The first two parts are really about the wood prep for what I want to emerge when done. The router bit comes later.

Self aligning miters
I like 45-degree lock miter bits for getting excellent, gap free miters in corners and they make clamping nearly effortless as they prevent the joints from slipping around during a glue up.

I bought a 30/120 degree birds mouth (BM) bit initially to give me an alternative to using the standard 45 degree chamfer for many things like lamp bases and edges on frames.

It has several options depending on how you slide your work piece over either of the surfaces. You can see that the cutter profile is really just a 90 degree rabbet bit on a tilted axis.

I then thought about using it for the intended purpose and experimented making a 6-sided box as a project.

Now is the time to use it for real.
One can simply make a monolithic hexagon or fancy it up a bit as I will be doing here.

Prepare the stock:
I decided to veneer some wood for a nice look. The BM bit only needs to be used along one edge of each side piece and it cuts best when used with the grain. I planned to have the veneered cores made from poplar and to orient the grain vertically, both to get the long grain cuts and have the veneer applied cross grain (like plywood) which also allows the final grain flow to go around the work.

The drum sander gives me a perfect surface for the veneer.

I’m aiming for side segments about 6” long and 2” high so the poplar piece is 6” x 12.5” x 3/8” It is always wise to plan for an extra piece in case you biff it, but of course I didn’t consider that until I had already finished (no biffing this time 8^)
I’ll cut the BM joint for all sides in one go. Wayyyy easier working this way versus trying to cut a clean joint on six separate parts.

Onto the veneer:
Why make one when you can make two? This section is really just about veneering.

I have a bunch of scrap strips of veneer so I decided to use these versus committing a wider sheet. This ups the difficulty level with aligning everything but why spend a few more dollars and save some hours when you can do the opposite?

I cut my veneer strips into approximately 2”wide by 6” long pieces, 12 each (for both surfaces). A cheap guillotine type paper cutter makes short work of this.

The veneers are zircote and Karelian birch. Enough small scale to still show character when used in these small sizes.

The strips are test positioned in preparation for the glue.

I use 3/4” Melamine for veneering cauls, nice and flat with a non-stick surface.

I’m going to veneer with everything stacked, This will be a sandwich (pronounced “sammich”) with five layers. Caul, workpiece #1, caul, workpiece #2, caul.

Two cauls are sized about 1/2” over the workpieces and one used for the center is just something I had lying around that was close enough.

The interior surfaces get a nice coating of pastewax.

Many veneers have pore holes which can allow glue to squeeze through while in the press and make a real mess. I like to prepare for this by placing a double layer of paper towel between the veneer and caul. This will sop up any squeeze through and make cleanup a lot easier.

Veneer glue up

A secret! I often get packages with all this free paper included as a gift. They never charge for it and it works great as a gluing work surface (don’t tell anyone or they will catch on!)

This is “cold press” glue which works much the same as any other common wood glue except it is thinner. Be sure to shake it up good!. I use an ink roller to spread it out, have some water handy to toss the roller into when you are done. It’ll keep the glue soft until you can get around to cleaning it, not when it’s rock hard the next day after you forgot about it!

I spread enough glue so I can roll out what looks like a layer of latex paint. Too much will just squeeze out everywhere and make a mess.
I do one side, lay on the veneers, then flip it onto the lower caul (with the towels in place) and repeat. This can be a stressful time since there are multiple strips of veneer that need to be aligned and they are curling up as you go!
But hey, saved some pennies versus using a full sheet!

I have the two panels, veneer applied, arranged in a stack.

The cardboard on the bottom acts as a isolater when in the vacuum bag. It protects the bag from the sharp corners on the melamine cauls. The stack also is taped to keep it from slipping around as it is inserted into the bag.

I put this all into the bag and seal it up.

There is a topping layer of cardboard along with a mesh which helps facilitate the air extraction.

I fire up the compressed air powered vacuum “pump” and get a reasonable draw down to about 20.5” Hg at this altitude. Must be a high pressure area moving in.

Fast forward two hours…

Looks like no serious squeeze through (yea!) The paper towel did stick to the gaps between the veneer strips as expected.

I use a razor as a scraper to remove any paper towel besot squeeze through areas while the glue is not fully hardened.

Up next…

A few more things to do to these panels before routing. next will be some framing at the miters and the excitement of the BM router cut. Even more exciting since there is no video, just still photos! 8^)

Stay tuned!

7 comments so far

View JimYoung's profile


400 posts in 2600 days

#1 posted 01-05-2021 04:26 PM

Thanks for posting your process. Good info, and I know the boxes are going to come out great.

Helpful hint for those of you who don’t have a vacuum bagging system. My wife has a FoodSaver that can vacuum seal food in plastic bags. The bag material comes on rolls in two widths and you can cut them to any length. The wider bags will accommodate about 9” wide materials at a few inches thick. I’ve used this with good results on model airplane wings (balsa over foam), and other things. This would be ideal for this type of project. It pulls a surprisingly strong vacuum and heat seals the bag, so you don’t need a pump running all night. This also allows you sneak it back into the kitchen before the wife figures out what you are doing!

-- -Jim, "Nothing says poor craftsmanship more than wrinkles in your duck tape"

View MrWolfe's profile


1472 posts in 1136 days

#2 posted 01-05-2021 04:39 PM

Great tips on this blog so thank you for this.
Thanks JimYoung for your tip too.
I’ve favorited this so I can follow your process and progress.
I kind of dig the mad professor experiments. Keep them up!!!

View splintergroup's profile


4712 posts in 2235 days

#3 posted 01-05-2021 04:44 PM

Good tip on the FoodSaver Jim! This would be interesting to try for small plywood/veneer panels where the traditional bag is overkill and clamps just never seem enough, let alone having enough hand room to tighten them all when the part is small.
The sneaking kitchen items is a time honored tradition, I know it well! 8^)

One reason I went with the venturi vacuum source is just as you point out. I don’t like the idea of a pump running the full time (2 hours) for regular pressing or the day-long process with a vacuum pot for stabilizing burls.

Get a good seal on the bag and the venturi will run only a few seconds every 30 minutes or so.

View James E McIntyre's profile

James E McIntyre

1102 posts in 2305 days

#4 posted 01-28-2021 05:57 PM

Great tips and techniques. Like your melamine cauls.

When I walk my dog on thrash pick up night I find parts of cheep furniture made from it.

It’s also great for jigs.

How did you get in involved with that birds mouth anyway? :-)

Is Proformax still in business?

-- James E McIntyre

View splintergroup's profile


4712 posts in 2235 days

#5 posted 01-28-2021 06:39 PM

That melamine is considered real wood now a days according to the labels on the cheap stuff in the stores (gack!)

I buy the 49” x 97” sheets. Real pain to work with until they get cut down, but each time I do a veneering, I have to cut an older set of cauls down to size. Eventually they just disappear 8^)

The ultra flat non-stick surface keeps me coming back.

Performax is long gone I assume. They sold there stuff to Jet so at least the parts are still available.

View James E McIntyre's profile

James E McIntyre

1102 posts in 2305 days

#6 posted 01-29-2021 10:04 PM

Wasn’t to long ago I heard people were using the packing paper as toilet paper. :-)

At that time my boxes were arriving with bobble wrap. Bummer.

-- James E McIntyre

View splintergroup's profile


4712 posts in 2235 days

#7 posted 01-29-2021 10:09 PM

Yep! Unless your ancestors were hearty pioneer stock, you were in a literal world of hurt 8^)

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