Bird mouth joint

[dusty]

Hazardous because of kickback from the wedge trapped between the blade and fence or something else?

The hazards are dependent on how you setup and how you control both the project and the cut offs. Lack of control is, in my opinion, the leading factor causing it to be hazardous.

It is even more hazardous for me because I am short and can barely reach across the saw table. Stock coming off the back side of the blade is "out of reach" for me and with the table tilted it is going to move to the down side unless you have control.

[JPG]

At first, I thought this was a simple task even with the tilted table of the Mark V. I no longer think so. Oh yes, it is simple but it is also hazardous. There was a time but no more. Not without a jig.

This is one job done more safely and probably more accurately on a table saw with a tilting arbor.

I am working on the concept of a jig to do this using a dado blade. If I work it out, I post pictures. No pictures means no success (that's the same as "failure").

JPG: Have you done what you detailed in post #17? If yes, please post a picture of the setup for the 60° cut.

No I have not, but I defer to Shipwright whom I was quoting. I am not sure how to tilt the SS table 60 °. I am not sure a tilt arbor will tilt that far either. I think 8 sided would work better(requires 45 ° blade angle).

[shipwright]

I'll try to get some pics on my 10ER tomorrow.
You don't need to tilt the saw (or SS table) 60 degrees. One cut is vertical the other horizontal so if you set the saw at 30 degrees, the flat cut will be 30 and the vertical one will be 60.
To be completely honest, I can't remember ever doing this on a SS but it won't be hard. As far as safety goes, it's hard to cut yourself when the saw is completely embedded in the wood as it is in these cuts. (IMHO)

Paul M

[dusty]

I am currently taking some meds that make me feel a bit rummy so I cannot do this for real. Instead, I spent some time doing it in Sketchup.

Yes, shipwright, you are absolutely correct. It can be done with the Main Table tilted to 30°. Furthermore, there is no significant hazard (except to the rip fence) presented by doing this.

To do this for real I believe it might be necessary to install a sacrificial fence to save the rip fence. Without that protection the blade gets uncomfortably close to the rip fence.

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Table tilted to 30°.

For this Sketch, I made the first cut with the rip fence (not shown) on the right side of the blade and the table adjusted for 3/4" depth of cut. Then the second cut would be made with the fence having been readjusted away from the blade and the table readjusted for proper depth. Depth of cut settings here are critical to a successful bird mouth.

DO NOT TRY THIS without a table insert. In fact, if I was going to do this I would create a custom insert.

[farley]

I am following this and defer to people with more experience, lets not forgot the birds mouth would be done on a rather long board, in my case, I was trying a 12" long board.

thanks everyone for all the thoughts and ideas.

[dusty]

I am following this and defer to people with more experience, lets not forgot the birds mouth would be done on a rather long board, in my case, I was trying a 12" long board.

thanks everyone for all the thoughts and ideas.

With proper outfeed support, cutting a birds mouth is no problem. Put a sacrificial face on your rip fence and go for it.

I got yelled at for doing this while taking these meds but I could not resist. I only cut a short piece. I dare not make sawdust anymore today.

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[ATTACH]22372[/ATTACH]




I did cut a special slot (at 30°) in one of my previously used table inserts.

farley: At first I read your post as 12'. Cutting a birds mouth at 12" doesn't even necessitate an outfeed table.

Side Comment: I sure wish I had a shed full of wood identical to the cutoff I used for this birds mouth.

[JPG]

Sheez! Where was my jr high geometry 'knowledge'?:o

60° on one side of the blade = 30° on the other side!

Thanks Dusty for walking out on the plank!;)

[shipwright]

Thanks Dusty, you nailed it and you saved me some time setting up and taking pictures.

[dusty]

Thanks Dusty, you nailed it and you saved me some time setting up and taking pictures.

Thank you and I am glad that I saved you the time. As I sat here thinking about the task I just could not help myself. I had to make the cuts to convince myself.

I made the one cut (not pictured here) without a sacrificial fence but again - I do not recommend that. The slightest movement of either, the headstock, the table or fence could bring on disaster. Disaster that can be so easily avoided with a sacrificial fence.

Don't do as I did.

[shipwright]

Actually, it's best not to try for a sharp point on the vertical cut. A little face remaining will keep it away from the fence (a little) and also insure a good running face against the fence on the second cut (and on the table on the outfeed side in the first cut).

Paul M