Similar to the gaffboat circular saw jig but at 15 deg.

Mark the timber with 15deg lines where you want to cut. Rack 'em up so the lines align and hold in place with a bar clamp. Throw on the 15deg jig and clamp, then cut.

 

@vindaloo...

most EXCELLENT!!!

 

Thanks Stick, KISS :wink:

 

experience MISS and move to the head of the class...

 

Thanks for the replies.

One more jig question.

I need to cut and route a dado on a bevel...

It's going to be very close to the end of the stock, and not very deep.

I'm planning on cutting 2 pieces of timber with a 15o side on them and putting the standard cutting/routing jig across that so that the base of the rises away from the cut and the stock can lay flat.

That's easy...

What I can't fathom is how to line it up, as there will be a gap at the standard jig edge between the jig and the stock, where the jig edge and stock would meet, if you carried an imaginary line through the plane of the jig, is where the cut for the far shoulder of the joint goes.

I o not want to be adjusting saw/router depth across the width of the dado, and the bar of the dado is to be at 15o from parallel of the edge of the stock.

In effect it is a recessed birdsmouth.

Does that make sense?

 

use Angie's angle gang cut guide w/ a top bearing mortising bit in your router......

note...
to get 15° on the computer use Alt+248...
I see your typed 15° as one hundred and fifty....

 

Thanks for the heads up on the degree symbol, bit it's not as cut and dry when using a mobile phone, LoL.

As to the cut, I think you mis understand.


I want to cut downwards and to the side at 15o, not forwards and across.

I can either rest the stock at a 15o angle to the bench, and have the router parallel with the bench (leaving an angled gap between stock and bench and stock and router)

Or I can lay the stock flat on the bench and then run the router at an angled to the stock.

This is OK if I am just cutting to the width of the cutter in the router, but I'm cutting much wider (63mm).

Does this make sense?

If not I'll draw a diagram (and edit my degree symbols) when I get home.

 

hmmmmm...
PLEASE draw your diagram...
in the mean time see if one of these jigs will work or at least give ya some ides...

 

Here is a rather abominable and exaggerated sketch I've drawn on my phone.

I hope that clarifies the cut I am trying to make...

As you can see, I want the line of the jig to run parallel with the line of the trough.

The cuts into the stock will be 15o from perpendicular, and the depth will increase along the trough.

I want to be able to clamp the jig to one side, but lining it up is going to be a nightmare as I will either have to sit down and calculate the exact distance between the stock and the to of the jig, and then cut a spacer to hopefully fit to line up with the near shoulder cut, or find some way of lining the jig with the far shoulder cut whilst maintaining the gap so I don't have to move it to do the near shoulder as well.

 

I hope that clarifies the cut I am trying to make...

two ways..
gang cut on a table saw w/ dado blade...

jig base...

make two runners
set the TS at 15°...
rip a 2 by or thicker that is plenty longer than the total width of your ganged together pieces....
set the rips on their angled cuts on your material...
one runner is to the right side of of the dado held in place w/ clamps that look like this...
the sharp point (long point/LP) of the runner is set to cut line...
do the same w/ the other runner only use the short point/LP... the long point on this runner is to the far left...
drill 15° angled holes in the runner to receive the clamps...

.

set the other runner to the left side of the dado...
this runner is mounted on a piece of ply that has a 15° edge...
use the ply acting as a flange to clamp the runner in place....
place spacer blocks on either end of the the runners cut to the width of mortise to maintain spacing...

the runners carry the router...
maintain angle and act as guides for the bearing on the mortise bit.. or straight bit...

you could cut a closed end slot as wide as your mortise in a piece of ply w/ 15° sloped walls and mount both rails to that...
it would simplify things and help out w/ the clamping...

 

Here is a scale drawing, stock is a length of 38x63mm

the deepest side cut is 38mm and the width of the trough is 63mm

 

@Carrot

Jon:
The depth of your cut, at the deepest (near the end) portion is 38mm (or 1 1/2 inch)
I would:
a. use a circ saw/guide with the bevel set to 15° to cut the end near the end (make sense)
b. make a jig at the same angle
c. use a straight bit that is long enough to bypass the corner of the stock near the end.
so. the bit would need to be 1 1/2 inches plus the distance between the stock and the parallel line to the corner

See attached

hopefully someone who understands my thoughts, and has some sketchup skills, can elaborate

 

That is pretty much the plan, but the problem I am having is working out of to align the jig in the first place. because of the distance between the floor of the jig and the near shoulder, there will either be a massive gap (impossible to line up with a cutting mark) or I will have to build the jig to exactly the correct size, and with a side running between the floor of the jig and the cutting line to allow alignment.

-----

Maybe this is the way...

Cut 2 triangular pieces of MDF with one side at 15°

Attach piece of stock parallel to their bottom edge, producing a natural alignment for 63mm tall.

Using the original jig for my saw, and a piece of stock as a spacer, cut a strip of MDF to the width required (63mm) minus the kerf of the blade (for a snug fit).

Place the spacer on the new jig with one edge touching the stock on the bottom edge, and the base of the spacer flat to the slopes of the triangles, and temporarily fix in position.

Now place the original jig on the slope, but it up to the spacer, fix in position and remove the spacer...

Or something like that anyway...

 

Ok, if I understand what stick said, you are ripping your 2 x ? at 15°
Setting the bevel of each piece so that it is parallel with the sides of the mortise you want to cut, extending the face of the moritise.
Then use some ply also cut at the same angle or other material as a wedge under the ripped 2 x.
The top face of your ripped material is parallel to the bed of the mortise???

 

I think @Stick486 is saying to rip a piece of 2x to use as guides.... But I'm not certain.

What I am attempting to make here are essentially recessed birdsmouths, a normal birdsmouth doesn't have a second shoulder.

The big issue, as with all my other posts, is the fact that I have to do about 20 of these so will be gang cutting them, hence the jig, otherwise I would just do it by hand.

----

Stick, is this what you were meaning?

 

the runner on the right is correct...
do exactly the same on the left...
but mount both runners to a piece of angle slotted plywood and w/ it extended to the left..
ply angled as in on the wall/edge/side of the cut slot....
use the ply as a flange to clamp with and it lays flat on the material to be cut......

the runner on the right will not be very tall at all...
the top of the one on the left will be coplaner to the top of the one on the right...