Thread: Help Figuring Out Acute Angles For Cutting Using Jig On Tablesaw

It looks as though you have built a tenon jig and are tilting the saw blade while holding the piece to be cut vertically. I can see all sorts of control issues with this style of jig.

can you build a table saw sled style jig that can hold the piece to be cut horizontally at the required angle, to a vertical saw blade? Something like a miter frame jig where the miter angle can be varied between 40 and 50 degrees.

The problem with type of jig you mention is repeatability. I need to cut 8 different angles to 0.1º tolerance so they mate with there opposing sides. I fear that I would spend infinity and a day setting each angle and test cutting to get even a single pair to mate up.

This is what I used for inspiration for my jig.



The jig works fine and the toggle clamp and the supporting fence hold the work piece in place solid. I am thinking that a Auto Adjust Inline Toggle Clamp would make it even better.

621183-STCIHH-25_2.jpg

I am getting a good square cut, I just cannot figure out the blade tilt angles.

Assuming your digital gauge reads 0 at vertical, just subtract the angle you want from 90 and tilt the blade to the answer; so if you want 48.1, you'd tilt to 41.9

I don't think your blade will tilt far enough for the acute corners corner though, the tilt tends to stop at 45 or 46. You could make a jig of a known angle to rest the timber on to artificially add to the tilt

Will this work in practice - if I set the tilt to 48.11 for angle A and 47.89 for angle B the sum should be 96º

Screen Shot 2018-01-02 at 5.27.36 pm.png

Screen Shot 2018-01-02 at 5.29.18 pm.png

A and B aren't the problem; you do them flat on the table. C and D are the ones you need to hold upright.

I would still do A & B upright because they are just so small ~100mm. The distance of my fingers from the blade is to close for my comfort level.

I have drawn C & D angles.

I will do some test cutting tomorrow to see if we can get it to come together.

Screen Shot 2018-01-02 at 6.37.49 pm.png

Unless your saw tilts well past 45, you CAN'T do A and B upright

Spacial geometry is not my strong suit - that is why I depend on sketching and CAD to wrap my head around the numbers

Fudge - I will need to build another jig to hold the small buggers flat.

Originally Posted by elanjacobs

Unless your saw tilts well past 45, you CAN'T do A and B upright

Also explains why I could not get the numbers add up today for angle A & B today.

Screen Shot 2018-01-02 at 7.09.58 pm.png

Originally Posted by elanjacobs

Unless your saw tilts well past 45, you CAN'T do A and B upright

Indeed, and for exactly the same reason that C&D can't be done flat.

The idea of pushing something vertically through a TS, even if held by a jig would frighten the kerrap out of me.

For the angles that are less than 45° I think I'd be inclined to build a sloped jig to lay and REALLY clamp the pieces onto. If the slope was (say) 15° then to cut a 41° angle you would tilt the blade by 26° (26 + 15 = 41).

The lower the slope the safer it would be. It's the same idea as the 90° jig, but just scaled back for safety.



Also, WRT to this:

Originally Posted by thumbsucker

Will this work in practice - if I set the tilt to 48.11 for angle A and 47.89 for angle B the sum should be 96º

Yes they add up to the right angle of 96°, but be aware that both cut faces will be slightly different widths. Granted, not by much, and it probably won't matter as the difference could be shunted away on the internal corner, but just something to note.

Leave the blade at 90* and use a mitre gauge to get the acute angle. If you don't have a suitable gauge then its not that hard to make one. At least you will be able to do sample cuts to check your settings.

Originally Posted by FenceFurniture

For the angles that are less than 45° I think I'd be inclined to build a sloped jig to lay and REALLY clamp the pieces onto. If the slope was (say) 15° then to cut a 41° angle you would tilt the blade by 26° (26 + 15 = 41). The lower the slope the safer it would be. It's the same idea as the 90° jig, but just scaled back for safety.

Interesting idea. I will try it out.

I still don't get why you are attempting to cut these angles vertically rather than horizontally.

A sled with a pair of battens at the complimentary angles should make the cutting a breeze.

Originally Posted by ian

A sled with a pair of battens at the complimentary angles should make the cutting a breeze.

Exactly. That's what I was getting at in a roundabout way.

Also, you may want to check your CAD file.

My CAD program gives me an even 48 degrees for A & B and 42 degrees for C & D