thumbsucker 2nd January 2018, 04:09 PM Please excuse my mechanical dim wittedness.
I am building a small cabinet. The cabinet has two doors that meet at an 84º\96º angles.
The door is constructed from panels composed from shop cut veneer glued down on to substrate. Which is edge lipped/framed with 16 x 16 mm solid oak strips which have a 7 mm x 7 mm groove cut into them into which the veneered panels sits. The idea is that the panels with act like giant biscuit/domino reinforcing the miters from the oak edge lipping/frame. Its kind of inverting the traditional notion of a floating frame & panel.
I am however a little lost and not the most mathematical person so I am having trouble figuring out the angles to set up my tablesaw to get the angles I need.
I have completed a few test cuts but everything does not come together. :roll:
I built a jig that can hold the small piece safely perpendicular to the cast iron bed, while keeping my fingers well away from the blade, some pieces are less then 100mm long.
This is a CAD of the door angles
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This is the jig I built (based on a few examples I found online that said this would suit my purpose) It holds the edge lipping square to the bed.
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This is the door. Cutting the 90º corners is easy and dead accurate but I am lost for the odd angles.
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Can anyone tell me what angle I need to set the blade to to cut each A, B, C, & D angles? (I am using a Digital Angle Finder accurate to 0.1º so I am rounding the angles in practice.)
ian 2nd January 2018, 04:21 PM 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.
thumbsucker 2nd January 2018, 04:58 PM 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.
https://www.youtube.com/watch?v=MmDOc19gixE
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.
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I am getting a good square cut, I just cannot figure out the blade tilt angles.
elanjacobs 2nd January 2018, 05:24 PM 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
thumbsucker 2nd January 2018, 05:29 PM 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
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elanjacobs 2nd January 2018, 06:29 PM 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.
thumbsucker 2nd January 2018, 06:40 PM 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.
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elanjacobs 2nd January 2018, 06:52 PM Unless your saw tilts well past 45, you CAN'T do A and B upright
thumbsucker 2nd January 2018, 07:02 PM Spacial geometry is not my strong suit - that is why I depend on sketching and CAD to wrap my head around the numbers
:doh2: Fudge - I will need to build another jig to hold the small buggers flat. :doh2:
Unless your saw tilts well past 45, you CAN'T do A and B upright
:doh2: Also explains why I could not get the numbers add up today for angle A & B today. :doh2:
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FenceFurniture 2nd January 2018, 07:41 PM Unless your saw tilts well past 45, you CAN'T do A and B uprightIndeed, 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:
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 96ºYes 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.
Bohdan 2nd January 2018, 07:47 PM 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.
thumbsucker 2nd January 2018, 07:57 PM 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.
ian 3rd January 2018, 02:33 PM 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.
FenceFurniture 3rd January 2018, 03:11 PM 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.
ian 3rd January 2018, 03:38 PM 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
elanjacobs 3rd January 2018, 03:46 PM 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
Yeah, I'm not sure why you'd do anything other that split the angle in half :?
If they're not equal it won't line up properly.
Mobyturns 26th January 2018, 07:17 AM Coming in late on this one, I would not be using a vertical fence and toggle clamp style jig either, it does scare the kerrap out of me too.
Why not leave the blade vertical and make a "donkeys ear" style jig?
Make one based upon the donkeys ear shooting boards used for hand planning and refining hand cut mitres. Derek Cohen has documented his donkeys ear build plus there are a number of other examples about. With a bit of clever design the "ramp" could be built so that it is adjustable over the small angular range required for your example i.e. 42 to 48 degrees. Setting the angles on the ramp with the sled running / referenced on the horizontal surface is simple with a digital angle gauge. Clamping the work piece on the ramp is much "safer" as nothing can fall down onto the saw blade.
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