cutting acute angles safely

[poolhound]

Thanks for all the ideas. Here is Jon's patented "acute angle jig." The angle fence is adjustable and lets me set angles from about 13- 41 degrees.

Watch out for this in Rockler or HF sometime soon

[LCHIEN]

so here's another way to do acute angles, I drew this up in 2004, I just found in my archives.

Probably OK for shorter pieces,not for 6' long in which it would be better to use the rip fence.

[poolhound]

Isn't the star two equilateral triangles?

Technically yes, but such "artistic license" has been employed many times in all kinds of uses. They key is to keep the star symetrical, although I have seen examples of jewelry where it isnt.

[poolhound]

In my opinion the jig that Shoottx suggests can be made safer.
The workpiece is pushed forward by the lip at the bottom.
The scary part is either letting the workpiece go with no hold down pressure or using your hand within a couple of inches of the blade.
Here's how you make it safer:
Put a piece of rectangular plywood under that jig, attached to the bottom of the arms. It should be as long as the jig and a tad wider than the fence to blade width.
One edge should be against the fence and flush with the right arm.
When you cut, the plywood will be trimmed at the saw blade of course. But the dangerous part of holding the workpiece as you slide it within inches of the blade can then be accomplished with a pair of hold down clamps mounted to the arm of the jig adjacent to the workpiece. You'll have to raise the blade the extra height of the thickness of the plywood.

Excellent point I was going to use hold downs as I value my fingers and would rather not have to recut due to movement.

[pelligrini]

Isn't the star two equilateral triangles?

[shoottx]

In my opinion the jig that Shoottx suggests can be made safer.

Yup, The question of hold down is important.

Since this jig was for a relatively short run, and since the boards I cut were longer than 8" my hold down fingers were safely away from the blade.

If You are going to do a lot of cuts, short cuts or keep the jig for awhile upgrading the hold down would be important.

I have not decided whether to keep this jig or just take it apart and throw the parts back in the scrap pile. If I keep it I will make the angle adjustable and add hold down capability.

[poolhound]

Jon said he needed angles less than 30deg, but he didn't say how much less (and he didn't say how wide, either).

angles will be approx 20, widths up to 3" max.

[poolhound]

Thanks to all,

We all agree that some form of jig or support is needed to alter the angle of attack e.g. for a 15 deg cut using a CMS make a 45deg wedge and set the CMS at 30.

I am leaning towards something that the workpiece can be attached to and run along a fence similar to what Mike just posted (thanks). Once I finish the design and get to the shop this weekend I will see what works out easiest, safest and most accurate.

FYI - the project is for an "Ark" for a local temple. You know how it goes, somebody who knew somebody who knew me told them I am a woodworker, so I get a phone call, "how would you like to build us......"

The design is centered around the "star of David" which is essentially 2 reversed triangle. The pic here shows the basic concept.

[LCHIEN]

In my opinion the jig that Shoottx suggests can be made safer.
The workpiece is pushed forward by the lip at the bottom.
The scary part is either letting the workpiece go with no hold down pressure or using your hand within a couple of inches of the blade.
Here's how you make it safer:
Put a piece of rectangular plywood under that jig, attached to the bottom of the arms. It should be as long as the jig and a tad wider than the fence to blade width.
One edge should be against the fence and flush with the right arm.
When you cut, the plywood will be trimmed at the saw blade of course. But the dangerous part of holding the workpiece as you slide it within inches of the blade can then be accomplished with a pair of hold down clamps mounted to the arm of the jig adjacent to the workpiece. You'll have to raise the blade the extra height of the thickness of the plywood.

[LarryG]

The other consideration is ensuring the boards you are cutting will clear the fence from the starting point.

This is the main reason I wondered how well a solution on the TS would work. Jon said he needed angles less than 30deg, but he didn't say how much less (and he didn't say how wide, either). I questioned whether there'd be room to keep the rip fence on the rails with a 6' long workpiece.

A big advantage of your method is that, even though the workpiece is moving, there's a lot more table area to support it than there would be trying to make the same cut on the typically miniscule tables of a miter saw. And the outfeed support problem is minimal since it's a narrow workpiece that won't have to move very far. All things considered, yours might well be the better method.

[poolhound]

Posting a picture or a sketch of your intent would provide a better understanding of your dilemma. What's the difficulty in cutting angles less than 45 degrees on the end of a 6' piece 3" wide on a MS or CMS?
.

As pelligrini stated its cutting small angles on the long edge. between around 35-45 isnt too bad but I need angles in the 20s.

[LCHIEN]

Attaboy, Mike (Shoottx) that's the way I'd do it.

That's just a bigger version of the ones you can buy, like this adjustable one from Rockler:

http://www.rockler.com/product.cfm?p...er=angle%20jig

HF has one too, almost identical for half the money.

I don't see how you can cut this on a MS or CMS unless it was a slider...

[shoottx]

Jon

If you are asking what I think you are asking, any way, here is a quick jig I put together on Monday to make a set of feet for a project. This jig was constructed at 15 deg.

To construct the jig, I trued up two pieces of scrap about 30" and cut the angle I desired on one end using a hold down and a backer board on the CMS. The rest was pretty straight forward.

You will neeed some sort outfeed support for 6' pieces. The other consideration is ensuring the boards you are cutting will clear the fence from the starting point.. (don't ask why I know that is important)

And here is the pictur with a piece of walnut for illustration.

[pelligrini]

I believe the problem is cutting an angle less than 45 degrees when measured from the long side. 90 would be a crosscut, 30 would be difficult.

[cabinetman]

I am still working on the design but I would say that the widest would be no more than 3". The material is Walnut and how many is tough to say at this point (still design dependent). Not a huge number i.e 100s but somewhere between 6 and 20 something.

The basic concept design as you may have guessed is a triangular structure, hence lots of acute angles that must be repeated.

Posting a picture or a sketch of your intent would provide a better understanding of your dilemma. What's the difficulty in cutting angles less than 45 degrees on the end of a 6' piece 3" wide on a MS or CMS?
.