Custom bevel angles on panel edges?

[metaxis]

Hi everyone, I have already learned a tremendous amount from reading different posts on this forum.. so I first want to thank everyone for all of your contributions. This forum is truly an amazing resource.

I'm in the market to buy a new cnc router - mostly for a variety of woodworking applications (signs, assembly parts, furniture, artwork, etc) but I am unclear about how certain cuts are best handled and/or how that might affect the machine I choose to purchase.

Specifically, I need to cut custom bevel angles on the edges of small panels that will be used for assembling the sides of various polyhedral shapes. The angle of these bevels will vary and are often uncommon (ex. 58.6 degrees, etc.). I know I can use V-groove bits for common angles (45, 60, etc) which allow the router to cut them with a single pass - but what about custom angles that are not available in V-groove bits? What is the best way to handle these bevels? I need to cut hundreds, possibly thousands of these small beveled panels but I'm not sure about bit-types, the number of axis required for the cnc machine to cut them, the path the machine would take, etc.

Any input would be greatly appreciated!

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[ger21]

Table Saw.

[HorridHenry]

The best you can do is have a traverse rail CNC router for just different angles of cut.

This consist just one driver and stepper although manually it would be far better.

The contraption needs two stiff rails about 30mm or thicker depending on the length of jobs needed? and a halfmoon shape carriage,the carriage will house the router and be adjustable in degrees to get any angle for routing.

Sadly I made one 2.5 years ago and sold it because the person who wanted it harrassed me to sell him it.

but it doesn't need a genius to work out how its made.

Tomorrow I'll knock up a drawing of the contraption when I get time if you're interested?

[metaxis]

Thanks for the reply Gerry but I have been using a table saw and it is has been extremely time consuming. The panels are irregular shapes with many sides and they are small. I built sleds with custom zero clearance inserts, hold downs and the whole 9 yards to cut the panels and it is taking far too long. I need to automate this.. There must be a way to cut simple bevels on a machine that can sculpt faces and images... etc. No?

[HorridHenry]

Table Saw.

Hah but Gerry,ythat only does straight bevels,what if he wants to use a ball cut router bit?

[metaxis]

HorridHenry, that's sounds interesting.. Would love to see a sketch of the idea.
As an example, consider cutting small pentagons with 58.3 degree bevels (12 of 'em make a dodecahedron).

Perhaps there is a way to cut all of the pentagons on a cnc machine first (with 90 degree standard edges) and then batch the edges to a specific angle using a router jig? hmmm..

thanks for giving this some thought.

[ger21]

Hah but Gerry,ythat only does straight bevels,what if he wants to use a ball cut router bit?

His bevels are straight.

Imo, a table saw would be far easier. Not only can a saw cut much faster than a router, but smaller parts on a router are harder to deal with than on a table saw.

The only way I see it working would be some type of tilting fixture to hold your parts.

[HorridHenry]

I suppose a normal wood CNC can be made but with a slight difference to the router mount.

ie have the router mount be able to angle at certain degrees left or right.

A Axis mount
B Router
C mount with center nut and bolt and an arc in the mount so that the router can be tightened up with a nut&bolt when turned at a certain degree to the job,but it will need some careful thought?

[denz]

How about this
So what can I do with this ... 5-Axis.

[louieatienza]

There are several ways you can do this:

1 - CNC all the pieces square. Then CNC a fixture for each different angle you need

2 - Use 3D rough and finishing with a ballnose cutter like Henry suggested, though this would take as long if not longer than the tablesaw.

3 - If you can fixture the rough pieces, Amana makes an adjustable bevel cutter for CNC, but it only is adjustable in 1 degree increments, requires a 3/4" tool holder, and costs over $450.

4 - Use a 5-axis router. If you can deal with repositioning you could probably get away with just a tilting head, or even tilting table.

5 - Buy the closest angles possible and have them reground. Amana and Onsrud both offer this service, and the cost may be minimal compared to the potential time saved.

6 - If you have access to a 5-axis CNC that is aggregate head compatible you can mount a saw blade head and tilt the blade.

7 - Mount an indexed rotary table to an angle plate (if the pieces are symmetrical) then you can adjust the angle, and rotate the fixtured piece. This might work also with a rotary axis.

8 - Santa has a lot of time before Christmas, may be you can hire his elves for a few months....

[zool]

Louis stated: 5 - Buy the closest angles possible and have them reground. Amana and Onsrud both offer this service, and the cost may be minimal compared to the potential time saved.

Or take an older bit and send it out to be reground at the angle you need.

No older bits, go visit friends, bet they have some. Buy them lunch.

Latter way is less expensive than feeding a group of elves. They eat a lot more than you might expect.

[metaxis]

Wow... thanks very much for the replies.

I have spent quite a bit of time doing this on my table saw. Custom built sled w/ adjustable fence angle, removable zero clearance bevel inserts to specific degrees, etc. So I can cut compound angles fairly easily. Though it's still too time consuming for doing hundreds or thousands of pieces.

I wonder if I could use a 5 axis mount with the 4th and 5th axes adjustable and fixed.. i.e. kinda like how henry suggested but with an extra axis of adjustability. That way I could cut a sheet of beveled pentagons with only 5 adjustments of the router mount. hmm.. might still be a pain in the arse to do.

I like the idea of re-grounding bits to specific angles. That would certainly be the easiest. I need to check on pricing.

And I love the idea of using the spindle as a platform tilting mechanism for setting up an angled jig.

Anyway.. thanks again everyone.. I need to give this some more thought.