Fluting

[kaaboom_99]

How would someone go about machining this on a PRT?
Is an indexer a must or is there a "Ball" bit that could perform this task? The flutes are to be 3/4", (5) of them on a radius.
Any suggestions on how to perform this in a product setup?
Thanks guys.

5080

[jhicks]

Perry, I assume you mean 3/4" diameter. Check out Magnate bits. They make some nice full round ball noses (not core box) for the "legacy ornamental mill" which just might achieve this cut.
Otherwise one could set up on angled base templates so the flute is 90 degrees and simply run it down the x. Have to be careful on positioning but I think you can get 3 of the 5 pretty easily with one of the magnate ball noses.

[kaaboom_99]

Thanks Jerry. I have done some looking and now am wondering if the Her-Saf bits would work.
Anybody know this?

[kaaboom_99]

Jerry, just looked at the Magnate site. They seem to have exactly what I was thinking. Do you think if you did the math that this whole piece could be cut without repositioning? (all 5 flute paths as the board is flat on the PRT spoil board?)

[mikejohn]

Perry
with the right ball bit it can be done, but if the flutes do not go the full length of the material you have to approach Z for the two outer flutes at an angle, from the side as you have drawn it.

.........Mike

[waynelocke]

I just got through using a long 1/2" ball bit and it should work for what you want. I would make the Z plunge a tad less than half the diameter because you will begin getting a C instead of a U if it plunges at all over 1/2 the diameter. Just be sure of your math and do a practice run.

Wayne

[kaaboom_99]

Thanks for all the posts guys.
This forum is still the best resource for guys like me who are still "Novices".

[ryan_slaback]

If you are worried about the Z depth and making sure you don't knock the top corners off, run a roughing pass with a straight end mill. Then you should be able to ball out the rest in one pass.

[kaaboom_99]

Thanks for the tip Ryan.

[jhicks]

Given the angle of the lower/outer flutes, It might work well if the file started outside the piece and then cut along the long axis and give you more than the 1/2 bit diameter or the C section Wayne described on the top of the 2 lower flutes but not on the bottomm outside edges. Once accomplished you could hand finish that Hi -C edge to remove it.
Good luck

[rg_engravers]

http://70.114.47.213/Shopbot/For%20forum/Perry%20Poore.htm
You can cut it both ways
Just use the same diameter bit as you want the slots to be

[rg_engravers]

O darn I now just seen the Upload Attachcment button

[mikejohn]

Perry
Do the flutes go full length?
If so its straight forward.
Its if the flutes start or end before the end of the piece you have to move the bit onto, or take it away from the material, so as not to "knock off" the upper corner of the 'C' with the two outer flutes.
The other 3 flutes do not have this problem.
Another point to remember is, the distance between the centre of the bit (x or y) is different between the centre flute and the one either side, and between this 'either side' flute and the outer flute.

...........Mike

[myxpykalix]

Heres an idea...I have a legacy ornamental mill also. Look at the indexed gear in back. The shopbot could drill your equodistant holes for indexing on a round piece of plywood. Take a second round piece, drill one hole at top. Make a crude "axle" with a dowel. Attach your piece to the center. Your piece, even though it is not round should follow the evenly spaced holes and make your flutes flat because each one is now 90 degrees to the bit. You can use these pilaster mounting dogs here:
http://legacywoodworking.com/products.cfm?product=46
or make your own. If you are dealing with Z height clearance issues if you make the part that holds the "axle" up off the table an inch or 2, that should give you room to "pivot" the workpiece. Go to http://legacywoodworking.com you might get some ideas on how to adapt it to your table without having an indexer.

5081

[kaaboom_99]

Great input guys!
I love this forum.
Thanks and keep the ideas flowin'