Uneven flutes

[Troyer]

Hieverone. Has anyone else run into this.Using the new version 3 I Fluted 16 1x8sx9ft with 6 futes in each one. flutes were 8ft long. I put the flutes at 1.5, 2.5, 3.5, 4.5, 5.5, and 6.5 one y axis. What I got was 1 1/2, 2 3/8, 3 1/2, 4 3/8, 5 1/2, 6 3/8.It caused uneven flutes.
When I check how far the bot move manually it measures correctly. Here is the file.
mz,.15
j2,12,1.5
mz,-.25
m2,96,1.5
mz,.15
j2,96,2.5
mz,-.25
m2,12,2.5
mz,.15
j2,12,3.5
mz,-.25
m2,96,3.5
mz,.15
j2,96,4.5
mz,-.25
m2,12,4.5
mz,.15
j2,12,5.5
mz,-.25
m2,96,5.5
mz,.15
j2,96,6.5
mz,-.25
m2,12,6.5
mz,.15

[beacon14]

Troyer,

It sounds to me like you have some deflection, either in the bit (too long?), the router bearings, the machine tolerances, or some combination of the above.
Your file is written to cut one flute from "left to right", then the next from "right to left" and so on. While this is efficient in that you dont have long jog moves between flutes, what is likely to be happening is that on the left to right moves, the bit is deflecting to one side, then on the next move (in the opposite direction) it deflects in the other direction, due to the rotational torque of the bit cutting into the material.
If your total deflection is 1/16", each pair of flutes will be 1/8" too close together or too far apart.
Grab the spindle (router off, or better yet, unplugged) and see if you can feel any side-to-side movement. Check all of your machine tolerances - rollers, springs, bolts, etc. How much wear and tear does the router have? Maybe time for new bearings. How long is the bit, and how far does it protrude from the collet?
You might also get improved results by taking lighter passes and slowing the feed speed some.
A quick fix would be to make all your cuts in the same direction.
Hope this helps,
David B

[jkforney]

Troyer
David has a good point, since it is every other flute that is off. What size bit are you using and do you have it properly seated?

A good check would be to run a test changing the direction of each pass (i.e. those going left to right change to right to left and so on). If it is deflection you will have it on the ones that were right.

Let us know what happens.

John Forney

[Troyer]

aaa haa that makes sense. I did check the router and bot for any play. can't see any in the shopbot and had the router bearing replaced about 15 hrs ago. I do have the router mounted with the old syle with clamps and there might be enough movement there. Using a 1 1/2 v bit with 1/2 shaft.Maybe running too fast. Move speed set at 2. I will try to run all the flutes the same way and see if that makes a diff. Thanks David and John for the ideas.

[sheldon@dingwallguitars.com]

Deflection is probably the case, but looking at your resulting measurements and part file, bit rotation should have caused deflection in the opposite direction. ie. 1-7/16, 2-9/16", 3-7/16", 4-9/16"...

[rookie432]

I had this exact same problem when I started doing flutes. For the life of me couldn't figure it out. Took a little time but came to realize that my 0,0 point was just slightly off. Corrected by chucking in a 60 degree vee bit, mounting my material and resetting my 0,0 to the very lower left corner of the board. The vee bit helps pinpoint this and showed that I was off about 1/16 in the Y direction.

Bill