[Kobal]

Newbie here.
Material is hard maple. Making a variety of engravings usually with raised letters or images.
Freud 2 flute 1/4" right hand cut carbide end mill 30 degree helix.
Router is Dewalt 611 with Precise bits precision collet.
Depth of cut is 1/4"
Have tried adjusted speed between 50-100in/min
Step over is 50%
I've varied RPM between 16-24k
I've adjusted pass depth as low as 1mm.
No issues with tear out at the top of the material and the pocket edges are clean and straight, no fuzz, chatter or tearout. The bottom of the pockets have small spirals that are slightly uneven and can be very time consuming to sand and finish particularly around small details.
Perhaps just the particular end mill I'm using but thought it worth seeking out advice before I sink more cash into end mills.
Ideally I'd like to get a finish that would minimize prep prior to staining.
Any suggestions on feeds, endmills or other possible solutions would be greatly appreciated.
Max shank size I can use at this time is 1/4"
Attachment 266576

[atwooddon]

My guess is your end mill is not perpendicular to the XY axis. Basically, it is leaning slightly which makes one edge of the bottom of the end mill lower than the other. When you move the bit back and forth on the bottom of your pocket you get 'grooves' where the low side of the end mill cuts deeper than the high side. You need to 'tram' your Z axis to ensure the end mill is perpendicular. To do this, you can simply bend a piece of wire so it has short piece that can be mounted in your router collet, then bends approx 45 degrees and extends out maybe 3-4 (or more) inches, then bend it again so it has a short vertical tail down toward the table of the machine. Mount the wire in the collet then lower the Z axis till the wire just clears the table. Now rotate the collet slowly and see if the gap between the bottom of the wire and the table stays the same. If it changes as you rotate the collet (higher on one side than the other then your router is not mounted perpendicular to the table. If you watch carefully to see where the clearance is different, you can tell which way the router is 'leaning'.

Don

[ger21]

In addition to tramming your spindle, you might want to try an endmill with radius corners.

[Kobal]

My guess is your end mill is not perpendicular to the XY axis. Basically, it is leaning slightly which makes one edge of the bottom of the end mill lower than the other. When you move the bit back and forth on the bottom of your pocket you get 'grooves' where the low side of the end mill cuts deeper than the high side. You need to 'tram' your Z axis to ensure the end mill is perpendicular. To do this, you can simply bend a piece of wire so it has short piece that can be mounted in your router collet, then bends approx 45 degrees and extends out maybe 3-4 (or more) inches, then bend it again so it has a short vertical tail down toward the table of the machine. Mount the wire in the collet then lower the Z axis till the wire just clears the table. Now rotate the collet slowly and see if the gap between the bottom of the wire and the table stays the same. If it changes as you rotate the collet (higher on one side than the other then your router is not mounted perpendicular to the table. If you watch carefully to see where the clearance is different, you can tell which way the router is 'leaning'.

Don

Thanks for both responses. I'll give both suggestions a go this weekend!

[Kobal]

Ended up rigging up something similar to the wire suggestion with a calibration blank, an angled bracket and a dial indicator. Router was tipped forward very slightly. Shimmed the base of the mounting plate with a 0.3mm feeler gauge and that got me to less then .001" across the full rotation. So many small variables to keep track of and so much to learn, particularly when building your own machine, but man is it fun! Thanks for the suggestions! Surfaced a 14"x18" slab of maple with a fishtail 2 flute and the spirals I was seeing are completely gone. Got the best results yet on the pieces I made today! Here's a picture that shows a piece I started before the fix and finished afterwards. The carved sections were done prior to the fix, so you can see some of the rough sections in the pockets. I surfaced it after the fix to minimize the appearance of the crack in the upper left corner. This is right off the machine without any sanding. Attachment 267042

[atwooddon]

Nice piece, that should finish up really well. Glad you found the problem.

Don