How can I get cleaner pockets?

[awalt1250]

When doing simple pockets or ever re-surfacing my spoilboard, I get small but noticeable ridges in my material when using a straight ended cutter.

Today I was cutting a simple 4"x4" pocket using an 1/8" bit, at .06 deep in cypress, and there were visible ridges inside the pocket.

The stepover values were left at default at 50%, which seem high to me.

I have checked the alignment of the spindle to the table and it is not too bad.

I'm running a Desktop that is less than 1 year old with low time on the bits and spindle.

Looking for any suggestions on correcting these ridges.

[Xray]

50% stepover is typical for roughing, but leaves ridges [as "roughing" implies].For finish, stepover is much smaller, 8-10%, and leaves a smoother finish - And of course, takes more time.
Trial & error will be required to find a happy medium between quality & time ,,, If in fact stepover is the culprit, other factors can be involved such as lost steps, worn bits ect.

[ken_rychlik]

The spindle is probably mounted crooked. Make a z shaped tool out of 1/4 inch round bar from the hardware store. Make it bend 90 degrees (a lttile more really) when it leaves the spindle or router, then have it go over to the side about 8 inches, then back down straight again.
Chuck this up in your spindle or router. DO NOT turn it on. :eek:
Rotate the device in a circle and slowly lower it until it just touches the spoilboard. If it is perpendicular to the bed, it will barely rub all the way around. If it touches on one side and is high on the other side that is your trouble. Adjust as necessary.

[coryatjohn]

>> DO NOT turn it on.

That, is about the best advice I've heard today.

You can increase the resolution of your gap measurement in the "Z" wire by shining a flashlight horizontally at the gap between the wire and the table. The shadow cast by the flashlight will allow measuring the gap with a ruler instead of a micrometer. It's really easy to get a nearly perfect spindle by using this method.

[steve_g]

Andy…
You have good advice already, but a picture is worth a thousand words! Here’s the gage I used today! Just a ½” dowel rod with a coat hanger in one end…Don’t worry about precision, it’ll work anyway. The longer the arm the more precision you can get, but too long and it’s awkward to use. After using this today, my spoilboard is glossy smooth!

SG

[Ajcoholic]

Why would you cut a 4" square pocket with a tiny 1/8" bit?

[scottp55]

Andy, If you are limited on bits ie. starter set, order of best pocket finish is 1/8 Ballnose 6% stepover, 61-040 1/8straight 8%, 1/4"downspiral 12% stepover. Straights or downspiral in as big a radius as you can use seems best. Take a piece of scrap and make some sample test pockets at various stepovers will give you some good info on bits you have. I learned a lot.

[cowboy1296]

I do pockets from time to time that take me down .7 of an inch. I break it into two tool paths. The first one is like roughing in 3-d. I do a 50% step over and go within .03 of the bottom of the intended pocket. The second tool path cuts out the remaining .03 but with a much smaller step over.

[awalt1250]

Thanks for all the suggestions, I appreciate it.

I was using an 1/8" bit in that big of a pocket because I forgot to change the bit. Yes, it took a long time to finish.