[canman77]

Hey everyone,

I've more or less converted a cheap Chinese machine into a decent small scale CNC router with a Makita RT0701C. I've got it clamped to the z truck with plywood clamps that do a great job.

Lately I've had requests for signs/plaques, so I've done a few from Home Depot poplar. I realize poplar doesn't machine very well, but it's cheap and good to test designs with. The problem I'm running into lately with the cuts I'm making is that they don't end up with sharp corners. They're stringy and fibrous...not really fuzzy like a lot of people complain about. It's just a rough edge, so when the job is finished I have to go back over each corner edge and sand off the junk to get a clean edge.

What I'm not sure of is if the poplar is the issue or if the bit is dull, because I also have the same problem with Home Depot birch. Maybe Home Depot wood isn't the best wood to use..? Quick rundown of how I'm running the jobs:

Feedrate: 1500mm/min (I can probably push it a little harder but I don't want to overtax my machine.)
RPM: 15-20K (I hover around the 3-4 setting on the Makita)
Depth of cut: 2-3mm (if I do 2mm, I plunge, if I do 3mm I ramp)
1/4" straight router bit (2 flute, HSS I think)

I'm not getting burns, and my cuts are clean on the endgrain (I believe that's the correct term) but the corners come out rough.

I realize it's hard to tell without pictures, but I've already sanded everything. But what do you guys think? Bad wood or bad bit?

[canman77]

Got a picture of another cut with the same problem. This was in white oak:

[lloydsp]

Sigh... ANY wood with strong fibers needs to at least be started with a down-cut spiral. After you get the surface cut, you may wish to switch to an up-cut bit to help clear chips.

Sigh.... I don't know what speed you're running the spindle... that can help some, too, but the down-cut cutters are the best way to clear up that problem.

Lloyd

[ger21]

That's normal, for some woods.
And that looks like red oak, which is one of the worst for fuzziness.
As mentioned, a downcut will minimize the fuzzing, but with red oak, there still may be a small amount.

[canman77]

Yeah that image is oak, I don't have any poplar images. The poplar is even worse than the oak!

I'll get a downcut bit, I didn't realize that was a factor.

Are there any woods that are less prone to the fuzz?

Thanks everyone!

[aarggh]

That's pretty normal for cross grain with straight cutters. To get rid of or reduce the fuzz at the top you need to use downcut spiral cutters which push the grain down so it gets sheared off., or route through a sacrificial board on top which will then give very clean edges.

Given the contact point of the fuzz is so minutely thin, I wouldn't have thought the once over with a block or sandpaper would be any effort?

cheers, Ian

[lloydsp]

"Are there any woods that are less prone to the fuzz?"
---------------
Basswood cuts pretty cleanly! <grin>

Lloyd

[canman77]

That's pretty normal for cross grain with straight cutters. To get rid of or reduce the fuzz at the top you need to use downcut spiral cutters which push the grain down so it gets sheared off., or route through a sacrificial board on top which will then give very clean edges.

Given the contact point of the fuzz is so minutely thin, I wouldn't have thought the once over with a block or sandpaper would be any effort?

cheers, Ian

No, you're right it's really no big deal to go once over with sandpaper and clean it up. I like to paint the pockets so they stand out, but I haven't found a better method than just spray painting the pocket and then sanding back the paint above the pocket to get back to wood (if that makes sense). So what I'd like to try is covering the whole face with painters tape, run the cuts, and spray paint right after and then peel the tape off and have a nice clean paint job.

My concern is if I have fuzz, the paint job won't be as clean. I'll run some tests tomorrow though and see what happens.

Thanks for all the tips!