Advice on chip-out of small areas?

I made this sign first in plywood, then in MDF. One issue I seem to have in both materials is that small “island” areas, like the interior of this “4” get knocked out. In this case, I painted the MDF first, did a 2-stage carve with 1/8" roughing first, then 1/16" finish cut using the default MDF cutting settings. Both bits were 2-flute and new. It worked pretty well although I was unsuccessful in changing the bit without accidentally moving the gantry.

So here’s my questions - any way to avoid losing these little pieces, and is the roughness of the edges about what is expected, or am I doing something wrong?

I think the only way to make sure little pieces don’t fly off is to make the cuts as shallow as possible. And pray to your deity of choice.

As for the edges, it’s possible your speed was a little high and the bit was deflecting. Try a lower speed and a shallower cut with a super-sharp bit, downcut or straight flute would be better than an upcut.

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What was the depth of cut for your bits?

I had this problem on a project and it was very frustrating. I ended up dousing my MDF with penetrating stain (oil based). Letting it dry for a few days, then carving it. It helped my sharp corners stay intact. However, STILL I lost half the dots over my i’s. But my letter were proud of a surface pocket. The opposite of your project. On your project, if you v-carve this you will not have this problem (if your bit is sharp). If you do not have v-carve pro, there is an open source v-carving program that will make this particular project come out beautifully (someone will chime in with what it is called).

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The compass rose was 3/16" deep - everything else was 1/8"

I have had similar problems. From what I can tell it is because MDF is such a soft material. Anything less than 1/4" thick or cut more than 1/4" deep seems to be really weak. Thin bits just snap of with the slightest pressure.

I don’t think there is an easy answer with MDF.
Shallower cuts (1/8") might help ?
Using a V Carving bit works well as the remaining material is wider at the base.

V-carve would certainly have this looking beautiful. But even with V-carve, I still loose some bits inside of smaller letters. Could have been the wood I was carving though. As for the open source software, are you referring to F-Engrave?

I think it is called F-Engrave. Saw some great work here on the forums and I believe it is free.

Yes, F-Engrave is free. I used it briefly, and for basics it is good. I had trouble getting it to import images, so I was limited to text. F-Engrave is no match for V-carve.

I agree. I’m totally spoiled by v-carve and mach 3.

And was that done in 1 pass? General rule is don’t cut more than half the diameter of the bit. So a 1/8 bit should not cut more than 1/16 deep in a single pass

No, for the compass rose it was 3 passes for roughing and 3 passes for detail. The text was 2 passes (@ 1/16") for each bit.

One thing I found recently (this week) was that my z axis is canted just slightly and that caused issue on the deeper cuts even running slowly on MDF. Just the nature of the material. I’m working on shimming the axis and testing it on weaker materials like this.