Advice on cutting rosettes?

[Jim27]

Looking to cut a few rosette blocks for window trim. V groove bit. Tried it with a cheap bit and things were awful. Got a good carbide bit that comes to a point (rather than a significant flat at the tip of the bit that some have). Works much better but still having a little trouble with rough surface and small chip outs. Just using pine at this point and wondering if I should go to something a bit harder and finer grained. They will be painted so no issue with grain look as long as it's smooth and takes paint reasonably well. 2 flute bit running about 8000 rpm for a surface speed of about 2 ft/min and a chip load of 0.002 per tooth.

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[ger21]

Are these V carved, or 3D?

Pics?

[Jim27]

I would say they are v carve but I could be wrong on the lingo - they aren't constant depth... Here is a picture of an actual and a model. All done with a 90 degree V bit.

[awerby]

A finer-grained and harder wood would probably help. You might try slices of end-grain, which won't have the same tear-out problems as your pine boards. Or use a urethane sign-board product, which doesn't have any grain at all.

[Jim27]

I am not familiar with the sign board material. Where would I get it? I could could pick through some boards at the big box stores (lowes/HD/Menards) and find some finer grain material, possibly fir or some other wood. What woods are good for this - i.e. what am I looking for besides tight grain?

[awerby]

Here are some links to urethane sign board vendors:

https://www.interstatehdu.com/

https://www.freemansupply.com/products/machinable-media

https://www.goldenwestmfg.com/foam-board.html

Wood species suitable for carving aren't usually sold at "big-box" stores, which are more concerned with softwood lumber used for construction. Look for hardwoods like walnut, butternut, cherry, maple and tupelo.

[Jim27]

Thanks for the advice. I recognize that the stock is not the best. But I am left wondering how they make moldings and such out of pine in production. The painted one is pine (fairly sure it's pine) and was purchased. Certainly not a hardwood. I know they make baseboards and other molding from finger jointed pine.

I have some left over cherry flooring that would work well but hesitated to use it as it is prefinished and thought the finish might be hard on the cutter. I have read that the finishes have I think it is aluminum oxide or something similar for a long lasting finish and that can be hard on cutters.

[ger21]

But I am left wondering how they make moldings and such out of pine in production

With a moulder, spinning an 8" diameter head.

Pine is very difficult to carve cleanly, especially with a V bit, where the RPM at the tip is effectively zero.
Generally, the harder the wood, the better it will cut.

At Home Depot, look for some Veranda Cellular PVC boards. These take paint well and will cut very cleanly.

[awerby]

Different species of pine can carve better or worse. I've seen some nice work done in sugar pine, for instance (although it has a tendency to show burn marks). But heavy cuts will tend to disrupt the adjacent surfaces more than lighter ones. You might try doing these in two or more passes, going progressively deeper each time, leaving a smaller amount to remove as a final cut.

[Jim27]

I am having trouble at the top of the material, not at the bottom of the cuts with the tip. The main issue is tearout of narrow peaks. Thanks for the advice. Will get some better material.

[elfrench]

A real wood store like Crosscut Hardwoods will usually have hardwoods for less money than the big box stores garbage.

Sealing the wood first will help lessen the tearout. Shellac is probably the best for this. Sharp tools are essential.

[boydage]

The last lot I did on my cnc router with a rosette cutter and a peck drill cycle on the Z. Perfect results. I think the rosette cutter was US$45? Is that cheating?

Oh. And I used untreated Pine.

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