Tooling - chip out in hard wood

[adam_m]

I was making some small wood plaques for a friend this weekend and I was noticing some chip out when using a down cut 2 flute bit in oak, especially around some of the smaller detail when I changed to a 2 flute up cut 1/8 bit. I'm guessing this could be caused by a couple of things, wood grain, feeds and speeds, bit size, etc.so I was curious about your experiences..

3 questions.

- Will a multi-flute but help in preventing chip out, up/down cut?

- Does anyone have recommendations on feeds and speeds?

- What's your opinion on the best wood when requiring engraving detail?

Adam,

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[ger21]

Without seeing exactly what you are doing, it's hard to say. Wood can be tricky. Sometimes it requires cutting in the opposite direction. In some cases, I've use Left handed tools to be able to do a production job at higher speeds without getting tearout.
One option may be able to make multiple, shallower passes. Oak is probably not your best choice.

- Will a multi-flute but help in preventing chip out, up/down cut?

Maybe a little, but probably not much.

- Does anyone have recommendations on feeds and speeds?

As fast as possible, to maximize tool life. And as slow as you need, to get the finish quality that you are looking for.

- What's your opinion on the best wood when requiring engraving detail?

Generally, the harder the wood, the cleaner the cuts. Closed poor woods like maple will "splinter" much less than woods like oak, but maple can tear out badly in other situations.

[louieatienza]

Oak can be one of the more difficult woods to machine xleanly especially cutting cross grain. That sais,

1) A multi flute bit would allow slower spindle RPM, which would not necessarily be better. You have to experiment with speeds and feeds. I prefer to climb cut, as the chip is "supported" behind the cut. Putting a coat of finish before machining sometimes helps.

2) Possible your dulling your tools from too small a chip, so you may have to increase feed, or lower spindle speed, or both. Then again if your machine has rigidity issues you may have to go the other way. Knowing what parameters you have now may help.

3) Basswood is one of the best because of its very fine grain. It's also one of the plainest woods however. Same with alder.

[adam_m]

Thanks for the reply's.

Here are a couple of up-close samples... scale is about a 2" letter. In general they look pretty good but the letter "E" is where most of the chipping occurred.

I've heard a lot about basswood and its carving features but as you said its pretty dull.

Do you guy's have a preference of hardwoods you would recommend, would a mahogany do better than a maple vs cherry?

I'm guessing that milling with smaller bits will also help with smaller scale items, but cut times increase exponentially...

Adam,

[louieatienza]

Run the outline first using a smaller endmill, and do the clear out pass second...

[ger21]

Run the outline first using a smaller endmill, and do the clear out pass second...

+1

[adam_m]

OK, make sense louieatienza,I'll give that a shot and see how it works out..

Adam,

[ger21]

Do you guy's have a preference of hardwoods you would recommend, would a mahogany do better than a maple vs cherry?

Cherry would probably be the best of the 3.
Mahogany today can be any of a number of species, some would be better than others. Grain direction would have a lot to do with it.
Any of these would be better than oak. I hate oak.