Tear out..

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Beltramidave
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Tear out..

Post by Beltramidave »

Bout to give up on 3d profiles. Can't seem to get it right.

Brand new 4flute .0625 tapered ball nose, 16k rpm. 10% stepover and I still get tearout and fuzzies. I have tried slowing my feed down, speeding it up changing rpm, to no avail. I believe that this is birch wood and I am carving with the grain. There doesn't seem to be a real standard as far as with or against grain and diagonal, doesn't seem to be much better.

Brand new machine too... What am I doing wrong? HELP! Can't afford to keep redoing these for as long as they take.
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Rcnewcomb
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Re: Tear out..

Post by Rcnewcomb »

What is the material?

A 4 flute bit is better suited for metal. I'd recommend a bit designed for 3D carving wood. These are beastly expensive and worth every penny: BDP - Tooling

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Beltramidave
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Re: Tear out..

Post by Beltramidave »

The wood is birch.
Those bits are pricey. The ones I am using are from Precise Bits.
So you are saying to use a 2 flute bit rather than a 4 flute?
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highpockets
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Re: Tear out..

Post by highpockets »

Yes, 2 fluted bits are better for wood.
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Re: Tear out..

Post by martin54 »

As Randall has already said a 4 flute bit is not the right bit for wood or plastic, single or 2 flute bits are really what you should be using, speed & feed settings will be down to some experimentation as they vary depending on different factors.
I asked about machining with or against the grain some time ago now & got varied replies from different forum members so now I just do my own experimenting on different wood types to see which way gives me the best results. Not tried 3d with birch only profile cut it so can't tell you what works best for me with that particular wood. I keep a little note book now as my memory is shocking :oops:

Have you tried reducing your stepover ? Most of the posts I have read about fine detail 3d carvings recommend between 6 - 8% stepover, I normally have mine set about 8%, it does increase machining time but anything that reduces sanding for me is better :lol: :lol: You didn't mention DOC in your post, if you are getting tearout then maybe look at reducing the DOC

I wouldn't give up but you may have to spend a bit more time experimenting, find a couple of small models that don't use a lot of material & don't take to long to machine & use them for all your tests :lol: :lol:

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Re: Tear out..

Post by Beltramidave »

What about engraving bits with flat tips? I know Scott has good luck with those with his small 3d stuff.
I have went down as low as 8% stepover. In the past. I know birch isn't the best wood to use, but I have seen some pretty good carvings out of pine.
I'm sure I won't give up, just frustrating.
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Re: Tear out..

Post by Leo »

Yeah frustrating - we all clearly understand that.

Fuzzies on wood - any wood - is just the nature of the beast.

The denser the wood the better off you will be.

Sometimes Corian can be used and then there is no fuzzies to contend with.

I like Hard Maple, and Cherry for 3D stuff. I am also ridiculous tight stepover at around .002 or so. Still get fuzzies. SHARP cutters help but do NOT eliminate. Pine is a nightmare. Tear out, fuzzies, just overall yecky to work with. It's OK to test, then woodstove. I do use pine, but not for 3D.

Use the largest radius tool that you can. You will loose detail, but can loosen the stepover and reduce time. Still gonna get fuzzies. If you are cutting a dome, maybe a 1/2 ball nose with .062 stepover will work. Using a 1/32 with a .002 stepover is a waste of time.

No fuzzies on HDU, or Corian or Brass, or Aluminum. PVC should also be a consideration. You could use a good quality MDF - maybe not from borg. MDF is fuzzy by nature but paints kinda well, after a good primer, and sands well after primer. With a little effort MDF, CAN, look GREAT. Does it always need to be wood? Just expanding boundaries here.

Use 2 flute tools as much as possible - still gonna get fuzzies in wood.

So - what to do about the fuzzies? First, you gotta give em some sort of sealant - Shellac is good. Then sand em out as best you can. You NEED the sealant, as fuzzies just bend back and forth under sandpaper. The sealant stiffens those doggone things so the abrasive grit can cut them off.
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Re: Tear out..

Post by Beltramidave »

Thanks for the suggestions, Leo. Corian is great to work with and I have about 30 sink cutouts sitting around waiting to be used with lots more where those came from. I really like making the lithos with them. MDF does carve great too and am starting to figure out how to make it look more like wood when finished. Cherry or Alder is definitely my favorite!

Scott is going to look at my settings and see if he can see something I am not doing correctly. I have to get this figured out cause I got this new machine taking up a lot of space in my already crowded shop.

Thanks again
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Re: Tear out..

Post by Beltramidave »

These are what I have been using:
http://precisebits.com/products/carbide ... se!!!#Tabs

Ron also has some 2flute:
http://precisebits.com/products/carbide ... CK!!!#Tabs

Ron makes a very good quality product, I think.
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Re: Tear out..

Post by Leo »

I use precise bits also.

I didn't know they had the 2 flute - that is what I will get next time.

Nothing wrong with them
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Re: Tear out..

Post by COWBOY1296 »

I do mostly black walnut and cherry. each project had its share of fuzzies. About 8 months ago i started cutting against the grain and fuzzies are a thing of the past. My go to bit right now is Amana 1/16 ball nose which is a 4 flute.
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