Bit Bounce

X-Carve
1

Does anyone experience (bit bounce) for lack of better terms. Using pine board 1.5 inches thick, a 1/8th inch bit I noticed that the bit seems to bounce off the material as it travel cross grain. I used the setting for plywood in Easel since there is no option for pine wood. The project came out fine, no burn on the bit. Is this normal?

Second part of this question and is directed to the Easel development team: Is there a plan to add different wood options for Easel Pro? I use a lot of pine board, oak and other woods not shown in the pull down menu

Thank you!

Andrew

2

The term you are looking for is “chatter”. It is normal, and is not something to worry about as long as you are getting good results. There are quite a few discussions on the issue, with many solutions for addressing the problem: https://discuss.inventables.com/search?q=chatter

3

Any machine can chatter, even super rigid ones.
Sign of chewing too much at the time, or just a combination of vibration and harmonics.

You may try to:

  • Reduce depth per cut
  • Increase RPM slightly
  • Optimize machine in terms of rigidity/stiffness
  • Add mass
  • Minimize tool stickout (a 3" exposed tool will bend much more than the same tool with only 1" exposed)
4

Not sure I agree with this statement… If you’re getting chatter, the bit really is “bouncing” around, and isn’t precisely following the intended toolpath. For roughing passes, this isn’t necessarily a big deal, but for detail/finishing passes, it’s highly undesirable.

Chatter can also be a precursor to bit breakage, since the bit is being loaded more than intended when it bounces back into the material. Again, it depends on your use case. Soft woods and plastics will be forgiving.

1 Like
5

I agree that in general chatter can be a real problem and cause damage to the bit and the work-piece. That’s why I gave the OP the proper term for the problem and the search link.

But for the actual question the OP asked (“only on cross grain”, “project came out fine”)? In that specific instance, it doesn’t sound like a problem.

6

Thank you to all who responded. I will try your suggestions and hopefully this will solve the issue. So far I haven’t seen any damage to the bit. Again, this only seems to happen on the cross grain. Yellow pine grain is pretty rough so I will experiment with other woods to see if I encounter the same problem.

1 Like
7

While pine is a soft wood, the grain itself can be rather hard. When sanding pine if you notice the soft wood between the grain is almost always a little lower than the grain. Wood grain can be really hard and pine is no different. Have you tried doing a cut in something like MDF?

8

Thank you. I agree pine grain is really rough, I don’t have much choice of woods here in the south. It is either oak or pine. I can get soft woods but find that harder woods provide a better result. I am new to the CNC world as I always did woodworking projects by hand. I will experiment with all of the suggestions I have received and get better at using the X-Carve. Thanks again