Thanks, I'll check.  I've no idea if this is set for speed machining.  I'm currently doing this with MeshCAM, as I'm still deciding on a 5 axis CAM software.  In MeshCAM there is a quality level, which is currently at 2.  I'll increase that for the next cut too, which I'm hoping will be tonight.

Barry

I'm currently doing this with MeshCAM

That's some critical information. Not sure what you're part looks like, but it appears to me that MeshCAM is the wrong tool for that type of part. A 2D CAM program could give you much more efficient toolpaths, that would probably reduce machining time by up to 75%, maybe more. With MeshCAM, more than likely, you probably ended up with a lot of plunging, which is bad with your downcut spiral. And the rough cuts that I thought were play in the machine, were probably due to MeshCAM's roughing toolpaths.

You didn't show a picture of the bit, but did it have a lot of plastic on it? It's pretty hard to break a 1/4" bit in wood, unless you get it pretty hot. But normally you'd see a lot of burning, and I don't see it. So if there was plastic on the tool, then there's a good chance that's the reason it broke.

I've been a MeshCAM user since the very first beta, and am also a moderator on the MeshCAM form, so I have plenty of experience with it.

Can you show a pic of your part? Were you going to use a ballnose bit for your finishing passes?

Oh, almost forgot. I wasn't being testy. Just trying to point out that I know what I'm talking about, and was disagreeing with the previous poster. And a few others. With wood, the general rule is to cut as fast as you can, provided you get acceptable cut quality. Disregard the quality of this particular part for now. Stepover is not really important when roughing wood, as you can easily use the full tool width. And if the chip load is not kept up near the recommendation, your tooling life will suffer.

Hi, yup, the bit was blackened and had bits of plastic still on it.  I didn't save the bit, threw it away last night.  There is a spot where the bit plunged into the wood just after melting the plastic.  There is plenty of burning there.  That's in the pict.  I'm trying to save the part as a surprise, so can't show it just yet.  I think people will really like it;)

That's good to know about you being the moderator for MeshCam.  I'll hit you up for tips I'm sure.  I may be switching to RhinoCam in the future though.  The machine is 5 axis, and I use Rhino to model with.

Ballnose bit?  You mean there are other styles?  I hadn't bought a ballnose yet, only flat ones.  I do have a 1/8 inch flat though.  Perhaps I should get a 1/8 inch ballnose for the finishing;)

Chip load?  what does that mean?

Barry

Hi Barry

My CNC is not running yet but here's a good site I found to calculate chip loads and cutting speeds in various  materials:

https://www.onsrud.com/xdoc/FeedSpeeds

Chip load is basically how hard you are pushing your cutter, it includes feed rate, step over, depth of cut and material hardness.

Cheers

Mark

Your too fast Ger

Hi, yup, the bit was blackened and had bits of plastic still on it.  I didn't save the bit, threw it away last night. 

You wanna kind of throw out those important clues up front to help the helpers!

LOL, I primarily stick to metal, but have to admit that was looking pretty gnawed.  Had to be something seriously off, and Gerry and the others were trying to get at it.  You want to keep a close eye on your cutters any time you have a little problem.  Should be nothing sticking to them and no discoloration.

Speaking of Onsrud, I'm getting ready to add wood to my G-Wizard feeds and speeds calculator.  Their feeds and speeds data is by far the best I've found so far.  Wood is basically pretty hard to track down.  Do you fellas have any other good sources of that data?

Cheers,

BW

Btw, I used the settings I mentioned above as a new test.  This finished no problems, and the cut is really sharp across the board.  I did put in the wrong bit profile for the finishing stage, but only mismeasured the length of the flute.  This made it burn in a couple spots, but otherwise, looking good.  Onward and upward.  Thanks for the info.  When this part finishes, I'll post picts in a new thread.

Barry

Barry-

I would also download the latest V3 beta of MeshCAM from http://www.grzsoftware.com/v2dl.php .  It has a totally new roughing system that is likely to give a much more accurate and smooth toolpath, and you'll never have to worry about "quality" values for roughing again.  Even though it's marked as a beta it's fine for day-to-day use.

-Robert