Breaking bits

[jerrymorgan]

I've broke a 3/16 in one cm of red oak and 1/8 in poplar and I don't understand why?

[fwharris]

Are you making these cuts at full depth or at a maximum pass cut?

[bergerud]

When making deep cuts in a single pass, one has to watch out for climb milling. This is when the bit cuts only on one side and tries to pull itself along and climb out of the cut. (The direction of the cutting edge and the direction of travel opposite.) Climb milling can easily happen when cutting out boundaries of patterns.

[Digitalwoodshop]

From what I am seeing, it looks like the bit was broken by a movement in the X Direction since it did not look like any side to side stray cut... a better picture with the bit removed would help determin that... Sort of a CSI investigation.... CarveWright Version,

To snap that bit, I would venture to guess that the Y would not have the Torque to do it... but I could be wrong.... We know that the X Torque can very well snap that bit and based on the investigation of the cut marks at the time of the break, it would be logical to expect the X Jumped.... That brings in my Friend the Brass Roller.... It could be the sole source of the problem.... The Board lost contact with the Brass Roller for what ever reason... From the board tipping up or bumping into a in feed or out feed tray roller... BUT COMMA... That does not look like the real problem as the CARVING is PERFECT.... Any Brass Roller Problems would be reflected in the Carving TOO and that is NOT the Case.... So NEXT....

Then we have something as simple as the feed rate for the Cut Path was JUST TOO FAST for the Bit's ability to cut the wood... I saw this when I was Vector Cutting plastic tags on a Carrier Board and using a 1/16th end mill. The machine used a feed rate that was faster than the bit could cut the plastic in one pass and since I used double sided tape to hold the tags to the carrier board, they would sometimes be pushed off the tape. The fix was to tell the machine I was using a 1/4 inch bit but actually use a 1/16th end mill and that locked the feed rate into it's 1st gear. It never shifted into 2nd gear the faster feed rate causing the problem...

Since you are dealing with solid wood, and IF the FEED RATE was TOO FAST.... The Cut would react in one of 2 ways... Cause the Board to SLIDE on the Drive Belts.... OR if locked in on a Rubber Belt..... SNAP the BIT.....

That is my take on this..... A Feed Rate TOO fast..... for a one pass Cut Path... Multi Pass Cut Path would solve the Broken Bits....

AL who

[atldal]

Snapping bits was my first indication of my x tracking problem.

[DJKnutsen]

I've just broken my second 1/8" cutting bit, on the same MPC, at exactly the same time-position in the project (months apart) and had a third instance where I was lucky enough to hit the stop before it broke.... In this project, it's just finished the initial carving, and requested the cutting bit... located and indexed the newly installed cutting bit, and moved to the spot to start that process... dropping the Z truck and slightly starting to move in the Y direction... but it never started the router motor!! and didn't stop the process or profuse any error message... so as I said, it happened three times, in the same MPC, the same point in the process, weeks and many other successful runs in between on other MPC's, twitch I was slow (but saw what happened) and broke the bit... once I was quick enough to kill the power and saved the bit... It seems to me that there is an error in the compiled (G code?) loaded onto the memory card for that MPC... but with no way to look at what is being sent to the machine, I can only guess. But I've not had any problems like this with any other MPC's, and yet... three time with this same one...??? Any thoughts... I'll call CW in the morning, but I suspect they'll try to deflect the blame away from a software or firmware problem... BTW..I'm running Designer 2.005, build 11800 with the latest firmware update, on a Mac desktop.

[lynnfrwd]

You mean deflect like maybe saying it could be a project problem?

[lynnfrwd]

Did you try re-uploading the project to your card? Maybe you can post that mpc file, so someone can look at it.

[DJKnutsen]

OK... call me cynical... by deflect, I was implying that they might not want to consider that their software could be the problem.. I did empty the memory card, and re-load the suspect MPC.. between results one and two.. no help. I can't upload the MPC here as it was a purchased package from Dick Bipes (the Synchronicity clock) and have been in contact with him and was assured that the MPC works. I'm new to CW... and have lots to learn, and lacking updated (Designer ver 2..?) printed reference material, I keep trying other options... but I'm running low on tool bits and lumber..!

[lynnfrwd]

Then I guess the question becomes, anyone else have same issue in 2.005 with Synchronicity Clock? Which mpc? I think there may be several.