New 1/8" cutting bit causing serious overheating problem

[aokweld101]

I was told to check the sharpness of a bit was to take the edge and rub it on your fingernail and if it shaved a layer from your fingernail then it is sharp.

[DickB]

Well, there can be no question about bit sharpness BEFORE the burning. The first bit had been used only a couple of hours before the first failure. I used a brand new, never been used bit on the second try which resulted in the second failure. The bits were factory sharp. My old bit which worked with no problem has countless hours on it and can't be all that sharp.

The difference in bits is the tightness of the spirals. The new bits have tighter spirals. I would think that would be part of the specs, not just a supplier change, but I would like to avoid guessing and welcome input from LHR. I have a third new bit in the box that is going to stay there.

I posted this to alert other users to the problem, let LHR know, and solicit input from other users. I request other users to count the number of spirals on your 1/8" cutting bit and compare to my new ones (refer to the photo). If you have the same bit, have you had any issues or noticed any difference?

Edit: To be clear what I mean, I count 5 spirals down the old bit and 7 down the new one.

[Digitalwoodshop]

WOW... My first thought was a BAD Mechanical.... As we saw this with BAD QC's in the OLD days where I blamed the latest version of Designer and was WRONG.... See the picture and the one on the Right I was BLAMING had BB Marks in the Bit holder.... From a BAD QC and a Mechanical FLOPPING AROUND of the bit.... MY BAD.... A BAD QC....

So since 2 new bits give BAD Results and 1 Old Bit gives GOOD Results.... (Good Job by the way) WE have something to work with...

It is possible that in the Bit Manufacturing Process... A Error was made... OR... Is the Sleeve 100% Centered.... DO you have a Dial Indicator to measure RUN OUT with the Bit INSTALLED in the MACHINE?..... THAT would be my next check...

AL

[DickB]

I ran a test mpc this morning, just the gear tooth cutout of a 32-tooth gear. Same piece of Baltic birch plywood, same mpc (Designer 2) first the old then the new bit. I measured bit temperature with a handheld IR thermometer at about 4-5" distance (cover switches temporarily bypassed). It has an aiming LED; the hottest temps were with the LED on the bit at about 1/2" above the board's surface. The old bit ran at about 105 - 110 degrees fahrenheit. It took cutting about 4-5 teeth to get to that temperature, then did not get hotter for the remainder of the cutout. The new bit got to 145 after a few teeth, then 160, then 170. At the eighth tooth I read 182 and I stopped the test.

I would like to get some comment from LHR on this topic. If time to investigate is needed, I understand. But as I said earlier, the three new bits that I just bought are not usable by me at least for this project. I need to have a source of usable bits.

Would other users please count the number of flutes down one side of your 1/8" cutting bit and let me know if you have one like the new ones I have? Old bit, 5 edges, new bit, 7. Is anyone having similar issues with the new style bit?

[RMarkey]

Give our support staff a call so you can return the bit to us.

[gapdev]

Most of mine have 5 edges down the side, including the 2 new ones I bought over the 4th of July. 1 bit that came out of a QC adapter is slightly longer and has 6 edges (has been used to cut without problems).

Kenny

[DickB]

Thanks. Just got off the phone, I can return the bits, but that doesn't really solve my problem. Next step per the tech is kick this upstairs next week, so I will wait till then.

[lynnfrwd]

Sorry. I'm not back until Monday.

[farmer]

I just received a new 1/8 bit today for my CT spindle and it is the same as my old one 5 spirals down the side 4 flukes.

[DickB]

Wanna trade?