Broke two bits in a day - does the collet need to be changed?

[mmak2916]

Started working this morning and managed to break two bits in one day! The first bit hit a hold down screw and the other one happened when the piece with tabs became loose. I not only ended up out $84 but also deflated...but it's all me to blame!

I ordered new bits and will be waiting for them to arrive which is probably a good idea while I cool myself down. The collet snaps back into the collet nut and it seems okay, not lose. Is it suggested to be replaced anyways? Anything else I should check to make sure I didn't damage anything else on the machine?

Thanks!

[MogulTx]

I would at least order a new collet to have on hand if you see that there is some problem in the near future.... I have a spare for each size ( .125, .25, .5") on hand. I think I pay around $12.5 each at Maritool.... cheaper than a bit!

[barrowj]

I have 2 spare and bought them and collets from here, great price and shipping even though they come from the UK. I ordered several of the metric collets also along with the nuts...

http://www.arceurotrade.co.uk/Catalogue/Collets/ER-Collet-Nuts-Wrenches-and-Spanners

[scottp55]

You could buy 100 new collets for the same price as ruining your spindle cone....Trash it and keep spares. They're only good for about 400 hours anyways, so I always keep spares in case one meets the floor.
If you still have both your eyeballs and all your fingers....I'd consider it a "Learning Day" :)
I usually wreck mine with a decimal point in the wrong place while "winging a cut on the fly":(

[mmak2916]

Thanks guys, I ordered a couple spare collets from Maritool. Yes, it was certainly a learning experience!

[banjomanwv]

How do you know when a collet is bad?

[mtylerfl]

The more important question is...how do you know the collet was at fault in the first place for causing the bit to break anyway? There are a lot of reasons why a bit could break which has nothing at all to do with the collet itself.

Wondering if you have a particularly compelling reason why you think the collet was actually at fault?

[bobmoore]

I would ask How do you know the collet is good. You really should replace them every year at least (they wear out like pinions wear out). If you can't remember when you last changed them I would change them. I consider them a preventative maintenance item. That said I wouldn't suspect a worn collet for a broken bit unless the bit slipped down in the collet. Bob

[mtylerfl]

... wouldn't suspect a worn collet for a broken bit unless the bit slipped down in the collet. Bob

Yes indeed...or excessive runout. We simply don't have enough information to know what caused the bit to break. I doubt it was the collet, but who knows? Nobody, really.

[steve_g]

I think what “mmak2916” is referring to are the statements common on this forum that you should replace a collet whenever you break a bit for any reason…Personally, I only replace the collet if the bit breaks in the collet.
SG

[Burkhardt]

…Personally, I only replace the collet if the bit breaks in the collet.
SG


Me too. I would also worry more breaking a 1/2" bit (not sure if my machine has enough oomph to even do that) than an 1/8" bit. I break these all the time and they are surely not going to damage anything.
Some caution is reasonable but you don't change the wheels on your car just on suspicion after hitting a bump. You normally check out if something is actually damaged. Same thing with the collet/spindle. As long as the runout is still good (easy to measure in a minute), the bit slips in and the nut tightens like always and no unusual vibration, I assume the collet is good. After all, the collet is some heat treated alloy steel with a large surface interface to the cone. Probably not that easy to damage except the bit cracks right behind the edge and nicks the inner bore.