Broke a 5mm Domino bit today

[Dan Lyke]

I was building some frames for the garden with Massaranduba/Brazilian Redwood today, made a plunge in one piece, flipped the Domino to the matching piece, and it wouldn't plunge.

Stopped the Domino, opened it up, saw that the end of the bit looked funky. Looked in the mortise of the piece I'd just successfully plunged, and there was the end of the bit. Picture of both pieces attached.

I didn't think I'd done all that much with this bit, I sure haven't made much of a dent in my stash of 5mm Dominos.

Anyone had similar issues? And should I send the broken bit off to Festool USA? Not a big deal, except the bit is $30 and I drove 25 miles each way to get the replacement today.

 

[ccmviking]

Dan,

Did that bit hit something in the wood?  The shiny circles worn into the bit look like what would happen if you hit a nail or staple in the wood.  Sometimes it can happen and you don't notice it.  It's hard to tell by the pics but it could have been weakened where those rings are.

Chris...

 

[tallgrass]

i have heard of bits and the shank breaking. i have seen the shank break, but have no idea as to why. it has not happened to me but to friends and yes i have seen the parts. so i wonder what is going on,,,,i am thinking thermal issues, but not sure.

 

[Dan Lyke]

Chris, i haven't been aware of hitting any metal, and it's unlikely that there'd be metal in any of the wood I've Dominoed, but I will look closer.

 

[Dan Clermont]

I haven't had any issues like that and have plunged at least a 1000 Domino's. Most were 5mm and 6mm.

The shiny metal makes me think you hit metal at some point and the bit finally failed. It may not have been this specific piece which had the metal but at some point it is possible.

Like Rick mentioned try to refrain from plunging too fast as that will fatigue the bit and also give you a sloppy Domino. The harder the wood, the slower you plunge.

I actually have a chart and will try to dig it out tomorrow

Dan Clermont

 

[honeydoman]

my bit also broke within the first couple of weeks using my dom... when I bought it last april.  it just broke.  hit nothing. wood was popular or pine or birch ply, don't remember which one.    but had to go to woodcraft and buy another one  and bought a spare.  never had the problem again and have done mucho domino holes.

 

[Dongar]

The marks in the bit were probably caused by hitting the carbide tip that broke off. I have a 6 mm bit that I plunged through about 80 16 gauge finish nails.  The carbide was badly chipped and much of the black coating was worn off but there were no deep score marks like your bit.
Donald

 

[Bill Wyko]

I have heard of wood having rocks inside and sand. When I was in Hawaii I saw a tree with a rock the size of a grapefruit buldging out of it.

 

[Warrior]

I have heard of wood having rocks inside and sand. When I was in Hawaii I saw a tree with a rock the size of a grapefruit buldging out of it.

That would make a pretty sweet bowl. difficult to turn though ;D

 

[Dan Lyke]

Yeah, that'd be an awesome burl.

I guess the most likely hypothesis so far is that I'm plunging too fast. I'll keep going with slower plunging and see what happens. Thanks for the feedback, y'all.

 

[mastercabman]

Dan.how deep did you go with that bit?
I have burn and broke a couple 5mm bit.It maybe because we are plunging the bit too much into hard wood?
Keep in mind that the bit spin very fast and moves side to side pretty fast too.maybe it is too much for a bit that small to be plunge too deep?

 

[Dan Lyke]

Dan.how deep did you go with that bit?

15mm (I was driving holes for 30mm Dominos).

 

[Sparky977]

I actually had this happen to me recently.  I was cutting the domino holes in maple face frames for some cabinets I built.  I broke 2 5mm bits in 2 days!  Of course, it happened at a very bad time with deadlines for the project looming.  The consensus came to by Festool and the guys at Woodcraft is that I was plunging too fast.  Also, both instances occurred as I was widening pre-existing holes.  I was having major alignment issues on 7' tall linen cabinets between the domino holes in the plywood, and the holes in the face frames.  I've come to believe that this too was due to too fast plunging.  Because of the difference between the plywood and maple, going too fast in the maple made smaller holes then the plywood.  The misallignment was 3/8" by the time it got to the bottom of the cabinet. 
So that all to say, its very important to not go too fast for the material you are plunging in.

Sparky

 

[mastercabman]

I actually had this happen to me recently.  I was cutting the domino holes in maple face frames for some cabinets I built.  I broke 2 5mm bits in 2 days!  Of course, it happened at a very bad time with deadlines for the project looming.  The consensus came to by Festool and the guys at Woodcraft is that I was plunging too fast.  Also, both instances occurred as I was widening pre-existing holes.  I was having major alignment issues on 7' tall linen cabinets between the domino holes in the plywood, and the holes in the face frames.  I've come to believe that this too was due to too fast plunging.  Because of the difference between the plywood and maple, going too fast in the maple made smaller holes then the plywood.  The misallignment was 3/8" by the time it got to the bottom of the cabinet. 
So that all to say, its very important to not go too fast for the material you are plunging in.

Sparky

it's possible that also happen to me,i guess we need to be more careful with the 5mm bit.but no  problem with other size.

 

[pingvinlakrits]

I have to chime in with the same experience; the #5 bit broke on me. Sure, I was working with hardwood, but it is not like I stressed the Domino and I think you would like to expect them to NOT break unless you A) drop them or B) run them into a nail/screw/concrete wall/my thick head.

They might be overhardened (for longlife!) and that could be why the smaller one breaks. As a whole I try and avoid the 5mm.

 

[vrasilla]

I had a 5mm bit break. It had only done 150-160 plunges. It happened also when widening an existing plunge. The tip that broke off and got caught up in the spinning shaft and got wedged blowing out the side of my workpiece. Pretty disappointing. I certainly wasn't plunging fast. Fast plunging may be an issue but there's certainly an issue with widening an existing plunge. It broke on the fourth widening plunge and with the first three I could hear the stress on it as it banged the sides.

Luckily I had the spare that comes with the domino systainer or I'd have been out of business for the day considering it was Christmas day

 

[Sparktrician]

I guess the most likely hypothesis so far is that I'm plunging too fast. I'll keep going with slower plunging and see what happens. Thanks for the feedback, y'all.

Listen to the motor.  If it's slowing down at all as you plunge the bit, you're plunging too fast.  Gentle finesse is the guideline here. 

[smile]

 

[Brice Burrell]

I had a 5mm bit break. It had only done 150-160 plunges. It happened also when widening an existing plunge. The tip that broke off and got caught up in the spinning shaft and got wedged blowing out the side of my workpiece. Pretty disappointing. I certainly wasn't plunging fast. Fast plunging may be an issue but there's certainly an issue with widening an existing plunge. It broke on the fourth widening plunge and with the first three I could hear the stress on it as it banged the sides.

Luckily I had the spare that comes with the domino systainer or I'd have been out of business for the day considering it was Christmas day

If you knew you were stressing the bit why did continue?

 

[vrasilla]

All bits encounter a level of stress in any usage. Having never widened existing plunge previously I was unaware that the difference I was hearing was an unacceptable level of stress. I took extra care to plunge straight and slow and I considered the operation within the tools design parameters. I think the bit broke easier than it should have and I believe others with a similar experience would agree.

 

[RONWEN]

I have heard of wood having rocks inside and sand. When I was in Hawaii I saw a tree with a rock the size of a grapefruit buldging out of it.

That would make a pretty sweet bowl. difficult to turn though ;D

Eiji, old friend, what have you been up too???  Long time no posts.  How is business?

One of the keys to the longevity of the bits is "feed rate".  They can't stand anywhere close to what you would do using a biscuit joiner although too slow feed isn't healthy for them either. 
When you consider the amount of material that little cutter is end milling out of the mortise vs. the periphery of a biscuit cutter it's a little surprising they do as well as they do.
Obviously, the vac should be at full suction.