27-09-2007 18:20

Cuog

Re: pic: A "Bit" of a problem.

Thats quite an interesting bend there, we have a much smaller bit somewhere that got messed up quite a bit(snapped then caught and bent the threads backwards) I'll have to find it and get a picture up here now for all to see the fun xD

27-09-2007 18:27

Gdeaver

Re: pic: A "Bit" of a problem.

It may be a dewalt bit, but its most likely a very cheap import . Sometimes it's worth the money to have a good set of bits.

27-09-2007 18:37

Tim Delles

Re: pic: A "Bit" of a problem.

Depending on the size of the bit, the pressure on the drill bit, and the quality of the drill bit, it is very easy to bend/break them.

Normally they just break right off...

27-09-2007 18:40

Herodotus

Re: pic: A "Bit" of a problem.

I don't think that is the case here, and I think it may have just been a single faulty bit. This is from a Dewalt pilot-point titanium bit set. We've been using the exact same set for about a year now, and never had any problems with the bits and occasionally we were drilling through MUCH thicker material. Then recently I got my own personal set of bits so I wouldn't have to run around looking for the few bits we had left(we have a horrible habit of... misplacing things) and it is my own personal bit that broke as we didn't have the pilot-point 5/16th bit for the class to use. But up until now, we've never had a problem with this set, in fact we love them.

Also, that single bit is $7, which doesn't seem like it would be a cheap-o bit. Still though, couldn't give you a real reason why it bent, as I have no idea.

27-09-2007 18:43

Grant Cox

Re: pic: A "Bit" of a problem.

Reminds me of the day when, while working on our arm, I broke off two bits and mangled another

27-09-2007 19:02

JaneYoung

Re: pic: A "Bit" of a problem.

It has been my experience with damaged tools and the persons responsible that they feel very badly when it happens. A bit that is damaged can't do its job anymore and your freshman knows that. It's great that you supported him after this happened. The shop is such an important place of learning and development - both in building robots and building teams. It sounds like your team is off to a great start!

27-09-2007 19:56

John Gutmann

Re: pic: A "Bit" of a problem.

Umm....I would guess it is titanium coated. If the bit was pure titanium the set would have be a very high price.

27-09-2007 20:02

Herodotus

Re: pic: A "Bit" of a problem.

That is highly possible. The set is labeled as "Titanium" it doesn't say if it is fully titanium or just coated. Either way, we weren't doing anything particularly tough to the bit, so it's just a bit odd that it would get such a nice little bend in it. At the end of the last piece being drilled the student was pushing a little bit hard and the bit got caught in the piece at the end, spinning the piece into the jig we had set up. But I had that happen to myself once when I was drilling basically the exact same part and the drill had been fine before.

The cutting point is still perfectly sharp though

27-09-2007 20:27

ebarker

Re: pic: A "Bit" of a problem.

Okay so is there any chance they drilled the hole with the bit turning BACKWARDS ? I've actually seen someone do that and melted a hole in an aluminum sheet.

27-09-2007 20:30

Herodotus

Re: pic: A "Bit" of a problem.

No, it was going the proper direction, that I am certain of. Really, it was probaly just a freak accident. The bit getting caught at the end, and the piece being drilled being twisted around and then back into the jig must have just been enough to bend the heated bit.

The main thing that surprised me is that it didn't just snap in half.

27-09-2007 20:32

Mike Harrison

Re: pic: A "Bit" of a problem.

Yes, drilling backwards would do the trick, an easy mistake to make for a new guy. But then again, haven't we all bent/broken/mangled our own fair share of bits. I know i've went through at least 5-6 rivet sized drill bits myself... not titanium but still...

27-09-2007 20:37

ebarker

Re: pic: A "Bit" of a problem.

Okay so is there any chance they drilled the hole with the bit turning BACKWARDS ? I've actually seen someone do that and melted a hole in an aluminum sheet.

27-09-2007 23:18

dtengineering

Re: pic: A "Bit" of a problem.

Sheesh... it's not a material or manufacturing problem... it's a SUPPLY problem... you've got a DeWalt Ti5443-C, for drilling curved holes, on the left and the matching DeWalt Ti5443-S for drilling straight holes on the right. Our local vendor gets those two mixed up all the time!

Jason

28-09-2007 00:39

Cory

Re: pic: A "Bit" of a problem.

Yeah it's not titanium. It's called Titanium Nitride coating. Helps with lubricity. Actually doesn't work all that well in Aluminum, from everything I've read (it doesn't resist chip welding in aluminum real well, apparently).

Any drill you might commonly come across will be made out of either High Speed Steel, Cobalt, or Carbide.

28-09-2007 08:36

Andy Baker

Re: pic: A "Bit" of a problem.

Exactly!!!

This reminds me of a story from my childhood:

My 2 grandpas were helping my dad build a deck on our house when I was about 8 or 9. My job was to fetch things they needed. One of my grandpas needed me to hand him nails for the decking boards.

"Andy, I need a good nail"
"Here ya go, Grandpa"
"No, that one won't work. It's for hammering the board up from UNDER the deck."

It took me a few times until I learned to hand him the nail with the head facing up and the nail tip pointing down.

Grandpas are great.

Andy

ps... as for the point of this thread, I too think that this bent bit is a case of backwards-drilling. C'mon, we've all done it at least once. Foley Frozen students are no different.

28-09-2007 09:26

ebarker

Re: pic: A "Bit" of a problem.

This week one of our boys did the backward thing and melted the hole.

I pointed out to the new girls in yesterdays meeting that they should not be timid and not participate because of fear of messing up and looking dumb.

This week makes at least 3 years running that the boys have drilled backward holes. The girls have never done that. And yes the girls have drilled at LOT of holes.

SCOREBOARD:
GIRLS - 0
BOYS - negative 3

28-09-2007 11:59

dlavery

Re: pic: A "Bit" of a problem.

Jason -

You have the part number correct, but the description is wrong. Everyone knows that the DeWalt Ti5443-C bits are for drilling conical holes. And from the bend in this bit, I would submit that this is actually a DeWalt Ti5443-C(i) bit, for drilling inverted conical holes, instead of the Ti5443-C(r) bit for regular conical holes.

-dave

28-09-2007 12:53

Tristan Lall

Re: pic: A "Bit" of a problem.

Cory nailed it—those bits, while decent, are just conventional high speed steel (HSS) inside. The bottom line is that it's misleading advertising calling them titanium bits. They're no more titanium bits than they are nitrogen bits, yet you don't see anyone calling them that, do you?

Though the TiN (titanium nitride) coating isn't the greatest for aluminum and titanium, it does resist abuse rather well, and the pilot points are rather useful, so those DeWalt sets aren't a bad choice for FIRST use.

You might be able to find TiCN (titanium carbon nitride) or TiAlN (titanium aluminum nitride) coatings that are more durable, and provide a little better performance in aluminum and titanium. TiCN and TiAln are actually more common on fancy endmills, than on drill bits, though. Even a black oxide coating is better than TiN, if you're only concerned with drilling aluminum (it won't stick as much to the chips).

In any event, $7.00 for that bit doesn't make sense. For example, McMaster-Carr sells something broadly equivalent for $2.61. (Look at their online catalogue to see the selection of drills that you could use instead.) Check your phone book for a machine tooling supplier or industrial hardware store in your area; they'll be able to find you something better.

Homemade friction stir welding?

28-09-2007 15:48

Herodotus

Re: pic: A "Bit" of a problem.

I don't doubt our students can drill backwards, but a drill press that has no reverse can't(or can it?). I'll have to remember what you guys said about the bits though. We only have some small sets right now and we were looking into buying a full drill index along with a handful of the bits we more commonly use. So I'll keep in mind what sort of bits we should be looking out for.

29-09-2007 23:05

t3hroxor

Re: pic: A "Bit" of a problem.

OH NOES!

30-09-2007 08:01

Chief Pride

Re: pic: A "Bit" of a problem.

"A bit can be replaced, you cant" - FOrmer metal shop teacher

whenever someone broke somehting you did feel really bad, but he always made a joke out of it so it was alright, and he was right too, as long as your not hurt everything is good

10-10-2007 07:38

robostangs548

Re: pic: A "Bit" of a problem.

Thats amazing... When ever i do that it busts into a million pieces. Bummer.

10-10-2007 09:48

DAN1504

Re: pic: A "Bit" of a problem.

i know that during the build season last year a bet was bent at 90 degrees... i wish i had a picture, it was pretty wierd.

10-10-2007 10:36

akedomakona

Re: pic: A "Bit" of a problem.

Funny, yesterday we broke the pilot tip of my 1/2 from the same set. We were drilling through ~1/4 inch steel. DeWalt to...

10-10-2007 12:31

T3_1565

Re: pic: A "Bit" of a problem.

Wow... I never knew that was possible... how well do you think that would work on say.... a robot???

11-10-2007 01:53

eugenebrooks

Re: pic: A "Bit" of a problem.

Lighten up on the pressure as you get close to breaking
through the back side. The bit can grab as it breaks
through, snapping it (or tweaking your wrist) if the drill
has enough torque. Putting lots of pressure on it as it
goes through can also cause you to lurch, putting a side
load on the drill and bending the bit as shown in the picture
at the start of this thread.

Have fun,
Eugene