pic: A "Bit" of a problem.

[Andy Baker]

Originally Posted by dtengineering

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

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.

[ebarker]

Originally Posted by Andy Baker

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.

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

[dlavery]

Originally Posted by dtengineering

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

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

[Tristan Lall]

Originally Posted by Cory

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.

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.

Originally Posted by ebarker

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.

Homemade friction stir welding?

[Herodotus]

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.

[t3hroxor]

OH NOES!

[Chief Pride]

Originally Posted by JaneYoung

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!

"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

[robostangs548]

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

[DAN1504]

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.

[akedomakona]

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...

[T3_1565]

Originally Posted by Tristan Lall

Homemade friction stir welding?

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

[eugenebrooks]

Originally Posted by akedomakona

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...

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