Can I buy an answer?

What diameter hole?

Matt

1@ .2244-.2283 with .2264" best size, 1@ .3429-.3469 with .3445" best size, and 1@ 21/32"

Later,

Charlie

Charlie:

Well, I guess that rules out my intended suggestion of using inserted drills. LOL

There should be many companies offering coolant through drills in

11/32" and 21/32" sizes. Although, .2264 might have to be a special grind.

I wish I had through the tool coolant, but I don't. The 3-flute carbides at YG1 are in fraction sizes, or I'd be all over those. My tool vendor is doing the family funeral thing so I can't complain about him being awol.

Later,

Charlie

Charlie:

I guess that trashes my through coolant drill suggestions as well.

Get a chunk of hot-rolled and practice drilling with some 135 degree split point stub length Cobalt drills. For the .2264 size, they make reamers in increments of every thousandth.

He might be able to make good use of a coolant inducing collar Bob. You lose some rigidity but that doesn't sound like an issue given the materials and hole diameters involved.

Tell me more about this coolant inducing collar, John.

And I wish I had time to poke holes in a plate, but I'm far so behind the 8 ball right now I wish I could just curl up and be the shape of the soccer ball I feel like I am right now.

Later,

Charlie

John:

I've used a "through coolant collar" when doing a series of holes using a large power feed manual machine with an inserted drill, (what a messy situation though - even with a makeshift tube guard around the drill). Thinking about it now, that no-doubt qualifies as one of those "World's Flakiest Setups". How would a "through coolant collar" work with the need for frequent multiple tool changes?

They make tool changeable units Bob. The coolant connection is made when the draw bar seats the holder to a block mounted just off to one side of the spindle. You have to make sure the drive key is properly oriented in the tool carousel or the coupler ends up 180 degrees out of position but you probably do that with boring bars already.

Here is a tool changeable High speed milling spindle.

Look here as well.

John:

Not to go into terminal thread drift, but look at this HSK tool holder chainsaw near the bottom of this page. I'd sure hate to be reaching in the machine when that puppy was running and have it's locating pins break. LOL

I don't have a favorite, mostly use small (less then 6-32) form taps for threading.

Scott

Just about any twist drill ought to go through 1/2" plate in one peck. Stub split point, if you're not spotting.

I was going to suggest using Master Drills. They're a straight fluted carbide drill. I use a 3.1mm (.122") to cross drill through a 7/16 round SS part on the Swiss. No spot, almost 4x dia. in one peck.

I buy them from Goddard Rotary Tool, here in Escondido. 760-740-6717 They stock them in fractions and numbers, but can get them in metric sizes.

Sounds like you need them right away, though. Guhring probably is the best source. Did you call them, or try to contact them online? I'd call them. Someone always answers the phone. 800-877-7202

Matt

============= As usual, very good replies/suggestions in this thread.

If this is for a high volume production operation, the following observations may be helpful (but these are from an American manufacturing plant, long, long ago in a land now far, far away).

Based on my observations [I was the SPC study guy] of a very high volume operation drilling forged [and some cast] slack adjuster bodies [big-rig air brake truck part] the drill manufacturer is not the critical factor, but the point [re] grind is, from a total consumable tooling cost perspective. The machine was a PLC controlled rotary index center, with drill bushing fixtures, flood coolant, and gear drive/gear feed [non operator adjustable] drill heads.

Because of production considerations [piece work] there was continual problems with the operators not changing tools on schedule to the point that we had to install a counter that locked the machine, and required supervisor key reset to resume after verification of tool change. The problems caused were not only excessive tool consumption because of extensive rather than touch-up re grind required [to the extent that it was frequently cheaper to scrap the drill rather than take the time to re grind], but the huge burrs generated required extensive/expensive hand re-work.

As I recall, the Peugeot drill point was selected as optimal for this use, but the Bickford and Relcon points were very close and may be better for your application. For what ever reason, we had to discharge several operators for attempting to resharpen their own drills by hand rather than using the supplied Peugeot re-pointed drills from the grind shop (even though we supplied a "kit" to each shift with the required number of sharp prills and a spare or two for the scheduled production). They seemed to feel the points didn't "look right," and indeed the Relcon looks worn out.

We used the Guhring parabolic flute drills with great success. These drills did indeed seem to clear the chips better than other drills. for one source see

FWIW - these drills had #2MT shanks. I still have 2 that I use very seldom because of their odd size [27/64]. We had two drill pointers in the grind shop, an Optima and a Brierly (continual arguments between the operators about which one worked "best"). Both seemed to work very well. The newer computer controlled grinders such as the Darex or Winslow may well be a better value for the money as well as requiring less skilled/experenced operators. The Conic, X and R points may also be an improvement. [All the machines look like a "spicy meatball."] Good luck and let the group know how things turn out.

Unka' George [George McDuffee]

------------------------------------------- He that will not apply new remedies, must expect new evils: for Time is the greatest innovator: and if Time, of course, alter things to the worse, and wisdom and counsel shall not alter them to the better, what shall be the end?

Francis Bacon (1561-1626), English philosopher, essayist, statesman. Essays, "Of Innovations" (1597-1625).

Thanks, George. Your answer sent me down one more track where Guhring led me to Titex. I got feed, speed and depth of cut info which I will utilize for my quote. :-)

Later,

Charlie

Tap drill for 1/2-13:-) Got a drawer full of worn out stub length 27/64 Nachi Cobalt's. One of these days I'll get a drill sharpener:-}

Matt