[jbrookes]

I am drilling 1/8 in. dia. 20XD (2.5 in) depth. I go in with a 1.5 in. cobalt drill then do another 1-1.5 in. with a cobalt parabolic. I have had drill breakage with the parabolic bit. I have been running at 2000 rpm and .001 ipr. I have been pecking with complete withdrawal every .3 inches in depth. One question is, do I need to take drill all the way out, or is a limited peck also effective?

I am looking at coolant-through at this point...Any recommendations in that area welcome, based on experience.

[heathcharris]

i would look at sumitomo carbide instead of cobalt. sumitomo has coolant thru carbide drills up to 20xd. of course i would not plunge in with 20xd i would step it in so you would be looking at 2 drills. it did not say what type of material you are trying to run is it stainless, cobalt based or high carbon? i am assuming it is at least stainless if you are breaking drills.

[ckindon]

.1" pecks. Don't use a parabolic drill.

[jbrookes]

respond to both responses:
yes, the carbides with coolant are way to go. I have a Kennametal, but their tech support is poor, and I wonder how good the $250 drill is. OSG is OOS til 6/15. MA Ford has length of 4 inches, may be too long for machine.

About person who said .1 inch pecks and no parabolic: that sounds right, but exactly how do you peck? What is withdrawal distance? Also, I will look for long regular spiral drills, non-parabolic. Are you negative about para because they are weak?

Thanks in advance
JB

[txcncman]

Parabolics are good...after you get over 1/4" or so. Until then, the helix is too great for effective chip removal, among other factors such as actual strength. It is all about physics.

[keebler303]

You need to retract enough to get the chips out of the hole. If that means all the way out, then you retract all the way out. If you don't retract enough to get the flutes cleaned out, they will load up and bind, breaking the drill.

Matt

[jbrookes]

went to their web site, and saw only short drills. Are you sure they have 20xd?
JB

[dannyboy411]

In my experience, Titex and Mitsubishi make some excellent deep hole coolant through carbide. Titex will go all the way to 70xD. OSG has a new deep hole series out as well, but I haven't had a chance to test them yet. I swear by the Titex simply because their cutting specs are bang on no matter what material I've tried them in. If you run them at the book numbers, they just work. The mitsubishi's I've run will put up with the same conditions, just with a little less tool life.

With the Titex I used to hold +/-0.001" over 30xD at a 3/16" Dia in Inconel. No peck, ridiculous feedrates. Whenever I need a deep hole with a tight tolerance they're the first place I go to. There is a bit of a trick to starting the XL drills, they need a pilot and need to be gently fed into and out of the pilot hole to save your corners. A little more programming than a simple canned cycle, but well worth it.

[ckindon]

MSC Industrial has a good selection of 12xD - 30xD in the 1/8" range. Materials are HSS, cobalt, or carbide. Pricing Ok except for carbide. What material are you drilling? Even in stainless, with conservative feed and peck, full retract, and good coolant concentration cobalt should be sufficient.

[jbrookes]

regarding the Titex recommendation, that's a coolant-through? Must be. Yesterday I spent all day on the phone trying to locate these drills. OSG has them - after June 15. Mitsubishi did not return my email, only way to contact them. Sandvik has one in stock, at $314. Titex was hard to locate. MA Ford, Iscar don't have 20XD.

So I settled for a 1/8 - 20XD Kennametal at $180 - 30% off retail of 257 at MSC. Kennametal is the only coolant through they carry in stock. In general, I like Kennametal carbide quality, so I'm hoping this drill will work.

I would like to get a lead on Titex versions of the 1/8 for future reference... I don't want to spend time pecking with a non-coolant drill, since this is for a mass-production part...Thanks all for the valuable info. Much appreciated. No such thing as a bad opinion in these murky waters...

[dannyboy411]

regarding the Titex recommendation, that's a coolant-through? Must be.

Yes, coolant through. Titex is a Walter brand (which is a sister company to Sandvik). Maybe you can sweet-talk your sandvik rep into finding them for you?

[jbrookes]

walter-titex + Sandvik.... I will try. I got customer service for Sandvik at their location in New Jersey. They referred me to several distribtors who carry Coromant, but don't stock the items..That's not a problem per se, since its all JIT these days...but it introduces a layer of uncertainty, as the supplier may or may not have the item...

[MetalZilla]

Hi,
try this Drill Pecking Calculator: Drill Peck Calculator