drilling a hole 12inches deep???

   / drilling a hole 12inches deep??? #42  
Wish I had seen this earlier: this is exactly what the shop I work in specializes in. A 12" x 2" hole doesn't even warm the machines up good... It would be easier to just buy on-size tubing on this one, but with the right tooling this would be child's play. We can drill up to 40' depending on hole size and allowable runout..
 
   / drilling a hole 12inches deep??? #43  
dwilliams35 said:
Wish I had seen this earlier: this is exactly what the shop I work in specializes in. A 12" x 2" hole doesn't even warm the machines up good... It would be easier to just buy on-size tubing on this one, but with the right tooling this would be child's play. We can drill up to 40' depending on hole size and allowable runout..
Click to expand...
Gun drill I take it? Sure would like to see a picture of that one! I'd also like to see a machining forum added here.
 
   / drilling a hole 12inches deep??? #44  
muddstopper said:
No doubt about it, buying a lathe is the cheapest part of this hobby. Tooling is where the money is. What I found really interesting is just what little amount of tooling is needed for some of the simple things I want to do. Its not so much what you have, but how you use it. I knew you could cut tapers with a Lathe, but I always thought you needed a taper attachment do it, After watching a few videos, I now know all You have to do is spin you compound around and cut from the end. Want to cut a gear, Lock the lathe head and just use a cutting bit to broach out the pattern.
Stuff like this I didnt know before starting this deep hole project,. Oh, I also found out how to make my own boring bar. They say a good machinist can take a lathe and build every part for a lathe. I probably
wont ever get to that level, but I'll practice and should be able to take care of most of my machining
needs.
Click to expand...
Buying my first lathe was one of the best things I ever did. One word of warning though, you will never stop buying tooling for it as long as you own it!
 
   / drilling a hole 12inches deep??? #45  
Mysfyt said:
Gun drill I take it? Sure would like to see a picture of that one! I'd also like to see a machining forum added here.
Click to expand...
Yes, and no: gundrill is a specific process, we do that up to 1.5" or so, anything bigger than that is done with what is commonly referred to as BTA drilling.. The machines for all intents and purposes just look and operate like standard lathes, the only real difference is the means of coolant introduction, and a lot of bar supports, etc. to keep the tool straight. Some do counter-rotating tools as well.

Here's some commercially available machines: Probably a little out of the budget of most farm shops...

BTA Deep Hole Drilling Machines with Ballscrew Feed | UNISIG
 
   / drilling a hole 12inches deep???
  • Thread Starter
#46  
Mysfyt said:
Buying my first lathe was one of the best things I ever did. One word of warning though, you will never stop buying tooling for it as long as you own it!
Click to expand...

I can believe that, I have spent the whole week watching ebay
 
   / drilling a hole 12inches deep??? #47  
Don't forget your local Craigslist also.
 
   / drilling a hole 12inches deep???
  • Thread Starter
#48  
Well, I received the drill bits I won on ebay. The 2inch bit does have the m4 taper , the same as my tail stock on the lathe. With drill in hand, I decided to give this one more try. I have been drilling a little bit at a time because of heat build up. My machine doesnt have any kind of cooling setup. With the 2 inch bit, its pretty easy to keep the chips out using air and just blowing into the hole as I drill. Hole quality just isnt there. I am running the lathe at 98rpms and hand cranking the tailstock for feed. Getting big shiney curls but piece heats up pretty quickly, so after about 3/4 to 1 inch of drilling, I just cut the machine off and walk away. The piece i am working on is pretty much unusable for what I intended to use it for, but I am just playing and trying to learn a little for the next time I run into this situation. I dont mind the time its taking to drill this hole, but I need to figure out why the hole is so rough, not what I am used to seeing drilling smaller holes. I am thinking that I might be running the lathe a little slow and speeding it up might improve the hole, so opinions and suggestions are needed.

I do think that my predrilling the hole out to one inch might have something to do with the poor hole quality while enlarging the hole to 2in dia. I do think next time I need a big deep hole i would try drilling a size or two smaller and then using the boring bar to finish the hole. Thats something I couldnt do when I drilled the hole out to one inch with my current boring bar. A 15/16 boring bar stuck out 12 inches on a rocker post tool holder just isnt too steady.

edited to add, I have seen a lot of large drills listed with a m42 taper, what taper is this, Metric? Do they make a sleeve to adapt from M4 to M42?
 
   / drilling a hole 12inches deep??? #49  
M42 is a grade of cobalt tool steel

you need coolant. The predrilled hole is the way I would go. Never expect a hole with a good finish from a drill that size, especially without coolant.

Get you a sprayer bottle and set it to "stream" and spray some coolant up in there. besides cooling, it keeps a weld from occuring on the edge of your drill due to contamination.
 
   / drilling a hole 12inches deep???
  • Thread Starter
#50  
So M42 is cobalt. Never had a cobalt drill bit, I guess thats supposed to be a good grade?.
Hadnt thought about just trying to spray coolant up in the hole. I have been just backing the bit out and squirting with cutting oil. Got about 9 or 10 inches drilled. I just drill ntil it starts heating up and walk away, but think I will try the spray bottle tommorrow and see how that works. On another note, I misread my lever positions for speed. I was drilling at 33rpms, bumped it up to 109rpm and things look much better.
 
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