Author Topic: Deep hole drilling 101 on lathe?  (Read 22586 times)

Offline PekkaNF

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Deep hole drilling 101 on lathe?
« on: August 20, 2013, 12:27:34 PM »
I got two 10 mm dia 300 mm lenght gun drills. They are well used and sharpened probably to a last useful point. These are for practice.

I would like to learn how to drill holes on spindles. Nothing very exotic and demanding - I only have some tempering steel rod tough.

I have found bewildering amount of info on web, but I'm having hard time finding a practical starting point. Somehow I find plenty of diagrams and then stuff that is such hardcore that I'm having really hard time assesing relevancy.

Wanted: Good practical approach how-to punch deep holes in a domesticated lathe.

Tall order?

Pekka

Offline awemawson

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Re: Deep hole drilling 101 on lathe?
« Reply #1 on: August 20, 2013, 01:17:53 PM »
Start by boring a hole that is accurately concentric, on size, and accommodates a sleeve that is a snug fit on the shaft of your gun  drill. Go at it with the gun drill slowly with plenty of lubricant and withdrawals for swarf clearance.



..... or so I am told .......
Andrew Mawson
East Sussex

Offline NeoTech

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Re: Deep hole drilling 101 on lathe?
« Reply #2 on: August 20, 2013, 01:43:48 PM »
I made a gundrill out of a spade bit,  then used a short hole drill and made a concentric sleeve that sat on the "outside" of the stock to be bored. So that the inner index wouldnt be messed up or you need to cut the oversized part for the sleeve off. But if i think about it i was prob. cheap and bought just enough barrel material. Errgh.. roundstock... Guns is illegal in sweden. ;D
Machinery: Optimum D320x920, Optimum BF20L, Aciera F3. -- I have not failed. I've just found 10,000 ways that won't work. http://www.roughedge.se/blogg/

Offline PekkaNF

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Re: Deep hole drilling 101 on lathe?
« Reply #3 on: August 20, 2013, 02:37:59 PM »
Guns are legal here and I have some of them. No interest of making any, because life is short to learn everything and permits and reviews are a hassle.

But I have in making some small auxiliary spidles and some grinding spindles... serious case of  :proj:

Most stuff needs hole for drawbolt, nice concentric hole would be nice on high speed (hobby high speed) spindles.

Never thought too much about drilling on the lathe, until broke too many drills in one seating trying to punch holes on tempering steel shaft...that still haunts me.

I'm going to drill start hole, ream it and start there. I also can find cutting oil pressure and demand charts, also some feed info. Also pictures of various setups (most professional and outside of my equipment and reach). I can afford breaking two gun drills before learning or giving up. :bang:

Pekka

Offline chipenter

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Re: Deep hole drilling 101 on lathe?
« Reply #4 on: August 20, 2013, 03:27:42 PM »
I replaced my lathe spindle and made a d bit 16mm dia , the only problem was heat build up as it got hot it would bind in the hole , and it heated up faster than it cooled .


Jeff
Jeff


Offline unc1esteve

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Re: Deep hole drilling 101 on lathe?
« Reply #6 on: August 20, 2013, 09:44:24 PM »
You Tube

   


   


   


« Last Edit: August 20, 2013, 10:23:03 PM by dsquire »

Offline unc1esteve

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Offline PekkaNF

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Re: Deep hole drilling 101 on lathe?
« Reply #8 on: August 21, 2013, 03:25:14 AM »
Thank you very much Steve,

That PDF was very much spot on info I was lookking for. I probably could not find it, because I was bypassing all stuff about guns - because I'm not making one. Logical or not, but that was pretty much I should have been lookking. Drilling lubrication holes on marine diesels is not easily converted to garage level application.

The info I got made me feel better. My application should be whole lot more simple, because I need whole lot shorter hole and I'm not going to load this one. This is going to be interesting  :coffee: reading some time and then a little bit of application  :zap:

The only thing I'm worried about is the spindle material. I have very little free machining leaded steel (and dimater is too small) and pretty much the only right size material I have is mystery tempering steel that eats my convetional drills...although turns beatifully with inserts.

But one step a time.

Thank you,
Pekka

Offline PeterE

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Re: Deep hole drilling 101 on lathe?
« Reply #9 on: August 21, 2013, 10:17:48 AM »
Would it be possible to grind a masonry (concrete) drill to a suitable angle and use that together with a suitable sleeve? In that case you get a carbide tip that well can handle tough stainless.

BR

/Peter
Always at the edge of my abilities, too often beyond ;-)

Offline Lew_Merrick_PE

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Re: Deep hole drilling 101 on lathe?
« Reply #10 on: August 21, 2013, 11:16:11 AM »
Pekka,

A true gun barrel drill is designed to drill extremely deep holes with very tight tolerances on diameter and straightness.  The business end actually burnishes the bore and has enough contact area (diameter X length) to keep if running straight and true.  They usually contact around 270 of the hole's periphery to achieve this.  The primary "secret" of a gun barrel drill is that the point is located exactly on 1/4 of the diameter such that the side-acting cutting forces are balanced.

It seems like overkill for a drawbar clearance hole to my way of thinking.  I drill 30:1 (depth:diameter) holes with fair regularity using only bell hanger twist drill bits.  So long as I keep the cutting edges sharp, I can drill such holes with no more than .010 inch (0.25 mm) wander when making gas passages that are typically .094 inch (2.4 mm) diameter X 3.75 inches (95.25 mm) deep in Rc 35-40 4130 steel.

???

Offline PeterE

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Re: Deep hole drilling 101 on lathe?
« Reply #11 on: August 21, 2013, 02:59:46 PM »
Pekka,

How deep is the hole you want to drill? If you look into my thread about the pin vice I show that I drilled a 3 mm hole 90 mm deep and it came out well centered in the other end. I did that using a combination of center drill, ordinary jobbers drill and an extra long jobbers drill.

To be fairly safe I used new drills to be sure the points were correct.

/Peter
Always at the edge of my abilities, too often beyond ;-)

Offline PekkaNF

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Re: Deep hole drilling 101 on lathe?
« Reply #12 on: August 21, 2013, 03:08:33 PM »
hank you.

Actually with that material I have tried many methods. Peck drilling  was no-go, work hardening does not work well..Some resharpened SDS long masonry bits worked somewhat, but after it started to chatter, tip chipped and rest you know. Some HSS-co twist drills seem to work and the short trough cooled drill was the only one that worked fine. I would be fine with 25x, if can drill on one go.

So trough cooled twist drill or something else...then gun drills wandered my way 20 apiece and I tought that it might be worth of finding out...I need pressure pump, holder and such anyways.

There are some other drawbacks and unknowns on this gun drills anyway, like if I read it right that it is not ideal if the material tends to make long continuous curly swarf and that is what I have.

Still some  :coffee: to go.

Pekka

Offline unc1esteve

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Re: Deep hole drilling 101 on lathe?
« Reply #13 on: August 21, 2013, 04:56:53 PM »
Pekka,
My need for deep holes was several.  A #46 hole one and one half inch deep and a .2180 hole 13 inches deep.  I had bought a metal bench that had an old Atlas lathe attached to it.  Missing parts, needed a lot of work.  I was going to use the bed for something else until I took a close look at it.  It was in good shape so I took it apart, replaced the missing parts, cleaned, repaired and painted it.

I added a variable speed DC motor and changed the pulleys to achieve 4000 rpm.  I checked with Timken, the maximum rpm for the bearings with oil is 7200 rpm.  I added a variable DC motor to the lead screw so I could slow down the feed rate.  I made a collet system to replace the chuck.  (This was also deep hole drilling.  Step drilled from both ends, then reamed).

I made a pressure vessel to supply air and coolant like the Sterling unit.  I then added a high pressure pump from a small pressure washer to increase the coolant pressure.

I purchased some carbide 'v' with a through coolant hole from EBay.  I bought some 'v' tubing from Drill Masters.

I hard soldered a gun drill the length I needed, 18 inches.  Ground it to size on the lathe and the T&C G.

Hooked everything up and that is where I stopped.  I have a few details to finish.  I have not made a test hole as of yet, other things got in the way.  One thing I am having trouble with is to keep the solder out of the coolant hole.  I purchased some anti-flux and have been doing some reading.

The material I am drilling is 4140.  I am going to purchase some stress proof before I continue so I can see which is better.  I believe the stress proof will be.

The long, curly swarf is to be avoided.  It will jamb and destroy the gun drill.  The higher the rpm, the slower the feed rate, the smaller the chip, the more success.

Long term project.

Offline PekkaNF

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Re: Deep hole drilling 101 on lathe?
« Reply #14 on: August 22, 2013, 01:33:34 AM »
Good work you have done with your drilling machine.

Thank you, you gave me some really good info.

My needs and drills are not that long, the two drills I have are 10 mm dia and about 350 mm or so, to make 300 mm long hole max. Should have done my reading first :doh: Pressure of the cutting oil didn't surprice me, but rpm of the blank did. Alhough I have one extra lathe body to experiment....but do I want to use time and effort to do it? Great learning experiment no doubt.

I read deep drilling parts of the linkked PDF and had some hard time trying to figure out tables and other numerical values that were missing units. Like "500 lbs" sounds to me more like force and not pressure....One table had oil volume, but not units etc....but reading the text of someone doing the production did give some pointters. Later on there was really nice chapter about drilling and reamin and plenty of general machining info. Halfway of the manual many pictures seem to be missing, but that is no problem here.

I'm going to track down the orginal drill makers data for this drill to see recommendations, that should give me pretty good idea viability of my idea.

Pekka

Offline PeterE

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Re: Deep hole drilling 101 on lathe?
« Reply #15 on: August 22, 2013, 12:59:25 PM »
Interesting subject this.

Just a question, why not step-drill? I mean that one starts with say 6 mm for 50 mm or so, change to a 10 mm and drill 40 mm, then chjange back to the 6 mm who now get guidance from the 10 mm long 6 mm hole, but is not affected by the 40 mm long larger distance. That way I guess that the load on the thinner drill becomes much less and the problem with heating is lowered.

Also by changing drills there will be a natural time for cooling both the workpiece and the drills.

Then the last question; Why not drill to a bit under final size and then bore the rest? That will of course demand that your lathe is long enough  :palm:

BR

/Peter
Always at the edge of my abilities, too often beyond ;-)

Offline PekkaNF

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Re: Deep hole drilling 101 on lathe?
« Reply #16 on: August 23, 2013, 02:14:15 AM »
The crux of the mater here is that I don't have available easy maching material to make spindles with holes. This material is bit of trouble. On the other hand is's nice to make axles and such. External turing works fine. The touble is only with internal turning or drilling a (relatively) long hole. I have tried several methods with warying decrees of success.

I have got this temprering steel bars from 12 to 25 mm dia and I can buy larger ones in cut length. I have a nice 40 mm dia and 30 cm long for one project. The good (and very important news for me it is that there is plenty of it and I can get always some more). The trouble is that I find it very hard to find anything easier to machine bar here. There are some mystery metals on junk yard and I have bought several bars these mysteries and after a little while I have found out why they were reject. Best gues machined beautifully, but had some inclusions on it. Broke a insert very few minutes....some were gummy and some bent after turnig them then bet other way when drilled. Some turned ugly no matter you tried...

It's 34CrNiMo6 to me, these are other names for same stuff (or close)
4340
817M40
En24
 
Some of the bars are rolled some bright, but all are in tempered state.

Very nice for external turning and works fine for short drilling (I have drills that eat this no problemo).

BUT: This material tends to make very long stringy swarf and it is workhardening and pretty tough. Therefore any peck drilling does not work. I get few pecks pretty ok and then one that will squal like pig.

Also smaller the drill, nastier it get's do drill long hole. It is easier to get a 10 mm 160 mm long drill than 6 mm 160 mm long drill that takes the beatting. Although I must say that if I had a 6 mm drill of 200 to 300 long that would make a pilot hole I would be very happy to use one and then feed 15 bar coolant trough it and use cheaper long 8 to 10 mm drill for final hole. Pretty good indication of this how drills are rated often something like 3xD or 5xD that means that lenght is 3 or 5 times the diameter.

It's pretty nicely explained here:
http://www.unisig.com/gundrilling-education/deep-hole-drilling.php
http://www.unisig.com/drilling-videos/deep-hole-drilling-101-video.php

Pekka

Offline unc1esteve

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Re: Deep hole drilling 101 on lathe?
« Reply #17 on: August 23, 2013, 08:56:03 AM »
Pekka,

Do you have an hydraulic cylinder repair shop near by?  The cut offs and bent pieces
in the rubbish can make good project material.  The bars are usually 1045.
The chrome turns off with carbide tools.  You can also purchase new material
but in larger sizes than 13mm.  It seems you need stress proof steel.

http://www.homemadetools.net/deep-hole-drill?gce=tab50&utm_expid=57824293-7&utm_referrer=https%3A%2F%2Fwww.google.com%2F

http://www.practicalmachinist.com/vb/search.php?searchid=1484507

http://bbs.homeshopmachinist.net/search.php?searchid=763358

Offline PekkaNF

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Re: Deep hole drilling 101 on lathe?
« Reply #18 on: August 23, 2013, 02:47:37 PM »
Pekka,

Do you have an hydraulic cylinder repair shop near by?  The cut offs and bent pieces
in the rubbish can make good project material.  The bars are usually 1045......

THANKS! I was really thinking hard to find right kind of second hand material...never thought of hydraulic cylinder rods. I can find the material used or even "new". I'll check it first weekday. Hmm....what kind of material is the tube? I'm going to check one junkyard and find one to test.

Pekka

Offline NeoTech

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Re: Deep hole drilling 101 on lathe?
« Reply #19 on: August 23, 2013, 03:38:33 PM »
Was more kinda in the lines of this i was talking about.. the "drillhead" holding the spade bit can be mounted onto a thinner rod for making it longer, guides and strong materials is needed though. Unless you are just making a short hole. =)

Machinery: Optimum D320x920, Optimum BF20L, Aciera F3. -- I have not failed. I've just found 10,000 ways that won't work. http://www.roughedge.se/blogg/

Offline shaddr3

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Re: Deep hole drilling 101 on lathe?
« Reply #20 on: June 27, 2014, 10:07:28 AM »
I joined the forums mainly because of this thread, and found quite a few more interesting threads. I apologize for bringing up an old thread, but wanted to know how this project went. I found unc1esteve's email to ask him about his progress.
I'm trying to attempt the same with my lathe. I'm looking at a bore diameter of .4375" at 36.5:1 in 6061 aluminum.

Offline PekkaNF

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Re: Deep hole drilling 101 on lathe?
« Reply #21 on: June 27, 2014, 12:18:06 PM »
I haven't got much further, BUT this week local machine tool shop is a sale on MT taper trough cooled extra long spiral drills. My holiday just started...I'm planning to go there, buy few drills and give it a try.

I'm wondering would side feed (after the MT-taper) or trough MT-taper.

Also I have been making half assed effort trying to find better material.

Pekka

Offline shaddr3

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Re: Deep hole drilling 101 on lathe?
« Reply #22 on: June 27, 2014, 01:20:00 PM »
What is your longitudinal feed on your lathe?

Offline PekkaNF

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Re: Deep hole drilling 101 on lathe?
« Reply #23 on: June 27, 2014, 01:49:21 PM »
What is your longitudinal feed on your lathe?

Uuh...Tail is on manual crankking...pretty well when swarf looks right, but that is really not acceptable because tail stock stroke is way too short.

On cross slide I have normal lathe feeds. I have got some results with spiral drill when feed is 0,10 - 0.15 mm/r.

Tempering steel is very nice for shaft/spindle, but it's pretty hard in tempered state, work hardens and produces very long swarf - hard to drill well. Turns really nice with lot of speed with carbide though.

What are you making? Milling, drilling or grinding spindle?

Pekka

Offline David Jupp

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Re: Deep hole drilling 101 on lathe?
« Reply #24 on: June 27, 2014, 02:21:23 PM »
For really deep hole drilling, the cutting bit is revolved as well as the work, and lots of lubricant fed to the drill tip to flush out the swarf.  I'm aware of a shop in Austria that can drill to 17m  for hole size around 2", but that does come down a lot as the hole size reduces.