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beanbag
07-20-2009, 04:53 AM
Looking to drill a hole thru a hardened steel rod. Don't know what the material is, but it feels like around a grade 8 bolt hardness on the inside. The outside is case hardened, but I won't drill thru that, so it doesn't matter. It is a piston shaft for a shock absorber, if that helps any. It has a main section that is 14mm diam for about 9 inches, and then a thinner section 8mm for about 2 inches. I need a hole all the way thru, but probably no wider than .1" or .125" in the thin section (for strength), and I don't really care what diameter in the thicker section, as long as the two holes meet up. I want to run wires thru the hole, so they don't have to be perfectly concentric, nor have a good surface finish.

I want to try doing this on a lathe, and don't have a high pressure coolant pump, so I probably shouldn't use a gun drill.
I have done some reading, and some suggestions I ran into include starting the hole with a ball end end mill, and then doing lots of little pecks with successively longer drills.

Some questions I had are:
Is a long HSS drill good enough, or do I need something harder like cobalt?
I believe the drill should have a short flute length?
What diameter drill should I use for the thicker portion of the shaft?
What should I do if the hole starts getting crooked halfway thru?
A good way to make sure the ball end mill starts exactly straight and on center? I was going to put it in a drill chuck that fits into the tail stock, but that doesn't seem like a good idea.

One problem is that the material seems to really work harden. I have a sample of the rod where it was snapped off in the middle (probably due to some horrible accident), and the texture of the material looked like concrete and a file would bounce off of it. Once I ground some away with a grinder, then the file would start to dig into the material.

I took the sample to a gun driller, and he said that he could "try" doing it. He wasn't sure, due to the suspected hardness of the material. I think he offered to do $150 for all 5 or so shafts I had. Am I better off just handing the job to him?

Thanks

macona
07-20-2009, 05:48 AM
I have cut through shafts from shocks with a regular bandsaw. They are ground and chromed but as far as I can tell they are not hardened.

So you should be able to use any standard drill. If you are drilling deep I would suggest a parabolic flute drill from someone like Guhring. A cobalt version couldnt hurt.

Use a spotting drill to start.

Rustybolt
07-20-2009, 08:19 AM
No matter if it's hardened or not, start with a center drill, and then the stubbiest drill first. Increasing the length of the drill as the hole gets deeper. make sure the drills are acurately ground. And, yes, peck drill, being carefull not to load the drill. Needless to say use a lot of coolant and as you go deeper retract the drill all the way out.

wierdscience
07-20-2009, 08:59 AM
Shock rods come in two flavors chrome rod which has a thin case under the chrome and a realitively soft center.Then there is Nitro bar which is nitrided 1045,it usually starts off at 38-40rc and then it's nitrided.

Either should drill,just the nitro bar will be tougher.So long as the drill is started on center and the correct speed is used a normal good quality HSS bit should drill it.

I would use coolant and don't let the drill bit dwell in the cut.If it's allowed to dwell work hardening will happen.

J Tiers
07-20-2009, 09:45 AM
No matter if it's hardened or not, start with a center drill, and then the stubbiest drill first. Increasing the length of the drill as the hole gets deeper. make sure the drills are acurately ground. And, yes, peck drill, being carefull not to load the drill. Needless to say use a lot of coolant and as you go deeper retract the drill all the way out.

OK, but do NOT use a center drill.

Use a spotting drill instead. It makes a dimple that the following drill can use, not a hole that will throw it off-line.

IF you make only the DIMPLE with a center drill, a properly ground lathe cutter, a suitable piece of flint, or whatever, that may be OK. Just don't get a cylindrical section going, and definitely do not drill deep enough get into the center cone.

Evan
07-20-2009, 10:32 AM
Start the hole with an ordinary centre drill or spotting drill if you have one. Then use the largest bit you are going to use and drill until the flutes are nearly buried, clearing the chips often. Then go down a few sizes and drill no more than a half inch or so. Go back up to the larger drill bit and drill out that half inch. Repeat. This gives room for chips when using the smaller bit and reduces the chip load on the larger bit. That is the biggest problem and what also causes the bit to wander. It's tedious but clear the chips very frequently and use plenty of oil. Do not bury the flutes on the smaller bit, that will cause the bit to wander as the chips pack unevenly. The large bit will follow the hole of the smaller bit.

Drill slightly over half way, reverse and repeat.

Stainless steel, 12" x 1" hole with a reduction to 3/4 near the far end. This took all day.

http://metalshopborealis.ca/pics5/lathepart1c.jpg

Paul Alciatore
07-20-2009, 11:57 AM
Have you considered EDM?

beanbag
07-20-2009, 06:28 PM
Have you considered EDM?

I just called around. It looks like it would work "for sure", but the cost is about $150 EACH.

beanbag
07-20-2009, 06:48 PM
Start the hole with an ordinary centre drill or spotting drill if you have one. Then use the largest bit you are going to use and drill until the flutes are nearly buried, clearing the chips often. Then go down a few sizes and drill no more than a half inch or so. Go back up to the larger drill bit and drill out that half inch. Repeat. This gives room for chips when using the smaller bit and reduces the chip load on the larger bit. That is the biggest problem and what also causes the bit to wander. It's tedious but clear the chips very frequently and use plenty of oil. Do not bury the flutes on the smaller bit, that will cause the bit to wander as the chips pack unevenly. The large bit will follow the hole of the smaller bit.

Drill slightly over half way, reverse and repeat.


That's an interesting idea. But doesn't it also mean that the smaller drill is un-supported along most of it's length while drilling? And also that the smaller drill will not be started on a "properly spotted" (or whatever you call it) point? It seems like an opportunity for the smaller drill to wander. But maybe the larger drill uses it's support to straighten it out?

Also, when you pull the small drill out, won't it leave bits of chips along the bore?

Evan
07-20-2009, 07:22 PM
The smaller drill and the larger drill have the same cutting edge angle I presume. The smaller drill doesn't need to be much smaller, your stated .125 and .100 will do nicely. As long as the drill is properly sharpened so that the edges both cut the same chip load AND it isn't pushed too hard it won't wander unless there are varying areas of hardness in the material. That is also why I suggest only drilling 1/2" at a time. Blow the chips out with air each time you clear the hole. Wear your glasses.

Rich Carlstedt
07-20-2009, 07:24 PM
A ball endmill will give you the straightest start for a drill of the same size. because you can enter the material sufficiently ( 1" ?) to give the drill Flutes ( not tip !) total support

In order to drill straight, you need to turn the workpiece, not the drill
The difference in accuracy is 10 to 1

The proper drill for the second operation requires that its "web" be no bigger than the prior hole diameter . This give freer chip flow, and reduces web forces

Rich

Fasttrack
07-20-2009, 07:37 PM
Did I catch that right? A .125" hole for 9"? I think I would think long and hard about using different material, even if it meant I had to buy it.

I guess, like you say, the accuracy isn't too important but it would still take quite a bit of time. I've done some deep holes in the >.5" range and, like Evan says, it soaks up a lot of time. At least it does for me... :)

Rich Carlstedt
07-20-2009, 07:58 PM
A gun driller can do it in about 9 minutes
He will probably be looking at 2 hours due to chip clearance and repetative cycles

Rich

JCHannum
07-20-2009, 09:18 PM
It is not a 9" hole, it is two 4-1/2" holes if drilled from either end. With the speed sufficiently high, drilling with the lathe should not present a problem. A well centered, straight starting hole is the secret. I usually only feed in one or two diameters at a time.

It should not be necessary to drill two diameters with a hole this small, it might in fact create problems to do so. If going to a larger size, step drilling can help, but the usual cautions for step drilling apply.

If anyone wants to drill some small diameter deep holes, I have a pack of #73 (0.0240") aircraft drills, they are 4" long.

beanbag
07-20-2009, 09:35 PM
A ball endmill will give you the straightest start for a drill of the same size. because you can enter the material sufficiently ( 1" ?) to give the drill Flutes ( not tip !) total support

Rich

I don't know of any long 3/32 ball end mills, so then I'd have to use 1/8, which is on the larger side of my preferred hole size. Maybe it is still ok. But it seems that unless the end mill is mounted EXACTLY straight and on center, it will end up making a bigger hole.

tattoomike68
07-20-2009, 10:16 PM
High RPM is key, I would not lock the tailstock just oil the ways and shove it in and pull it out and go easy on entry. just like pounding on the ol lady. :D

beanbag
07-21-2009, 05:41 AM
Also, what if the tailstock is not exactly centered or pointing straight forwards, due to cheapo drill chuck taper fit into tail stock body. And general all around crappiness.

Evan
07-21-2009, 06:00 AM
Then expect crappy results.

macona
07-21-2009, 06:14 AM
You can always make a holder to hold the drill in the toolpost. You might be able to get better alignment than you bum chuck.

beanbag
07-21-2009, 06:23 AM
Well, it's not my lathe, but what are some of the things I can do for tail stock de-crapification? I suppose I could look into alternate drill holding configurations and machine alignment procedures. Or take it to the gundriller.

JCHannum
07-21-2009, 09:00 AM
You can indicate the drill or a drill blank with an indicator mounted on the lathe spindle. The T/S can be shifted side to side or shimmed to raise it to dial it in.

Hardened drill bushings are used to locate and guide drills in jigs. You might consider making a hardened guide (think some sort of cap turned up from drill rod and dead hard) attached to the end of the rod to center the drill bit and reduce flexing.

beanbag
07-22-2009, 07:24 AM
Thanks for the suggestions so far.

Today, I went to buy a couple of drills, and intend to "practice" on a steel rod to see how that goes. The salesman/former machinist was against the idea of step drilling, saying something about how a drill is not designed to cut at the very edges only, and that it would wander around. I can buy Evan's points about the reduced chip load advantages of step drilling, but what are some of the drawbacks?

The salesguy also showed me a very long 1/8" end mill, like 3-4" long, a.k.a. end mill on a stick. I didn't even know there was such a thing. That got me thinking that this might be a good tool to re-straighten out a hole that started going crooked. Would this work? And if so, should it be a ball end or straight end, long or short flutes?

Again, this seems like a case where there is a naively easy way to do something, and then the much harder and proper way to do something.

Rustybolt
07-22-2009, 08:21 AM
On a hole that size , just drill to size. The important thing is to center drill first and take your time and not crowd the drill. Use plenty of coolant. Patience is the key here.

If you use an endmill there is a very good chance it will snap, being more brittle than a drill bit.

This has been done before. It isn't rocket science.

JCHannum
07-22-2009, 08:22 AM
The salesman is correct. With a larger diameter hole, pilot drilling the hole with a drill the size of the final drill's web is OK, but with this small of a hole, one pass is best.

The extended end mill might offer an advantage, it is up to you to decide if the cost justifies it's use. I would use a stub length drill to start the hole and use progressively longer drills that are good quality and sharp myself, but that is me. Once a well centered hole is started, peck drilling to keep the chips from building up and a good cutting fluid should do a good job for you.

As an aside, stick with your tool supplier, it sounds like you have access to a good one. That is one of the advantages of dealing with a local, professional tool supply over mail order or Harbor Freight, you will deal with people who know what they are talking about.

beanbag
07-22-2009, 08:58 AM
One last question for now:

Coolant or oil?

recoilless
07-22-2009, 03:08 PM
I was just reading "War Baby" last night, specifically the section on the method used for drilling the 3"-4"x 5/16" dia. hole on side of M-1 carbine receiver for recoil spring guide. This was a challenge to the machinists of the 40's, at least the ones doing work for Inland, Underwood, Winchester, etc.
The hole was drilled at 5/16" of depth at a time, slightly undersized, then reamed for final diameter. I believe that lard oil with soda was the drink they fed the drill. I don't have the book in front of me at this time. The work was performed on a drill press and took about 4 minutes per hole.

I hope this is relevant to today since a lot of machines we (I) own are of the same vintage as those used in 40's. I doubt lard/soda is used much anymore, but methods could be similar. Then again, the absolute accuracy of this particular hole might not have needed to be as accurate as what you are looking for, just needed to be proper depth and leave enough metal around hole to have strength.

Good Luck, Paul

Rustybolt
07-22-2009, 07:19 PM
One last question for now:

Coolant or oil?


If you have flood coolant or oil, use it. I use a brush dipped in oil to clean the drill after it is withdrawn and a small squeeze or spray bottle of cutting oil for the hole. Each time the drill is withdrawn.

I don't know if this has been mentioned before, but rule of thumb is; first pass 3 to 3 1/2 times the diameter of the drill deep. Second pass , twice the diameter of the drill deep. Each subsequent pass no deeper than the diameter of the drill. parabolic drills might make it a little easier, but on a hole that deep, not much.

Tune your radio to your favorite station, take a leak, and have at it.

tattoomike68
07-22-2009, 08:15 PM
One last question for now:

Coolant or oil?

If you have a coolent pump shoot it down the hole as hard as you can, add some guards to hold the coolent in the machine. (sheet metal, cardboard, old rubber belting. fab up something with angle iron and vice grips and whatever you can find)

The 1/8" hole will need lots of RPM even in hard steel, I say 1,000 RPM minimum. 2,880 is the rpm for mild steel so 1,000 RPM is a moderate speed for harder steel. Go much slower and you will just break bits.

The rule is if you burn a drill up you are going too fast, if you break the bits you are going too slow.

parabolic drills do deep holes real nice, pay more and get those.

good luck.

Rich Carlstedt
07-23-2009, 03:05 AM
You can buy 3/32 ball endmills.
The endmill will not straighten out the hole, it will break.
If you have runout that creates eggy holes, you need to fix that !
First off
To do any long hole work, the setup must be exceptional..period !
If you have a crappy lathe or your tailstock is not alligned to the spindle centerline, then you must do the following to create a tool holder which is deadnuts center matched to the spindle !
Decide on the size you will drill, ie 3/32"
Mount a "soft" flat center in the tailstock.
Note: You could take a surplus center, and cut off the bullet point, and weld a 1x1x1" steel block to it.
Lock the tailstock quill.
Mount a 3/32 ball mill in the headstock spindle chuck with a drill head or your 3 jaw.
Be sure it runs true.
Slide the tailstock into the ballmill and start the hole in the steel block.
Do NOT USE the tailstock ram ! Slide the tailstock on oiled ways
Finish drilling with a 3/32 drill to 3/4" deep
Note the position of the tailstock ram extension and mark it. Also mark the "block center location to the ram with a paint mark on both pieces.
Remove the block and drill/tap for a setscrew .
remount the block in the exact same position ( Both !) with the quill locked !
You now can drill work and be assured the drill is perfectly centered to the work piece, as the block becomes a "Chuck" to hold the drill or endmill

Rich

beanbag
07-23-2009, 03:15 AM
Great idea. Any reason why I couldn't do a similar contraption and mount it to the tool post/carriage?

For example:

mount a block in the tool holder.

Drill, using the headstock, two holes in the block: one as the drill holder, and one as an "indicator" hole.

Take the block off, and drill and tap a set screw hole on the mill.

Put block back on toolpost, use a center finder in the headstock to re-indicate.

tattoomike68
07-23-2009, 03:29 AM
Dump the dumb ass idea of the ball end mill, thats just dumb as $hit.

A spot drill does the job/:rolleyes: pock the end and nail it. Ball end mill? whos dumb idea was that? thats freaking dumb as hell.. Oh man thats just funny as hell.

Carm
07-23-2009, 07:34 AM
Rich Carlstedt gives good advice, well seasoned. True, he's not given to rhetorical outburst.
Whatever grabs yer tool, bud.

JCHannum
07-23-2009, 10:33 AM
I had not heard of using a ball end mill for starting a drill on center, but if Rich says it works, you can count on it working. I am sure Rich can also give a very cogent explanation of why it works without resorting to profanity or insults.

Thanks for the tip, I and others appreciate these tips. It is a shame that we have to put up with the "contributions" of a few others to gain them.

Rich Carlstedt
07-23-2009, 05:00 PM
I think Mike, You should look at what other people do to perform good work before you shoot off.
There are many ways to skin a cat, and we can learn everyday
If you have a better way, explain it ?

Let me explain my way, with things I have done

Here are two pictures of a small die we gundrilled back in 1986
The 4 foot gundrill at .750 diameter had to be within .015" of "true" center when it exited 38 inches later ( Mat: 4140 Rc 28-32)'
Some of our dies were even bigger.
For fellows not familiar with Gundrilling, when you turn your workpiece as a regular gundriller does, he can hold errors to .00075 per inch.
When the workpiece is stationary, it ain't easy .
SO everything must be done to ensure accuracy of drilling
What you see is the setup I made (this is not commercial !) inorder to do this.
Thats a 25 HP high pressure pump in the background. We are running 2,000 PSI at about 8 GPM. The chip collecter is a SS Sauce pan I stole from my wife and modified it with a 3" plastic hose adapter to carry away the HOT (160 F) oil and chips. We feed at .001 to .0015 IPM at 800 RPM using a 20 HP Spindle on a 5 Inch Bar. We were NOT a gundrilling house, but Die Makers
To start the process, the machinist starts the hole (.750" d) and goes in about One to two inches, then he withdraws and puts the gundrill on the spindle. he can then follow through with the hole. Whats important is that the starting hole (Ball Mill) and the drilling occurs without any change in setup, only one axis moves ! ( critical for accuracy !)
Remember this fellows, reamers give you great size control, but no direction control, and drills follow the line of least resistance.
What about endmills you ask ? well if you look carefully, they have a negative rake on the flute ends,
that actually can cause a "wondering at start" , not good. If you need a flat bottom, use a Ball first then follow with a endmill and its flutes will then be guided by the walls..

Center drilling works in a drill press Mike, but has little assistance for deep hole drilling when starting, because drills can behave like licorice sticks
You need rigidity , accuracy and tolerance control.
It is VERY seldom you can take a brand new drill and have it make a good size.
They wobble due to manufacturing issues, the more pressure they see, the more they "Wrap Up" and that means wiggle and angular deflection.
Yes, a heavy duty spotting drill is good, but I want you to think about this one issue --What keeps a drill straight? The point ?
but the point can easily be deflected !
If you look at the very tip of a drilled hole, you find a flat spot ..magnify it Mike.
That flat spot does not occur in a ball milled hole, as a Ball Mill is custom ground so all flutes cut evenly, and in fact THEY BALANCE ONE ANOTHER, which drill flutes DO NOT DO.
The result is a straight and to size hole FOR STARTING a long drill
By having the start hole, You give the flutes support, NOT THE TIP, and this insures a more accurate result for deep hole drilling
http://i273.photobucket.com/albums/jj220/StationarySteam/Shop%20Tools/TwoMeter3LayerDieonGundrill-1986.jpg
http://i273.photobucket.com/albums/jj220/StationarySteam/Shop%20Tools/P4230182.jpg

FYI
The parts we did ranged upto 12,000 pounds and all had a 16 or better micro finish. Our deepest holes were 42 inches

Rich

Rich Carlstedt
07-24-2009, 01:02 PM
Just got a email over this issue

Quick Reminder,:
For the effects I mentioned, a Ball Endmill for starting must be the same size as the desired drill size,
not smaller, or larger !
This is very important

Rich

Rustybolt
07-24-2009, 03:29 PM
just drill the hole already.

PatTheRat
07-28-2009, 10:44 AM
Very informative thread.

Rich-

I make dies that are 2.375 long out of 7/8" steel of an unknown alloy (not hardened), that I have to drill a 9/16" diameter hole 2.250 deep in, then I swap ends and drill a .413 small hole on the backside.

I have to drill many of these on an on going basis. After many attempts with various feeds and speeds and drills on my old 11" Logan using the tool rest, I was blessed with a Hardinge chucker for next to nothing, and I added a flood coolant system. Still my holes are off center a few thousands sometimes (machine/bit lined up dead on) which doesn't effect the overall function, but I want to get it closer.

I've been using a #5 center drill, then a Melcut 11mm 3 flute solid carbide drill (4" long) peck drilling the entire depth with flood coolant shot in the hole as high on the pressure as possible, pulling back frequently to remove chips. I use this 11mm as I bought 2 dozen in an auction, and it drills nicely.

Then I use a 1/2" end mill, then 35/64 HSS drill, and finish with a 9/16" reamer. The last 3 steps go very fast and are easy on the bits.

Could my problem be the #5 center drill start? I've tried spot drills of various angles and sizes with no noticeable improvement over the center drill.

The closest ball end mill I have is 1/2".

What would you suggest to improve my start?

PatTheRat
07-28-2009, 10:48 AM
If a ball end mill start the exact 11mm size would be the ticket, how many flute and how deep? I can get a 2 flute carbide usa made.

Rich Carlstedt
07-28-2009, 02:01 PM
Pat
You want a 4 flute 11 mm if possible as it is more stable (stronger, less deflection) than a 2 flute.
You need to go in deep enough so that at least a flute cuts where a previous flute was located.
For example, on a four flute, say the helix angle requires a 2 inch length for one full turn. That means 1/4 of the turn is where flute overlap starts to occur and this would be at 1/2" ( 2/4= .5") now you can't consider the ball portion, and it must be added, so if you have a .25 radius (1/2" BEM), you need a minimum of .25 +.5 = .75" depth for this to occur-minimum !
Sorry if it sounds complicated, but to achieve accuracy requires work.
It never falls from the tree !
The trouble with fours versus twos is more frequent chip cycles
You can try a two, but need to go deeper per above flute overlap
so time may be equal when done
Back Later, I have to run now
Rich

PatTheRat
07-28-2009, 05:44 PM
Not complicated, and I fully understand.

THANK YOU...!!!

tattoomike68
07-28-2009, 08:05 PM
So what good is a ball end mill? its not a spotting drill. thats a dumb ass Idea.

go to any production shop and you wont see a ball endmill as a spot drill thats just dumb as hell and you better know it, you will be laughed out of the shop.

goofballs and thier dumb ideas.. :rolleyes:

PatTheRat
07-28-2009, 09:41 PM
If a ball end mill will cut a perfect concentric start hole, and guide hole by diameter, it seems to me it has done what a spot drill start cannot do. Personally, I have not had good luck with spot drills. I've had better luck with end drills.

I think the idea is worth a shot. My problem is I can't find a 4 flute 11mm at a reasonable cost.

Rich Carlstedt
07-28-2009, 10:12 PM
Pat
A little confusion.
You have a 9/16 hole in one end, and a .413 in the other.
where do they not allign?
Is this for a Piston and rod perhaps?
Are you talking about C/L misallignment ?
I see the .413 breaking into a C'bored hole ?

Are you limited in stroke ?
I would consider a stepdrill with .413 diameter tip and a 35/64" body
Also consider having a custom ground ball mill .413 made
You would ballmill it, then stepdrill, then ream.
No other tool changes and no end for end swapping

Melin's are great mill cutters !

Rich

beanbag
07-29-2009, 04:43 PM
If a ball end mill will cut a perfect concentric start hole, and guide hole by diameter, it seems to me it has done what a spot drill start cannot do. Personally, I have not had good luck with spot drills. I've had better luck with end drills.

I think the idea is worth a shot. My problem is I can't find a 4 flute 11mm at a reasonable cost.

What's an "end drill"?

You could take a 7/16 ball end mill. It might already be 11mm. Or if too big, you could get it "resharpened" for about $10.

PatTheRat
07-29-2009, 05:34 PM
I meant to say center drill. Counter sink.

You know if you want to talk about dumbass ideas I think tattoos are at the top of the pile...:D And that ain't a pile of roses ..:eek: :rolleyes: :D

beanbag
08-26-2009, 07:05 AM
Finally got around to drilling that hole today. Thanks to the various suggestions from folks here, it worked out ok. I put a 3/32" hole halfway thru a 9" rod, and came in from the other end with a 1/8". The holes mostly matched up, with a slight offset of about 0.014". Not too bad.

I was working on a communal lathe, so first I had to re-align the headstock.

I made some blocks with a slot in it to hold the drill on the tool post. I couldn't really use the tailstock because the drill chuck would never quite point the drill straight. Using the carriage to feed the drill worked out pretty well because I got a good feel for what the drill was doing, and also I had a Z DRO.

The rod to be drilled was mounted in a 4 jaw and centered, but I did not check that it was coaxial.

I used the method of a ball end mill to start the hole. That didn't work so hot, but mainly because I forgot about the suggestion to indicate the drilling bit by using an indicator mounted to the chuck. Oops, maybe next time. The offset end mill made a slightly bigger hole, but at least I could tell I was slightly off since the chips were mostly coming off certain flutes.

For drilling, I used oil for lubrication and rpms from 200-300. I know that is not even 10 sfm, but for some reason, drilling always goes better for me when I go at these very slow speeds. I get longer, smoother chips instead of these short broken ones. Maybe next time I will try going faster?

I took pecks of about 1/2 the diameter. That created enough chips to fill half the flutes.

Only issue left for me is how to determine how straight a hole is going, mid drilling. My plan is to go as far as possible with the 3/32 hole and flip over and switch to the 1/8 by the time the 3/32 hole starts to wander. I could get something like a 12" drill and just stick it into the hole and see if it matches up with my drill in the holder, but I think what would work better is a stiffer material that I would be sure is not bent. Something like an alumina rod, or some other ceramic, except I'm not sure where to find such things locally.

Black_Moons
08-26-2009, 08:58 AM
Maybe I was doing something wrong, but whenever I try and drill with an unlocked tailstock, I get horrable chatter.

'I was working on a communal lathe, so first I had to re-align the headstock.' Who misaligned the headstock? :P

PatTheRat
08-26-2009, 11:08 AM
Sounds good BB.

I totally solved my drilling problems with one word... Hardinge. :D

Got an old HC chucker lathe with coolant system and holy cow, my days of drilling on the Logan are over. It is one precise drilling machine. $675 total in the beast with 3 days labor getting it online.

I start with slow speed and sharp- 1/4" split point carbide screw machine bit as a spot drill and oil, then slow with flood coolant and my 11mm 3flute carbide bit into about 3/4".

Then I kick it into high speed and continue my 11mm hole with a hard stream of flood coolant (moose juice) and smooth long pecks pulling back just before the flutes fill up, and shorter pecks the farther in til the end.

Work stays cool. Bits stay cool and sharp. I can also do all of my reaming with power feed and walk away from the machine as well.

I am one happy camper here. ..:cool:

ckelloug
08-26-2009, 12:12 PM
Rich,

Thanks for sharing your ultraprecision deep drilling insights. I imagine I'll never have to do something like what you showed but your description was fascinating and in my opinion worthy of a textbook.

Despite the generous help I've received from Mike on several problems here involving drilling, I'd have to say that I don't think you're a dumbass ;)

--Cameron

beanbag
08-29-2009, 05:19 AM
This time I did a whole lot more "indicating".

Checked that the workpiece was actually parallel to the rotation axis and not just centered.
Made extra sure the drill was parallel.
Used an indicator mounted to the chuck to make sure the drill was centered.
Used all cobalt drills.
800 rpm this time.

Due to the better centering this time, the initial cutting with the endmill went pretty smoothly. However, one thing I don't understand is why the carbide endmill made magnetic chips. The effective chip load was probably a lot less than with the drills.

Things went a little faster this time, and it only took me about 3-4 hours to do what a gun driller could do in a few minutes. This time, the two holes lined up perfectly. It's like that underwater tunnel between [this european nation] and [that other island european nation]. I'd like to take a picture, but my camera ran out of batteries, so just image Evan's picture, except with 1/8 and 3/32 holes.

Thanks for all the suggestions. I'm feeling pretty dam smug right now.

OK, batteries recharged
http://i139.photobucket.com/albums/q286/beanbag137/IMG_0268.jpg

Carm
08-29-2009, 08:50 AM
7P's
Proper prior preparation prevents piss poor performance.

andy_b
09-14-2009, 10:30 AM
i've been preparing to do some deep drilling (deep for me anyway, about 0.75" diameter and 15" deep). what do you do if your lathe bed is not long enough to have a 16" long drill bit hanging out of the tailstock without putting several inches of the drill into the workpiece? do you just insert the drill into the workpiece, start the lathe, and hope for the best?

andy b.

JCHannum
09-14-2009, 11:54 AM
One way of doing that is to remove the tailstock and use a chuck or Morse Taper toolholder in the toolpost. You will gain quite a bit of distance this way.

andy_b
09-14-2009, 01:53 PM
thanks, JC! are chuck or Morse taper holders a common item for a QCTP (AXA size), or is this something i will need to machine myself? i don't recall ever seeing one of these, but then again i have never looked for one.

i was debating what type of drill to purchase, but i think i will see what type of holders i come up with before buying the drill. since i don't have the drill bit, i am open to any suggestions as to what would be the best setup to look for. something in the 0.75-0.80" size range will work.

i was also thinking of making a boring bar, and if i am not going to use the tailstock, this is another option. of course, i guess even with a boring bar, i would need to have an initial hole of some sort already there. if i was to go with a 0.75" ID bore, how much clearance would there need to be for a boring bar? could a piece of CRS 0.625" (5/8") in diameter work, or would it need to be more like 0.5"?

andy b.

beanbag
09-14-2009, 02:25 PM
Make a clamp that holds the drill to the tool holder post. Then the drill can stick out the back as far as you want. Also, if you are using a drill with a short flute length, this means that you don't have to get drills of different lengths. Start with the drill clamped near the front, and occasionally advance the drill in the clamp.

JCHannum
09-14-2009, 04:59 PM
Aloris and Tools for Cheap have Morse Taper toolholders;

http://www.tools4cheap.net/products.php?cat=9

You can also either hold a drill chuck with a round shank in a boring bar holder or make a sleeve for a boring bar holder to hold a drill directly.

Rich Carlstedt
09-14-2009, 06:36 PM
These are nice too

http://www1.mscdirect.com/CGI/NNSRIT?PMPXNO=1794872&PMT4NO=70599295

Aloris -Jacobs Chuck holder

Rich

beanbag
09-14-2009, 08:35 PM
I've never had good luck with a drill chuck pointing a drill straight enough. Is it just because I am surrounded by crappy chucks?

andy_b
09-14-2009, 08:58 PM
thanks guys! i like that idea of clamping the drill in a boring bar holder. and it just so happens my AXA holder is 0.75" in diameter. :) it looks like a 0.75" hole will be what i go with. it also gives me an excuse to pick up two more of those boring bar holders.

Rich,
that Aloris toolpost chuck is NICE. of course, for $224 i could probably have someone drill a few of these holes for me. :) if i ever go into the deep hole drilling business i think i would pick one of them up.

andy b.

JCHannum
09-14-2009, 09:13 PM
These are nice too

http://www1.mscdirect.com/CGI/NNSRIT?PMPXNO=1794872&PMT4NO=70599295

Aloris -Jacobs Chuck holder

Rich

They are nice, but for $225.00 less the chuck, they are a tad pricey for occasional use.

I did not take photos a couple of years ago when I drilled two 20" cannon barrels 16" deep. My lathe is 36" between centers and has about 44" of bed length past the chuck. I was further handicapped by the fact the lathe is in a corner, and there was not enough room for the drill to clear the barrel. I ended up with a two piece 7/8" drill bit that I would pull out half way and dismantle to remove the rest of the way to clear chips.

Rich Carlstedt
09-15-2009, 01:19 AM
Jm
They come with a Jacobs chuck.
I got mine years ago on a MSC sale for 120 bucks .

Setup is neat.
First square the Aloris post against the chuck
Then you put a dowel in the chuck , and place the holder on the post, but leave it loose.
Then tighten chuck on the dowel, this gives it the Vertical height, and you screw the adjusting nut down. Thats it, set for life
when you put the drill bit in the drill chuck, the back of the chuck has a countersink hole in perfect center with the drill chuck. Adjust your cross slide until your dead center fits in the countersink, and now your cross-slide is set. drill away

Rich

JCHannum
09-15-2009, 09:50 AM
Rich, I stand corrected. That does take some of the sting out of the price.

A toolpost mounted drill holder of whatever design adds to the versatility of the lathe but it is tooling that is often overlooked. Being able to use the lathe powerfeed can be an advantage many times.