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StephenK
05-12-2006, 04:55 PM
I have to drill .022 holes (#74 bit) in .250 in. dia. 303 stainless steel rod to a depth of .500 to .625.

I have available a micro drill press of possible the Sherline Mill (CNC) to do the job.

Even though I have drilled small dia. holes before I have never done any in stainless steel.

Suggestions Please.

Evan
05-12-2006, 05:22 PM
That is equivalent to drilling a 1/2" hole a foot deep. Not going to work in SS. That is a job for either an electron beam or a laser.

Peter N
05-12-2006, 05:33 PM
Perhaps you could find someone to fast hole drill them (EDM).

Peter

Millman
05-12-2006, 05:48 PM
You CAN drill it, because I've done it. You probably know about peck drilling? The slightest chip will break the drill and it's a PITA. Use the highest quality bit, high rpm's and keep it clean, Real clean. Hope you are not planning running production, though. It'll be all right.

John Stevenson
05-12-2006, 05:50 PM
Why does it need to be that diameter, that deep ?
can you get away with opening the hole up for say 1/2" then just finish the last bit at the smaller size ?

.

mochinist
05-12-2006, 06:52 PM
That is equivalent to drilling a 1/2" hole a foot deep. Not going to work in SS. That is a job for either an electron beam or a laser.Cmon Evan dont spout off if you dont know what your talking about, I do it all the time in SS, copper, and aluminum, up to an inch deep.

I use a cnc mill to do it, it can be done on a manual machie though with a sensitive drill chuck, but it is gonna suck. Since you have a sherline cnc mill use that.

StephenK
05-12-2006, 07:04 PM
The part that I'm making is 1.00 length x .250 Diameter with a luer taper whick is approx. 3deg. This is for the front .500 in. It has to be stainless and that is why I chose 303 for the machining.

One end is threaded, 10-24 x .250 length. The .022 hole is for a hypodermic needle cannula. This is for an assembly fixture.

I gave it a try by the peck method, hand operation on the sherline lathe and was able to drill in just shy of .500 on the first try.

Back in the 70's when I worked for a J&J Company I remember them drilling small holes in stainless steel using a set up that was made in their shop, air operated and doing peck type drilling.

Although I haven't done that type of drilling on the Sherline CNC Mill I'll spend some time to find out how to set up that program and give it a try.

Thanks guys.

Evan
05-12-2006, 07:10 PM
I do it too but the first time it work hardens in the SS that is the end of drilling the hole. Hopefully it won't matter too much if a few drill bits break off. The first time I drilled holes like that was in the 1960s when I was about 14. I made a flying spot scanner.

JCHannum
05-12-2006, 07:46 PM
You might consider 416 stainless. It is a free machining stainless, used for gun barrels. Machinability is .91, compared to .68 for 303.

It is slightly magnetic and not as corrosion resistant as other stainless grades.

mochinist
05-12-2006, 09:06 PM
I do it too but the first time it work hardens in the SS that is the end of drilling the hole. Hopefully it won't matter too much if a few drill bits break off. The first time I drilled holes like that was in the 1960s when I was about 14. I made a flying spot scanner.Wow stroke yourself much

Mcgyver
05-12-2006, 10:08 PM
duplicate, sorry

Mcgyver
05-12-2006, 10:12 PM
JC, isn't the 303 free cutting as well... 304 she's whore, 303, she's for me. I'd guess that partially or mostly makes the work hardening concern go away? it would seem next impossible with conventional machining if it wasn't free cutting as how would ever 'get under' the worked hardened area with such a small chip?

JCHannum
05-12-2006, 10:26 PM
303 & 416 both have sulfur added for free cutting. 416 is more free cutting than 303, and is heat treatable.

The .91 and .68 machinability figures are compared to C1212, which is free cutting low carbon steel as 1.

Evan
05-13-2006, 08:18 AM
All the austenitic stainless steels work harden, including 303. In fact, the addition of sulphur makes it less ductile as well. The free machining rating does not take into account work hardening.

For best results in drilling the bit must be sharp. Since it isn't practical to resharpen such small bits spares should be on hand. Unfortunately, the indication that it is becoming dull will be that the hole cannot be drilled. When that happens a new bit will not help either.

StephenK
05-13-2006, 08:32 AM
I don't know why some people complain about this forum. Just reading the results about my question on small hole drilling I'm getting quite an education on stainless steel.

Thanks guys.

No problems only opportunities.

Millman
05-13-2006, 11:03 AM
For best results in drilling the bit must be sharp. Evan, thanks for the info. I always make sure my bits are real good and dull.... sometimes Heat em cherry red and bust the tip with a BFH. Or maybe polish the tips on a handy chunk of concrete.

nheng
05-13-2006, 11:11 AM
A dial indicator will help with any pecking or feed operation as it tells where the drill tip is. If you look at Cameron micro precision drill presses, you'll see a DI reading the column to (moving) head distance. Same would apply to a Sherline.

Very low runout of the spindle/chuck also helps.

Den

JRouche
05-13-2006, 11:37 AM
As stated above the chip is gonna kill the drill. I have had good success drilling smallish holes and aiming a small but high pressure jet of compressed air directly at the hole. So during the peck the air helps to keep the chips outta the hole. JRouche

Rustybolt
05-13-2006, 11:38 AM
I've drilled alot of holes #74 and smaller, in large quantities.By hand. If at all possible have the process automated. Even with the finest quality sharp drills after about a dozen holes or so the drill will want to wander.They will also break. If you must do them by hand, chuck the drill as short as possible and rev the hell out of it.Set up the job so that you're comfortable, someplace to rest you arms and butt, because you're going to be sitting a long time and feeding that drill a half a diameter at a time. If hole alignment isn't critical you could drill from both ends, but be warned the holes almost never line up perfectly.

Scishopguy
05-13-2006, 05:54 PM
As the others have said, this is a PITA. The best thing I have found is a hand sensitive chuck, that you feed with your fingers. There is a return spring that makes it easier to handle. You get that fine feel of when the drill is cutting and when it is starting to skate. You can do it but, like Russ says, get a stool that is comfortable because you will be there a while doing it. Air is a great idea too.

Jim (KB4IVH)

mochinist
05-13-2006, 08:02 PM
A dial indicator will help with any pecking or feed operation as it tells where the drill tip is. If you look at Cameron micro precision drill presses, you'll see a DI reading the column to (moving) head distance. Same would apply to a Sherline.

Very low runout of the spindle/chuck also helps.

DenInstead of the indicator, use the column Z axis handle. Take your sensitive drill chuck and extend it to the maximum extension, now bring up the Z axis till the drill just touches the part, zero your Z axis dial and then bring it up to your comfortable amount for each peck, I would say .002 to .004 for that size drill. It takes awhile, but it guarantees that you will not try and push it to much, with drills that small it is really hard to even feel when you are cutting. I would still try and figure out how to use the sherline cnc if I was you though.

quasi
05-13-2006, 09:18 PM
I once bought a machine to do this type of thing in a lathe, it was a peck drilling attachment. It mounted on a lathes compound like a tool post grinder. I believe it was made by Dumore, I saw one in a KBC cataloge a while ago. The fellow I bought it from was a foreman at the old COMENCO plant in Calgary, and when they closed they auctioned all the maintence tools to the workers. He had a lot of stuff from there. He said they used this thing for drilling holes in some kind of jets for some burners.

I cant remember how big a drill it would hold, but it wasn't much, maybe 1/8 or so max.

EDMTech
05-14-2006, 02:06 AM
An EDM drill (aka, hole popper) would make extremely quick work of that project. Depending on what the holes are for and the finish required, it might require light finishing, but it still sounds like much less aggrivation than using a drill. Also, no worries about work hardening or breaking a bit and, ironicly, having to get it EDM'd out :)

Evan
05-14-2006, 06:36 AM
For best results in drilling the bit must be sharp. Evan, thanks for the info. I always make sure my bits are real good and dull.... sometimes Heat em cherry red and bust the tip with a BFH. Or maybe polish the tips on a handy chunk of concrete.

Ever resharpen a drill bit? If so, why? Could it be because you were drilling with a bit that became dull and needed resharpening?

Millman
05-14-2006, 07:08 AM
Just poking a little fun at you, Evan..sometimes the way you word things reminds me of people reading from a textbook. My God man; a sharp and honed drill bit is just common sense. I'm sure everybody here already knows that.

Evan
05-14-2006, 07:24 AM
Yeah, ok. I got that habit from my father. He was a science teacher. Still, it's really hard to see if a #74 bit is sharp or not. If it is even a little dull then you are screwed because it will work harden the SS in a heartbeat. It is possible to get solid carbide bits that size although I wouldn't try using them by hand.

StephenK
05-14-2006, 01:24 PM
I've been spending a little time setting up to do this job. There are alignment fixtures to be made so when all is done I'll certainly fill you in as to what method works the best. So far I have drilled on hole to a depth of just under .500 without a problem. This is by the peck drill method on my sherline lathe by hand moving the tailstock. Certainly not the best method but I wanted to feel how the drill cut.

Earlier I posted that I have available the Sherline CNC mill, with which I'm not familiar in the programming for peck drilling and also the Cameron micro drill press. I have used the Cameron DP for many small holes in Aluminum when I made vacuum forming molds.

One thing that I haven't checked out is drill bit type. Which one would be the best for this procedure? I have on hand some carbide and others that are labeled Cotter Pin Drill made by Cleveland drill. When finished I'll see about posting pictures and further details.

No problem just a challenge.

Mcruff
05-14-2006, 05:55 PM
I have drilled a ton of holes in the .018-.030 size over the years. I have a 1/8" albrecht chuck that I use for this purpose only. I simply use the peck method on a Bridgeport. I have also used a finger chuck with very good results, find you a fine cutting oil and go at it. I used to have to drill .031 holes 1 1/2" deep on a regular basis in 302 and 303 SS, never really had a problem once I realized that drills that small are disposable and when you think they are getting dull pitch them.
If you have lots of them to do a hole popper (edm) as mentioned is the only way to go, then lap the finish with fine thread and diamond compound. I watched a hole popper about 15 years ago burn a .009 hole thru a 4" long piece of carbide in under 4 hours, it was accurate end to end within .004, it would do a .125" hole thru 1/4" thick SS in under 20 seconds.

Diksne
03-22-2007, 05:33 PM
I'm looking for a sensitive feed device for small drills like the one we have in a shop where I worked part time before I retired. It is NOT like the common type available today that has a spring-loaded, free spinning disc or knurled ring above the chuck that you pull down to advance the drill. The one I'm looking for has an Albrecht chuck that is attached to a 1/4" spindle. The spindle is mounted in a ball bearing and is fed downward by a rack-and-pinion mechanism mounted to one side and operated by a 2" diameter plastic wheel with a horizontal axis. The return is accomplished by an extension spring inside a hollow 1/2" diameter shaft mounted concentrically above the 1/4" spindle. The 1/2" diameter shaft fits into a collet or chuck.
Having used both types of feed device for drilling small holes, I have found the rack-and-pinion device much more sensitive and definitely preferable to the other one.
Problem is, I can't find another one for my own shop. I have asked Albrecht about it, and they have never heard of such a device. The manufacturer probably just happened to use an Albrecht chuck. There is absolutely no marking on the device to indicate where or by whom it was made. The only marking is the name Albrecht, Germany on the chuck.
Does anyone have any idea what this is, who made it, or where I can get another one?
Diksne@aol.com

lane
03-22-2007, 07:42 PM
You need to build one of these
. From Jerry Howell plans , it will do the job.
http://i178.photobucket.com/albums/w277/lane5263/LMicroDrillPress.jpg
Use lots of Tap magic and any time you hear the drill make s strange sound change it out .