Hello. I’m deep hole gun drilling 17-4 stainless steel. I’m drilling 8.5” deep in a HAAS ST20 with high pressure coolant. The drill I’m using is a 12” long carbide tipped Sterling gun drill that’s 0.687” diameter. I’m having a really hard time getting the drill to stabilize. I’ve tried SFM from 70-100 and feed rates of .0008-.0025 with not much change in surface finish or overall machinability. I’ve drilled 416 and titanium before using the same drills and haven’t had nearly as many problems. I’m also reaming the holes with a 12” reamer with 5/8” shank from Rock River reamers to 0.695 and the reamer is leaving lots of lines in the bore. I’ve tried 80-110 SFM on the reamer and .006-.014 feed rate without really making the lines go away. the Any help or insight would be beneficial.
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Gun Drilling and Deep Hole reaming
- Thread starter Jud96
- Start date
- Replies 12
- Views 2,725
hvnlymachining
Hot Rolled
- Joined
- Jun 21, 2019
- Location
- St.Onge
When you say high pressure, how high? Also, coolant type can make a huge difference in different materials. There's quite a difference between 17-4 and 416. I don't have any experience with deep drilling titanium for reference.
One more thought, is sharpness and coating, if you've used that drill before it may be due for a resharpen, and check for chip welding.
Hopefully someone here has better advice, but just thought I'd offer my .02
One more thought, is sharpness and coating, if you've used that drill before it may be due for a resharpen, and check for chip welding.
Hopefully someone here has better advice, but just thought I'd offer my .02
I would start the hole with a 3XD or 5xD Cardbide Thru Coolant Drill, Then Follow in with the gun drill. Id also peck the gun drill with a small dwell before the retract to make sure chips are breaking off. Is the hole after drilling a thru hole prior to ream? IF not id look for a thru coolant reamer. With finish requirement you are looking for it sounds more like a gun drill & hone job vs a gun drill & ream.
Ox
Diamond
- Joined
- Aug 27, 2002
- Location
- Northwest Ohio
I think that I recently ran a job out of 17-4, and I think that stuff just likes to sing when being drilled.
???
You are in a lathe?
A 5/8 shank on a .695 hole is pretty stiff, and 8" deep - the cutting end is going to be trying to relocate the shank end.
I am sure that you are mis-aligned more than the back-taper of that reamer. Alignments on a mill are pretty good (single holder (spindle bore) and a live tool) but a live part and turret/blocks/holders set-up just aint the same.
I'd say that you want to sweep the holder bore, AND THEN - after reaming, try jogging the reamer in and out of the hole. Can you see or feel it "bumping in" at all? Not only look from your current vantage point, but also from 90* around it too.
If you have to adjust the turret position AT ALL to git a good alignment, then your tool will be OK, but your shank will not be if you adjusted anywhere besides the sweeped location. And as you get deeper, your trailing edge flutes will be trying to move your shank to be in alignment, and you will be getting rub. This is likely where your lines come from.
???
I am always the champion of running floating reamer holders, but this is an extreem case for it's use.
It is even possible that the drill may benefit from one as well.
Is the gun drill superior to a tipped drill? The tipped drills of recent years have sure put the hurts to the gun drills.
Have you looked into an Allied Gen3 unit? IDK if they go that deep or not?
As above, a through coolant reamer would seem to be a requirement here. I've had those holes put in via a Hole Popper before*. Not sure if they can go that deep or not?
* Thank you to "you know who you are".
-------------------------
Think Snow Eh!
Ox
???
You are in a lathe?
A 5/8 shank on a .695 hole is pretty stiff, and 8" deep - the cutting end is going to be trying to relocate the shank end.
I am sure that you are mis-aligned more than the back-taper of that reamer. Alignments on a mill are pretty good (single holder (spindle bore) and a live tool) but a live part and turret/blocks/holders set-up just aint the same.
I'd say that you want to sweep the holder bore, AND THEN - after reaming, try jogging the reamer in and out of the hole. Can you see or feel it "bumping in" at all? Not only look from your current vantage point, but also from 90* around it too.
If you have to adjust the turret position AT ALL to git a good alignment, then your tool will be OK, but your shank will not be if you adjusted anywhere besides the sweeped location. And as you get deeper, your trailing edge flutes will be trying to move your shank to be in alignment, and you will be getting rub. This is likely where your lines come from.
???
I am always the champion of running floating reamer holders, but this is an extreem case for it's use.
It is even possible that the drill may benefit from one as well.
Is the gun drill superior to a tipped drill? The tipped drills of recent years have sure put the hurts to the gun drills.
Have you looked into an Allied Gen3 unit? IDK if they go that deep or not?
As above, a through coolant reamer would seem to be a requirement here. I've had those holes put in via a Hole Popper before*. Not sure if they can go that deep or not?
* Thank you to "you know who you are".
-------------------------
Think Snow Eh!
Ox
Last edited:
Ox
Diamond
- Joined
- Aug 27, 2002
- Location
- Northwest Ohio
If you don't have the daylight for the reamer holder (it's gotta be tight in there with that job!) then I would expect that you should prolly bore a bushing in place*, and then go with that offset, regardless of what the tip is dooing. The tip will pull on (with resistance) but if your shank is out of line, it will always be rubbing.
Another option here is to cut your shank down enough to let it flex a bit more. I've never done this, but I have a chum that has. ... although, come to think of it, the next time he came and borrowed a reamer holder from me. ... And that was a mill application!
*This would need done each time the job is set up.
-----------------
Think Snow Eh!
Ox
Another option here is to cut your shank down enough to let it flex a bit more. I've never done this, but I have a chum that has. ... although, come to think of it, the next time he came and borrowed a reamer holder from me. ... And that was a mill application!
*This would need done each time the job is set up.
-----------------
Think Snow Eh!
Ox
You don't mention what condition it's in.
crossthread82
Hot Rolled
- Joined
- Apr 1, 2022
- Location
- Maryland
This. H900 vs H1150 vs annealed are totally different animals.
Ox
Diamond
- Joined
- Aug 27, 2002
- Location
- Northwest Ohio
OK, had to go look for an RFQ today anyhow, and the Gen3sys only goes to 10x
But another thought is that I have seen someone advertising gun drills with inserts now.
Been a while since I have seen that ad, so not sure who it was right off.
I may have to research that now...
I think that I have a new Cutting Tool Engineering mag waiting for me at home.
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Think Snow Eh!
Ox
But another thought is that I have seen someone advertising gun drills with inserts now.
Been a while since I have seen that ad, so not sure who it was right off.
I may have to research that now...
I think that I have a new Cutting Tool Engineering mag waiting for me at home.
---------------------
Think Snow Eh!
Ox
Ox
Diamond
- Joined
- Aug 27, 2002
- Location
- Northwest Ohio
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Think Snow Eh!
Ox
Blaser Swisslube
Aluminum
- Joined
- Jul 30, 2009
- Location
- Goshen, NY
We're not sure how high-pressure your current coolant is. However, for this application, we'd recommend something like our Blasocut BC-940. It's a high-performance, high-pressure coolant, great for materials you're referencing.
This 17-4 PH is Condition “A”. I just found that out. It’s not drilling well at all. I attempted to drill it with an Iscar insert drill with the recommended speeds and feeds from the iscar rep and the drill insert failed 4” into the part and trashed the drill. So this stuff is a headache.
Ox
Diamond
- Joined
- Aug 27, 2002
- Location
- Northwest Ohio
With Titex [from my experience] I might start with their S&F.
Anyone else, cut S by 1/2 and F by 1/4 and make your first hit.
Those guys are all trying to sell carbide by the numbers.
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Think Snow Eh!
Ox
Anyone else, cut S by 1/2 and F by 1/4 and make your first hit.
Those guys are all trying to sell carbide by the numbers.
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Think Snow Eh!
Ox
You may like to look at this;
I use them in cast iron and they work well. Support is good and they have inserts for many different materials.
I use them in cast iron and they work well. Support is good and they have inserts for many different materials.
