Hello my friends, i got some drawings of gundrills and d bits and i'm thinking about soldering a shank to cooling the bit and expel the chips. Then questions popped into my mind: could you use a steel capillary tube? if the answer to the above question was yes, what diameter of the hole would be enough to have a good flow of fluid? the bit I'm designing has only 2.5mm of space where the hole can be drilled (it's the traditional D-bit in which the cutting area is milled to half the diameter, that is, 5mm -2.5mm= 2.5mm. a hole 1mm into that 2.5mm area of this D-bit, would that leave 1.5mm and exactly 0.75mm of wall. Would that 0.75mm of wall thickness withstand the pressure of 1000psi? would the 1mm hole provide enough fluid flow for the troughs to come out? still on the stem: the rod with a smaller dimension than the bit, but without a flute, would it be possible for the chips to come out around it?
designing my own gundrill
- Thread starter Mordecai
- Start date
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Would it be easier to use the dbit like a reamer? By that I mean drill with a drill bit 10 or 15 thou under size and then use the dbit to finish bringing the hole to size. That would minimize the amount of chips and maybe save you having to flush out the hole.
Thank you for the advice. But I think a twist drill in a 16" deep hole would cause a deflection that wouldn't be repaired by one reamer. I figure I'd have to drill a much smaller hole and use another two or three reamers to get a straight, polished result. Furthermore, what I was really interested in was the challenge of designing and building a gundrill. I believe that this Gundrill chat is too saturated in this forum, because I'm having few replies. Or it could be that my questions are stupid or the guys are building gundrill and it wouldn't be interesting to spread the knowledge. thank you friend
Maybe try one of the gun building forums or a gun forum in general??
I have to believe that if anybody here could help you, they would. This forum is very beginner tolerant. Even the simplest questions get replies because we have all been there and just like to help.
I think it's probably your question is just out of the knowledge of the forum. I don't even know anyone who has drilled a hole 16 inches deep let alone tried it myself.
I think it's probably your question is just out of the knowledge of the forum. I don't even know anyone who has drilled a hole 16 inches deep let alone tried it myself.
Getter-Done
Member
I use these at work to drill holes in rollers for different factories.
It has a pipe that is formed then a carbide tipped piece is welded to the end.
A high pressure coolant tank is hooked to the tool holder to send the coolant thru.
Link of Drills: Made in USA - 1/2", 32" Flute Length, 33" Depth of Cut, Carbide-Tipped Shank, Single Flute Gun Drill - 08535270 - MSC Industrial Supply (mscdirect.com)
It has a pipe that is formed then a carbide tipped piece is welded to the end.
A high pressure coolant tank is hooked to the tool holder to send the coolant thru.
Link of Drills: Made in USA - 1/2", 32" Flute Length, 33" Depth of Cut, Carbide-Tipped Shank, Single Flute Gun Drill - 08535270 - MSC Industrial Supply (mscdirect.com)
Here's a good place to ask your questions , Lots of good guys that like to help .
https://www.practicalmachinist.com/vb/gunsmithing/animal
https://www.practicalmachinist.com/vb/gunsmithing/animal
DavidBC
Active Member
I posted a design of a D drill on this forum yesterday. If you have a look at the design you will see that it has a vee groove the full length and a small hole also the full length. The hollow tube that is attached to the D drill and also longer than the depth of the hole is also deformed to match the vee in the D drill. Coolant is pumped up this tube which then forces the swarf from the drill to be forced up the vee on the outside of the tube. Once the D drill is started in the pilot hole it cannot be withdrawn until it comes out the other end of the length of material you are drilling.
Richard Carlstedt
Well-Known Member
Done lots of Gundrilling to 40 " depths from 3/8" to 1" in Diameter and also designed and built a Gun Drill platform /system
I do not want to discourage the poster as sometimes great things are discovered by experimenting and doing things that no one else has done
So let me say a few words about the parameters of these drills.
Gun drills are very frail and made with thinwall steel tubing. The strength is not related to the tubes wall thickness, but to the pressure it operates at. The higher the pressure the more rigid the the drill. the more rigid the drill, the faster the feed rate can be .
Our drills ran at 4,000 PSI (and some small drills -not ours) go to 10,000 PSI. At 4,000 PSI on a 3/4" drill, we would feed at .0005 per revolution ( 800 RPM) .
Part of the pressure is lost due to chip evacuation. at the exit hole to drive chips back to the spindle which may bleed off 25 % of the pressure, so the drill only has 3,000 in our case and the other 1,000 is used to drive the chips out of the hole. The most difficult part is oil control and filtering. You need to collect the oil , then filter it so you do not destroy the high pressure pump...obviously, the higher the pressures, the more sensitive the pump becomes and The smaller the oil system is, the harder it is to do this.
I think gundrills them selves are pretty cheap, but maybe the poster has a weird size that he wishes to make. I don't understand his design , so cannot comment on its operation or considerations. I assume he wants to do this in a lathe, and the small drill means requires very high rotation speeds .
I covered some of the aspects of gundrilling in another post on another thread years ago and you can access it here.
https://bbs.homeshopmachinist.net/forum/general/44496-deep-hole-drilling-101?t=43432
One of the problems of posting is having a college kid thinking he has all the answers with no expeience in the real world , so there is some digression with impossible theory posed by naysayers.. just read my text , to get more gundrilling concepts.
Rich
I do not want to discourage the poster as sometimes great things are discovered by experimenting and doing things that no one else has done
So let me say a few words about the parameters of these drills.
Gun drills are very frail and made with thinwall steel tubing. The strength is not related to the tubes wall thickness, but to the pressure it operates at. The higher the pressure the more rigid the the drill. the more rigid the drill, the faster the feed rate can be .
Our drills ran at 4,000 PSI (and some small drills -not ours) go to 10,000 PSI. At 4,000 PSI on a 3/4" drill, we would feed at .0005 per revolution ( 800 RPM) .
Part of the pressure is lost due to chip evacuation. at the exit hole to drive chips back to the spindle which may bleed off 25 % of the pressure, so the drill only has 3,000 in our case and the other 1,000 is used to drive the chips out of the hole. The most difficult part is oil control and filtering. You need to collect the oil , then filter it so you do not destroy the high pressure pump...obviously, the higher the pressures, the more sensitive the pump becomes and The smaller the oil system is, the harder it is to do this.
I think gundrills them selves are pretty cheap, but maybe the poster has a weird size that he wishes to make. I don't understand his design , so cannot comment on its operation or considerations. I assume he wants to do this in a lathe, and the small drill means requires very high rotation speeds .
I covered some of the aspects of gundrilling in another post on another thread years ago and you can access it here.
https://bbs.homeshopmachinist.net/forum/general/44496-deep-hole-drilling-101?t=43432
One of the problems of posting is having a college kid thinking he has all the answers with no expeience in the real world , so there is some digression with impossible theory posed by naysayers.. just read my text , to get more gundrilling concepts.
Rich
Richard Carlstedt
Well-Known Member
David, I took a look at your reference posting.
Pretty interesting approach. Not sure I understand the do not withdraw comment ??
Any info on creating the crease in the tube ?
The poster may have some se of this approach.
Please remember, my post is what is done commercially.. hobbiests always find a new way to skin a problem
Rich
Pretty interesting approach. Not sure I understand the do not withdraw comment ??
Any info on creating the crease in the tube ?
The poster may have some se of this approach.
Please remember, my post is what is done commercially.. hobbiests always find a new way to skin a problem
Rich
ajoeiam
Well-Known Member
I don't have anything like the experience at deep hole drilling like some of the proceeding posters but I have done twist drill holes at over X75 dia - - - like a 1/4" hole (6 mm) some 24" deep into a shaft for lubrication purposes. Remember measuring the cross hole depth just for giggles after that was done and I had been able to keep the drill wander down to under 0.075". Not perfect - - - but not terrible either. It was tedious though - - - pecking in about 0.100" steps and retracting clear of the hole every 2 or 3 pecks. The feel of the drilling was important - - - I didn't want to weld the drill into the hole with bound chips - - - that would have really impressed the boss!!!!!!!! Remember feeling shoulder stress afterward from tossing the tailstock back and forth so much - - - but it got the job done!!
Drilling much less from each end and then seeing that the meeting area was almost a circle - - - - that was reassuring.
Dunno if I want to drill a hole and achieve perfect concentricity over a long length.
Would bet if you hired it done and asked for a tight spec - - - - you would pay some serious $$$$$ and most places would say - - 'no thanks'.
I very much appreciate your care in formulating your answer and saying that you don't want to discourage me. I really appreciate it. But I never give up and I never give up. I love mechanics, I really do and despite having followed another professional path, every single day I'm on the net researching and disturbing the peace of others. every day. I have a deep love-hate relationship with mechanics. Hate when I theorize some concept of something that exists and someone comes along and says it's not the way I'm thinking. I feel like a complete idiot. But I love figuring out how things are made and I admire people who have dedicated their lives to creating something and people like you who take time to respond to a newbie. thanks. As for the question you asked about the groove in the tube, I read this reply during the night and that question made me lose sleep. I was thinking about making a seam tube, because I believe it would be easy to mold a sheet from a mold and then weld. But since things are never as we imagine, I believe that the pressure described by you for this work, 4000psi (I believed that 1000psi was enough) a seamed tube would not support. So I developed a theory and I wanted you not to laugh at me. I believe we can create a milled mold with the characteristics of the shank, ie a shank with a 100° groove along the entire length. Then calculate the perimeter of this mold and define a tube that has that perimeter as the internal diameter. Place this mold inside the tube and with a wedge from the mold to the groove, press it in a press until it acquires the shape. However, we would have to find a steel that was elastic enough for that. I don't know what the external finish would be and if I also needed a diameter grinder, the groove would cause vibration in the operation. I've never done it, never seen it, but I wanted to try. thanks for your support.
Hi David, that gundrill project you shared on the Forum was in another thread of mine. I disturb, I'm like that. Forgive me. By the way, I know very well whose project it is. From Howe. From the book "Modern Gunsmith, Howe". I have it, both volumes. I read every day. I have a ton of prints, posts and cad drawings from gundrill and reamers. But there are things he doesn't address, maybe because it's so simple. What made me look for the D bit was the fact that I couldn't get the rod and thought about how I could manufacture it. But I theorized a concept. I even shared it with another friend. I hope he doesn't think I'm an idiot. Hahahaha. thanks for your time. And forgive me for perhaps using jargon that is not present in your language. I don't speak English fluently.
Richard Carlstedt
Well-Known Member
Mordecai. Yes, I do not want to discourage you, but I feel you should be armed with facts about Gundrilling ....to help you.
Yes , 1,000 PSI can work, we had instances where we drilled on a Lathe that was used normally for ordinary work but we needed drilling so we used it and ran at 800 PSI because that is all the pump would do...and it worked .
It worked in my opinion because we could "Feel" the drill wanting to twist, and that resulted in slowing down our feed rate...but how do you tell someone about "Feel" ..that is a skill only achieved through failure !
another example.
Looking at D Bits...You have to consider the chip formation (size ! and length)
You need to look at the post i referred to where I show Gundrilll profile. In gun drilling, two different chips are formed with one chip being wider than the other . Now if the chips are too big, how will they get out of the drilled cavity ? With D bits, they have a wide chip and that becomes more difficult to evacuate , so D bit design is important.
Your English is fine and being creative is always an advantage in tough problems !
Rich
Yes , 1,000 PSI can work, we had instances where we drilled on a Lathe that was used normally for ordinary work but we needed drilling so we used it and ran at 800 PSI because that is all the pump would do...and it worked .
It worked in my opinion because we could "Feel" the drill wanting to twist, and that resulted in slowing down our feed rate...but how do you tell someone about "Feel" ..that is a skill only achieved through failure !
another example.
Looking at D Bits...You have to consider the chip formation (size ! and length)
You need to look at the post i referred to where I show Gundrilll profile. In gun drilling, two different chips are formed with one chip being wider than the other . Now if the chips are too big, how will they get out of the drilled cavity ? With D bits, they have a wide chip and that becomes more difficult to evacuate , so D bit design is important.
Your English is fine and being creative is always an advantage in tough problems !
Rich
Rich-
I wondered about the art of accurately drilling barrels.
Do they ever draw barrels back and forth over a stationary reamer, with no rotation of the reamer or barrel?
I had a relative ask me if I could enlarge the bore on one of his pistols, since I had a lathe, and therefore must be a machinist.
I told him "LOL, this would be the quickest way I can imagine that you would be down at the gun shop buying a new barrel".
Gunsmithing is a bit of an art it would seem, and not much room for error I would think.
Pat J
I wondered about the art of accurately drilling barrels.
Do they ever draw barrels back and forth over a stationary reamer, with no rotation of the reamer or barrel?
I had a relative ask me if I could enlarge the bore on one of his pistols, since I had a lathe, and therefore must be a machinist.
I told him "LOL, this would be the quickest way I can imagine that you would be down at the gun shop buying a new barrel".
Gunsmithing is a bit of an art it would seem, and not much room for error I would think.
Pat J
Richard Hed
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I don't repluy becausse I know nothing about them
Hi my friend Rich, Look at my gundrill rod project. What a beautiful thing. What are the chances of this failing miserably? haha.
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Richard Carlstedt
Well-Known Member
Pat, I really can't comment on gun barrels as I never made one.
The one central concept of gun drilling is to rotate the work piece with a stationary drill (1.) But Professional drillers also rotate both the work and the drill (counter-rotate) (2) and most of my work was rotate the drill with stationary work piece (3) .
Each has it's own issues , parameters and inaccuracies. It also seems to be a closed field, or one with "Secret Arts" .
With only the work spinning, you get 10 times greater chance of accuracy versus stationary work as an example ( drift from Centerline is about .0001" per inch versus .001with stationary work)
I have heard of gundrillers straightening barrels after drilling ( making the bore straight and then returning the OD and Tapers ) . but am unaware of any reamer use ,
The real problem to me is doing the rifling ..now that is a skill.
Rich
The one central concept of gun drilling is to rotate the work piece with a stationary drill (1.) But Professional drillers also rotate both the work and the drill (counter-rotate) (2) and most of my work was rotate the drill with stationary work piece (3) .
Each has it's own issues , parameters and inaccuracies. It also seems to be a closed field, or one with "Secret Arts" .
With only the work spinning, you get 10 times greater chance of accuracy versus stationary work as an example ( drift from Centerline is about .0001" per inch versus .001with stationary work)
I have heard of gundrillers straightening barrels after drilling ( making the bore straight and then returning the OD and Tapers ) . but am unaware of any reamer use ,
The real problem to me is doing the rifling ..now that is a skill.
Rich
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Bentwings
Well-Known Member
I maybe missed your projected diameter. As long as you can grind a good point I YHINK you could be ok. You might look into using stress proof steel tube or round rod it may not warp as much if you cut a groove for the flute. Otherwise you might try 413 or 4240 round stock. Try aircraft spruce or mc master Carr for material . There may be an exact size you need. Turning a long skinny rod is a challenge for sure. Mak sure your late tracks dead straight. . You can get turned, ground and polished material. Maybe try discount steel . They are based here in minnesota but I think they have a branch in Texas. Mark williams is a big supplier for the drag race guys he also has extensive machine shop services at reasonable rates. He may do center less grinding too . A big part of your project will be grinding an accurate cutting edges. Another thought is carbon fiber rod or tubing CF is far stiffer than any steel there are lots of epoxies that will stick anything to CF. Maybe consider slipping CF tube over the steel to stiffen it . It’s not an easy material to machine carbide woks but CF is abrasive . It’s tensil strength is over 5 time that of steel so you don’t need super heave wall but solid rod would be very stiff . I YHINK CST composites is still around. They have all sorts of Kevlar and CF plus epoxies. We use quite a bit of CF in our rc airplanes. I’ll be interested in your progress and thoughts. What ever you do with CF be sure all safety stuff is in place. You don’t want CF dust or particle on you or in you. I can’t imagine getting a sliver in an eye. Iweare safety glasses all day even eating. They are bifocal but the only eye ware
Byron
are that helps me at all .
