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fritz · Silver Status Member

Custom tool makers I suppose.

turtlemann14 · Member

9x20"...

is that big enough? i would think that you would need a 36" bed at least

boring bar? they make them, but i have never seem one so long

maybe drill and ream?

Jaxom · Senior Member

I was waiting on a slew of call backs yesterday, so it gave me some more time to research. What I'd ideally be looking for is a diy "hobby" gundrill machine.

From what I seen in diagrams and read, a gundrill machine isn't much different then a metal lathe. Major difference being that the bit is spun by a motor and the stock is held still.

I've already begun sketching up some ideas on how this could be built for a home hobbist. But since I don't have years of experience in machine work or even the education in these matters, I'm stuck on a few things.

Basicall you need a rail on which the gundrill bit and motor will be. On that same rail you'll also mount the bar stock.

The actuall gundrill bit is hollow so that cutting fluid can be pumped through to the head. The bit is also usually twice the length of the stock being cut. In this way you don't have to readjust the bit in the chuck as you move it forward. The bit is also supported by what looks like few sets of pillow bearings in order to allow it to spin, but keep it from binding and bending.

Some companies carry a combo bit that does both the boring and reaming in one step. After this is done, I'm thinking one could remove the motorized head and replace this with a pair of hydrolic long rams and mount a button bit to this part and press out the rifling.

The bits I'd be stuck on. Is a connection for the cutting fluid to attach to the gundrill bit while it's spinning. And what method by which the "head" unit to travel along the rail with precission.

broommaster2000 · Moderator

Smooth bores can work pretty well up to 25 yards.

turtlemann14 · Member

you would have to have something like the carriage and bed on a lath

as for the fittings, can't you just put one on the axis of the bit?

something like a banjo bolt? (but not clamped at the ends, yes it would leak)

kanyon · Silver Status Member

Jaxom · Senior Member

I know nothing about these. You have a picture example of one? What are they made of?

Drilling the bore is actually the easy part. It's doing the rifling that things become interesting.

Alstone · Moderator & Site Supporter

Jaxom I get the impression that we have been here before, have a look at this post:

http://airgunhome.com/agforum/viewtopic.php?t=3108&highlight=deep+hole

Jaxom · Senior Member

Alstone,

Yes, you're right. I asked questions, recieved answers, then did more research. Now I had more questions again. Not trying to rehash the same questions over. Sorry if it seemed that way.

I figure, that if Gunsmiths like Quackenbush, Barnes and many others can make their own barrels, that we should be able to figure it out as well. Heck with you, kanyon, joe, and bob...and many many others, I'm surprised there isn't a Airgun Home brand ag yet!!! LOL

By asking all these questions...This is what I've come up with so far.

By taking a heavy duty "rail" that's say 72" long mounted to a level bench. On one end of the rail you'd mount the barrel in some holders that would look simlar to pillow berings. On the opposite end have a "head" that has a motor and "chuck" to hold the gundrill bit. To prevent the bit from wobbling additional mounts (pillow bearings) will be needed.

One company sells a bit that does both boring and reaming in a single pass. What I haven't worked out is how to attach a hose to the end of the bit "rod" that's hollow. Because you pump cutting fluid through the center of the rod to the cutting bit.

The next issue I have is how to control the advancement of the head. I have made a few weldments using small I beam, but that's metal rubbing on metal. Not effient or prescise as this project would need to be.

I don't have a the training to know what they're called, but there's that stuff that looks like a gear, but only long and flat. Using fine toothed what ever this stuff is called mounted to the center beam and gears meshed into this would control the advancemnt. Heck, I can see even using a stepper motor to control the advancement speed.

Once the barrel has been bored/reamed. The "head" would be be removed and now a frame with hydrolic long arm rams installed (can get these from northern tool btw) to press the button rifling bit through the barrel.

Perhaps this is a just a pipe dream of mine. Perhaps not. You never know, do ya? Just think of this, what if that neaderthal hadn't kept trying to move something, and didn't give up, we wouldn't have the wheel.

rsterne · Moderator

I find it hard to believe that they drill a gun bore with the barrel stationary and the drill bit turning.... When you drill in a lathe, the turning of the work tends to center the drill bit automatically.... I can imagine trying to drill a 24" long hole by turning the drill bit, and watching it break out of the side of the barrel half way down, or at least being wayyyyyy off center at the other end.... but what do I know.... Rolling Eyes

Bob

jsp · New Member

It's my understanding that gundrills are designed to be extra stiff to prevent wander on the bits. Essentially they're a tube with a single flute down the side. Cutting fluid is pumped down the center and pushes the chips out down the flute.

A source for the heavy duty rail could be a piece of railroad track. Mill it mostly flat and finish the job on a reference flat (a piece of granite that's been ground to +-0.0003" of flat). Only problem is that the reference flat and milling will run to quite a pretty penny. You could use a piece of glass as a reference flat, but you won't be able to get as flat. You could also take it to a machine shop that has a surface grinder.

Another problem you'll run into is the cutting fluid pressure is (AFAIR) 60Kpsi.

For advancing the barrel onto the drill (or the drill onto the barrel, I understand that with different commercial gundrilling machines sometimes the bit spins and sometimes it's the work). I think a leadscrew would be the best way to do so.

Essentially, what I'm thinking is the rail, properly flattened, has a workholder riding on it that clamps to the underside of the rail with roller bearings to ensure that the workholder/rail mounting is always flat and perpendicular. At the other end of the rail is the head that drives the gundrill and the power for the leadscrew (suitably reduced so you're only advancing the work very slowly (I'm not sure what the appropriate feeds and speeds would be)).

I think you'd want your button rifler to be a separate machine if at all possible. Trying to add too many features to something tends to make it all suck. Simple is more robust. One interesting thing you could try with the button rifler is having a fairly long bore riding portion on the button, and instead of pressing it in with a rod, press it in with hydraulic pressure. IE: instead of button -> rod -> hydraulic press -> hydraulic pump use button -> hydraulic pump.

Alstone · Moderator & Site Supporter

Have a look here :

http://www.lasc.us/RangingShotBarrelMakingFeature.htm

http://en.wikipedia.org/wiki/Gun_drill

http://www.riflebarrels.com/articles/barrel_making/drilling_rifle_barrels.htm

http://www.riflebarrels.com/articles/barrel_making.htm

http://thane.indiabizclub.com/catalog/374692~gun+drilling+machine~thane

Al

scroller99 · Veteran Member

Too bad you didn't live closer, I have a big metal lathe in the metal at school, and a decent steel fabricator close by that I use to get my steel for renovations at the schools. I could use the lathe all weekend and every night after school Twisted Evil

jsp · New Member

Many thanks for the links Al.

It simplifies things considerably to only have to deal with 1000-1600psi cutting fluid.

Those articles also had a good overview of feeds and speeds, which brings up another problem. Truing the blanks. That will require a nice accurate lathe.

J

Alstone · Moderator & Site Supporter

On any long barrel of quality the outside diameter would be finished between centres after boring, with a following steady to guard against any sag, this would apply to barrels from .177 to 16” or over and it takes care of run out during the boring process, once this as been done any tapering etc can be applied. This of cause does not apply to the majority of barrels made for the bottom to mid end of the market, which are just bored and finished as a straight tube, and that includes some top quality air gun makers, for powder burners it’s a bit different as you have to allow for temperature and pressure variations along the barrel.

Al