backlash and rifling question

[Loose nut]

I have to build a rifling machine to rifle the barrel of my 1/6 scale WW1 18 PDR. artillery piece model. It is non-firing so the rifling doesn't have to be as good as a real firearm but I want it to look proper. The barrel will be 16" long, .55" cal. with 17 grooves .004" deep

I have had a rack and pinion device that will be perfect for a sine bar type machine as well as a piece of dovetailed bar that will make a great sine bar fall into my lap.

Now for the 64 dollar question. Any rack and gearing system will have a certain amount of backlash in it. After the cutter is drawn through the bore it will be backed out and have to be repeatedly drawn through many times for each groove. If the cutter is pushed back thought the barrel and then pulled forward to take the backlash out will the cutter line up with the groove accurately enough to produce good results.

 

[jack404]

G'day Loose nut

Rifling is a art i learned a long time ago so will give the following advise but wont be upset if you toss it totally


i make muzzle loading black powder rifles if people know Cabela's in the USA ther house brand brown bess rifles are from yours truely.

for a 0.004" deep cut i would use a single draw

even for SAE 4143 steel a decent rifling button will cut deeper than this and a single pass through will cause you less drama's multiple passes are a issue due to the indexing factor ( recreating the cut)

i'll draw you up a simple rifleing machine i have made for other people and post it here

if your set on a sine bar rifling gadget then its a very involved and slow process due to the need to be accurate.

may i suggest if you dont have a button that you go to www.dmetools.com i did deal with wwwdanjon.com for many years but they have gone to pot sadly.

buttons are not cheap and can be made but need to be done very accurately to make a good result and to be safe.

i dont make buttons any longer the results are much better and cheaper with a made one i have learned

what twist do you want for the barrel??

i need that to scale the wheel to turn the tool and to work out the angle for the teeth

this system has NO BACKLASH is a single pass that will create your rifling and flatten the lands( top of the rifling) to minimise the need for lapping the bore.

it makes a week process a day job with results good enough to actually use in a weapon

cheers for now

jack

 

[Loose nut]

Jack, I'm not set on a sine bar type machine, It's only a consideration because I have some parts I can use to McGyver a machine together, this is a one time use and keeping costs and time invested down are a priority. I was going to use the single "cut" type of rifling head because I can make that myself, but that isn't a definite either, buttons are a little pricey. This doesn't have to be functional quality it only has to look good. The rifling is 1 in 16 twist and the material for the barrel liner is steel tubing, high grade steel but I'm not sure of the exact type (heat exchanger tubing, I can find out). I'm making a barrel liner separate from the barrel so that when I mess them up the whole barrel isn't going to be scrap.

I appreciate the help and the plans will help a lot, I always keep an open mind (lots of things leak out though) for ideas and better ways to work.

I actually have a book on make rifling buttons but I wasn't going to try that, maybe I will now. It will only have to last one barrel.

Thanks.

P.S. I do know Cabela's, they have a store not to far from here (a couple of hundred miles), nice work on the Brown Bess.

 

[jack404]

I appreciate the help and the plans will help a lot, I always keep an open mind (lots of things leak out though) for ideas and better ways to work.

no worries on that i'll recommend this site from a friend in NZ

http://www.network54.com/Forum/576299/thread/1202627982/A++Few++Boring+and+Rifling++Machine+Designs

there are three blokes work on the one page and some older refrences (POP mechanics Gunsmith America, Penn Rifle builders)

the main reason i stated a button is the ammount of lands you require ( 17 ) indexing that in a .55 cal will be a nightmare. in a 6" cal gun its doable as you can manually set the cutter and index the head by eye almost

but.55" thats almost sub millimeter indexing (1.28312171mm lands actually) or 1.72783435" radius div 34 ( 17 lands x2) =0.050818657352941176470588235294118 "

remember cutting circles you cant cut off the last digit to round it out otherwise your last cut is closer or further that the first and that you CAN SEE.

17 lands is a bugger to work out the indexing so the cuts are perfect

the test of a perfect cut is you cut all then redo the first one and its spot on perfect
and thats a bit fine to make with 17 and why my recommendation for either a button or less lands

1-16 twist is great ( have the scales all set for this ) so the wheel will be a standard size ( the wheel size controls the twist rate for the tool ) so not much figuring there.

but do think about the lands number if your set on 17 well theres a project in its self

i am very glad your going to make a liner this will make things easier

so if your set on 17 lands i may actually ( if you agree) set up here to make a liner for you

I have a 1942 made Howard rifling lathe and barrel calculator ( how i got the numbers so fast) i bought from lithgow small arms here when they closed

and i doubt that there is another way to make this with the accurracy to get 17 equidistant lands without recreating the full rifling lathe othetr than a button die ( and yes for 17 lands it will not be cheap i suspect $250-$300 USD range plus rod)


could you do this with 8 or 6 lands?

1 the maths for 360 deg is sweet
2 the grooves will show better
3 you can then copy the tool in the link above ( i've made a few of these and they work well but i make 4 blade versions to make 2 pass for 8 lands) and do 2 passes only and have a great result with a index of either 60 or 90 deg( lots easier than 21.176470588235294117647058823529 deg for 17 lands)


have a think, look at the page, figure what you want in the end and i'll start on the drawing ( corel draw away!!!)

cheers for now

jack

 

[jack404]

ok back with a quick drawing ( and nasty my drawing skills are not good )

first one is a frame to hold the barrel and the indexing head/twist control wheel

the barrel is held in 2 bearings that have extending collars welded to them to allow bolts to go through the collars and hole the barrel securely.

second is the actual jig

even though i have not drawn it so the wheel is inside the frame the top pully is mounted to the frame
to ensure a straight feed pull on the indexing head /twist wheel


the numbered items are as follows

1 barrel
2 pulleys to ensure the 3/8th cable ( i use bike chain but pre stretched cable works well)
3 indexing head/twist control wheel
4 screen door spring ( to ensure tension on the wheel , the frames side holds this away from the central shaft when everything turns)
5 Hydraulic ram ( i have a manual lever pump)
6 rifling tool rod
7 3/8" cable

position the barrel in the frame and secure to the bearing collars to allow free movement

feed the die rod from the rear of the barrel and connect to the ram that should be positions about 1/4" away from the front ( allowed everything to be positioned and the cable brought up to be tight)

the indexing head /twist control wheel is also bolted to this forward collar and via the cable, when the hydraulic ram is withdrawn, the cable attached rotates the wheel at the predesigned rate to give the 1-16 twist. the cable its mounted to the ram.

the pullys ensure a straight cable pull at the wheel
the door spring prevents any freeplay in the unit or "overrun"
a single pass with a button with such a unit does a great job

if you make a tool as in the above link 2 passes will be needed to make 6 or 8 lands

again for 17 lands indexing it will be a real job and suggest a button from someone with a lot of experience ( more than myself) or again i can "have a go myself of a proper machine" but it will be a big job, if interesting



the reason these guns had such a weird barrel was to match the tooling in the ammo factories that make 1/4 " grooves in the shells and to allow them to save funds in retooling the shell factories ( they made way more shells than guns) and retooling was hard as the toolies where ladies working in the factories. great for fixing what they had but designing new stuff they where restricted from doing custom work, dunno why i have seen some of the small custom work they have done and its top class work

cheers

jack

 

[Loose nut]

no worries on that i'll recommend this site from a friend in NZ

http://www.network54.com/Forum/576299/thread/1202627982/A++Few++Boring+and+Rifling++Machine+Designs

i am very glad your going to make a liner this will make things easier

so if your set on 17 lands i may actually ( if you agree) set up here to make a liner for you

Jack, I have been to that site already and got a lot of ideas there they have made some nice equipment.

I can go with 18 grooves instead of 17, that would make it easier to index, I doubt anyone would notice, but there has to be that many for it to look authentic.

Thanks for the offer , but I really want to make this myself if possible. I'm thinking a 3 groove button and then 6 passes will do the 18 grooves and keep the indexing simple.

A couple more questions

1. how big a hydraulic ram in tons or metric equivalent (be kind I don't do metric very well)
2.If I use a hand pump hydraulic ram, that is to short, can the push be stopped part way and the ram reset with a push rod extension to make another push without messing up the rifling. Hard to explain hope it makes sense.
3. I can calculate the size of the wheel for the proper twist and the rest looks easy enough but I can't see how the door spring works
4. I'm assuming the frame has to be pretty robust to hold up to the strain.
5. do you think a tool steel button (home made) left fairly hard would hold up long enough to make one liner, including some scrappers, I can make more then one to get the job done.

My decision to use liners was based on the fact that I will probably trash a few dozen before I get a good one and the barrel has a lot of fancy work on the exterior that I would want to remake every time. I'm crazy not stupid!

I'll stop now and think up some more questions, Thanks, very much.

 

[jack404]

I can go with 18 grooves instead of 17, that would make it easier to index, I doubt anyone would notice, but there has to be that many for it to look authentic.

Thanks for the offer , but I really want to make this myself if possible. I'm thinking a 3 groove button and then 6 passes will do the 18 grooves and keep the indexing simple.

A couple more questions

1. how big a hydraulic ram in tons or metric equivalent (be kind I don't do metric very well)
2.If I use a hand pump hydraulic ram, that is to short, can the push be stopped part way and the ram reset with a push rod extension to make another push without messing up the rifling. Hard to explain hope it makes sense.
3. I can calculate the size of the wheel for the proper twist and the rest looks easy enough but I can't see how the door spring works
4. I'm assuming the frame has to be pretty robust to hold up to the strain.
5. do you think a tool steel button (home made) left fairly hard would hold up long enough to make one liner, including some scrappers, I can make more then one to get the job done.

My decision to use liners was based on the fact that I will probably trash a few dozen before I get a good one and the barrel has a lot of fancy work on the exterior that I would want to remake every time. I'm crazy not stupid!

G'day Loose nut good thinkin on the 18 that makes it a point fix ( exact degree measurement) 20 degree is a lot easier to manage pity my brain does now work that way DO'OH! glad yours does and frankly i'm VERy ysglad your going to do this your self i was thinking last night "what have you got your self into if he says yes please?"

answers

answer 1 , 12 ton will do a single pass and cut 4143 at 0.01 depth 5 ton will do what you want 0.004
i have cut 0.005 with 5 ton a few times but use 8 ton as thats the standard here for a tractor steering arm ( what i use)

answer 2 because you will NOT EVER fire this yes you can but there may leave a mark down the bore
rent the ram a common stroke size is 18" for car body straightener kits and looking on the net i see they are cheap in the US to rent but again because it will never be fired yes you could use a shorter stroke ram but it may jam up on you and frankly look ugly and be hard to remove the chip if its still connected.

answer 3 the door spring is mounted by a pin to the wheel and runs exterior to the frame, i use door springs because they are cheap and have a real long stretch and will stretch around the frame ensuring the spring never comes near the centre rod. you preferably do not want the spring to go near or touch the centreline rod or ram.

answer 4. i use 1 1/2" angle iron for thr barrel frame 2 peices welded together each part for strength . the front part i use some 4140 30mm bars from barrels i screwed up drilling long ago and still have a few about ( maybe 20 left) drilling .308 barrel outa 30mm has to be perfect and so i have some waste ones, but any strong metal will suffice just make sure your welds are solid or use 3/4 " high tensile bolts as a minimum

answer 5, i have a home made one 4 blade not 3 from k110 tools steel and drill rod its done maybe 25 barrels in .40 S&W 2 pass ( 8 lands ) so its done 50 or so passes in total and it ready to do another 25 from the looks of it, the cuts for that are .005" each pass and a 5 ton ram was used for some of them no worries


Tip make your liner a inch longer than you need to allow trimming if you make a boo boo you know it fast (first 1/4 " ) so you can trim that off and have it look perfect even after 10 boo boo's ( i know this part well)

again good call on the liner and going to 18... 10 and 20 degree is much easier to work with and index

cheers

jack

 

[Loose nut]

Jack, I have been looking around and found that I can get a "import" (we all know the quality there) 5 or 8 ton ram with a 19" stroke for between $60.00 and $100.00 CDN so I will bite the bullet and get one, that way I can push through with a full stroke and I will have it if the will to make others gets me.

I should have figured out the spring thing but some days the obvious isn't.

I have some 2" square tubing that I can use for the frame it should do the trick and if you have a picture of one of your rifling machines could you post it, just in case I get another not to obvious day.

Thanks for all the help.

P.S. another question, when you are pushing the button through with a hand pumped hydraulic ram, each time you pull the handle down, the button stops while you lift the handle up for another stroke will it leave a mark. Does that make any sense, again kind of hard to explain.