GTA

All Springer/NP/PCP Air Gun Discussion General => Machine Shop Talk & AG Parts Machining => Share Your Simple Home Projects (TRICKS-N-TIPS) => Topic started by: nervoustrigger on November 06, 2013, 01:05:42 AM

Title: DIY barrel crowning
Post by: nervoustrigger on November 06, 2013, 01:05:42 AM
Hey guys,

I decided to make a little writeup to show how I go about crowning a barrel using a drill press.  It's a fairly low-tech way to achieve a perfect, high-tech quality crown.  Pictured is the crown of a .177 Crosman barrel I did last week.

I hope someone finds it useful.  Let me know if you have any questions!

Title: Re: DIY barrel crowning
Post by: Rannoch on November 06, 2013, 02:08:55 AM
Sorry if I'm being stupid, but is the crown in the first photo concave?  In the article the last photo of the crown it looks flush.  I've been tempted to take a mill file to my Stoeger in hopes of making it more accurate.  Thanks for an interesting article. 
Title: Re: DIY barrel crowning
Post by: nervoustrigger on November 06, 2013, 05:53:58 AM
No problem.  Both are concave.  In the last photo, the crown it is slightly less concave than the first.  I did not taper it as much because that particular rifle has a shroud that extends past the end of the barrel that guards the crown from damage. 

If you want an opinion about the crown on your Stoeger, see if you can snap a decent closeup picture of it.  I do like the precision of dressing the crown in the drill press, but if you are careful you can still make an improvement to a poor factory crown without removing the barrel from the rifle.  If it is pretty shabby to start with, filing it first may be the answer.  But if it's square and the bevel is uniform and there is just a burr that causes it to snag a cotton swab, I would just give it a few twists of finger pressure with 400 and 600 grit.  Then finish up by chucking the round-head brass screw into a drill, slathering the head with polishing compound, and spinning it against the crown in an orbiting motion.
Title: Re: DIY barrel crowning
Post by: Tater on November 06, 2013, 11:06:05 AM
Very nice tutorial Jason. No drill press here but I think I could make due if necessary.
The .pdf should probably be added to the GTA library.
Title: Re: DIY barrel crowning
Post by: Rannoch on November 06, 2013, 11:50:22 AM
Great article, and sound advice.  I'll give the brass screw a try.  Thanks. 8)
Title: Re: DIY barrel crowning
Post by: SeanAT on November 06, 2013, 02:13:27 PM
Nice DIY for having to make due with what you have. Nothing beats a lathe for ease and precision though. If I didn't have one I would definitely give your method a go.

The nice thing about a lathe is that you can center the facing operation from the bore by making an aluminum insert. Then you face from the center out.

Here's an 11 degree crown done on a CR600 barrel...

(http://i40.tinypic.com/dfajx5.jpg)
Title: Re: DIY barrel crowning
Post by: reeko on November 06, 2013, 02:20:41 PM
thank you!

great idea with the drill press  :D
Title: Re: DIY barrel crowning
Post by: GoneShootn on October 23, 2015, 02:43:14 PM
Nice DIY for having to make due with what you have. Nothing beats a lathe for ease and precision though. If I didn't have one I would definitely give your method a go.

The nice thing about a lathe is that you can center the facing operation from the bore by making an aluminum insert. Then you face from the center out.

I know this is an old post, but I'm going to try a couple of questions, anyway:

1. How steep is the lathe learning curve for this sort of thing? I am fair mechanically and have considered buying a small lathe, but I have no one to tutor me on its operation.

2. Could you explain a bit, or give a link, on making an insert and using it to center the crowning operation? If this is too technical a question for here, then maybe you can point me to a site where the info might be found.

Jere
Title: Re: DIY barrel crowning
Post by: Geoff on October 23, 2015, 03:05:56 PM
I have a couple spare crosman barrels, I may drag one over to my dad's house to use his press to try this

thank you for the DIY
Title: Re: DIY barrel crowning
Post by: nced on October 23, 2015, 07:42:28 PM
Nice DIY for having to make due with what you have. Nothing beats a lathe for ease and precision though. If I didn't have one I would definitely give your method a go.

The nice thing about a lathe is that you can center the facing operation from the bore by making an aluminum insert. Then you face from the center out.

Here's an 11 degree crown done on a CR600 barrel...

(http://i40.tinypic.com/dfajx5.jpg)
Having successfully crowned a R9 barrel with a minilathe and a "dead sharp cutter" years ago after chopping a R1 barrel for the R9, I decided to chop my R10 barrel and the result wasn't too good. After chopping the barrel I centered the OD in my steady rest, faced the muzzle, then cut a 45 degree crown bevel. When inspecting the crown I noticed that it was wider on one side than the other. Puzzled I checked the centering with my dial indicator and sure enough, the OD of the barrel was centered. Further inspection showed that where I cut the R10 barrel the bore had wandered "off center" relative to the outside diameter..
Title: Re: DIY barrel crowning
Post by: martis880 on September 13, 2021, 04:34:29 AM
thank you for this guide! I have access to a drill press but not a lathe, so I think I'm going to give this a shot.

I'm not sure I understand how to use the emery wheel. I'm having trouble visualizing how I would sand down the barrel while it's chucked up and know that the final result is square, without the dremel being fixed in place.