crowning

[boiler_house7]

I was wondering if could get some help and insight on tooling for crowning barrels. It seems it may be best to use HSS, i really don't know. but i can't really find any tooling setup for this. I do not have a grinder as of yet to make my own and was wondering if someone makes tooling perhaps specific to this task. is it best to cut straight across or put a light chamfer on the riflings. Thanks Bill

 

[stenger]

Use carbide turn it really fast and take a light finish cut. This will produce an outstanding crown. I'll run about 1000 RPM on my finish pass. Make sure you cut from the bore out to prevent any burrs.

SPR rifles

 

[Preacher]

Here is what you need for cutting crowns...
Arthur R. Warner Co..
(724) 539-9229
Kit #15 35 Degree Profile (V) Right Hand
Price: $90.00
HIGH SPEED STEEL — WHY USE IT?
High Speed Steel is a cutting tool material used in drilling, milling, turning, threading, boring, broaching, gear cutting and many other machining operations. High Speed Steel is used for form tools, slitter knives, guillotine knives, parting tools and many other types of cutting tools. High Speed Steel cutting tools are used in all phases of production and are widely used in both machine tools and in portable machine tools.
High Speed Steel is noted for its ability to perform at slow surface speeds, while providing a good surface finish, without chipping or breakage.
High Speed Steel offers reliable toughness. It is commonly used in applications with interrupted cuts and it is notably tougher than carbide and ceramic materials. It also resists chipping in cutting applications.
The toughness allows for Steep Positive Cutting Configurations to be generated. The positive cutting tool configurations demand less horsepower and will lower the level of heat generated during the operation when work hardening is a concern.
High Speed Steel retains good wear resistance in both metal working and wood working applications.
High Speed Steel cutting tools have a sharper cutting edge than carbide cutting tools. The work piece is cut rather than fractured which results in an improved surface finish.
High Speed Steel is used in applications where contamination of scrap is a concern.

 

[Eddie Harren]

After all of that expert advice the matter should be clear. It's what is great about this forum. Many people who are good at what they do and who will also share their knowledge and help others.

 

[stenger]

I am not getting into a disagreement about cutting materials on a public forum. This is what I want you to do. Take a HHS tool and crown a barrel then take a carbide tool and crown the barrel just the way I told you. Then send me a private PM about how much you like the carbide.

Take Care
SPR

 

[boiler_house7]

Eddie, your right. Lots of knowledge on here and would have a heck of a list to send all the thanks to. I just don't know if i can spin the heavy 10 fast enough to make the carbide work on a small surface speed area like a crown, thus mainly why i was thinking HSS for possibly sharper cut at lower rpm. Thanks preacher for all the insight and time. Bill

 

[jkohler]

I use a circle type f solid carbide bar the inserts have a .007 radius. I also use the same bar for preboring the chamber. The arther Warner bar preacher mention above is a good bar to have. I have the left and right hand kit I belive the inserts have a .015 radius on them. Mine came with a carbide insert as well as the HHS inserts.

 

[Rustystud]

Lots of ways to skin a cat.. Piloted tooling, boring bar, etc. I always finish my crowns with 800 grit paper. You can see your self in one of my crowns. They are 79 degree and slightly counter bored for protection.
Nat Lambeth

 

[Zebra13]

I think Brownell's sells a pre-ground crowning tool made of HSS. If you use it strictly for crowning, and you don't crash it, I doubt it will ever need a trip to the grinding wheel. Just keep it honed up with a stone and it will last forever. I use a HSS bit I ground and it has never been back to the grinder.

I cut recessed 90 degree crowns, and put a small chamfer on the bore via the compound set at 45 degrees. Works for me. I don't think there is any "best" way to crown. Rather, what ever crown you use (90 degrees, 11 degrees, etc) should be "best" quality.

Justin

 

[boiler_house7]

Thanks a lot for all the replies. Bill

 

[Minesweeper3433]

I liked using hss until a friend showed me how to grind a cuter from a broken 1/4 solid carbide endmill. Damn thing leaves a mirror finish. We cut it with more angle and clearance that I am used to putting on HSS but it cuts very very well.

 

[jonbearman]

I use a circle bar with carbide on my 13 inch southbend at the highest speed which isn't that fast like the heavy 10. The only thing you need to do on the finish cut is to take a .0005 cut or so and back it out slow as a snail and it looks polished when you are done.

 

[skeetlee]

Sharp carbide with lots of speed and very slow feed. Lee