Theoben Rapid Forum

The old way was using a cuter with the compound set on 11°
Then after Cutting it, you then polished the bore-crown surface with a brass thimble with lapping compound.
(https://photos.imageevent.com/scl_electronics/gun/air/websize/crown2.jpg)

The final results...
(https://photos.imageevent.com/scl_electronics/gun/air/websize/crown1.jpg)

Now I use a Manson Crown Cutter.
It has 3 Carbide cutters staggered to give a smooth cut..
(https://photos.imageevent.com/scl_electronics/gun/ultimaterapid/websize/20200909_122237.jpg)

What is unique about the Manson Crown Cutter, it use a fixed arbor in the bore to keep the cutter concentric!
It has a nylon bore brush on the end to remove any debris from the cutting..
(https://photos.imageevent.com/scl_electronics/gun/ultimaterapid/websize/20200909_125920.jpg)
(https://photos.imageevent.com/scl_electronics/gun/ultimaterapid/websize/20200909_1301521.jpg)

So I secure the barrel in my 3 jaw chuck. The cutter has an adapter so you can drive this with the supplied 1/4" ball driver bit in the tailstock quill. The unique thing about this cutter that I love.. Notice the thin spiral threads of cut metal! Set my lathe in low speed, a drop of cutting oil on each carbide cutter, apply light pressure. Stop to clear cutters of metal swarf, add a oil to the cutters..rinse and repeat.


Here is the cutter in Action!
(https://photos.imageevent.com/scl_electronics/gun/ultimaterapid/websize/20200909_122313.jpg)

The result is a perfect cut 11º Crown. The bore-crown is sharp, burr free, without a ridge or fold-over
Polishing is not need unless you want it to look good!
(https://photos.imageevent.com/scl_electronics/gun/ultimaterapid/websize/20200909_122407.jpg)

Another .22 barrel ready to shoot...

Stuart

Great info Stuart.much better than a grinder ;D.would not mind having a go with that set up.
KevG

Very clean neat and tidy finish and looks very smart.
I have not seen it done that way.
Thank you for the pics and info.
Regards kev.

Here is another look at the finish of the Crown.
I hit it with a little #0000 steel wool, and a bit of polishing compound...
I was very careful not to compromise the Crown itself!
(https://photos.imageevent.com/scl_electronics/gun/ultimaterapid/small/20200918_162610.jpg)

Stuart