Greg, The Rigby flats on a Ballard kind of intrigue me.  It looks like you are incorporating the flat into the profile of the barrel blank and final profile will be a round taper.  I’m curious how you are machining the flat and finishing the the round in that area?  I always assumed the Rigby flats were soldered on, in the same manner as a rib on double gun barrels, after the barrel was profiled.
Bob

Chuckster wrote on Aug 14^th, 2021 at 7:57am:


Chuck,
First thing, not all barrels run concentric inside to outside.  I had a couple of these to choose from and one did - within a couple.   
{Next, I despise in-accurate machines and tooling, do what it takes to make them correct or else make sure you understand what their flaws are and work with them - a little soap box rant about to happen... I've had employees that didn't trust the dial on the machine so they use their travel indicator for their depth of cut but then you look at how they have their dial sitting... rarely square to the ways??? I ask them if they are taking into account for the hypotenuse?  get a dumb look... my dials work or we repair them.  Mills, lathes, jig bores, grinders, etc. } end of rant.
Now the three jaws, on this particular machine - I keep the scroll fairly clean and lubed with a good diemakers grease.  If my runout gets much in excess of .001 at the diameter range I work in most, .5" to 1.5" I regrind the jaws. (diameters on either side may run out a little more than that so if it matters I have other machinery that accommodates these demands.)  Generally only takes about a half or one to get them true again.  I'm anal about who runs this machine, it looks like a junker but I've spent time making it work for me. 

Bob, 
The Rigby Flats I've done on my rifles always begin with lumps left on the barrel - then removing everything that doesn't look like a flat .  With care and time and a good rotary table or indexer, you can get these close but it's a lot of hand work.  The radius on the end of the flat is all hand work as is matching the space in between the flats to match the rest of the barrel contour.  A bright light and a dim room really pronounces this contour blend.   
I picked up a Sheffield air gage some time ago - used it to see what the effects of making Rigby Flats has to the bore, it's measurable.  About as much as cutting a dovetail and then installing a front sight... or torqueing up v-threads vs. square threads.  They all have effect.   Soldering on a rib or a sight has a very measurable effect and the larger the bore, the more effect.

Steve Durren has an excellent article in a past ASSRA Journal on how to make Rigby flats. 

American Single Shot Rifle Association's 
ASSRA Single Shot Rifle Journal Vol. 59, No. 2 March-April 2005

For those who might be interested.

Made a little time and roughed out the flats on this barrel.  There's still considerable file time to make things look halfway presentable but the idea's apparent?   Most Rigby Flats are much narrower but I chose to go with a flat continuing with the width of the action.  It would have looked a little better had the blank diameter matched up with the action rather than the step down.  Not a masterpiece but an oddity.

I actually like your Rigby Flat front sight base a lot, though just for looks in my mind's eye, I'd have made it a bit shorter.

Bill Lawrence

Bob,
I've often wondered if I could bend a barrel this way and because of that I never seem to over tighten things, I chase it around because it's not tight enough to hold it solid.   
I have spent some time with an old time barrel straightening press and in most cases it took more pressure to straighten a barrel than one thinks.  (if you have JV Howe's volume 2 Modern Gunsmith, page 151 show's the press configuration).  I've made small bushings for different calibers that intensify the light rings in a barrel, it'll indicate how straight a barrel is for a novice.  With practice and experience one can look down a barrel and see the light rings without the bushing.  If you question yourself, make one of these place it in the barrel and experiment with your clamping force. 

Bill,
There was a little madness to my method on the length of the front flat, if I change sights and go to something like a 17A it would look proportionally better.  Where the flat ends will be the end of the barrel when I'm all done.  Thanks for the comments though.
Greg

This is very true Otto, it is a tedious process and I'm an ass about who touches this lathe- I'm even tough on the guy that runs it the most...  On my larger machines and the TL cnc's  I use the Gator brands and even an early Bison brand true adjust.  It's convenient if you have parts with good or finished surfaces and doing multiples.
I use a lot of 2J and 5C's in Sjogren collet chucks on the TL's and Monarchs.   If a barrel is concentric, there's a collet that fits, and the machine isn't busy - things get real easy and life is good.
Greg

If not careful when grinding the jaws on a three jaw chuck. Is it could no longer close far enough to hold a small object such as a small drill bit. I myself made that same mistake and unfortunately I limited the abilities of that three jaw chuck.