Progress on rifling machine and rifled choke tube!

[longbow]

My cutter looks just like the one in the Bev Fitchett link... it is a piece of file with the faces ground off leaving the edge as a multi tooth cutter. Easy to make but not as effective as i would have thought considering the source. Oh well!

To be honest there is an idea I hadn't thought of is a circular saw blade. If the carbide is narrow enough and not too long it might work and if so the carbide wouldn't likely dull for a whole choke tube or maybe even a whole barrel. Obviously cutting speeds are low when cutting by hand.

For now I think I am stuck with either replacing the cutter I have in kind or possibly making a hook or scraper style cutter out of a file or high speed steel as Randy suggested. Since I don't have easy access to tool steels, unless possibly I get something used from a local shop and grind it to shape, I'll likely use a file and carefully grind a cutter out of it. As I said, I am at least 1/3 the way there so at worst I'll have to make a third cutter to get the full depth of rifling. They really aren't that hard to make but I do have to make sure they are pretty much the same length and for sure the same width to fit the partially cut grooves.

If I do this again (IF!) I'll look at the circular saw blade Idea. Or possibly another source of carbide cutter. Good idea!

Longbow

[missionary5155]

Greetings
Keep on Keeping on my friend ! I can remember when this was just a dream. 1/3 is a .333 batting average ! That is light years down the way from a dream.

[longbow]

Mike:

It has been a long haul! Actually, I got started this several years ago but life got in the way so it got dropped. First the dog was winding down so I spent time with the poor old guy then my mother's health started to deteriorate so that distracted me even more then there were other issues so I just didn't get back to it. But I'm back on it now and making good progress.

One thing that I do not like is that the factory blank choke tube is very short. It really may not matter because the twist is so slow but I'd rather have 3" or 4" of rifled choke tube then about 2". We will see what we will see.

I see you are back in Peru again for a bit. Do you do much shooting there? I recall you saying you had a place to shoot but I'd guess reloading supplies are scarce? What guns/calibers do the locals use?

Take care.

Longbow

[longbow]

Disaster has befallen me!

I remade the cutter to a single tooth hook style cutter and it worked... a little too well! It cut well from the get go but tended to grab and stop so requiring a bit of force to get moving again, in either direction, I am guessing that there was enough force at some point that the choke tube slipped so became out of time with the cutter and it removed the sides of the lands already formed.

Since I had the bore at a small dimension I may be able to salvage the choke tube by matching up to old grove then cutting to full depth . The lands may be a bit ratty or I may be able to bore to decent condition and still have enough rifling depth. We'll see!

Regardless I will regrind the hook cutter to 90 degrees or maybe slightly negative so it is a scrape cutter and not likely to grab. I ground it to 5 degree positive rake per internet instructions. I kinda wondered if I should have gone with 90 degrees for scrape cutting! Now I know. Maybe even a couple of degrees negative would be best. I'll try 90 in the botched choke tube to see how it does.

So, I went from not aggressive enough cutter to too aggressive a cutter!

Here is a pic of the original style cutter from a piece of file using edge of file teeth and my wooden rifling head with the hook cutter epoxied in (shim papers go between the shoe and head):



Hah! That hook cutter looks kinda poorly in the photo but does it cut! It takes curls of metal out! The rifling machine and cutter work if only I could get things right! Actually the file edge did well rifling the piece of pipe for a test. I only went about 0.005" rifling but it was clean and sharp.

This stainless didn't like the file much. The hook cutter certainly cut it but a bit too much. I'll dial it back and try again.

Longbow

[Cap'n Morgan]

Longbow.

When broaching it's important the relief or clearance angle (that's the angle between your rifling and the top of the tooth) is rather small (between 0.5 - 3 degrees) otherwise the tool will chatter - especially when the tool has a large rake angle (hook-shaped) I learned that lesson the hard way when working as a tool grinder.

[longbow]

Cap'n Morgan:

I didn't get any chatter at all but I did get some grabbing which when it happened required a firm tug on the handle to get moving again. I tried pushing back which worked sometimes but not others.

Possibly the lack of chatter is because my back rake was ground at 5 degrees but was actually more like 3 degrees because I tipped the nose of the cutter down a bit when I epoxied it in. That also increased the rake of the cutting edge which may have added to the grabbing.

The wood rifling head is a bit springy of course as are the paper shims but it all works quite well... other than I screwed up the choke tube!

The hook cutter cut amazingly well but when it grabbed and I tugged I am guessing I managed to move the choke tube a bit under the clamp so next pass took a bit of the side of the lands as I went around. I was getting nice curls of metal so it cut pretty well but was unfortunately cutting lands as well as grooves! A better clamp would help of course but you can only squeeze a thin walled choke tube so much before it distorts. I think better to solve the cutter grabbing issue.

I am thinking that a 0 rake of maybe 1 or 2 degrees negative would solve the grabbing and make it a scrape cutter. I did try a negative edge on an old file I ground like a scraper and the sharp edge did take metal off pretty well... fine shavings but consistent and clean. It would certainly take longer to rifle but if it works I don't care.

I may have enough meat left in this choke tube to get a decently rifled bore but if so the rifling won't be as deep as I planned.

Hard lesson learned (I think!). Best to scrape slowly and not get grabbing than to work faster and mess up the choke tube... though that was't the intent. The file cutter basically quit cutting and as Randy commented, I was "wearing" the rifling into existence. I'll try the scraper idea next. If it works, and this slow twist rifling works, I'll make another, better rifled choke tube.

In the mean time. I decided to modify my 7/8 oz. Lee slug mould to add a stem for screwing wads to. Now that turned out perfectly! I am about to start a new thread with pics.

Longbow

[missionary5155]

I have no doubts 300+ years ago men were working out the same details in small shops all along the colonies. Least today the availability of communication helps us all to learn and think and see.

[longbow]

Yes, Mike! Speaking of lost arts! Maybe not lost but but modern barrel making is a far cry from the old hand cut barrels. Those old guys knew what they were doing and did it well!

I am sure they had all this worked out 300 years ago because they made almost the whole rig out of wood with a case hardened cutter all made by hand as in ~ no bench grinder, Dremel, factory made files, Redi-Rod, or other conveniences.

I started with the edge of a file per Toad Hall Rifleshop directions and that did cut rifling in the 3/4" pipe pretty well (my first post in the thread). I only went about 1/2 depth as I was just proving in principle.

However, when I tried rifling this factory choke tube the file edge was inconsistent, grabbing sometimes but mostly sliding pretty easily and not cutting much. When I went to the 5 degree positive rake single point cutter the situation reversed! Fast! That cutter took out curls of metal and started pretty well but I suspect as it formed the groove and made full contact the chip was a bit too much so it stuck requiring significant effort to get moving again.

During the stick and pull harder bit the choke tube must have moved under the clamp so was then out of time. Likely a lesson learned long ago as well "Clamp that barrel down hard boy!" I can hear being yelled at the apprentice.

From these recent experiences though I have to think that 0 to slightly negative rake tools were most likely use in hand rifling. Scraping may be slower but I bet it is cleaner and dependable without the sticking issue. I'll find out as I will continue on this choke tube to see if it works. As I said, there may yet be enough meat to get usable rifling though it won't be as deep as I wanted. Still worth trying.

Longbow