Author Topic: making square reamers for shotgun bores (Read 10480 times)

jerrywh · « **on:** July 11, 2016, 11:51:33 PM »

Rolf.
Here are a couple photos some reamers I have made. The top one is a more modern type reamer and I am showing it to illustrate the taper on the end. This tapper is very important for a shotgun with a choke because the choke section of the bore must transition smoothly or the pattern will be destroyed. The biggest square reamer is for a 10 gauge and the smallest is for a 50 cal. but the sizes can be altered by using a different backing stick. These are made from square files that were annealed and then hardened and tempered after being formed by grinding and filing. The final cutting edge is polished with a diamond plate but can be done with any stone. The metal needs to be about .100" smaller than the bore. When used a shim is placed between the stick and the reamer to increase the size after each pass. I use .001 and .002 " shims but many of the old barrel makers just used paper shims. You can find these in some old antique gun and blacksmithing books. They must be turned by hand and use a lot of oil. The finish is actually better than a modern reamer produces. If polished well they will leave a polished bore.
It is hard to see in the photo but there is about a .040 tapper to each on the leading edge. The end where the drive rod is connected is best annealed. You can see the temper colors on the drive end.
you can also use these for rifle bores or preparing a barrel for a liner

Acer Saccharum · « **Reply #1 on:** July 12, 2016, 12:24:55 AM »

Awesome!

The wood backer gives some compression and spring pressure to the cutting edges. Most unlikely that the tools will dig in with careful use.

Pennsylvania Dutchman · « **Reply #2 on:** July 12, 2016, 02:18:31 AM »

This is the drill and the square reamer that I used to drill and ream the barrel for my .62 smooth rifle that I showed photos of a while back.. The drill is 19/32" and I reamed to .620. I sawed the reamer out of a large flat file then machined it to size on the surface grinder. I only have the leading edge sharp. I lightly rounded the trailing edge with a diamond stone. I reamed under power in my lathe with the reamer shank in a tool holder on the tool post. I used lots of sulfur based cutting oil on the slowest speed on my lathe. It took about 30 minutes for a pass of 42". I used .003 thick paper for shims. The bore comes out glass smooth with a square reamer.

The reamer is 12" long, .370 wide and .273 thick. I used hickory for the wood backer. The shank is 3/8" CFR welded to the reamer. I sawed it out of the file with an abrasive blade being careful not to ruin the temper of the file. You can see the taper lead in on the end, otherwise the reamer sides are parallel.
Mark

hudson · « **Reply #3 on:** July 12, 2016, 06:58:01 AM »

Interesting, I have tried power reaming on my lathe with the square reamer. As my lathe only goes down to 80 RPM, kind of scary. I am planning on making a reaming bench. My question is size of the reamer for different calibers. Another question is sharpening one side verses two. There seams to be some disagreement on this.

Thanks

James Wilson Everett · « **Reply #4 on:** July 12, 2016, 03:41:16 PM »

Guys,

This is really great information. Thanks for posting this. I have found that square reamers are a lot easier to use than the modern ones. Modern reamers will tend to wander off the bore center if the machine setup is in any way imperfect, ruining the job. The square reamers will always track on the bore center. Here are some photos of my take on this topic, These square reamers are sharp on two edges, rounded on the other two. I use regular notebook paper shims with a lot of oil. I have found that the shim stays with the reamer without any attachment wire, the lantern stock helps this. With each new paper shim I turn the reamer through the barrel starting from the breech end and passing the length of the barrel in - out several times until the reamer seems to stop cutting. Then add a shim. Always starting from the breech end will result in a slight taper to the bore, the muzzle being a few thousandths of an inch smaller than the breech. For the wood backing, I start with a popcicle stick. The reamer is W1 tool steel, or 1095 carbon steel.

Jim

http://americanlongrifles.org/forum/index.php?topic=31614.msg303333#msg303333

Pennsylvania Dutchman · « **Reply #5 on:** July 12, 2016, 04:43:11 PM »

My lathe will run 32 rpms on the slowest speed. I don't remember what feed rate I used, but it took about 30 min or a little longer to make a pass thru the 42" blank. I didn't have any thing holding the wood backer on either. When the reamer came thru the barrel, I took the backer and shims off and backed the reamer thru the barrel for another pass. I wiped the bore with a patch and reoiled it. I added another paper shim for each pass. I had read in one of my old gun books, maybe Greener's, on how to make these and the source I read said to lightly round the trailing edge. I doubt if it would make much difference either way, as the trailing edge would be at such a shallow angle to the bore that it wouldn't do much cutting anyways. A tightly patched round ball pushes thru the finished bore smoothly with no change in resistance. A longer taper than I used on my reamer probably would result in a nicely choked bore for a shotgun, if you didn't ream all the way thru.
Mark

Rolf · « **Reply #6 on:** July 12, 2016, 08:52:00 PM »

Thank you all for Your input. I will try to make a square reamer as suggested. How long should anshotgun reamer be? Length of taper portion?

Best regards
Rolf

James Wilson Everett · « **Reply #7 on:** July 13, 2016, 03:38:46 PM »

Guys,

Also, the proper use of these tools, often called "armory reamers" will result in a very slightly tapered bore. If you always start the reamer at the breech end, the bore will measure a few thousandths of an inch smaller at the muzzle due to compression and wear of the wood backing and paper shim pack. A good discussion is found in the old topic:

http://americanlongrifles.org/forum/index.php?topic=24226.msg232386#msg232386

Jim

Pennsylvania Dutchman · « **Reply #8 on:** July 13, 2016, 03:57:06 PM »

James, I wonder if bore taper would depend somewhat on the length of the reamer? I noticed that your reamer is only about 4" long and Jerry's are quite a bit shorter than mine also. My reamer is almost 12" and the wood backer close to 11". I couldn't measure or feel, with a tightly patched round ball, any taper in my longrifle bore or the pistol bore that I reamed. Maybe a longer wood backer would wear less as it reamed?
Mark

jerrywh · « **Reply #9 on:** July 13, 2016, 07:36:28 PM »

My reamers are about 7 inches long and the tapper varies. On most shotguns the tapper going into the choke should be at least 2 inches long but I don't think it can be too long. 3 or 4 inches would be OK in my opinion.
The long reamers tend to take any minor bends out of the bore. A gun will shoot where ever the last 6 inches of the bore is pointing regardless of where the rest of the bore is pointing. Many old shotguns have crooked bores to a minor degree and it was ignored for that reason.

Rolf · « **Reply #10 on:** July 26, 2016, 09:49:45 PM »

Finished my first attempt at making a reamer. Took a worn out nicholsen metal rasp. Cut a strip off with an angel grinder. Ground off the teeth and flaten it in the mill with a Crown carbide bits. Used plenty off coolig fluid. The files temper is undamaged. Polished the reamer by hand with Diamond hones sold by Lindsay for sharpening. Took two days to get rid of all the scratches. Got to be the most tedious job I've done so far.

The reamers dimensions are:
Length: 10 in
Width: 0.433in
thickness: 0.207in

This reamer is intended use for 0.54 and 0.58 Caliber pistol barrels. But I was wondering if it big enough for 18 and 16 gage shotgun barrels?
If not, what would be the best size reamer for these shotgun barrels?

Best regards
Rolf

jerrywh · « **Reply #11 on:** July 26, 2016, 09:57:37 PM »

Rolf. That reamer should work on a 16ga. It is about the same width as the one I am using now on a 16ga. barrel. 18 ga. also. Just use different backing sticks.

Long John · « **Reply #12 on:** July 27, 2016, 04:22:36 PM »

jerry, please forgive me but I'm "kinda slow".

As I understand these reamers it seems that they are a square cross-section cutting tool that is situated in a wooden cradle, of sorts, of sufficient thickness to hold the cutter against the barrel wall. The cutter is attached to a long rod that allows you to rotate the cutter/cradle assembly as you push it through the bore. The square cutter literally scrapes a thousandth or so off the bore as it is rotated during its trip down the bore. Do I have that right???

If so I have a couple of questions.

Does the cradle of wood position one edge of the square cutter against the barrel so that there is a 45 degree angle between the cutter face and the tangent to the point of contact? Or does the wood cradle position two edges against the barrel interior?

Is there a size relationship between the bore diameter and the cross-sectional dimensions of the cutter? Does a 12 gauge bore require a larger cutter than a 28 gauge bore or just a thicker cradle?

I have a pistol I need to ream from 54 caliber to 55 caliber and this might be the way to do it. When you are reaming a bore how much increase in bore diameter do you generally achieve?

Thank you for sharing your knowledge.

Best Regards,

John Cholin

jerrywh · « **Reply #13 on:** July 27, 2016, 07:44:20 PM »

Long John.
In theory both corners of the reamer scrape the bore. They don't cut they scrape. However I have found that some of the time it is only the trailing edge that scrapes. I can't say as it matters as long as it does the job. I have found that if you try to take too much at one pass and force the cutter too hard it will gaul the bore and gouge small pieces of metal out of the bore. As far as size relation goes there is a wide range and I have never tried a small cutter in a large bore. I make mine about as large as I can and still get a wooden backing on them. I don't see how those guys can get the backing to stay up with the cutter when it is not attached to the backing. This is a slow process and hard work for an old man by hand.
I am not criticizing anybody but note this. In the last photo of James Wilson's post look closely at the wooden backing stick. See the grooves in the stick. That is caused by pieces of metal getting stuck behind the backing stick. This is a sign of the cutter gouging metal out of the barrel and the fact that the backing stick is too soft. A real hard stick will help prevent this from happening. I tried maple and walnut but the best I found was hickory. I have been thinking of making a brass or copper backing for mine.

Pennsylvania Dutchman · « **Reply #14 on:** July 28, 2016, 12:15:17 AM »

Jerry, It is hard to see in my photos, but I have a shoulder on the shank that is welded to the reamer for the hickory backer to seat against. The reamer was pushed thru the bore. I have a shallow groove in the shank end of the backer that I initially had a piece of small copper wire attaching the backer to the reamer. After a couple of passes I decided it wasn't necessary, as it was easier to remove the backer and shims at the end of the pass for cleaning. I used .003" thick paper shims and the scrapings resembled grey flour. It took all day to ream from a 19/32" drilled hole to .620" finished bore. I don't remember how many shims that I used. My lathe will run 32 rpms in the lowest speed, so I let the lathe do the work while I worked on another job in the Mill.
Mark

jerrywh · « **Reply #15 on:** July 28, 2016, 02:49:28 AM »

Dutchman, sounds good. Now I understand your method. I was thinking. The smaller the cutter is in diameter the more it burnishes rather than cutting. If you draw a square inside of a circle that is large as possible And then draw a smaller one you can see the difference in the scraping edge angles in relation to the bore. So a wide reamer would cut better than a narrow one. A narrow one would be better for polishing. However these reamers leave a very smooth bore and I have not found it necessary to polish afterward.

Pennsylvania Dutchman · « **Reply #16 on:** July 28, 2016, 05:39:35 AM »

Jerry, I have been thinking about your post. Wouldn't a narrower reamer be more aggressive than a wider one? The narrower the reamer, the less negative the cutting edge would be to the bore. I other words the closer to the centerline the cutting edge would be the more aggressive the cutter and more likely to dig in instead of scrape.
Mark

jerrywh · « **Reply #17 on:** July 28, 2016, 06:00:53 AM »

dutchman.
When you say narrower I assume you mean from top to bottom. I agree that it would scrape better but I don't think it would dig in unless you tried too much of a cut a tone pass because of the angle on the edge Ideally I think the edge should be just above center but I haven't tried it yet. I have had problems hardening thin blades . They tend to warp a lot more than the thicker ones. I ordered some .01 tool steel to make my last one.

Pennsylvania Dutchman · « **Reply #18 on:** July 28, 2016, 06:19:52 AM »

Jerry, I mean narrower in width, as in the leading edge and trailing edge are closer together. If I'm understanding you correctly, narrower top to bottom would mean it would need a thicker wood backer. Narrower in width would make the leading edge closer to the centerline, therefore more aggressive. Think about a standard chucking reamer with 6 flutes. The cutting edges are on centerline of the tool. If you made a reamer with the flutes ahead of the centerline it would be less aggressive and more of a scraping tool. The farther ahead of centerline you make the cutting edge the less cutting action you would have.
Have you tried any air hardening tool steel for thin blades? A-2 or D-2 are both very stable in heat treatment.
Mark

jerrywh · « **Reply #19 on:** July 28, 2016, 05:50:54 PM »

Narrower and the leading edge will cut better, Right. The trailing edge won't cut at all.
I'm 80 years old and I hope this barrel is my last one to do by hand so I,m not looking for any new way. I will probably just engrave and give engraving lessons as long as I can. I thought about making one out of HSS, but what for?
When you set up for reaming on your lath how do you run the oil? And what do you do if the reamer hangs up? Do you have a clutch on the drive or something?

Pennsylvania Dutchman · « **Reply #20 on:** July 29, 2016, 04:38:26 AM »

I just flooded the bore with an oil can and squirted some more in periodically as it was reaming. I had the shank of the reamer clamped in a tool holder on the tool post. I didn't have a clutch or anything in case it hung in the bore. I could probably adapt a shear pin to the tool holder end of the shank if I use it again.
40 years ago when I was in Twin Lakes Vocational Technical School for Machine shop, I made a square reamer to ream a pair of .410 barrels I drilled. The reamer was .250 square. It left the bores very smooth, but they had very fine lines parallel to the bore almost like splines. They were probably only .005" wide at the most and very very shallow, maybe not more than .002" or .003". I always assumed they were caused from using too narrow of a reamer for the bore size, but I don't know.
Mark

Steve Bookout · « **Reply #21 on:** July 29, 2016, 08:52:17 PM »

I am enjoying this conversation immensely. I am presently reaming a barrel from .70 to .75 caliber. Most of my reamers are made from 4 square files. The presently utilized reamer is square but out of A2. There is no taper to speak of on this one, but the forward edges of the square are faceted at a 45 for about 3/32". You're all using lathes. My boring machine is cranked by hand. A lever and rope are used to advance the carriage when working alone. Anyone want to lend a hand?

jerrywh · « **Reply #22 on:** July 29, 2016, 11:47:41 PM »

Steve
I like your setup a lot. How about using a weight on the end of the rope and run the rope over a pulley. Then you won't have to pull the rope all the time. You could add weight as needed or remove some.

Steve Bookout · « **Reply #23 on:** July 30, 2016, 07:45:32 AM »

I have often thought about that, Jerry. In fact, Tim Crowe and I hashed it over this past week. I've procrastinated quite a bit mulling this over and have decided I will "invent" some Rube Goldberg contraption (I'm sure) when this barrel leaves the bench. Have used the reamer so much, the Babbitt bearings need to be recast. Thanks for the kind words.

Steve Bookout · « **Reply #24 on:** July 31, 2016, 03:43:58 AM »

Here are a half dozen pics from the blacksmithing/gunsmithing seminar taken this week here at Toad Hall. Ye bearded one, Tim Crowe, member of the ALR site and his brother are the two gentlemen working the reamer besides myself. If you be wondering, the long item in the swarf pan is a string used to attach the shoe to the reamer earlier. The proper British term for the wooden shoe is spil. Holland & Holland still use the term and also, at least, in New Zealand. The other pics high lite the reamer. The photos are not of Hollywood quality, so take them for what they're worth....a picture is worth a thousand words, you know...

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Author Topic: making square reamers for shotgun bores (Read 10480 times)