Blue Sun Room GRAPHICS - IMAGES
Big Damn Hero Gun: Part 3
Tuesday, December 25, 2007
The Callahan Mk.1, all dressed up and waitin' to go somewhere fun. The brass bits up front really screw up the balance, but I can still twirl it. If'n I do this again it'll be made from much lighter materials. At 3# 7oz she's a bit heavy for my taste.
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Comments
Wednesday, 26 December 2007 18:26
Awesome! What kinds of bits & pieces did you use to cobble this thing together. Barrel, cylinder, hammer...
Wednesday, 26 December 2007 19:18
I am very struck that you considered and discarded the plan I still have, of buying a non-working reproduction and having it modified. I like that yours is a break-open rear loader. Myself I do not have access to real machine tools - just dremels and such - so I would like to learn more about how you did this woek step by step. Lovely result, and a real contribution to the fandom. If by any chance you attend the upcoming Browncoat Ball or Dragon I'd love to see this in person.
Regards,
Q
Regards,
Q
Wednesday, 26 December 2007 22:55
Thank you for the compliments. I'll do the blow by blow on construction in installments, so stay tooned....
First bit: The upper frame.
I'm a blacksmith, so I've got lots of oddball stuff in my scrap pile. You never know what a customer is gonna want.
The barrel is thickwall round tube, a bit over 5/8" diameter O.D. The back strap is 1" O.D. square tube, having an I.D. of 3/4". The front of the upper frame is 3/4" square stock, drilled to take a 1/2" round plug so I could weld the barrel to it square.
The cylinder was a real pig. I cut a section of truck axle, annealed (softened) it in my forge, then drilled out the center hole and the hole for the large pin/guide for the extractor plate. Gotta add a second pin as the extractor plate sometimes twists a little, jamming the cylinder. Of course, the holes weren't straight, so the cylinder axis was off-center, requiring some time with a file to get it close to round again.
The cylinder axle is a section of grease gun barrel that I spun down to just under 3/8".
You don't need a full machine shop, but it helps. You can do a lot of this kinda work with a circular saw with abrasive metal cutting blades, a 3'8" variable speed drill, a good vise, drill bits, and files. If you chuck up the drill in the vise you can use it as a lathe to turn down anything that'll fit in the drill chuck using a file.
More next time.
First bit: The upper frame.
I'm a blacksmith, so I've got lots of oddball stuff in my scrap pile. You never know what a customer is gonna want.
The barrel is thickwall round tube, a bit over 5/8" diameter O.D. The back strap is 1" O.D. square tube, having an I.D. of 3/4". The front of the upper frame is 3/4" square stock, drilled to take a 1/2" round plug so I could weld the barrel to it square.
The cylinder was a real pig. I cut a section of truck axle, annealed (softened) it in my forge, then drilled out the center hole and the hole for the large pin/guide for the extractor plate. Gotta add a second pin as the extractor plate sometimes twists a little, jamming the cylinder. Of course, the holes weren't straight, so the cylinder axis was off-center, requiring some time with a file to get it close to round again.
The cylinder axle is a section of grease gun barrel that I spun down to just under 3/8".
You don't need a full machine shop, but it helps. You can do a lot of this kinda work with a circular saw with abrasive metal cutting blades, a 3'8" variable speed drill, a good vise, drill bits, and files. If you chuck up the drill in the vise you can use it as a lathe to turn down anything that'll fit in the drill chuck using a file.
More next time.
Thursday, 27 December 2007 06:13
The first bit, continued......
OK, so now the cylinder spins on the axle. I ran a 1/4" rod through the hollow axle, and soldered the extractor plate onto the rod. Under the barrel I welded a small steel stud with hole for the rod to spin in. Because the rod is so long it was kinda vulnerable under the barrel, so it got covered with a section of 3/8" gas pipe. No more worries about the rod getting banged up & bent.
For the cylinder to crank around you need two things: a ratchet wheel and the hand/pawl which is driven by the hammer. I coulda made the wheel outta small diameter pipe and cut teeth in it, but opted for a thick washer with spokes cut into the perimeter. The number of chambers in the cylinder = the # of spokes or teeth on the wheel. The wheel is just silver-soldered onto the extractor plate. This turned out to be a good thing as later on I needed to turn that wheel a bit in relation to the plate to get the timing/indexing correct.
That about covers the upper frame/barrel/cylinder assembly. If you really wanna figger out old-timey guns go to the Dixie Gun Works site & have a long gander at the exploded views. I’m partial to the Rogers & Spencer or the 1858 Remington. Both are dead simple with few parts.
OK, so now the cylinder spins on the axle. I ran a 1/4" rod through the hollow axle, and soldered the extractor plate onto the rod. Under the barrel I welded a small steel stud with hole for the rod to spin in. Because the rod is so long it was kinda vulnerable under the barrel, so it got covered with a section of 3/8" gas pipe. No more worries about the rod getting banged up & bent.
For the cylinder to crank around you need two things: a ratchet wheel and the hand/pawl which is driven by the hammer. I coulda made the wheel outta small diameter pipe and cut teeth in it, but opted for a thick washer with spokes cut into the perimeter. The number of chambers in the cylinder = the # of spokes or teeth on the wheel. The wheel is just silver-soldered onto the extractor plate. This turned out to be a good thing as later on I needed to turn that wheel a bit in relation to the plate to get the timing/indexing correct.
That about covers the upper frame/barrel/cylinder assembly. If you really wanna figger out old-timey guns go to the Dixie Gun Works site & have a long gander at the exploded views. I’m partial to the Rogers & Spencer or the 1858 Remington. Both are dead simple with few parts.
Thursday, 27 December 2007 07:54
The second bit: Lower Frame
I started with the 1" square tube for the horizontal , and a piece of 1" X 2" rectangular tube for the vertical section. Those were soldered together to hold the alignment while I made two inner plates. After measuring up the inside of the lower frame shell I made a cardboard template. This was used to assure an accurate fit of the plates and was used as my pattern for them. You gotta cut stuff like the plates a bit over sized, then trim by filing until they fit right. With the plates welded in place the interior space of the lower frame was now 3/8" wide vs. the 3/4" of the tubing. The plates extended to the rear of the tubing shell, making the upper part of the grip. The plates also made the frame thick enough that I could drill & tap holes for the various screws.
Now for the grip. I mocked up a grip out of wood to get a comfortable size & shape for my hand. This was temporarily attached to the lower frame with screws so I could carve and shape it. When I had it right, the wooden grip shape was transferred to another cardboard template. The front & rear grip straps were cut outta 1/4" plate, then cold bent to match the template. I added a butt plate after realizing that wood grips tend to get really beat up along their bottom edges.
With the grip welded in place I fitted up the upper frame, then secured it in place with a nut & bolt. Behind the cylinder on the lower frame is the recoil plate. In this case, just a honkin’ big washer with the right sized hole to admit the ratchet wheel. Took some fiddling to fit that up right so the ratchet didn’t drag. Soldered in place for fit-up, then welded in for good.
The last bit on the lower frame was the latch. Just a short section of 1 1/4" square tube with a side cut out of it. Two holes with screws, plus some fitting up and it securely holds the frames together at the backstrap.
I started with the 1" square tube for the horizontal , and a piece of 1" X 2" rectangular tube for the vertical section. Those were soldered together to hold the alignment while I made two inner plates. After measuring up the inside of the lower frame shell I made a cardboard template. This was used to assure an accurate fit of the plates and was used as my pattern for them. You gotta cut stuff like the plates a bit over sized, then trim by filing until they fit right. With the plates welded in place the interior space of the lower frame was now 3/8" wide vs. the 3/4" of the tubing. The plates extended to the rear of the tubing shell, making the upper part of the grip. The plates also made the frame thick enough that I could drill & tap holes for the various screws.
Now for the grip. I mocked up a grip out of wood to get a comfortable size & shape for my hand. This was temporarily attached to the lower frame with screws so I could carve and shape it. When I had it right, the wooden grip shape was transferred to another cardboard template. The front & rear grip straps were cut outta 1/4" plate, then cold bent to match the template. I added a butt plate after realizing that wood grips tend to get really beat up along their bottom edges.
With the grip welded in place I fitted up the upper frame, then secured it in place with a nut & bolt. Behind the cylinder on the lower frame is the recoil plate. In this case, just a honkin’ big washer with the right sized hole to admit the ratchet wheel. Took some fiddling to fit that up right so the ratchet didn’t drag. Soldered in place for fit-up, then welded in for good.
The last bit on the lower frame was the latch. Just a short section of 1 1/4" square tube with a side cut out of it. Two holes with screws, plus some fitting up and it securely holds the frames together at the backstrap.
Thursday, 27 December 2007 17:50
The third bits: Mechanicals
I marked the outside of the cylinder for what would be 8 chambers (this includes the extractor plate pin hole). In the horizontal part of the lower frame I drilled a small hole where the cylinder stop would poke up through, then rotated the cylinder to each mark and center-punched it through that hole for the cylinder stop divits. A real revolver has semi-circular cutouts in the cylinder for the stop to latch into but that seemed like too much effort for a prop piece.
Next came the hammer, roughed out of 3/8" plate, then power sanded and filed to fit. The lobe for the end of the cylinder stop and the two detents for the trigger ended up a lot closer together than I wanted, but worked out anyways. To power the hammer I used a strip of 1/16" high carbon steel (fillet knife stock) for a flat main spring. The spring sits in a socket inside the grip bottom just like the originals.
The trigger is 1/8" sheet, cut and filed to fit from a cardboard template. The cylinder stop was more challenging, though. I ended up making it out of 3/16" angle iron. The problem being that the nose of the stop was centered in the frame, but the rest of it needed to be off to the side so as to clear the trigger. Took some figgerin’ and head scratchin’ but I got ‘er done.
The other end of the stop needed to be bumped by the hammer as it was drawn back, yet return to the “up” position at full cock. More head scratchin’ ensued.
The trickiest bit of all was the hand, or pawl, to jack the cylinder around. As the hammer goes back it pushes the hand out through a slot in the recoil plate, engaging the ratchet, spinning the cylinder. Timing is a function of hand length, hammer throw length, and the tooth/spoke position of the ratchet. Took me three different hands before I got one that works fairly well. My hat is off to Sam Colt, one smart dude.
A word here about the springs that make things go. Flat springs, like in the originals, work just dandy IF you get ‘em positioned correctly and IF you make ‘em outta the right thickness stock. Get the position wrong and crunch them and they take set and don’t work right. Too thick and they either snap off or get crunched and take a set. Use small coil springs if ya can, far less hassle. Because of the springs on hand, trigger, and stop, I prolly took the thing apart an extra 50 times before getting it right.
The last bit to get screwed in place was the trigger guard. Just a flat cover to go over the trigger and stop with a loop of thin steel for a guard. Some minor fitting up on that and one of the easiest parts to make.
Thursday, 27 December 2007 18:30
The last bit: Doo-dads
Well, it just wouldn’t belong in the verse if it didn’t have some useless, but shiny, doo-dads hung on it somewhere. I’m partial to brass ‘cuz you can do a lot with it, it’s easy to work, and it’s pretty.
Both regulator bits are brass plumbing pieces scrounged from who knows where. The one on the right is part of a valve assembly that had a quick release fitting. The knurled steel adjuster is the remains of a tap wrench I scragged doing this project, twisted the jaws right out of it threading a hole. Oops. The left is just a length of brass tube with the over-pressure release cap from another valve assembly. Don’t rightly recall where I got those turned brass ball things, I think they’re lamp finials.
Tying those together is a simple hollow box formed from brass sheet. I guess all that time spent building a Firefly outta brass came in handy. The whole assembly has a pair of brass clips on top that slide over the extractor rod housing under the barrel. Finished it off using cold gun blueing paste to get a nice dark patina.
There ya have it. About a month’s worth of figgerin’, cuttin’, cussin’, head scratchin’, and designing on the fly. Quite a few things I’d do different, like making the cylinder hollow to reduce weight, less material in the frame, and use coil springs vs. flat, but I think it turned out not too shabby. It does work using roll caps glued to the extractor plate, but it makes a gorram mess inside, requiring disassembly for cleaning. Next one’ll be better, mebbe set up to take plastic ring caps.
Sunday, 30 December 2007 08:11
Just realized I left something out. In the pic in BDHG Part 2 it looks like there's cartridges loaded up in the cylinder. They're dummy too.
Repeated dry firing was making the end of the firing pin mushroom out. So, I drilled holes in the extractor plate and stuck the ends of expended 22 cartridges in them. Now the firing pin is hitting soft brass instead of the steel plate, no more mushrooming.
Gotta watch when I pop open the gun as they tend to fall out and disappear. Thought it'd be neat to carry extras with the roll caps already glued on, but with the mess they make it just wasn't worth it.
Repeated dry firing was making the end of the firing pin mushroom out. So, I drilled holes in the extractor plate and stuck the ends of expended 22 cartridges in them. Now the firing pin is hitting soft brass instead of the steel plate, no more mushrooming.
Gotta watch when I pop open the gun as they tend to fall out and disappear. Thought it'd be neat to carry extras with the roll caps already glued on, but with the mess they make it just wasn't worth it.
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