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D&E .22LR 1874 Gatling Gun Build


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#1 Pmercer

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Posted 22 December 2010 - 03:35 PM

Hi.

I've been building a 1/3 scale 1874 gatling gun in .22LR which is based on plans by D&E model drawings and thought I'd share my progress. I made a fair few parts when I first started the project a few years back, but a change of career meant I didnt have access to metal working machinery for a while. I've now got a bit of a workshop set up in my garage so will endeavour to get further on with the build.

I've finished a lot of the components and have made rough castings of most of the other parts. As I machine the castings, I'm gradually going to start being able to assemble some of my parts together.

I'll get some photos uploaded on here as regularly as I can.

#2 Pmercer

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Posted 22 December 2010 - 03:39 PM

Here's the main base to the gun. It's made of 6mm thick brass sheet. I've turned up two collars and pressed them into the base. The blue wheel is a prototype part I made, but it will be replaced eventually when I have machined up the brass wheel. There are 3 small stainless screws in the wheel that hold it onto the collar. This has been sitting for a while, hence the tarnish.
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Here's the cast wheel:
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#3 Pmercer

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Posted 22 December 2010 - 04:10 PM

Here's the main shaft. it doesn't look all that pretty but the finish isn't that bad:
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Here's a key for the gear hub. You can see where it fits on the photo below.
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Here's the gear hub
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Here's the driven gear. I decided to buy the gears rather than make them.
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Here's it assembled.
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The gear hub screws onto the main shaft, so when it turns one way it is fine, but if you rotate it the other direction, it unscrews. I'll either loctite it or add another keyway at some stage.

#4 Pmercer

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Posted 22 December 2010 - 04:29 PM

This is the start of the barrel group.

Here's the bolt carrier that the bolts fit into. It's got tape round it to protect it whilst I was lapping the bolts in. In the bolt hole nearest you can see where the black marker pen hasn't worn off. I won't drill important holes with a drill again now I know what happens. Milling bits from this point on I think. Mind you, this is the same idea as the bolt on the Sterlings having a flute down them for crud removal. The hole to the left of no1 hasn't been lapped in yet as I've only finished maching 5 bolts.
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Here's the pan. This is the casting and hasn't had anything done to it yet.
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Heres the breech ring:
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This is the shaft:
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Here's the front shaft. I suddenly realised after making this part that I had better check the overall length of my gun to keep it legal. I subsequently had to make a longer front shaft....
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#5 Pmercer

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Posted 22 December 2010 - 04:57 PM

More of the barrel group:
The blue pan is a prototype as I've not cleaned up the brass casting yet.
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Here is the breach end of the barrels. I've still got to cut the chambers, screwcut them and cut an extractor groove.
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Here's the muzzle end of the barrels. I still need to cut and taper the length of the barrels.
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#6 Pmercer

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Posted 22 December 2010 - 05:08 PM

Here's the top cover.

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#7 Pmercer

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Posted 22 December 2010 - 05:22 PM

Here's the cascabel plate and plug.
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The rear isn't finished yet. I need to machine a thread onto it to match the receiver once it's made
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#8 Pmercer

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Posted 22 December 2010 - 05:43 PM

This is the oscillator assembly:

Here's the oscillator pin:
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Here's the oscillator knob:
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Here's the oscillator adjusting screw:
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Here's the oscillator cap:
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Here's the assembled unit:
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#9 bruski

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Posted 22 December 2010 - 06:04 PM

Nice job with your progress and castings. It won't be long before you are test firing your gun now.

#10 Pmercer

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Posted 22 December 2010 - 09:01 PM

Thanks. At the moment, a lot of the parts have a dull tarnish on them, which added to the fact that I've not got a proper finish on any surface yet means my work looks shoddy. As time goes on, I'll start to get proper finishes on all parts.

#11 bruski

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Posted 23 December 2010 - 07:36 PM

There is plenty of time for polishing after it is done. I have done enough prototyping and projects in the past to realize that somethings don't always work the way they are supposed to and need some re-machining which means repolishing again. Good luck!

#12 farmkid

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Posted 03 January 2011 - 12:44 AM

I'm in awe.

I admit that I haven't visited the site for a while, simply because the projects here are so far beyond my skill level that I can't contribute anything. But I had to come back out of curiosity.

Rethink: despite my inability to contribute tech suggestions, I _can_ give praise, and my jaw drops when I see home casting and machining like this.

Carry on, our new Gattling-wielding overlords!

#13 bruski

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Posted 20 January 2011 - 06:43 PM

Did you use Petrobond sand for your castings?

#14 Pmercer

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Posted 21 January 2011 - 04:38 PM

I built some of the parts out of wax on a Thermojet machine and then sent them off for ceramic casting. Basically they add sprues etc then dip the parts in liquid ceramic. Once the ceramic sets they melted out the wax and filled the voids with metal. The ceramic is then chipped off.

For the remainder of the parts I used a machine that builds parts out of polythene. Same post treatment though.

#15 Pmercer

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Posted 27 January 2011 - 07:17 PM

I've cleaned up the casting of the Pan. It was fairly easy to clean up, but time consuming as I wanted to keep the edges crisp and not round any edges off.

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If you look carefully, you can see some pitting from the original casting. I'll fill these small holes in with silver solder. They won't affect the running, but don't look too nice.
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Ok, so I've attempted to fill the holes with silver solder. Now to clean off the flux and the surplus metal. You can see a reddening on the brass which I can only assume is the copper coming to the surface due to heating up.
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I still need to machine the Center hole to final diameter and clean up the recess where a large extractor washer fits.

#16 Pmercer

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Posted 27 January 2011 - 09:58 PM

Ok, so I went downstairs to machine the last few operations on the pan, and can't find the chuck key for the lathe. Typical. I bored the center hole out though, so at least it fits onto the assembly now. I didn't get a photo of it as it's not quite finished yet.
Here's a photo of the Pan, the bolt carrier, the main shaft and driven gear. It's a fairly good start to the barrel assembly being completed. I put the five finished bolts in the assembly as well as three inert .22 rounds.
I noticed that the bolts dont all slide into the Pan nicely, so a bit of additional filing is required, but I wont do that until I've got all 10 bolts done and rotate the pan for best fit. I also noticed that the .22 rims catch on some of the grooves of the pan, so some additional filing will be required for that as well.
I also marked out the barrels where they need to be turned down with a taper. When I've got my chuck key back I'll finish the barrels as well and fit them.
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It's nice to see some of these parts assembled at last. I couldn't find the stainless M10x1 bolt I'm sure I already made, so I quickly threaded a steel M8 bolt to hold the assembly together.

#17 Pmercer

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Posted 29 January 2011 - 01:41 PM

When I started building this gun I modified all the dimensions to allow a .22LR to be the caliber of choice. I then carried on manufacturing parts.
One day I realised that although I thought the gun would be long enough to be legal, I'd better check. Anyway, it came up short. It needs to have a barrel length of at least 12" and an overall length of at least 24". At this stage I hadn't made the barrels so the easiest solution would be by extending the front of the gun, ie the BARRELS (unmade) and either the SHAFT or the FRONT SHAFT. For some reason, at the time, I decided to remake the FRONT SHAFT, but now I'm not too sure.

The central shaft is split into three:
The MAIN SHAFT is not seen and goes inside the BOLT CARRIER, PAN and BREECH RING.
The SHAFT is the long section that goes between the BREECH RING and the BARREL RING (brass disc on right hand of picture) and screws into the MAIN SHAFT
The FRONT SHAFT is the section to the right of the BARREL RING and is supported in the RAIL FRONT which isn't shown. The FRONT SHAFT screws into the SHAFT and traps the BARREL RING.

In the pictures below;
The top picture shows how long the SHAFT and FRONT SHAFT should originally be. Below it is a barrel that is of the length I need it to be but positioned so that you can see how the front of the FRONT SHAFT and the front of the BARREL relate to each other and also the BARREL RING.
The bottom picture has had the extra long FRONT SHAFT fitted and the BARREL positioned correctly to give some idea how the BARREL RING now fits in. The BARREL RING is a lot further from the front of the gun now.

My question is this: Should I use this extra long FRONT SHAFT to solve my problem, or should I make a longer SHAFT? The main difference would be where the BARREL RING ends up. By design, it should be nearer the front of the gun than it currently is.
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#18 bruski

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Posted 31 January 2011 - 06:12 AM

Nice work pmercer, your bolt extractors are looking great too. Did you custom grind the cutting tool from an end mill, or make one from scratch?
I have a bit of advice that you will find out soon enough when you start cranking away with it. The shaft needs to be tightened extremly tight where it goes through the barrel plate, pan and the bolt carrier or the alignment will change on you. The better solution would be to drill the parts for dowel pins to keep everything in alignment after you finish the other bolts and get everything aligned just right. I don't know why they didn't use hex stock for the rear part of the shaft in there design to start with.
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#19 Steve McKuhen

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Posted 04 February 2011 - 12:16 PM

Pmercer, have you got to the stage of a test fire?

#20 Pmercer

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Posted 04 February 2011 - 03:55 PM

Bruski

As I was assembling these parts the other day I thought there was a risk of movenent when its working. Great idea about a dowel pin - I'll definitely do that.
The other thing I noticed at the rear is that the DRIVEN GEAR is woodruff keyed to the GEAR HUB to prevent it turning - however the GEAR HUB is screwed to the MAIN SHAFT which is fine when cranking the gun forwards, but if you reverse the handle, as you may do to clear a stoppage, it unscrews. Maybe I'll locktite the thread on.

Steve, the parts shown are the only parts finished so the gun doesn't fire yet.




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