Going Bigger! Step-by-step Fabricating a .75 cal Black Powder Cannon *FINISHED*

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Hello!

This is the third in my series of cannon fabrication build-alongs. This one will be slightly different as its going to take me quite some time so I'll be doing it in pieces. What has enabled me to do this particular build was my acquisition of a Logan 820 lathe. It is a 10X24 lathe meaning it can turn stock up to 10" in diameter and its 24" between centers.

Here is a picture of the lathe itself:


The machine is a 1947 and has some nice features such as its automatic gearbox which prevents me from having to swap out gears to change threading or feed speeds. The amazing this is this lathe came with a lifetime of tooling. Hundreds of pounds of tooling like this:




I could go on for pages but it also came with 4, 6 and 8in chucks in three and four jaw configurations, milling attachment, steady rest, shaping attachment, etc etc. I easily scored 5X the lathe's value in tooling.

Installing the lathe was fun...i did it solo and at about 750 pounds it was not for the faint of heart. I wont show pictures of that process as it probably violated all rules of safety and involved a come-along and an eye bolt in my ceiling.

Without further ado, here is the beast piece of steel this cannon will be fabricated from....2.75" in diameter, 12" long and weighing in at almost 15 pounds. When i took it out of the box it came in through the mail I thought to myself "maybe i went a little too big." This is a serious hunk of metal. 1018 steel.


First thing I did was chuck it up and to take a light surface pass across everything. The surface was chromed or something as it came off in some seriously scary and odd colored curls. Here's a few of those first passes. This took some adjusting in terms of my feed rates and RPM as the increased diameter meant the surface speed was much higher than I had been used to running less than 1" stock.

As with any horrible looking steel, it started looking gorgeous under the surface:


Once i took a surface pass the first thing up was what will turn out to be the most tedious of all: Drilling the bore. Metal this big required support. In this pic you can see the steady rest all set up and lubed as well as the center drilled hold where I had held the piece for the initial turning. No part of this process can be done without support unless I want to risk a 15 pound metal projectile swinging around my shop.


Next post will be the drilling process.
 
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With the lathe came a nice more taper 10" drill that was 17/32 (.53) this would be my "pilot" hole. Needless to say, a 12 inch piece of steel and 10" drillbit plus tailstock maxes out this lathe with its 24" bed:


Drilling the initial bore is an exercise in patience as I drilled, lubricated with cutting fluid, and cleared chips. Here's the bore initially drilled which shows how small a .53 hole looks in this stock:


I drilled the .53 hole to a pre-set depth which was based on the OAL of the cannon I wanted plus I'm using a feature called a powder chamber. What this means is that there will be a chamber for the powder which is smaller than the main bore. This increases strength but also allowed me to make for a longer bore as I did not have a large drillbit as long as this initial drill. The full length of the .53 bore was somewhere around 9".

From here I swapped to a .75 drill. This was MUCH easier than the initial bore as the bit had more room for chips.:




Somewhere around here I cut the crap out of my hand trying to clear some of the metal curls. I just grabbed a pile and one was a razor and gave me a nice reminder that steel is not my friend.

After a while , I was done. I maxed out my .75 drill right to the tailstock giving me about 8" of .75 bore with a stepped powder chamber.


I did a quick measure and found I could put well over 100 grains of powder in the reduced chamber. This should be PLENTY for either an earth shattering signal cannon blast or to launch a lead ball off into oblivion.

Next up i decided to go ahead and give an initial muzzle profiling before I move on to the trunnions.

First a quick facing pass:


Followed by adding a crown:


And a little countersink at the bore itself...looking great!


Next up is how I do the trunnions.
 
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Simply put, I find trunnions to be a PITA.

They must be placed in the right spot, predicting where the balance will be in the barrel and ensuring the breech is heavier than the barrel, but also set at dead centerline, in line with one another, parallel and square. Its much more of a pain than it looks when they are done. This is how I solve them...others use different methods.

First I locate where they were to be placed:


I first drill a pilot hole about 3/4 of the way to the bore. These trunnions do not go all the way through. The 3/4 wall depth causes no safety concerns as these are quite a ways down the bore from the breech where all the pressure occurs. At the breech you always want at least one bore thickness around the chamber. IE for a .75 bore I would need a minimum of 2.25 inch stock to meet safety dimensions. I'm well over that and could go as far as .85 if I wanted but .75 is easier to find ammo for (3/4 ball bearings are easy to find)

This pilot hole helps locate the larger trunnion pocket drill and will also be tapped and threaded. Here is the pilot with a .75 main pocket drilled. Not pretty but doesnt need to be:


Tapping the pilot:


I'm tapping this for a 1/4-20 threaded rod. This was a horrifying moment as i broke a tap inside the hole. UGH. I was lucky enough that i could use a punch and back out the broken portion or else things would have gone wrong quickly.

I then turned down some 1" stock to just over .75. I went for a pressure fit in the trunnion pocket. These trunnions were also drilled and tapped to accept the same 1/4-20 threaded rod:


Completed trunnion:


These trunnions thread in VERY tightly. It requires leather wrapped around them and a vicegrip to get them in and out which is exactly what I want. In the final assembly the threads will be permanently lock-tited with red thread locker and the trunnion will be smeared with JB weld to fill every possible gap. The forces on these trunnions will be all shearing forces and I cannot imagine what it would take to shear the W2 toolsteel they are made from.

All this work was so that I could attach one trunnion. I then put the faced trunnion down on my vice bottom which ensures the hole I drill on top will be square to the first trunnion and I indicated to ensure i'm square to the stock just to be sure:


This all went perfectly and both trunnions thread in tightly, square, parallel and even to one another. Success!



Having the trunnions in place then allows me to squeeze them in my vice to locate the fuse hole exactly square to the trunnions. I drill my fuse holes at a 5-10 degree back angle towards the breech.


Thats the last of my first installment. Not bad for a long night's work. Trunnions will be removed and the cannon will be put back on the lathe for some major profiling work. I already removed at least a pound or two of steel as evidenced by this 9" pile of swarf:


I will probably have many, many hours at the lathe from here to turn down the barrel and to shape the ball at the end. I'll put up pictures of that process as soon as I have more time in my shop.
 
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Going Bigger! Step-by-step Fabricating a .75 cal Black Powder Cannon

Awesome!

I am saving my pennies for a lathe and milling machine. Looks like you got a good deal on that lathe, assuming the price was right.
 
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Awesome!

I am saving my pennies for a lathe and milling machine. Looks like you got a good deal on that lathe, assuming the price was right.
The deal I got was akin to highway robbery. I paid less than $750 for everything and the milling/taper attachment and a single spare 8" chuck are worth about that much used if I were to sell them. It also came with, for instance, an entire box of Jacobs chucks of various sizes. I could probably sell these chucks for about as much as i paid for everything.



I wont even mention the almost 2 pounds of carbide inserts and holders. I may never need to buy anything for this lathe. I di have to buy a new belt as the prior owner had mistakenly put a 42" leather belt on when it should have had a 39". This nice thing about logan lathes is that the company is still in business and you can buy every part, piece and screw directly from then should anything break or wear out.

Here's my mill...also an insane crigslist score. I got it for 600$ DELIVERED and installed in my shop...i dont know what they were thinking as the scrap value for the steel was more than that. Its a 1944 Bridgeport "m-head" with a 36" table which is known as a "baby bridgeport" since it only weights around 1800 pounds and is a smaller overall height and size than a more modern one. Perfect for a home shop.
 
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marvelshooter

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As a longtime machinist I can see that you certainly know your way around that lathe. Much more so than the guy who buys one thinking that doesn't look too hard but doesn't really have a clue. Nice work.
 
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Going Bigger! Step-by-step Fabricating a .75 cal Black Powder Cannon

I'd bet $5 I saw that lathe on Craigslist and thought damn I wish I could get it. Nice catch... That and the mill
 
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Still going...beginning to look more like a cannon...just doing this by eye...i'll change around the rings/features as it gets more refined...



 

namedpipes

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This is SO much better than a 3d printer!

So there is no chance of Innernet misunderstanding, I'll clarify: Amazing work. You have great talent. Please bring this cannon to a shoot.
 
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More progress!

I started by smoothing out the muzzle and making a few small adjustments overall. :


I then finished off a few of the rear sections and removed a bit behind the fuse section:


Now was the time when I had to turn the cannon around to work on the rear section. This is a bit sketchy as it meant i had to clamp the muzzle in the chuck but there is no longer much "meat" to grab onto, nor do I want to crush/ruin the muzzle. I first lightly put it in the chuck, then set up an indicator to ensure it was squarely in the chuck. Turning the chuck by hand, i used a dead blow hammer to tap the breech until it spun with no movement on the indicator:


Out comes the steady rest again so that I can secure the barrel while I center drill the rear. I'll also leave the steady rest on there for the remainder of the work. Here's the center drill lined up.


Center drills drill a pilot hole, then an angled hole that exactly match the grind on a live or dead center so that they hold securely:


Beginning to remove metal. I have a TON of steel to remove here. The ball on the breech is only going to be about 1/2 its diameter which means I have over an inch of steel to remove a tiny bit at a time.


Here's where I stopped for the night. Almost ready to start the main work creating the ball.


At this point I have a TON of metal swarf accumulating. I've been throwing it in a barrel and its beginning to look like modern art. For reference, this is a 55 gallon shop barrel and its nearly 1/2 full of shavings. They are a variety of colors. I'm using carbide inserts so if the swarf isnt blue, I'm not feeding it fast enough!

 

Fixxah

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Re: Going Bigger! Step-by-step Fabricating a .75 cal Black Powder Cannon

Will you just make a Howitzer already. :-o

-Trolling via S3.-
 

MAGG

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yeah this thread is epic...feels like we are right there in the sop with you(awesome photo skills as well) I do not know much about machinery but the basics but the way you explain stuff is right on
 
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Thanks everyone!

For what its worth, i am NOT a machinist by a longshot, but I did stay at a holiday Inn last night :) I've worked with steel as a part-time hobby making knives for years but I have very limited experience with a lathe. I've read a ton of materials on how to do varying things and researched quite a bit, but I'm figuring things out as I go. I tried to do many of these things witha wood dowel before metal just to be sure I wasnt about to wreck anything.

Everything I am doing I learned from websites and the south bend "how to run a lathe" as well as a few army manuals I found online. Its not exactly rocket science...but it is a bit terrifying when things go wrong.

My day job involves 8 hours of data and computers!

I'll have more pics next week...i'm off to Foxwoods this weekend!
 

warwickben

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Going Bigger! Step-by-step Fabricating a .75 cal Black Powder Cannon

The hardest thing on a lathe are,
spinning stock off center to make lobes like on a cam shaft. Not getting chatter.
And for me remembering if the lathe dials account for taking off material on both sides .

Looks good ,man.
I wish I had the money to get my own mill and lathe .... One day .
 

Viper22

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Tiktock, your cannon threads keep getting better and better. This is some great work. 100 grains is good. Wakes up the neighbors. [wink]

Drilling that initial pilot hole for the bore takes forever!
 
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Tonight on the menu was fabricating the cascabel, which is the ball at the breech of the cannon.

This is pretty tedious and time consuming work. I dont have a jig or radius tool, to help me here so its all by hand, bit by bit! I put on some tunes and off we go!

Here is some additional reduction I did to start and a cool pic as you can see the curl just slicing off the bar. I believe this was about a .015 cut:


I then set out some rough marks and began the initial plunge at the breech end:


I started roughing in the curves. Going by eye I started oversized as I knew i'd be taking quite a bit off as I stepped it in from both sides:




Beginning to look like a ball now!


Continued in next post....
 
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At this point I started getting down to a small rib of metal holding the tailstock connection, which made me nervous. I also began running out of room for my turning tool:


Screw it! I just ended up cutting it off with a hacksaw:


Out came the files and sandpaper and I quickly did some light shaping:




Nice! I still need to do some filework and blending but the hard part is done! Its not perfect but I'll get it pretty close before I am done.


What is still left on this cannon:
-Final shaping and detail work on all edges
-Final true-up and evening of any ridges and angles
-Final sanding and blending of all tooling marks
-Trunnion measurement and attachment
-Carriage fabrication

I'll get some more time in the shop later this week!
 
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