Potato cannon carriage #5: Forward armor

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Blog entry by JJohnston posted 08-15-2010 04:07 AM 3128 reads 2 times favorited 9 comments Add to Favorites Watch
« Part 4: Ignition Part 5 of Potato cannon carriage series Part 6: Some tweaks and the test firing »

First, I didn’t like the way the ramrod just stuck out of its tube, as shown in part 3, so I made a longer one that fits the rod completely. I put a small eye screw with a keyring in the end of the rod so I can fish it out.

The tube now has a cap on both ends; I put a light chain on the access cap to keep it from getting dropped or lost. I’m not super happy with how chunky the forward tube bracket is.

Now I’m starting on the armor plating. The “armor” is 1/8” plywood.

The framework for the armor is an H-shape of 1/2” thick poplar that sits on the forward part of the axle frame.

Another view:

The tops of the frame members are mitered at 45 degrees, and there are 2 additional gussets. I had a hard time clamping these. In fact, I gave up on clamping and just held them in place until my hands got tired.

The back of the armor.

The front. I had such a hard time clamping the upper flaps, I ended up putting in some screws. These are hinged on the real thing.

Here’s how it will look assembled, from the front. I didn’t quite capture the M101 howitzer; it looks to me more like a World War 1-era piece – I think it’s the narrow, spoked wheels. You can also see how oversized the forward ramrod tube bracket is.

From the back.

Next installment: Artwork

-- "Sorry I'm late. Somebody tampered with my brakes." "You should have been early, then."

9 comments so far

View Canadian Woodworks's profile

Canadian Woodworks

611 posts in 1724 days

#1 posted 08-15-2010 04:36 AM


-- Paul Lemiski, Ontario Canada, Custom Wooden Rocking chairs and tables

View Jimthecarver's profile


1122 posts in 2439 days

#2 posted 08-15-2010 04:57 AM

I have to say this is going the extra mile on a project. Totally cool, I have been watching your progress.
Great design and build.

-- Can't never could do anything, to try is to advance.

View Brad_Nailor's profile


2531 posts in 2611 days

#3 posted 08-15-2010 05:56 AM

This is the coolest thing I have ever seen! I love it..I have always wanted to build a potato cannon, and this is an awesome version. Nice engineering, design and build.


View Brad_Nailor's profile


2531 posts in 2611 days

#4 posted 08-15-2010 06:21 AM

I was enthralled by your cannon and I have just spent the last hour reading the whole blog and looking at your design. I agree that the forward muzzle bracket is a little too beefy and I hope you don’t mind if I offer a suggestion. I whipped up a quick Sketchup design…this was a fast and dirty design exploration i apologize for the lack of detail… and I made both the barrel and the push rod cylinder the same size…
I was thinking that you could use some PVC T connectors that are oversized and a small piece of PVC to connect them..

Or, if that wouldnt work you could just use slightly over-sized pipe sections and then you would have to chamfer the connecting pipe to the sleeves. Just an idea that I am kicking out there…I think it might suit the look a little better. Again…love the project and how its coming out so far. I also agree that its the wheels that are throwing your look off. they are too thin, and not the right scale for the cannon.


View Dennisgrosen's profile


10850 posts in 1769 days

#5 posted 08-15-2010 07:07 AM

I have follow the your building of this with pleasure
but now I´m a little scared, maybee I shuold start digging that trench in my backyard :-)


View Eric_Somerville's profile


20 posts in 1545 days

#6 posted 08-15-2010 03:03 PM

try not to get any glue on that STi !

You may have covered this in an earlier blog but what do you plan to use for fuel? Right Guard Aresol Deodorant (Brown Can) always worked well with no sticky residue like you get with hair spray. Propane can also be easily used but I’m sure you already know this.

-- EDS

View JJohnston's profile


1577 posts in 1945 days

#7 posted 08-15-2010 05:44 PM

Too bad I can’t get my nephew to think about the extra mile. Or even the ordinary mile.

Thanks for the suggestions. One of the problems I have to solve is attaching the bracket to both tubes non-permanently, so it has to be a mechanical connection – no glue. I also can’t put any holes in the tubes – it has to clamp somehow. I’ve considered a much cut-down version of what I used, leaving only the part between the tubes, and a hose clamp to hold it together – but hose clamps (IMO) are crude and unsightly. I’d welcome more suggestions. PVC saddles, for example, but there’s still the hose clamps.

Dennis – you’re in trouble as soon as I figure out a way to integrate the cannon into the “workshop” feature of LJs. Then I can simply zero in on anybody’s shop and let fly.

I’ve only ever used Static Guard for fuel. I’ve heard the newest version of Right Guard is non-flammable. As for the car, there’s so much sawdust on it, the glue wouldn’t even touch it. I could wait for it to cure, then just brush it off.

-- "Sorry I'm late. Somebody tampered with my brakes." "You should have been early, then."

View Brad_Nailor's profile


2531 posts in 2611 days

#8 posted 08-15-2010 08:23 PM

OK…how about a similar concept. You get 2 T’s one for each piece (barrell, and the push rod storage), large enough so each will just slide through easily. Then you could drill small holes in the walls of the T and put in threaded inserts or large set screws that would gently tighten against the barrel to hold it in place. then you could connect the two T’s with a coupler or a short length of PVC. If you want to slide the barrel out you just loosen the set screws.


View Dennisgrosen's profile


10850 posts in 1769 days

#9 posted 08-15-2010 08:36 PM

I knew it!!
this potatocanon is only the first step in domination and conger the world
the next is a balistic potato-rocket conectet to L Js shop-server

I better ad a Balsabunker over my trench


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