Author Topic: Half Scale Pack Parrott (Lotsa Photos here) (Read 2874 times)

Powder keg · « **on:** April 15, 2006, 12:12:02 PM »

Hi Everyone,

One of the many projects I have going at the moment is a half scale "Pack" Parrott. Being a gun that was probably never built this is a unique barrel and I am going to take a few libertys in the final design. mainly on the carriage. This barrel will be 18" long and have a 1 11/16" bore. Like the biger Parrott's it will have a reinforcing band shrunk onto the breech. It will be placed on a unique Naval styled carriage that will give the option to shoot from level to about 45 degrees. I am going to photo document the whole process of building and solving problems that arise along the way. To maxamize my settup time, I've decided to build four of these. Two are spoken for. If anyone else is interested in buying one of these please let me know. I hope everyone enjoys the pictures.

Here I am starting with the raw 4" shaft. I chucked it up in my 3 jaw and indicate the free end in to center the shaft.

For some reason 4" shaft is less expensive than 3.5" shaft :? I drilled a center hole in the muzzle end of the shaft and started turning the excess metal off the barrel.

Almost have it down to size!

This is the settup I use for drilling the holes out. I have some spade bits that I built long shanks for. I'm building some new shanks that will have coolant through the center of them. This will keep the bit from burning up Grrrr. It will also flush those pesky chips out of the hole.

To be continued.........

Powder keg · « **Reply #1 on:** April 15, 2006, 07:45:10 PM »

Hi again,

After the hole is bored, I fliped the barrel over and proceded to trim up the other end. I turned the outside to match the other end and faced the barrel to legnth. I just used a long steel rule to make this measurement. You can see the steady reset that supports the end of the shaft.

After The barrel is trimed to legnth I turned the cascadable diameter to size and legnth. Next I blued the end of the shaft and scribed a line where the radius on the end of the barrel would end.

I do this part of the breech first to make some room for my tool bit when I cut the neck portion of the cascadable.

Here is an action shot. That big tool likes to chatter a bit so I was running it slow with some coolant on it from my newly made coolant system.

Here is what the profile looks like after I finished filing on it a bit. This was all done freehand. I decided to leave it like this for now. I will be able to chuck it up better on my mill when I mill the pockets for the trunnions.

More to come........

Cat Whisperer · « **Reply #2 on:** April 16, 2006, 03:02:45 AM »

Great shots!

Something I'll have to do after I get the CAD drawings done of the Daniel King Howitzer.

CU_Cannon · « **Reply #3 on:** April 16, 2006, 01:28:03 PM »

Great looking work!

They would look good on the pack carriage for the mountain howitzer. Much more work than the naval carriage though.

Keep the pictures coming.

Powder keg · « **Reply #4 on:** April 20, 2006, 06:30:49 PM »

I had a chance to get quite a bit more done on this project. When steel is heated it expands a bit. When it cools it will shrink back to the size it wase. I am going to use that princable to hold the reinforcing ring onto the barrel. I've prepared the tube ahead of time. Sorry no pictures.

The first step is to turn the barrel down to a specific size. I made the barrel .004" bigger than the hole in the tube. It dosent sound like mutch but that would be a very tight press.

Here is the settup to heat the bands up. The fire bricks reflect the heat instead of soaking it up. The pipe on the right is the burner out of my metal melting furnace.

Here I am just starting to get the metal warm. My home made burner will make a blue flame 1" in diameter and 6" long. Very hot!!!

You can see the metal changing color in this picture.

You have to conanstly move the fire around to avoid cold spots and make sure the piece is heated even.

I'm only going to take this up to a blue heat. About 800 degrees!

After the blue is even, I shut the propane off and pick the band up with those big waterpump pliers lying there and......

Crap my camera Broke :shock: :x

Double D · « **Reply #5 on:** April 20, 2006, 11:47:57 PM »

Quote from: Powder keg

Crap my camera Broke :shock: :x

WAAAAAA!!!!

Santa Dave · « **Reply #6 on:** April 21, 2006, 08:33:35 AM »

Boy PK, you sure know how to build suspense!
(sorry about the "pichture box")

Question: when you machine thru the re-inforce for the trunion I would be most interested in seeing the joint between the re-inforce and the barrel before the trunion is installed.

By the way, if you ever decide to use the hot oil method to shrink fit be prepared for a divorce! the oil when it gets hot enough stinks beyond description! (But it does heat evenly!)
Dave

Powder keg · « **Reply #7 on:** April 21, 2006, 12:08:44 PM »

The thing started working again? It really was broke and No the sleeve didn't get stuck on :-D All four went on really good.

Here is the sleave on the barrel.

I left the sleeve about 1/64" long so I could trim up the end to match the radious where the two meet. You cant hardly see the seam even when you look really close.

Santa Dave · « **Reply #8 on:** April 21, 2006, 12:59:11 PM »

Just plain damn beautiful!
I envy your skills!
Dave

Rickk · « **Reply #9 on:** April 21, 2006, 02:17:24 PM »

slding that heated thing on musta been a tense moment. I assume if it stopped moving, it would never move again.

I used to work at Pratt & Whitney many, many years ago. I saw how they pressed turbine ablade ssemblies onto the main shaft.

They did what you did in reverse... instead of heating up the entire turbine, they put the main shaft into a chest freezer filled with dry ice to shrink it.

I was a plant electrician at the time, so I was not into the whole "stick engines together" thing. I do have a really good buddy who has worked there designing engines for the last 30 or so years... want me to ask him about the tradoffs of the hot vs cool technique?

GGaskill · « **Reply #10 on:** April 21, 2006, 05:01:25 PM »

The primary difference is that it is difficult to get much of a temperature difference by cooling. The coldest readily available material is dry ice (-109° F) which would give you a difference of less than 200° F from room temperature. Liquid nitrogen is a lot colder (-321° F) but the material starts getting brittle (see this article.)

Heating allows you to get a much greater differential and is within the capacities of the home shop. Obviously you have to limit the heat input so you don't damage the metal (melting, altering or causing heat treatment.)

So there are times for each process and they can be combined.

Terry C. · « **Reply #11 on:** April 22, 2006, 03:27:37 AM »

Quote

I assume if it stopped moving, it would never move again.

Nope, it's a pretty much a one-shot deal (at least in my experience). Get it expanded enough to go on and get it in place before it shrinks. Been there, done that.

Another factor that influences how difficult the assembly will be is the amount of fit interference. The less required, the easier it will be to assemble.

Wes used .004" interference and that's more than enough for this application I'm sure. That he was able to fit four of them with no probems is a great testament to his skill and patience.

Back when I was buiding prototype parts for heavy equipment drivetrains, I've fitted pieces of similar diameter with as much as .025" interference. Now there's some pucker factor!

During assembly, you also have to deal with heat transfer between the hot and cold parts. As soon as the hot band gets into close contact with the cold barrel, the barrel starts to expand. It will set into position long before it actually shrinks to its original size because the diameter of the barrel will increase.

And that is the real point (finally) of this long-winded post. Once it stops moving you aren't dealing with just a band anymore. Heating the band enough to remove it will be difficult because the barrel is going to expand with it. You might be able to get it hot enough that you could drive it back off, but that would be as destructive to the band as cutting (and could damage the barrel). Better just to cut it off and start over.

Like I said: Been there, done that.

Powder keg · « **Reply #12 on:** April 22, 2006, 06:44:22 AM »

Thanks everyone for your compliments!

Santa Dave, The trunnions go on the barrel ahead of the reinforcing band. So there won't be a seem there to show.

The place I work for builds and Re-builds te biggest Snowblowing equipment in the world. http://www.kodiaknorthwest.com/
We repair gearbox shafts and housings this way a couple times a month. So it isn't all that new to me. When I first started there though I had several BIG sleeves freez on in the wrong place. The big 300 ton press wouldn't budge then :shock: All you can do is machine the sleeve off and start over.

Next I plan on setting these barrels up in my mill to machine the recesses for the trunnions. I think I'll have to build a extension for my mill to get everything to fit though.

Later, Wes

GGaskill · « **Reply #13 on:** April 22, 2006, 08:04:25 AM »

When a shrink fit piece stops in the wrong place, sometimes you can force it on with a big press. Sometimes you can't. It depends on how smooth the pieces are and how much interference there is. The usual allowance is .001" per inch of diameter and that can sometimes be finished with the press. Heavier fits will eventually be too tight to move.

Two of the pieces of my golf ball mortar stuck but I was able to press them into place with a 6 ton jack.

Powder keg · « **Reply #14 on:** April 22, 2006, 12:58:18 PM »

I ran into a major problem with using this barrel on the carriage I had planned. The customer wants to be able to get 45 degrees elevation so he can use it like a mortar if he wants to. With that big reinforcing band on the breech the barrel can't drop between the cheeks. To fix this problem I'm going to legnthen the rim bases 3/8 - 1/2 of an inch. It won't be that noticable but I wanted to mention it.

Later, Wes

Cannonmaker · « **Reply #15 on:** April 22, 2006, 06:28:11 PM »

Just a note on those Kodiaknorthwest snow blowers Wes helps to build, when they test them by driving one of those down the boat ramp into the Snake River, oh -boy watch the water fly!!!

Powder keg · « **Reply #16 on:** May 10, 2006, 05:19:35 PM »

Took longer than I wanted to get these up. I had to repair my dividing head. Someone installed double setscrews and the bottom one tore out most of the threads holding the chuck adaptor on. After that was done I had to build a table extension so it would all fit on the table.

Here is a picture of my settup on my mill.

A quick way to center your cutters over a shaft is to blue the shaft so you can see what is going on. slowly rais the table and move it in and out untill you get a little scratch ontop of the shaft. just center your cutter over this scratch and you are ready to go. like this.

Next, starting with a 1/2" endmill I cut the pocket to depth. Then I went back in with a 1" end mill to open it up a bit.

I tried a 1 1/2" end mill but my mill was to shakey so I just used my boring bar to open the pocket up to just under 2". I used the dividing head to role the shaft 180 degrees and did it again.

I then rolled the shaft 90 degrees and drilled for the vent liner and drilled and tapped for a front sight.

Cat Whisperer · « **Reply #17 on:** May 11, 2006, 01:37:39 AM »

THANKS WES!

Excellent series! I can see now that I need to build a fixture for my dividing head (to be able to slide it on and off the mill for those operations).

slide-flipper · « **Reply #18 on:** May 11, 2006, 08:30:04 PM »

"I'm not a smart man..." (Forest Gump). And you guys just reinforced that feeling of inadequacy! "Divider head"? Mills in your home shop? .004 tolerance/interference whatever? Dang, I have trouble figgerin' out what's bigger a 7mm or a .280... Thankfully I like the .30's (isn't that .308?).

Really, I HOPE that when I retire from AF, I move next door to one of you machinist/Mr. Fixit kinda guys... I would PAY you to teach me just a little bit of that stuff...

Of course I do know lot's of cool acronyms...

slide-flipper

Tropico · « **Reply #19 on:** May 19, 2006, 02:22:29 PM »

This is the best thread going ! Dont stop now !!! I been watching this since I got back May 7'th., I know its tough., but you make it look easy. These parrots are way cool. That sleeving trick really adds the meat to it., got me re-thinking the plan Wes.

Powder keg · « **Reply #20 on:** May 19, 2006, 03:12:34 PM »

Thanks for the compliments guys! I haven't stoped, Just been busy.

After I got done with the mill work I set the barrel back up in the lathe and turned the profile. I got messed up on the order of the first barrel and after the taper was turned I had to set it back in the mill and make a small spotface so the front sight will sit flat.

Here you can see the profile of the cascadable. I think they turned out pretty nice :grin:

The next step was to turn the trunnions. this is pretty straight forward so I havent included any pictures of this part.

The rimbases were turned so that they were about .0015 bigger than the pocket I milled into the barrel. I balanced everything on my new toy and pressed the trunnion into the barrel. It took 2000 psi to fully seat the trunnion into the barrel. the bar under the barrel was faced off in the lathe so the ends are parallel. This let me push everything straight.

Later......

Santa Dave · « **Reply #21 on:** May 19, 2006, 05:48:00 PM »

SuperNEAT! (as usual!)

Double D · « **Reply #22 on:** May 19, 2006, 06:32:36 PM »

...and you will be welding those trunnions in place...won't you?

accuratemike · « **Reply #23 on:** May 19, 2006, 07:10:42 PM »

Wes, looks fantastic ! Keep 'em coming. I am watching with great interest. MIKE

EL Caz 66 · « **Reply #24 on:** May 19, 2006, 10:44:45 PM »

Wow, I'm impressed looking foward to seeing the final product. Great Job!! placing my order now for a 1/4 scale will it be ready before
christmas. :lol:

Powder keg · « **Reply #25 on:** June 08, 2006, 01:29:29 PM »

I am Posting these out of order because I was so busy trying to get this done before the customer arrived I didn't have a chance to photograph the evedince. He was very happy! I'll post carriage pictures of the next one I build. I really hated to let this one go. It is a very nice looking gun.

EL Caz 66 · « **Reply #26 on:** June 08, 2006, 02:11:36 PM »

Nice job !!! :lol: Is there a waiting list for the next barrel...

Ed