Golf Ball Caliber 1840 10" Seacoast Mortar

[The Jeff]

While my first golf ball mortar isn't a bomb waiting to happen, I have been interested in making a new one. My first mortar's powder chamber is a piece of 1.75" diameter 1018 sledgehammered into a 5.5" section of DOM tubing with .75" thick walls. At the time I didn't have a lathe and that was the best I could do. Now that I'm getting a little better at machining stuff I thought I'd make a better mortar that actually looks like a historical model.



When I first got my lathe I had grand ideas about making a 13" long golf ball howitzer based off of one of CU_Cannon's plans. I bought some 4" 1018 and started working on the cascabel, but the project was a little over my skill level and possibly my lathe's capacity. This hunk of metal has been sitting under my workbench for 2-3 years and I decided it'd be a good candidate for my 10" seacoast mortar.  I'm using GGaskill's plans which are conveniently scaled to golf ball bore.



I cut off the cascabel and muzzle so I had 7" of material. Obviously what was left of the howitzer's pilot hole will start the bore of the new mortar. 



 Next I faced off the muzzle so I could measure back to where the diameter changes.



Turning the taper over the bore. 





Boring bore boring. I opened it up to 1.723, so it's right at 1/40th windage.



Drilling a 5/8" powder chamber for a maximum capacity of around 100 grains. I figure that will get me out to 100 yards with steel Fox balls at 45º. I went with 5/8" because from what I've read, I think long narrow powder chambers are a little more reliable and efficient than wider ones.



I don't have a ball turning attachment, so I drew the breech in CAD and then drew a horizontal line every 50 thousandths. Then I could select the next step and see how long the cut should be. Believe it or not, this is the first time I've used the tick marks on my lathe's knobs. I took a "machining" class in college and it was really a lot of fun. I didn't learn much because there were too many students and the teacher was truly incompetent. However, that class was responsible for making me to get my own lathe to play around with. Anyway, I'm starting to figure out easier ways than stopping the lathe every 30 seconds to measure with calipers.



The stepped off hemisphere.



10 minutes with an angle grinder and files. 



Done! Or so I thought. I can't believe I forgot the little "lip" at the start of the breech's taper. I think I was so excited about how well the hemisphere came out that I completely ignored it.



I managed to get the tube back on my lathe relatively straight and deepened the breech's taper to make that lip just behind the cylindrical part. I also bought 75 Fox balls. Man these suckers are no joke! I tossed one up in the air and it came down with a satisfying "THUNK!"



I usually like trying to make everything myself, but cutting the mortar bed out is a bit much. I'm sure I could do it, but instead I drew up some plans and took them to a local metal fabricator and am having him cut them out with a water jet. The main piece is 3/4", while the thinner outside piece is 3/16". I plan to weld the seam and try to blend everything together with a grinder/dremel to make it look like one cast piece. The lifting lug is 1/2" and the inner trunnion supports are 3/8".



That's as far as I've gotten. I'm currently stuck until I get material for the trunnion and the bed pieces are cut out. 


Thanks for reading.

[Cat Whisperer]

GREAT sequence of pictures!   THIS is what this forum is all about!  Starting from scratch, screwing it up, learning, making it happen!

(NOT to say you screwed anything up.)

Pictures of the process are what makes it so WE can do it too!

[little seacoast]

Nice work!  I remain in awe of the talents displayed by the metal workers here.

[The Jeff]

Here's the parts I got back from the metal fabricator. He had to make two lifting lugs because otherwise the piece would fall through the grate on the machine. I'm glad it worked out like that because it'll give me a second chance if I mess one up welding.



The material for the trunnion is 1-3/8" 1018 which I turned down to 1.3 or so. It's a little loose in the sides of the mortar bed, but a few layers of paint should tighten it up. The next problem was how to scoop out a hollow for the hemispherical end of the mortar. I don't have a milling machine, so I did the next logical thing and grabbed an angle grinder and started for China! I would have gotten further but for some reason my grinding wheel seemed to have disappeared. 



  After buying another grinding wheel I had the trunnion finished. It fits surprisingly well.



I didn't take a picture, but prior to welding I beveled the edges of trunnion so I could get way down to the centerline. I'm not a great welder, but I think I got a solid weld. At least the trunnion hasn't fallen off yet



I cleaned up the weld a bit and stuck it on the mortar bed. For some reason pictures make the sizes look wrong, at least to me. I think once I put the wooden cross pieces in the bed won't look so flimsy and the proportions will look right. 



That's all I've gotten done so far, thanks for reading. 

Nice work!  I remain in awe of the talents displayed by the metal workers here.

Thanks. I think a lot of the little I know about metalworking came from reading other build logs, or experimentation. And a healthy dose of luck

(NOT to say you screwed anything up.)

I've said this before somewhere, but in my projects I go from one step to the next in constant fear of royally messing something up. No major ones so far!

[Winger Ed.]

Cool project & great progress on it.
 
On my 1844 seacoast designed mortar,
I used a strip of leather to take up the slack where the trunnion sits in the base.

I think your weld is just fine. 
Example:  Look at how trailer hitches are put together- there's less welding on a hitch rated for 10,000 pounds.
When the mortar fires, the recoil pushes the weld together- or into itself.
Recoil doesn't exert much force trying to pull the barrel off the trunnion anyway.
 

[The Jeff]

I think your weld is just fine. 
Example:  Look at how trailer hitches are put together- there's less welding on a hitch rated for 10,000 pounds.
When the mortar fires, the recoil pushes the weld together- or into itself.
Recoil doesn't exert much force trying to pull the barrel off the trunnion anyway.

I was thinking more about shock load and the trunnion flexing. Currently the trunnion is unsupported in the center 4 inches and that's where it's thinnest. There will be some inner trunnion supports and a segment of thick tubing to replicate the brass part of the carriage though, so that'll help. I wouldn't be concerned if it was a Coehorn style bed where the trunnion is supported for its full length.

[GGaskill]

If you had inlet the trunnion into the breech of the mortar such that it was still a full diameter round bar, I would say the weld is only keeping the pieces from coming apart.  But the way you did it, the welds are the primary mechanism to transfer the recoil force from the breech to the trunnion so they need to be sound.  The thin part of the trunnion in the middle does little in the current configuration beyond aligning the ends.

[Winger Ed.]

[quote I was thinking more about shock load and the trunnion flexing. Currently the trunnion is unsupported in the center 4 inches and that's where it's thinnest.
 
If the worst thing happens-------- Let it flex.  So what,, it flexes.
How many babies & new born puppies is that going to kill? 

Do ya think your project is going to fragment, and kill everyone living in your USPS ZIP code
I don't.   
Its a Golf Ball mortar---
The way you've built it:  I think it'd hold together if ya used pure Nitro Glyicerine for a propellent.
----And somehow could put a Golf Ball into orbit around the darn moon.----
 
Since that isn't practicle------
How many hundred pounds of Black Powder are we talking about touching off (per shot) anyway ?
----To develope something under 30,000 psi Chamber pressure---
Yeah, that's alot... unless you compare it to a ,,,,
A .30-06, .308/7.62NATO, 0r even a 5.56/M16-rat gun, that runs along at almost 60,000 psi.

All kidding aside:
You've got a really cool, and safe project going.
If the trunions bend,,, or the base developes cracks-----
shoot it a few more times and watch how much more they bend & crack each time......
When ya get home,,, get out some epoxy cement for the wood, and a hammer.
Put the Steele back where it belongs & weld on the thing some more.
Repeat the cycle again the next chance ya get.
 
 

 

[The Jeff]

Here's the latest progress:





The oak pieces that go between the metal sides are cut out, and I welded on the lifting lug and rimbases. I was surprised at how close to level the mortar sits when suspended by the lifting lug. I've also been grinding, filing, bondo-ing, and sanding the joint between trunnion and tube. It's getting there but it still needs a bit of work.


I bought some No. 2 wood screws for the metal straps around the wooden pieces. Screwing those little wood screws in ought to be an experience. I think I'll grind down an old flathead screwdriver to make some narrow parallel sides so the head won't strip as easily. Obviously a pilot hole will be a good idea.


I have found four high resolution, period photographs of 10" seacoast mortars and 4 beds have square nuts while 2 have hex nuts. While either style would be correct, I prefer the looks of square nuts so I picked up some 7/16" square nuts for the 1/4-20 threaded rod that holds everything together.



All pictures are in the public domain.

If the trunions bend,,, or the base developes cracks-----
shoot it a few more times and watch how much more they bend & crack each time......
When ya get home,,, get out some epoxy cement for the wood, and a hammer.
Put the Steele back where it belongs & weld on the thing some more.
Repeat the cycle again the next chance ya get.

Yeah, I plan to keep an eye on it and see what happens. I'd rather not have to fix it, but at least it's an option if I need to.


Thanks for reading!

[Artilleryman]

The heads of the bolts are square also.

[The Jeff]

The heads of the bolts are square also.

Yeah, I'm planning on welding a nut onto one end of the threaded rod to make a bolt.

[Artilleryman]

The interesting thing about nuts and bolt heads then and now is that then they were a lot bigger in proportion to the bolt diameter than they are now.

[smokemjoe]

 Great job and using that older lathe, Keep up the good work, Nice to find someone new that has skill. Joe

[The Jeff]

Next I made the bolts and drilled 1/4" holes for them. The material is A36 hot rolled steel which seems considerably harder to drill than 1018. The bit made a disconcerting clicking noise unless I kept it drenched in cutting oil. At first I thought little parts of the bit's edge were breaking off but it looked ok to me. I don't have much experience in metalworking, is that a normal sound to hear when you're drilling? On two of the holes I ran into a hard spot about 1/2 an inch deep where the bit just would not cut. It wasn't getting dull because it would cut fine when I moved to the next hole. I just let the bit grind away for a while and it eventually made it through.



To make sure the holes lined up, I clamped the second side to the first and made some shallow divots.



Then I unclamped them and finished drilling all the way through.



Next I put the bolts through the holes to align the two sides. Then I carefully removed the bolts and shimmed my wooden pieces to the correct height and clamped the sides together. Then I drilled the wooden pieces with a cordless drill. My bit wasn't long enough to make it through the 3/4" side and the 4" piece of wood so I had to drill from both sides. The holes came out a bit crooked so I enlarged the two ends of the hole to 9/32" and about 3/8" deep which allowed the bolt to slide easily through the hole.



Some of the holes in the wood are mighty close to the surface, but I think they'll be ok.



And here's the bed put together. The bolts need to be cut off, and I need to make the two longer rods for the front and rear ends that stick out so handspikes can maneuver the piece. The threaded section will be just wide enough to get the nuts on, and I'll file down the threads on the overhanging part to make a smooth cylinder for the handspikes. I also drilled a 1.75" long, 3/32" diameter vent. It intersects right where the 5/8" cylindrical section of the powder chamber turns into the drill bit point. Eventually I'm going to get a cheap 5/8" bit and grind the point round to make a hemispherical chamber. If I'm going to all this effort to make a beefy mortar I might as well do it right.

Great job and using that older lathe, Keep up the good work, Nice to find someone new that has skill. Joe

Thanks. The lathe is from the early 1940's. It was originally sold to a machine shop in New York, then a local nuclear physicist acquired it at some point. After he passed away I bought it from his wife when she was selling off his machinery. It's been a learning experience for sure.

The interesting thing about nuts and bolt heads then and now is that then they were a lot bigger in proportion to the bolt diameter than they are now.

That's interesting, I hadn't even noticed. Are they smaller today due to better materials?


Anyway, thanks for reading!

[Victor3]

 Cool. Can't wait to see it all painted up and ready to fire. 
 
 That little South Bend of yours sure brings back some memories. I grew up with the same lathe in my Dad's garage and made my 1st machined parts on it when I was ~8 years old. Sold it to a friend ~15 years ago but now wish I hadn't. Great little machine.
 
 Puting my safety geek hat on...
 
 Please be careful when running a heavy (for the size of the lathe) unsupported piece. With what appears in your pic to be a 'finger-nail' hold in the chuck jaws while boring, not much would be required to make it come loose during a cut. Best to stand down near the tailstock if you have to secure a workpiece that way.
 
 It would be a good idea to shield the wiring going to the motor. It appears to be somewhat open to chips. Aside from possibly causing a short, long stringy chips could grab and rip out the wires, really messing up your day.
 
 Having seen a few accidents, I started a thread here about lathe safety a few years back. I'm pretty sure there have been more inuries to hobbyists in making cannons than firing them; they just don't make the news...
 
http://www.gboreloaded.com/forums/index.php/topic,171628.msg1098801838.html#msg1098801838

[The Jeff]

I've been pretty busy lately so I haven't updated in a while, but I'm getting towards the end of this project. 80% of the work is done, now it's just down to the last 20% that takes forever.


Thanks for the safety reminders Victor3. While I think the wiring wasn't as close to the chips as the camera made it appear, I did cover the wires better. You're right about no steady rest though. When I bought the lathe it didn't come with one and I've been putting off buying/making one for too long. I'll definitely get on that before doing anything that would require one.


The next thing to do was to make the half moon shapes in the side so the nuts can freely rotate. I should have drawn them on my CAD drawing and let the water jet cut them out, but I didn't think that far ahead. So instead I chucked an abrasive die grinder bit in the drill press and set the depth so I could grind out the shape. It took a long time.



Next I cut the bolts off to the right length and took the threads off the end for the handspike ones. The reason they aren't installed is because I forgot to take into account the width of the nuts.    They lined up perfectly with the side of the carriage though! 



New handspike bolts made and installed.



Next up was the metal straps around the wooden spacers. I cut the four strips out of 18 gauge sheet metal with a skill saw. Then drilled a 1/16" pilot hole in the wood, 3/32" clearance hole in the metal, and then countersunk with a 5/16" bit. I used a flathead eye glasses screwdriver set to screw in the #2 wood screws. And I just noticed I forgot the center screw on the left hand side.     



Here's the piece that supports the center part of the trunnion. From what I've read, it was originally made out of brass and had two "feet" on the sides that went down to the ground. Was brass stronger in this application than cast iron? I would assume it'd add a nontrivial amount to the cost of the mortar bed. My trunnion is 1.3" in diameter, so I started with a piece of DOM tubing 1-3/8" ID and 5/8" wall thickness. I faced it off until it would just slide between the sides of the carriage, then I used a hand held band saw to cut a 90º wedge out. 



Then I clamped it in place and welded. I've been holding off shooting the mortar until this piece was installed because I wanted as much support under the trunnion as possible. I'm sure it wouldn't matter with golf balls, but I primarily want to shoot Fox balls in this one.



Here's the most recent picture, up to 34 pounds! I still need to weld on the "feet" to my "brass" crosspiece, and I still haven't worked up the courage to try making a square threaded elevating rod and nut. Other than that there's just prettying it up left. Does anyone know if a white stripe would have been painted down the centerline of the tube? None of the period pictures I've seen had it that I could tell, but I've read it was one of the ways to aid in aiming. 



And here's a video of the first two shots. 25 grains FFg and a steel Fox ball went 38 yards, while 50 grains went ~150. I need to get some 1Fg.

Thanks for reading!

[dominick]

Jeff,  Nice work!  Dom

[Double D]

This is looking awesome!

When you get finished take some picture at eye level.  The aerial views are nice but don't show the real perspective.


You have done a great job!!!

[The Jeff]

Thanks for the kind words dominik and Double D.

When you get finished take some picture at eye level.  The aerial views are nice but don't show the real perspective.

That's a good idea. I recall seeing an eye level picture of your Dom Dictator and a mound of dirt that I thought was an original Civil War era picture for a moment.

[Double D]

Just take eye level pictures.  Eye level for the scale of the gun.

At 1/6th scale a 6 foot man would be 1 foot and eye level would be about 8 inches.

[rifleshooter2]

Thats a great mortar well done. Keep building I look foward to seeing more of your work.
 
Andy

[seacoastartillery]

     Jeff,    I had some friends over the other day and I showed them some photos of your  10-Inch Seacoast Mortar Model 1840  on this thread, saying, "Now there is what you can accomplish if you try really hard to re-create a historical cannon or mortar."  Superb job, Jeff!

     Take a look at this link and you will see it's really an 1840.  It's not your fault that this mortar has been incorrectly identified on drawings and websites for years.

                         http://robinsonsbattery.org/79215.html.


Tracy

[The Jeff]

Thats a great mortar well done. Keep building I look foward to seeing more of your work.
 
Andy

Thanks, rifleshooter2. I can't wait either until it's all painted up and done.

     Jeff,    I had some friends over the other day and I showed them some photos of your  10-Inch Seacoast Mortar Model 1840  on this thread, saying, "Now there is what you can accomplish if you try really hard to re-create a historical cannon or mortar."  Superb job, Jeff!

     Take a look at this link and you will see it's really an 1840.  It's not your fault that this mortar has been incorrectly identified on drawings and websites for years.

                         http://robinsonsbattery.org/79215.html.
Tracy

Thanks for pointing out the model issue. While researching I think I saw more 1844's than 1840's so I just assumed that was the correct date. Perhaps I'm not using the right search terms, but there doesn't seem to be very much on the web about this particular model.


Your re-creations are what inspired me to try making scale models as best I could. Fortunately the rough edges on mine can hide behind the small pictures that I post. 

[The Jeff]

Not a lot of progress, but I've been working on the barrel. I've got 2 layers of Bondo and 3 layers of glazing putty around the trunnion/rimbase/tube joint, and around the lifting lug. I also put a thin fillet of glazing putty around the muzzle and base ring.





Next I used an airbrush kit to spray on some flat black  Rustoleum enamel. I've never used an airbrush before, my father used it quite a bit in his duck decoy carving hobby. It took a fair amount of experimenting before I realized the air hose was clogged, then I found out the paint nozzle and air nozzle have to be just right. By that point I'd thinned the paint down so much thinking it was too viscous to be sucked up the tube. Eventually I got out the instructions and things went together better. 



I stamped the muzzle face before painting but forgot to take a picture of it. My initials are where the inspectors would be, it's No. 1, and I took the average of 3 weights to come up with mine. At first I thought about calculating the volume of my mortar and seeing what it would be in cast iron and then scaling to full scale, but my powder chamber is different than an original so there was no point in doing that. I didn't stamp the trunnions because I filled up the hole for my live center with a welder and the weld was too hard to stamp.



To come up with the weight, I found 2 references on the Robinson's Battery website (5,575 and 5704) and I bumped up the contrast in a Civil War era photograph until I could make out the markings on its muzzle (5800). (5575+5704+5800)/3=5693





And here's a shot of the tube from the side. The paint's a little thin in places so I'm going to do a few more coats.

[burnsb]

Next I made the bolts and drilled 1/4" holes for them. The material is A36 hot rolled steel which seems considerably harder to drill than 1018. The bit made a disconcerting clicking noise unless I kept it drenched in cutting oil. At first I thought little parts of the bit's edge were breaking off but it looked ok to me. I don't have much experience in metalworking, is that a normal sound to hear when you're drilling? On two of the holes I ran into a hard spot about 1/2 an inch deep where the bit just would not cut. It wasn't getting dull because it would cut fine when I moved to the next hole. I just let the bit grind away for a while and it eventually made it through.

I realize that this was posted a while ago but I thought I would mention some things about the trouble you had drilling A36.
 
A common name for A36 in the shops I've worked in is "crap" steel.  It varies wildly in quality in my experience, sometimes it cuts like butter and sometimes it is as hard as a rock.  I was told that this is because it is a recycled steel and the steel may have come from cars or grandpa's old chisel. One manager claimed that he's ran into carbide in it before.  I don't know if that's true but you can definitely hit hard spots in it sometimes.  You may also be getting work hardening.  When you hit a hard spot touch up your drill and then slow the speed and increase feed.  You may have to resharpen as you cut through it.  Get mean with it. 
 
What are you using as cutting oil?  For use in my garage I really like the Oatey dark thread cutting oil they sell at Lowe's.  It seems to be really thick old school sulphured cutting oil, sticks to a drill really well.

[The Jeff]

Next I made the bolts and drilled 1/4" holes for them. The material is A36 hot rolled steel which seems considerably harder to drill than 1018. The bit made a disconcerting clicking noise unless I kept it drenched in cutting oil. At first I thought little parts of the bit's edge were breaking off but it looked ok to me. I don't have much experience in metalworking, is that a normal sound to hear when you're drilling? On two of the holes I ran into a hard spot about 1/2 an inch deep where the bit just would not cut. It wasn't getting dull because it would cut fine when I moved to the next hole. I just let the bit grind away for a while and it eventually made it through.

I realize that this was posted a while ago but I thought I would mention some things about the trouble you had drilling A36.
 
A common name for A36 in the shops I've worked in is "crap" steel.  It varies wildly in quality in my experience, sometimes it cuts like butter and sometimes it is as hard as a rock.  I was told that this is because it is a recycled steel and the steel may have come from cars or grandpa's old chisel. One manager claimed that he's ran into carbide in it before.  I don't know if that's true but you can definitely hit hard spots in it sometimes.  You may also be getting work hardening.  When you hit a hard spot touch up your drill and then slow the speed and increase feed.  You may have to resharpen as you cut through it.  Get mean with it. 
 
What are you using as cutting oil?  For use in my garage I really like the Oatey dark thread cutting oil they sell at Lowe's.  It seems to be really thick old school sulphured cutting oil, sticks to a drill really well.

Thanks for the insight. Sorry I didn't reply sooner but I completely missed your post. I was using "Ace Thread Cutting Oil" which I've now read is practically useless. And the bits I was using were probably not the best, just a Walmart special. Something like 100 assorted bits in small diameters for 20 bucks. Later I did a bit of googling and saw a bunch of people saying A36 is made of everything from tin cans to leaf springs so hard spots aren't unusual.


I'm just about out of cutting oil so I'll get some of the Oatey's and see how that works.

[seacoastartillery]

What are you using as cutting oil?  For use in my garage I really like the Oatey dark thread cutting oil they sell at Lowe's.  It seems to be really thick old school sulphured cutting oil, sticks to a drill really well.

      Small world, Burnsb.  We had been using Mobile Oil's Mobilmet 404, a non-sulfur cutting oil having a light color, but that was a distributor substitute for the old Mobil Heavy Sulfur Dark Cutting Oil which they didn't carry anymore.  When I saw the Oakey Dark Cutting oil recently, I had to try it out.  BINGO!  This Oakey stuff smells just like the heavy sulfur cutting oil we have always used.  So what if it smokes a bit when you a turning some steel at a higher RPM.  Jeff, you have to give this stuff a try.  Now if we can only get Lowe's to carry it in Gallons, we be in business!

                        I love the smell of sulfur oil smoke in the morning.  The smell, you know that burned sulfur smell,
                                  throughout the whole shop.  Smells like..................."Industry".


Tracy


The product and other oils we use.




A close-up of our new cutting oil. 

[GGaskill]

This might work:
IPS Sulphur Cutting Oil

Shipping would add to the cost so it might not be better than buying from Lowe's.

[Rock6.3]

My lowes has the Oatey dark thread cutting oil in gallon containers:
http://www.lowes.com/webapp/wcs/stores/servlet/ProductDisplay?langId=-1&storeId=10151&catalogId=10051&cId=SEARCH&productId=3553412&cm_mmc=SCE_gps-_-gps-_-gps-_-Oatey%20Gallon%20Cutting%20Oil&CAWELAID=1090662380

[GGaskill]

"Pipe Joint Lubricant."  I sent them an email about that.