Half scale Coehorn

[GGaskill]

I finally put this into the finished projects category. Click the image for a larger version.



It's steel but painted bronze.  Bored for beer cans.

[Powder keg]

Very nice job G!!! Looks great! Have you shot it yet? How bout an action shot? Later,

[Double D]

Looks good George!  You got paint and detail ,everythings there.  But like Powder Keg, I'm looking for the smoke and fire.  Blaster will be along shortly and ask for a picture with powder can next to it also for scale.

Don't fret about beer cans, you can always make a ball mould,  Powder Keg will tell you how.

Nice work!

[Cat Whisperer]

But where do you get the 1/2 scale beer cans?


.

[GGaskill]

The Coehorn has already been delivered to its recipient so I doubt I will get any action pix.  As for scale, the long side of the mount is 14.2" long, the height of the mount is 4.12" and the barrel is 3.98" in diameter.  So a powder can would be a little more than 1 1/2" higher than the mount.  

As for 1/2 scale beer cans, it will launch 1/2 beer cans, scale be damned.  (-:

[Blaster]

Great looking tube and bed on the Coehorn.  Now if only there had been a powder can right next to it.  Blaster (Bob in So. CO) :wink:

[Powder keg]

Did you build the handles also? They look nice.

[GGaskill]

Yes, I made the handles from 1/8 x 1 flat stock and 5/16 round stock.  I also made a bending jig and a welding jig to make the parts.  I can add pix if any one is interested.

[Powder keg]

Please do. So the handles have sheet metal washers welded on'em? They almost look forged. Thats usin your thinker. Nice job G.

[GGaskill]

The handles are made from three pieces--the 5/16 round stock and two pieces of 1/8 x 1 strap.  Each piece of strap had two holes drilled in it, one for the handle and one for the mounting bolt.  The bent handle piece was put in the number two jig (number one was for bending the rod) with the pieces of strap fitted over the handle and a locating pin to keep the parts in alignment.  The handle piece was then ground flush with the back of the strap pieces (or a little below flush.)  Next I TIG welded the lower 3/4 of the handle to the strap pieces from the back so no weld is visible from the front.  Then I disk sanded the strap pieces to shape (that was a lot of sanding.)  The strap pieces could be preshaped but that would complicate the welding; doing it this way made it easy not to melt the wrong places.  I thought about trying to forge them but I don't have a good anvil and am not much of a blacksmith.

I should have taken some pictures but I was in a hurry to finish this.  It had already taken twice as long as I expected.  I'll make a couple of sample parts and take some pix of them.

[Cat Whisperer]

Great looking tube and bed on the Coehorn.  Now if only there had been a powder can right next to it.  Blaster (Bob in So. CO) :wink:

But if you're too embarresed to put a powder can in the pix a beer can will do.

Do put up the pix of the bending and welding jigs - we'd love to see them.

[Cpt Ed]

GGaskill:

It is BEAUTIFUL,

I like what I see. Do you want to make another one???

PM me. Thanks.  

[GGaskill]

The problem with taking a pic with a powder can is I no longer have the mortar in my possession.  I suppose I could try to insert an image with Photoshop but that would be cheating.  Just for reference, a Goex one pound can is 5 3/4" high and 3 7/8" wide (virtually the same as the barrel diameter.)

As far as making one for hire, that one has maybe 50 hours in it.  Inletting the mount was the most time consuming part of making it.

[guardsgunner]

GG,
   The time is the part nobody really looks at on this type of hobby stuff. If it was even just T & M in the real world thats just over $1600.
 Nice work.

[GGaskill]

OK, here are the jig pictures.  This first image is the bending jig made from a couple of scraps of 1/4" plate and two cut off 1/2" bolts.





These next pix show how the rod is bent.  The jig is held in a large vise.  The rod is marked at the beginning of the bend and heated with a Mapp gas torch until red, then bent 90 degrees around the rightmost pin, then dunked to cool it off.  It is then put into the jig again with the first bend around the leftmost pin, the beginning of the second bend is marked, it is taken from the jig and heated to red again and then returned to the jig and bent 90 degrees. 



All heating is done only in the area of the actual bend or the bend does not stay tight to the pin.



It is then dunked again and sawed off the long piece (this has already been done to the piece in the pic.)  We make all the pieces and then move to the welding table.  The flat pieces have already been made on the milling machine.  One hole for the handle and one for the bolt are drilled in each piece.  The welding jig is a large scrap of steel with two holes for locating pins and the side milled out to hold the handle piece in position.





The piece of scrap sticking out in the middle is a field expedient spring (it is slightly bent) that holds the handle down tight (it compensates for a mistake made in milling the width of the cross-wise slot.)  The width of the wide T locates the handle side-to-side.  The two pins are loose (can be tapped out, not floppy loose)  so the welded part can be removed from the jig relatively easily.  In the next picture, the weld zone is indicated by the arc of green paint.



(The handle used for this demo is a reject which is a little too wide, which is why the left hand rectangle above is not square.  It could have been made square by tapping the handle against the jig after tapping out the right locating pin, but then the holes going through the mount would have needed a little tweeking.) 

Any way, weld all the parts with a TIG welder with no filler rod.  Flip them over and scribe the outline of the finished shape on each flat piece and attack with a disk sander until all the steel that is not a Coehorn handle is gone.  (-:

[CU_Cannon]

Nice looking work.  The handles are the hardest part.  I still need to make some handles for my last two mortars.  How did you make the carriage bolts?  Was the head welded on or was it machined from one piece?

[GGaskill]

The carriage bolts are ordinary 5/16 Home Despot (actually Lowe's as I recall) carriage bolts that had the heads turned down a little and the round top partially faced off with the remaining original curved head surface forming the chamfer.  It might be worth the trouble of finding some without the raised markings found on those so you don't have to file them off.  I ended up removing the square portion under the head so I didn't have to cut square holes through the handles.  There was enough friction in the holes to prevent turning anyway.

[Cat Whisperer]

George - Thanks for posting the pix.  It's a real game bending metal of that thickness to such a tight radius and then doing it again and again.

[GGaskill]

I have a tendency to over bend from experience of bending cold but there is no spring back when bending hot so you don't have to over bend.  It took almost all of the handles I made for this mortar to learn this (a dozen bends.)  Also, the dunking after each bend was an in progress enlightenment.

[GGaskill]

This is another of the threads whose images were on my crashed webserver.  But I reshot them and reposted them to the rebuilt server so they are back.

[GGaskill]

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