i was thinking that you should mill a bit of a powder tray onto /into . so the slow match would set it off more reliably .
the 'quill' is much like DD's idea and it is quick and loud .
Gary, We both like your idea of making a little powder tray or raised vent field with a powder holding depression machined into it. It will be done.
Victor, With the uneven surface we are dealing with, I think we will go with Frank's soap suggestion. Thank you, and if I ever have a heavy object to move on concrete, I will keep UHMW-PE in mind.
Frank, Thank you. Your description of the heavy transformers sliding on soaped steel rails reminds me of the tale my father used to tell about the bad thing he and his sister used to do on a gentle railroad grade behind their farm in Newington, Connecticut. He soaped the rails for 50 feet or so when they were kids in the 20s and then hid in the woods until the 2 PM freight came along. They squealed with delight when the large drivers spun on the soaped track before the engineer applied sand under them. Bad kids, very bad!
We had quite a busy day on Saturday. We decided to remake the baseplate which supports the Chamber Piece, the Tube and the Cosmetic Shroud. The old ½” thick steel plate was just too difficult to mill and unnecessarily heavy. Mike spotted a ¾” aluminum tooling plate 24.25” X 24.5” at the scrap yard 3 months ago and grabbed it for $42.50 about half of the new cost. We decided to use it as a very strong replacement for the rusty old steel baseplate. So, our goal for yesterday’s work was to make the new baseplate and to align the Tube assy. upon it and layout corresponding holes in the Chamber Piece to be drilled and threaded ½-13 UNC.
We had some help early in the day when we were making the process plan, but none in the afternoon when we were executing it. There were so many critical alignments to accomplish that our plan had 22 steps and the registration marks, which allow precise alignment upon re-assembly, were not forgotten. We used the Monster’s shell hoist to good advantage and it allowed two people to do lifts where 4 would have been required without it. Although we were still at it at 9 PM, we were satisfied that we had accomplished everything on the plan, and had not made one mistake in measurement or alignment. We double and triple-checked every measurement and alignment before going on to the next step. Today we are ready to drill the bottom of the Chamber Piece which is a milestone in this mortar’s construction. See the story in photos below.
Regards,
Tracy and Mike
Here Mike scribes around the Shroud which has been squeezed repeatedly, but is still ¼” out-of-round and has a little hump where the butt-weld is. With aluminum, you can cut, following the scribed line, with your wood cutting bandsaw at regular wood cutting speeds and then grind exactly to the line on the 12” Disk sander to match the profile of the Shroud’s bottom edge precisely.
The layout of the baseplate’s two bolt circles, first the 4 hole, 9” Dia. Chamber piece B.C. and then the 4 hole, (it will become 8 hole), 3/8” lag bolt, 18” Dia. B.C. ,for Baseplate to wooden wedge holding bolts.
Holes drilled.
The 267 Lb. Chamber Piece rests on the 40 Lb. Baseplate after being hoisted up on a timber support to allow transfer punching of Chamber Piece securing Bolt Circle through the drilled Baseplate. All Tube hardware must be assembled before the necessary alignment can occur.
The Tube is hoisted and then lowered over the Chamber Piece. All twelve ½-13 bolts attach the two, making a 477 Lb. assembly.
Mike does the rigging after we figure out how to center the hook. When your working with sisal rope, where gloves!
As we lowered the Shroud onto the Tube and Baseplate, we noticed that one edge kept digging into the aluminum, so we moved the hook over to provide more lift where required.
I handed the ½’ transfer punch and hammer to Mike, but he said, “Not me, buddy, that thing weighs 603 pounds now, you get under there!!” And so, having lots of confidence in my pile of timber, I did.
Two prick-punch marks denote proper Shroud to Tube alignment for accurate re-assembly.
Mike uses an automatic center-punch to mark the vent’s location. Half way between the handles and 5” from the Shroud’s bottom edge, he makes a dimple to guide the drill. Remember that we want to fire charges as small as 6 oz., so knowing that the Chamber piece is 11” long and that the 4” Dia. Chamber is 8” long including the hemispherical end, we position the vent at the point where the hemi is tangential to the chamber walls 2” up from the chamber’s bottom, 5” up from the bottom of the Chamber Piece.
Mike drills a 1/8” pilot hole, then a ¼” hole with an 8” long aircraft drill bit to spot the vent location on the 12.5” O.D. of the Tube. I aligned the long bit with a precision square for up and down and I crawled up on the muzzle to eyeball left and right alignment, then he drilled both holes.
As the light fades, the whole thing is disassembled and hauled into the shop for machining.
