Author Topic: I had a good weekend too... (Read 1943 times)

MikeR C · « **on:** January 20, 2008, 05:09:26 PM »

It could have been funner,

But it should bring fun later.

Thx MikeR C

Evil Dog · « **Reply #1 on:** January 20, 2008, 05:11:41 PM »

Definitely a good start. When do you anticipate smoke and fire? A 1 pound lead ball fishing weight will also work quite well.

MikeR C · « **Reply #2 on:** January 23, 2008, 03:36:13 PM »

The fun continues...

I have decided God never intended Man to bore 4140 on a cheap Chinese 9X20 lathe. It would ring like a bell, part of the problem might have been no steady rest...
Hence the brake hone. I am not going to take out all the machine marks, just smooth it off a bit. I won't live long enuf to get it completely smooth.

lance · « **Reply #3 on:** January 23, 2008, 03:50:47 PM »

Mike, i hope you live long enough for smoke and fire pics!

MikeR C · « **Reply #4 on:** January 23, 2008, 04:03:00 PM »

Lance,
Don't you worry about that. I'm going to have the trunnions on this weekend and hopefully fire it, assuming my cheap Chinese mill will cut the recess.
I never subscribed to the whole "patience is a virtue" thing. A couple of years back I bought a rifle in Spokane and made it back home about dark, I took that rifle out in the dark and shot it by headlights using the scope rings as "peep" sights. I'm not good at waiting.
I think I'm going to drill the touch hole 3/32 for 1/16" fuse. What I really hope is I live long enuf to put one of your bases on it. That is my plan, that's why I bugged you about the dimensions. I do believe if I had to do it over I would use 1018 instead of 4041.
Thanx, by the way for your replies,
MikeR C

lance · « **Reply #5 on:** January 24, 2008, 04:40:52 PM »

Mike, one thing i didn't tell you, was, why mine is painted a color that most people think is blue. it's not, anyway, a person very dear to me wanted to help out, even picked that color, special made, just for me. I couldn't say no........But, my full size one will be getting plain boiled linseed oil. i started to oil it last week, but there's snow on the ground here, snow causes extra farm chores.

MikeR C · « **Reply #6 on:** January 25, 2008, 06:27:34 PM »

So, the saga continues:

After a zillion .010 cuts it is approximately half round. I started filing it smooth, when it is smooth enuf then it will be off to the mill for the trunnion. I believe I'll use a 1 1/4" diameter bar sunk halfway in and bolted to the barrel.
Thx
MikeR C
PS Lance, I think I'm gonna blacken the barrell and paint the base red...

MikeR C · « **Reply #7 on:** January 26, 2008, 04:13:00 PM »

The trunnion pocket is now cut, I used a 3/4" end mill to get it started and the a boring head to finish to size:

At this point I had to stop and figure out what the carriage was going to look like so I'd know how long the trunnion needed to be. Lance graciously provided me with some measurements so I drew one up so I could cut the trunnion to length:

Hopefully tomorrow I will get the trunnion attached with two cap screws, although I bielieve the wife has other plans for me...

Thx
MikeR C

lance · « **Reply #8 on:** January 26, 2008, 04:49:01 PM »

Mike, just looking at your drawing, to me, the center cross member is too far back. on mine with the 15" sides, i cut the dado at 7 1/2" to 9", that measurment is from the front. mine's not centered, the face of the cross member is at center..............P.S. i like my red painted one too! that's what is so fun, if you don't like a color, it's much easier to build another one.

MikeR C · « **Reply #9 on:** January 26, 2008, 05:19:26 PM »

Lance, you could be right about the middle member. My thinking is this, and I could very well be full of it, in the side view you can see that the barrel is at 45 deg, I placed the middle cross member so that it will swing to 45 deg towards the rear as well. The museum photo looked like the trunnion was centered between the cross members, to me anyways.
I placed the rear cross member so that the space between the middle member and rear member is a square. I also made the framing 1 1/4 which is narrower than what you sent me. I'm not too worried about recoil as I will probably only shoot golf balls. All I need now is some wood...

Thx
MikeR C

lance · « **Reply #10 on:** January 26, 2008, 05:51:27 PM »

Mike, sounds like a neat ideal to me. i just make what looks good to me and as close to the picture as i could guess at. i was going to drive to Gettysburg and measure the one in the museum, but the curator told me the private collector put it back in his collection. The curator e-mailed the owner and told him i wanted measurements, i never heard a word back. my barrel is at a 45, it's never swung back from firing, i can tighten the trunnion caps so that with my bare hands i can't pull the barrel back. one more tip you might want to do..........on the backside of the cross member where the barrel rests at a 45, add a small 1"x1" piece of 1/8" flat steel. i just drilled a hole in the center and used a wood screw. that will keep the barrel from denting the wood edge, and turning your 45 into a 40 something............. i have lot's of wood, too bad you live sooooo far away.

GGaskill · « **Reply #11 on:** January 26, 2008, 07:15:47 PM »

Hopefully tomorrow I will get the trunnion attached with two cap screws, ...

Hopefully you will weld the trunnion instead of using screws. The screws will impinge upon the chamber area.

MikeR C · « **Reply #12 on:** January 27, 2008, 12:44:53 PM »

I don't have the equipment to weld it, and from what I've read 4140 is not trivial to weld without preheating. I don't know if it makes any difference but the trunnion is 1018, maybe dissimilar metals could cause welding problems as well. Since this mortar is designed to shoot golf balls it has a small chamber, like so:

This shows a vertical slice through the center of the tube, I have rechecked the dimensions on the tube "as built" and they follow the drawing above.

I plan on bedding the trunnion in Loctite 680 retaining compound, this should keep stuff out of the space between the trunnion and tube (corrosion). Then I'll drill and tap for 1/4" stainless cap screws set flush, I will probably Loctite them in with red. The trunnion cut and screw holes follow the "wall thickness equals the chamber bore" rule, see the above drawing.
From what I've read golf balls don't produce a lot of recoil, and this is a proven design (taken from DoubleD's contest entry). so I think I'm going to be all right.

Thanx
MikeR C

Cat Whisperer · « **Reply #13 on:** January 27, 2008, 03:36:20 PM »

Mike -

Good planning on location of bolts - I've been doing that for years on 4140 mortars.

Suggest you take a look at the sharp inside corner at the bottom of the bore - it's a stress riser. It would be much stronger if it were a radius! (golf balls? no problem)

MikeR C · « **Reply #14 on:** January 27, 2008, 04:10:29 PM »

Yes sir, my intention was to take the 30deg angle out to the bore and not leave the small right angle step. There's no way my lathe would have cut the bottom of the bore with a form tool and the only boring bar I have that fits my compound is 1/2" I realize I need heavier tooling. I broke the last corner of the last insert so that's where I quit. I changed the drawing to reflect that change. I AM taking some liberties because it IS for golf balls. I also believe the chamber is small enough that even if it is fired with lead balls I expect it will hold up.
I very much appreciate the comments from everyone, I'm building on what I've learned reading prior posts and the comments offered. I am assuming that if the way I've done something is misguided someone will point out where I've gone astray.

Thank you,
MikeR C

GGaskill · « **Reply #15 on:** January 27, 2008, 08:02:51 PM »

... and from what I've read 4140 is not trivial to weld without preheating.

Very true, and a major reason I use 1018 for artillery since the extra strength of the alloy steel is not needed if one maintains traditional proportions.

MikeR C · « **Reply #16 on:** January 28, 2008, 02:40:04 PM »

I learned my lesson, I won't use 4140 again unless I have to! Only problem is, I can get drops from work, for just hauling them off, up to big. They use it for shafting an' other stuff.
Well the deed is done, blizzard today and I stayed home from work:

I'm trying to decide if I want to drill the touch hole before I get the fuse. I want to use 1/16" fuse, and I found some, so I figure 3/32" (1 1/2 calibers for fuse hole right?), I just don't want to drill it twice

Thx
MikeR C

Terry C. · « **Reply #17 on:** January 28, 2008, 03:42:15 PM »

It's always easier to drill it out larger, if it's too small.

Drilling it smaller when it's too large is a bit more of a challenge.

A word about fuse: The American Visco that CannonFuse.com and some other sites sell is often referred to as 1/8" fuse, when it is actually a bit undersized. My last two projects have 9/64" and 1/8" vents (1" and 5/8" dia. chambers, respectively) and I've had no problems using this fuse in either one (provided the vents are cleared between shots, as they should be).

Most 1/16" fuse, on the other hand, is actually a little larger than 1/16" diameter. It'll still work fine in a clean 3/32" vent.

A 1/8" vent also allows me to use the Vis-Quick which is about the same diameter as the Am. Visco. Vis-Quick is a very fast-burning fuse and in short lengths fires almost as fast as a quill.

lance · « **Reply #18 on:** January 28, 2008, 04:28:01 PM »

i drilled a 1/8" vent, only reason i picked that size was to average out some different fuses i had. but all i use now for fuse is that 2mm green viscoe from pyrocreations.com. i've never used the vis-quick, i'll have to try it sometime.

MikeR C · « **Reply #19 on:** February 16, 2008, 02:47:50 PM »

Well, it's finally done and I took it out this afternoon between snow fluries:

The chamber holds about 50 grains of 3F and that shoots the ball somewhat over 200 yards. A half full chamber shoots about 75 to 100 yards. Just perfect, I was able to see one ball out of 4 at full charge, any more and it would just go bang and you would never see the ball.
It came out pretty well, when the barrel is swung to the rear it is very well balanced and easy to carry. Wife likes the red color and I am welcome to keep it in the house, bonus! Sorry about the lack of a powder can, but the hole is golf ball size!

Thx
MikeR C

Tropico · « **Reply #20 on:** February 16, 2008, 03:08:17 PM »

Damn ! That's nice indeed., your wifee has good taste in mortars., It would be a welcome addition to my home as well. Thank you for the thread .,construction., fire and smoke.., very very nice indeed sir. By the way your handles look great along with the rest.

Terry C. · « **Reply #21 on:** February 16, 2008, 03:12:24 PM »

Looks great!

lance · « **Reply #22 on:** February 16, 2008, 03:26:22 PM »

Mike, it's beautiful!!!! I always enjoy seeing your work,plus you know that's my favorite mortar design to look at

accuratemike · « **Reply #23 on:** February 16, 2008, 03:29:20 PM »

Quote from: MikeR C on January 23, 2008, 03:36:13 PM

I have decided God never intended Man to bore 4140 on a cheap Chinese 9X20 lathe. It would ring like a bell, part of the problem might have been no steady rest...

You just have to build one of these:

I had a pretty bore going at that point. I didn't screw it up until I was cutting the radius between the bore and chamber (freehand, my holder will take a 3/4" boring bar, actually came out good), on the last pass I forgot to move the tool in before retracting the bar. Oh well, shoot it twice and you can't see the finish.
Nice work, looks great! MIKE

HF 9x20
RongFu JFC45N2F
More time (to come up with work-arounds) than money

MikeR C · « **Reply #24 on:** February 16, 2008, 04:17:34 PM »

Gentlemen,
Thank you for the kind words, luckily you can't see all the mistakes as the picture is too small! I hadn't considered making a larger steady, I think I will look into that.
I am looking for a dimensioned drawing of the CS 24 pounder mortar barrel like what is on my base, if anyone has one. I have scaled my mortar base the best I could from Lance's photos but I need the actual dimensions for the barrel to finish up my drawings.

Thx
MikeR C

seacoastartillery · « **Reply #25 on:** February 16, 2008, 04:39:49 PM »

MikeR C, Very, very nice!! We really appreciated your process photos too; they add a lot to a project like this. Fire and Ice! We're jealous; got to get out soon despite the snow drifts.

Congratulations!

Mike and Tracy

Cat Whisperer · « **Reply #26 on:** February 17, 2008, 03:30:50 AM »

MikeR C -

Thanks for posting pix of a mortar firing IN THE SNOW!

That PROVES it can be done in the winter!

rifleshooter2 · « **Reply #27 on:** February 17, 2008, 05:41:20 AM »

MikeRC
Very nice job. She's a fine looking piece. And you can keep in in the house, lucky you.

Andy