Author Topic: Another Golf Ball Mortar Contest entry (Read 4452 times)

GGaskill · « **on:** March 21, 2005, 12:20:56 PM »

I am going to update this old post on my golf ball mortar so all the posts are in one string rather than duplicating info in two separate posts. The drawing and other stuff is at the bottom.

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I've started on my entry; machined the tube and the breech plug for a .002" shrink fit. I heated up the tube to expand it (blue heat) and dropped it over the breech plug and they got stuck (breech plug canted and wouldn't go farther.) HUMBUG! Not wanting to scrap the parts, I made a piece to fit the inside of the bore and the face of the breech plug and took them and my 6 ton hydraulic jack out to my press and was able to force the breech plug into the bore square and then on past the shoulder at the bottom. So I made another piece with a hole in it that would allow the breech plug to be forced all the way home. After application of more hydraulic power, it is in position. Yay! On with the program. (The pictures are reshoots of the originals and do not quite match up with the descriptions, but they're close.)
[img width= height=]http://mysite.verizon.net/gfg/images/gbmortarandfriends.jpg[/img]
Object at left is the base into which the breech plug was eventually pushed. Object in center is mortar tube and breech plug with tapering. Object at right is the pushing plug placed between the jack and breech plug.

[img width= height=]http://mysite.verizon.net/gfg/images/gbmortarchamber.jpg[/img]

Looking into mortar tube at breech plug and chamber.

Next step is to radius the back of the breech plug.

Cat Whisperer · « **Reply #1 on:** March 21, 2005, 12:27:44 PM »

I am looking foreward to seeing all the different designs this contest will produce.

Let me know if you need additional steel.

GGaskill · « **Reply #2 on:** March 21, 2005, 12:40:13 PM »

OK for the moment. Thanks for the offer.

GGaskill · « **Reply #3 on:** March 23, 2005, 09:30:27 PM »

Mortar as it stands:

The curve was done via the step-and-file method. Next to do are the reinforcing bands and trunnion.

This image was lost.

Cat Whisperer · « **Reply #4 on:** March 24, 2005, 12:54:13 AM »

I sense a classy lookin' mortar in the process.

Tune in tomorrow....

Powder keg · « **Reply #5 on:** March 24, 2005, 01:40:11 AM »

Good look'n mortar GGasKill!!!

GGaskill · « **Reply #6 on:** April 03, 2005, 06:25:07 PM »

I made some progress on my entry this weekend. The front band was expanded with my Mapp gas torch and it slipped on real easily. The main band was forced on with the 6 ton hydraulic jack and press combination. Coloring is heat bluing but it will eventually be painted bronze or brass color. The trunnion is not yet attached; I need to practice brazing with my TIG torch before doing a keeper.

[img width= height=]http://mysite.verizon.net/gfg/images/gbmortarwithbands.jpg[/img]

Cat Whisperer · « **Reply #7 on:** April 04, 2005, 01:09:24 AM »

Wooooooooeeeeee!

You're setting a high standard!

GGaskill · « **Reply #8 on:** April 21, 2005, 01:07:13 PM »

Regarding the firing part of the contest--do we get sighters or are the uncounted two of the seven supposed to be the sighters?

HotGuns · « **Reply #9 on:** April 21, 2005, 01:12:28 PM »

I dont get it...

why dont you just turn one solid peice and be done with it ? Its not that big a chunk of steel.Why go though all of the extra steps when turning it would be easier ?

GGaskill · « **Reply #10 on:** April 21, 2005, 01:20:52 PM »

You're right; making the barrel from a single piece would be lots easier.

The "contest" is to see what different people can do to make an artillery piece from two specific pieces of scrap--a short piece of tubing and a shorter piece of round. It's a challenge issue.

Cat Whisperer · « **Reply #11 on:** April 21, 2005, 02:51:51 PM »

Quote from: HotGuns

I dont get it...

why dont you just turn one solid peice and be done with it ? Its not that big a chunk of steel.Why go though all of the extra steps when turning it would be easier ?

George said it right - it's the challange. DD & I have been exchanging emails over some time about doing a contest. I just fell into place when I came up with the 1144 stress proof and he came up with the white oak.

For me personally, since I've got a bunch of the steel, I've tried three or four variations and am about to do several more. It's opened up some new ideas on how to put these things together and make them look authentic in form.

Further, there are several folks doing these that have very very different ideas than my own - fascinating to see the creativeness.

Stay tuned to see how they perform!

Double D · « **Reply #12 on:** April 21, 2005, 04:30:20 PM »

Fire 7 shots and the closest 5 count. You've got all summer to practice.

GGaskill · « **Reply #13 on:** April 21, 2005, 07:16:30 PM »

So we can fire as many sighters as we want before firing the 7 for the record?

Double D · « **Reply #14 on:** April 21, 2005, 11:32:25 PM »

Fire as many as you want to figure out your charge fro the range, how to fire and aim, you bet.

In the actual matches you are given set up time where you lay the mortar set up your aiming stakes get everything aligned, or what ever it is you do to get on target. Then when the match starts you fire the seven rounds and I believe you have 1 hour, if I remember right to get them all off. There is also a time limit between shots to be sure that all ember burn out. We should probably revisit that.

GGaskill · « **Reply #15 on:** April 22, 2005, 05:59:28 AM »

Normally, they require 3 minutes from shot to introducing a new charge into the bore. That is not a restrictive delay. With the short bores, we can look all the way to the bottom to inspect the bore for glowing embers and refrain from introducing powder if we find any.

GGaskill · « **Reply #16 on:** April 26, 2005, 08:15:18 PM »

More progress on my golf ball Coehorn; the mount is dirty from the spotting black but the OD paint will take care of that.

This image was lost.

CU_Cannon · « **Reply #17 on:** April 27, 2005, 05:34:38 AM »

Your intimidation tactics are working well on your competition.

Great looking work!

GGaskill · « **Reply #18 on:** April 27, 2005, 08:07:44 AM »

"Your intimidation tactics are working well on your competition." (-:

Don't be intimidated. You don't have to make a model of a Coehorn for the contest. Use your imagination and make something different.

Double D · « **Reply #19 on:** April 27, 2005, 09:31:28 AM »

Hey it looks like the wood I sent is no good, the corners got rounded in shipping...send it back and ill get you another piece... I'm so helpful!

GGaskill · « **Reply #20 on:** April 27, 2005, 11:11:37 AM »

(-: Thanks for the generous offer but I have enough left from the piece you sent to start over. (-:

CU_Cannon · « **Reply #21 on:** April 27, 2005, 04:43:54 PM »

Quote from: GGaskill

Don't be intimidated. You don't have to make a model of a Coehorn for the contest. Use your imagination and make something different.

Now you are just patronizing me. :wink: Just kidding.

I have a few tricks up my sleeves.

GGaskill · « **Reply #22 on:** July 22, 2005, 07:47:42 PM »

After all the hoopla over the appropriateness of 1144 in the handgonne threads, has any one actually fired one of their golf ball mortar contest entries?

Cat Whisperer · « **Reply #23 on:** July 23, 2005, 12:57:31 AM »

Yes and no. I'm not sure which of the half-dozen I've built with the 1144sp that I'm going to use for my entry(ies). But I've shot several of them.

The pressures involved with golf-balls at 30 yards/meters is so low the type of steel is a moot point. Further, the strenght of the 1144sp is so much greater than the other steels (including the 12L14 and other free-cutting steels) that [I feel] the misgivings are misplaced. Having said that, I will hold my final judgement off until I do (or see) emperical testing. The lead (12L44) and the phosphorous (1144sp and 12L14) are in there to assist in the machining - it may be that both or neither would be good choices for larger projectiles (heavier) and/or higher pressure; but for golf-balls the strength is more than adequate (IMHO).

Double D · « **Reply #24 on:** July 23, 2005, 03:12:04 AM »

Yes about 30 rounds.....

There some issues 20-25 years ago with one of the gunbarrel makers using stressproof in smokeless powder rifle barrels. Barrels were bursting. But I don't know that stress proof is 1144.

I also could not find anything to support the sudden brittleness of 1144 as one person alleged. He made the statemne t but offered no proof. But then I am no metallurgist and the numbers could be right in front of my nose. I have yet to see anything that tells me that we shouldn't be using 1144 for our golf ball mortars. Charges are small, pressure is low, metal walls are thick. I'm shooting mine!

Here is the Data from La Salle Steel.

Carbon Steels 1144
Related Metals:
HR-Penn(tm)
Clean Cut 45(tm)
Fremax 45(tm)

Specifications:
ASTM A29
ASTM A311
ASTM A510
SAE J1397
SAE J403
SAE J412
UNS G11440

Chemistry Data
Carbon
0.4 - 0.48

Manganese
1.35 - 1.65

Phosphorus
0.04 max

Sulphur
0.24 - 0.33

General Information
Physical Data

Density (lb / cu. in.)
0.283

Mechanical Data

Form
Bar-Round

Condition
Cold Drawn

Temper
68

Tensile Strength
125

Yield Strength
100

Elongation
12

Reduction of Area
34

Brinnell
269

Compare with 12L14 a common steel used in Muzzleloading gun barrels used with black powder

Carbon Steels 12L14
Related Metals:
Penn-Lead(tm)
Tull-Led(tm)
Xtrocut 300(tm)

Specifications:
ASTM A576 (12L14)
SAE J1397 (12L14)
SAE J403 (12L14)
SAE J412 (12L14)
UNS G12144

Chemistry Data

Carbon
0.15 max

Iron
Balance

Manganese
0.85 - 1.15

Phosphorus
0.04 - 0.09

Sulphur
0.26 - 0.35

General Information

Principal Design Features

12L14 is considered to be one of the fastest machining bar products produced today

Machinability

12L14 is rated at 190% of 1112. Its machinability is a direct result of a fine dispersion of lead particles throughout the alloy.

Physical Data

Density (lb / cu. in.)
0.283

Mechanical Data

Form
Bar-Round

Condition
Cold Drawn

Temper
68

Tensile Strength
78

Yield Strength
60

Elongation
10

Reduction of Area
35

Brinnell
163

...and 4140 the traditional Gun steel.

Yes about 30 rounds.....

There some issues 20-25 years ago with one of the gunbarrel makers using stressproof in smokeless powder rifle barrels. Barrels were bursting. But I don't know that stress proof is 1144.

I also could not find anything to support the sudden brittleness of 1144 as one person alleged. But then I am no metallurgist and the numbers could be right in front of my nose. I have yet to see anything that tells me that we shouldn't be using 1144 for our golf ball mortars. Charges are small, pressure is low, metal walls are thick. I'm shooting mine!

Here is the Data from La Salle Steel.

Carbon Steels 1144
Related Metals:
HR-Penn(tm)
Clean Cut 45(tm)
Fremax 45(tm)

Specifications:
ASTM A29
ASTM A311
ASTM A510
SAE J1397
SAE J403
SAE J412
UNS G11440

Chemistry Data
Carbon
0.4 - 0.48

Manganese
1.35 - 1.65

Phosphorus
0.04 max

Sulphur
0.24 - 0.33

General Information
Physical Data

Density (lb / cu. in.)
0.283

Mechanical Data

Form
Bar-Round

Condition
Cold Drawn

Temper
68

Tensile Strength
125

Yield Strength
100

Elongation
12

Reduction of Area
34

Brinnell
269

Compare with 12L14 a common steel used in Muzzleloading gun barrels used with black powder

Carbon Steels 12L14
Related Metals:
Penn-Lead(tm)
Tull-Led(tm)
Xtrocut 300(tm)

Specifications:
ASTM A576 (12L14)
SAE J1397 (12L14)
SAE J403 (12L14)
SAE J412 (12L14)
UNS G12144

Chemistry Data

Carbon
0.15 max

Iron
Balance

Manganese
0.85 - 1.15

Phosphorus
0.04 - 0.09

Sulphur
0.26 - 0.35

General Information

Principal Design Features

12L14 is considered to be one of the fastest machining bar products produced today

Machinability

12L14 is rated at 190% of 1112. Its machinability is a direct result of a fine dispersion of lead particles throughout the alloy.

Physical Data

Density (lb / cu. in.)
0.283

Mechanical Data

Form
Bar-Round

Condition
Cold Drawn

Temper
68

Tensile Strength
78

Yield Strength
60

Elongation
10

Reduction of Area
35

Brinnell
163

...and 4140 the traditional Gun steel.

Alloy Steels 4140

Related Metals:
Folder
Finkl 4140(tm)
Maxell Tooling Alloy(tm)

Specifications:
AISI 4140
AMS 6349
AMS 6381
AMS 6382
AMS 6390
AMS 6395
AMS 6529
ASTM A193 (B7, B7M)
ASTM A194 (7, 7M)
ASTM A29 (4140)
ASTM A320 (L7, L7M, L7D)
ASTM A322 (4140)
ASTM A331 (4140)
ASTM A506 (4140)
ASTM A513
ASTM A513 (4140)
ASTM A519 (4140)
ASTM A646 (4140)
ASTM A711
ASTM A752 (4140)
ASTM A829
SAE J1397 (4140)
SAE J404 (4140)
SAE J412 (4140)
UNS G41400

Chemistry Data

Carbon
0.38 - 0.43

Chromium
0.8 - 1.1

Iron
Balance

Manganese
0.75 - 1

Molybdenum
0.15 - 0.25

Phosphorus
0.035 max

Silicon
0.15 - 0.35

Sulphur
0.04 max

General Information

Principal Design Features

This is one of the chromium, molybdenum, manganese low alloy steels noted for toughness, good torsional strength and good fatigue strength.

Applications
4140 is used in a tremendous variety of applications, too numerous to mention here.

Machinability

Machinability of this alloy is good in the annealed condition. In the heat treated and quenched condition machining is best limited to finish grinding.

Forming

As with all the low alloy steels forming may be done by conventional methods with the alloy in the annealed condition. These alloys have good ductility, but are tougher than plain carbon steel and thus usually require more force, or pressure, for forming

Corrosion Resistance

This alloy is a steel and is not corrosion resistant. Protective coating must be used in corrosive, or water, environments.

Welding

Weldable by all of the conventional methods. Note that welding with the alloy in the heat treated condition will affect the mechanical properties and a post weld heat treatment may be needed.

Heat Treatment

This alloy is hardened by heating to 1550 F and quenching in oil. It is best to normalize the alloy by heating at 1675 F for a long enough time to permit thorough heating, followed by air cooling, prior to the hardening treatment.

Forging

4140 may be forged at 2200 F down to 1700 F.

Hot Working

Hot working, if required, may be done in the range of 1900 F to 1500 F.

Cold Working

The alloy readily cold works in the annealed condition by conventional methods.

Annealing

Annealing is done at 1600 F followed by slow furnace cooling.

Aging

Not applicable to this alloy.

Tempering

Tempering temperatures range from 400 F to 1200 F depending upon the hardness level desired. The lower the tempering temperature the greater the hardness of the alloy. For example tempering at 600 F gives a tensile strength of 225 ksi while tempering at

Hardening

Hardens by cold working, or heating and quenching - also see "Heat Treatment" and "Tempering".

Physical Data

Density (lb / cu. in.)
0.28

Specific Gravity
7.83

Specific Heat (Btu/lb/Deg F - [32-212 Deg F])
0.114

Melting Point (Deg F)
2580

Thermal Conductivity
23

Mean Coeff Thermal Expansion
7

Modulus of Elasticity Tension
33

Mechanical Data

MSO currently has no data available for this grade

Double D · « **Reply #25 on:** July 23, 2005, 06:05:33 AM »

1144 can be stressproof...http://www.niagaralasalle.com/pdf/stressproof.pdf

GGaskill · « **Reply #26 on:** August 30, 2005, 05:10:20 PM »

OK, below is the drawing for my entry. It consists of five pieces, four shrink fitted together to make the barrel and the trunnion brazed on the back. (The brazing is my current hangup. I need to make some practice beads before doing a real gun.) The inside diameters of the muzzle ring and reinforce should be adjusted to give about .001" interference fit and the rings should be heated and slipped on the barrel. The muzzle ring is 1/8" down from the end of the barrel and there is 1" between the muzzle ring and the reinforce.

As I mentioned above, I intended to do the same with the breech plug but got it sideways. It might be a better idea to simply press the plug into the barrel cold.

Cat Whisperer · « **Reply #27 on:** August 31, 2005, 12:32:26 AM »

George -

Thanks for the drawing AND all the details of the process.
I'm impressed with the elegence of adding the two rings - something I've thought of doing, but now that you've given me the challange I'm sure I'll try. Nice touch on rounding out the base too.

How did you hold the the pieces when hot?

Were there any issues in positioning them (did they cool/shrink quickly or did you have a few seconds to position them)?

GGaskill · « **Reply #28 on:** August 31, 2005, 07:47:39 AM »

The muzzle ring slipped on easily but it is small and easy to raise to a uniform temperature. I usually make some kind of temporary setup that limits the distance the expanded piece can go on. I think I put a clamp on the tube to act as a stop (been a while since I actually did it.) If you want the maximum size difference, you can fill the tube with dry ice and acetone (do this away from open flame) to shrink the tube as well as heating the ring for expansion. I probably should have done the tube and breech plug that way (shrink the breech plug and expand the tube) but was lazy.

I hold the pieces with anything that will minimize the amount of heat loss; a piece of wire, asbestos welding gloves, etc., or support a piece on something that has small contact points.

Steels have a coefficient of thermal expansion of about 6 microinches per inch per degree Fahrenheit, so you need to calculate your diametral differences based on how hot you can get the piece you need to expand. I usually figure a heated temperature of 600 degrees F and an ambient of 100 degrees F (easy arithmetic and a little safety factor) for a net of 500 degrees expansion. So for a 2" diameter piece, you would get .000006" times 2" times 500 degrees = .006" expansion. You only need about .001" per inch interference for an adequately tight joint so that would give you .005" clearance for assembly. But you need that .005" clearance for the whole length of both pieces or it will likely stick short. With only .001" shrink, you can pretty easily press the pieces into place if they don't go all the way while heated.

GGaskill · « **Reply #29 on:** October 01, 2005, 07:26:19 PM »

I finally got around to firing this mortar and it was interesting. I was using green fuse and Fg powder, with charges ranging from a full .40 S&W case to two full .45 ACP cases (which filled the powder chamber.) Both range and report were erratic. The maximum charge netted between 90 and 100 yards range. The minimum netted between 20 and 30 yards range. One .45 ACP case full gave 25 to 40 yards range. In no case was there any useful consistency.

I have concluded that Fg powder is too coarse for this size gun and will try with finer powder next time. No pix were taken.