Author Topic: New Guy Needs Some Honest Advice (Read 3752 times)

lightning · « **Reply #30 on:** April 24, 2006, 05:36:44 PM »

I checked the FAQ and did not find any info on vent pieces. Am I looking in the wrong place? Thanks

Double D · « **Reply #31 on:** April 24, 2006, 09:06:28 PM »

Your are right it isn't there..trhy here http://www.graybeardoutdoors.com/phpbb2/viewtopic.php?t=18455

entsminger · « **Reply #32 on:** April 25, 2006, 08:40:38 AM »

I know where you're coming from in a way. This liner stuff is confusing. I've read what seems like a million posts on this forum from guys who are brilliant in artillery but I still don't really understand if a steel liner is needed on the cannon I hope to own some day. I hope to own either an 8 or 10 inch 1861 mortar someday and from what I hear most cannons should have a seamless steel liner to be safe to shoot. Problem is the only two repudable companys I know of ( Paulson Brothers and Hern) who make such a reproduction full size cannon don't use liners on their mortar. I've read the complete cannoneer and chatted alot about this but still am unclear if such a mortar needs a liner or not? Some say it should and some say they are thick enough no to need one? I guess I need to find the artillery school some of you guys must have got master degrees in artillery at so I can understand this all better.

Scott

Double D · « **Reply #33 on:** April 25, 2006, 11:00:31 AM »

Scott,

The mortar you were talking about building needs a liner.

Hern does use a liner.

I don't believe Paulsen Bros. uses a liner and does not need one. Norm can you comment on that.

Scott have you contacted Paulsen Bros and asked them if they use a liner, and why or why not?

Artilleryman · « **Reply #34 on:** April 25, 2006, 05:51:15 PM »

I shoot an original 8 inch siege mortar that was cast in 1865. It doesn't have a liner. I am unaware of any Civil War period siege mortars that burst during the Civil War or at any other time. None of the siege mortars that I have seen original or repro are lined.

Eight inch siege mortars were designed to fire a 45 lb shell to a distance of 2000 yards using 2 lbs of mortar powder. The barrel weighs in excess of 1000 lbs, a wall thickness of 4 inches, and a bore length of 16 inches. If repros are made of a quality iron there shouldn't be any problem unless you were foolish enough to attempt to fire an eight inch solid shot that weighs 65 lbs (iron or zinc). If the barrel is made of an inferior grade of iron you are also at risk (who do you trust?).

The bronze (gun bronze) 24 pdr Coehorn does not need to be lined either, provided that it is made of quality bronze. It is designed to fire a 16-17 lb shell to a distance of 1200 yards. If you make the tube from a high tensile strength steel it does not need be lined because the tube is the liner. The tube was not designed to be made of cast iron so if you have a cast iron tube it may be questionable as to it having enough strength for the heavier long range charges. Some repros are made of cast iron with a sub caliber bore which gives you greater wall thickness and lighter projectiles. Discussions about Confederate Coehorn mortars and wooden mortars is another topic since they were made as an expedient

A comment about projectiles. Mortars were designed to throw shells that are lighter than solid shot for the same bore size. As the bore size increase the weight of the solid shot goes up quite a bit. Solid shot of iron, zinc, or lead should not be fired in mortars.

Also mortars should not be fired at elevations higher than 60 degrees (Civil War period Coehorn have a fixed elevation of 45 degrees) since there is the possibility that the projectile could drift back (depends on the wind) and fall on the gun crew, and the higher elevations put more stress on barrel, bed, and platform (if you use one).

The range of the projectile of course is depends on the powder charge and elevation. Mortars were designed to fire exploding shells, and the explosion could be seen at the mortar's effective range. Since we do not shoot exploding shells there is no point in firing a projectile to a range where you cannot see it land. If you do this you will not get up to the service charge which means less pressure.

This is a lot more than I intended to write before I started.

GGaskill · « **Reply #35 on:** April 25, 2006, 06:50:26 PM »

The mortar you were talking about building needs a liner.

I assume what you are talking about here is the mortar simulator made from the propane tank.

entsminger · « **Reply #36 on:** April 26, 2006, 05:58:34 AM »

I love you guys!! I've found no where else where I get such good responces to my sometimes dumb questions.
I did talk to Hern Iron works and they say they don't use a liner in their 8 inch mortar because they say the walls are thick enough. They do use liners on their smaller cannons. I briefly talked to Paulson Brothers and they esentially said the same thing and Paulsons test fire theirs to be sure their safe. Cannons Online said if they were to make a 10 incher it would have a liner but I know of no one eho has one of theirs?
The kicker is that I still hear lots of people say a liner is a must and I don't know if these big mortars because of their thicker than normal barrels are exempt from the liner need or not.
I can't find anyone who owns either a Hern of Paulson mortar . I talked to Arron or Freddy Frederickson who built their own 8 and ten inch mortars and do shoot them alot and they say they used a tougher grade of iron rather than typical gray iron on theirs so it's supposedly safe?
Scott

Artilleryman · « **Reply #37 on:** April 26, 2006, 10:42:33 AM »

When comparing mortars to cannons and the need for liners consider this. A 24 pdr siege and garrison gun uses 6 lbs of powder, a 24 lb shot, and 2 degrees of elevation to get a range of 1147 yards. A 24 pdr mortar uses 8 ounces, 17 lb shell, and 45 degrees of elevation to get a range of 1200 yards.

An 8 inch Columbiad uses 10 lbs of powder, a 65 lb shot, and 6 degrees of elevation to get a range of 2010 yards. An 8 inch siege mortar uses 2 lbs of powder, a 45 lb shell, and 45 degrees of elevation to get a range of 2000 yards.

It is apparent that mortars operate on much lower breech pressures than cannons. So seige mortars cast from a good quality iron do not need liners like cannons.

GGaskill · « **Reply #38 on:** April 26, 2006, 10:52:17 AM »

Also, when comparing plans for the two types of artillery, the breech walls of the mortars are much thicker than those of the field pieces, which is not surprising as the field pieces were supposed to be mobile and the mortars relatively immobile.

Rickk · « **Reply #39 on:** April 26, 2006, 04:24:31 PM »

Quote

"as the field pieces were supposed to be mobile and the mortars relatively immobile."

GGaskill... I live on a farm, have a tractor, and move "stuff" alot.

Anything that weights 1000+ pounds and doesn't have either legs or wheels just isn't supposed to move .

reddog · « **Reply #40 on:** April 26, 2006, 06:11:11 PM »

I don't get it. I run A paving machine, I move A lot of "stuff" too. Whats that got to do with anything that was said on this post? Nobody said they were making A 1000 pound morter. :?

Double D · « **Reply #41 on:** April 26, 2006, 08:28:44 PM »

Actually Reddog that is exactllywhat they are talking about -- full size size Siege mortars...well in excess of 1000 lbs.

By the way did anyone notice that Paulsens have an 8 inch for $7500.

entsminger · « **Reply #42 on:** May 04, 2006, 02:09:17 AM »

I know Paulson Brothers sells a 8 inch 1861 repro mortar for around $7500 and a 10 incher for $10,500. Hern Iron works also sells an 8 for $5600. I've only saved around $3000 and that took me forever so I have along way to go towards getting any of those mortars.
I would really like to talk to someone who has bought one of those and shoots it but can't find anyone who has??

Scott

lightning · « **Reply #43 on:** May 06, 2006, 04:14:20 AM »

I found air gaps in the iron casting of this barrel (see the first posting) and contacted Tim with Gray Star. He was very apologetic and said he would send me another one when he got the next batch from the foundry. A few weeks later he emailed me and said he had been having quality control problems with his foundry and was in the process of finding a new facility, and it could be a quite a while (months or longer) before he could get me a replacement. Since I had begun this project to be a non-shooting cannon in the first place, Tim and I agreed to a partial refund. I am satisfied with this resolution and Tim was quick in his communication. Tim told me that the liner itself would withstand the shooting pressures, but after reading all of the postings from those more knowledeable I decided against even trying. (I have ordered a coehorn mortar with a seamless liner that will be next my project. I will definitely be shooting it)

BUT, I decided to use this cannon as a learning experience. I completed the carriage, painted the barrel, and decided to drill the vent hole, just to make sure I could do it. Even after reading all of the postings, buying an American made drill bit, using a drill press and trying to be careful, you guessed it, I broke the 1/8" drill bit off right as it was apparently in the liner. Broke off 2/3 of the bit.

It's not that big of a deal at this point but I would like to know what the solution to the broken off drill bit in the barrel is, in case it happens in the future. Any suggestions as to how to fix the problem? Thanks in advance!

Rickk · « **Reply #44 on:** May 06, 2006, 04:45:04 AM »

EDM should do it. Rather than even trying a drill bit, I had mine EDM'ed to begin with... figuring I would be there either way.

lightning · « **Reply #45 on:** May 06, 2006, 05:21:36 AM »

My ignorance is showing. What is EDM?

Double D · « **Reply #46 on:** May 06, 2006, 06:15:43 AM »

Quote from: lightning

I found air gaps in the iron casting of this barrel (see the first posting) and contacted Tim with Gray Star. He was very apologetic and said he would send me another one when he got the next batch from the foundry. A few weeks later he emailed me and said he had been having quality control problems with his foundry and was in the process of finding a new facility, and it could be a quite a while (months or longer) before he could get me a replacement. Since I had begun this project to be a non-shooting cannon in the first place, Tim and I agreed to a partial refund. I am satisfied with this resolution and Tim was quick in his communication. Tim told me that the liner itself would withstand the shooting pressures, but after reading all of the postings from those more knowledeable I decided against even trying. (I have ordered a coehorn mortar with a seamless liner that will be next my project. I will definitely be shooting it)

Lightning you are the second person to come on here with problems with Graystar. He is quick to respond to the questions because the last time he got ripped pretty good here in public about his products and it was obviously his fault.

Before you buy another barrel from him or anyone I suggest you get yourself a copy of the The More Complete Cannoner and read up on what you should look for in a barrel.

On to other things.

Vent holes. Your vent hole should be 1 1/2 callibers large. What that means is that the vent hole should be 1 1/2 times the diameter of the of the fuse. Fuse is 1/8 your hole is 3/16. That would be in a solid barrel.

In a cast barrel with a liner the hole will be much larger to accomodate a vent liner. Something closer to 3/8 to 1/2 inch. Lined barrels should never be fired without a vent liner.

Powder keg · « **Reply #47 on:** May 06, 2006, 06:46:13 AM »

There is a picture of a vent liner floating around here somewhere, but I cant find it? Does anyone know where it is?

jeeper1 · « **Reply #48 on:** May 06, 2006, 07:54:51 AM »

EDM is Electrical Discharge Machining.

Double D · « **Reply #49 on:** May 06, 2006, 08:33:53 AM »

Excerpt from THE MORE COMPLETE CANNONEER compiled Agreeably to the Regulations of the War Department as published in "Artillery Drill" by George Patten, 1861 and Containing Other Observations on Antique Cannon By M.C. Switlik with selected excerpts from other artillery manuals

Vents

Here's what a vent liner looks like. Make to size. make to fit. Fuse hole down the center.

Seems like a prudent thing to make. Make from copper or stainless steel Don't have it protrude into the chamber as it mught snag the powder bag. The round top is recessed into the barrel deep enough so the square top is recessed also. The file the top flush.

If you have a misfire you can remove the plug and have better access for flushing. You could also make a plug to fit your hose to get the water or CO2 in the chamber.

Make sure you use anti sieze compund on the threads.

Powder keg · « **Reply #50 on:** May 06, 2006, 09:43:03 AM »

Thanks Douglas!!

dunnagan · « **Reply #51 on:** June 25, 2006, 02:05:57 PM »

Hi, I am also new to this world of cannons. I have purchased a 6 lb 1841 cannon from Hern and am eagerly anticipating its arrival. I have been reading your posts on drilling the vent hole and have a couple of questions. If you would take the time to help me out I would certainly appreciate it. First, I am trying to figure out how to determine the placement for the vent. Should we try to hit the rear of the chamber or should we try to be in the middle of the area that will hold the powder? Yeah may be a dumb question but I am not sure that we could hit the right spot if we try to hit the exact end of the chamber. I assume we measure down the inside of the barrel to see how deep it is and then transfer this to the outside and drill.... But I could be completely wrong and I don't really want to mess this up. Second, my cannon is being delivered to a machine shop here and I am wondering if I should have them drill out the vent on their machines. If I do this should I have them tap the hole so that the "vent piece" that you guys are talking about can thread into the hole?. If this thing were wood I would be all over this but I am not so good with metal. Your help and suggestions so far sound great now I just need you to "help me land". Thanks again for your time.

Cat Whisperer · « **Reply #52 on:** June 25, 2006, 02:16:28 PM »

dunnagan -

WELCOME to the board. You've started right - asking real-life questions.

Looking forward to seeing pictures of your smoke!

dunnagan · « **Reply #53 on:** June 25, 2006, 02:45:05 PM »

Thank you, I appreciate your words of welcome. It is my intention to bring back to life at least a section of "Rourke's Battery" and this cannon is the first step in breathing life into that dream.

As a bit of a background note: John Rourke (O'Rourke) was Captain of the 1st Illinois Artilery battery L under the command of James Mulligan. My research shows that John spend several years in and around Harpers Ferry and Petersburg Virginia. He is a person of special interest not just because of his wartime exploits but also because his brother in law to be wrote a song about him. You may know the song: When Johnny Comes Marching Home" by Patrick Sarsfield Gilmore. That's the one.

He was a well respected Captain of Artillery it only seems fitting that we once again get his battery into the action! We have a long way to go though as we are not even sure at this point what the fuses should look like or where we should get them. We will work it all out though and then you will see some action - and some smoke!!!

Double D · « **Reply #54 on:** June 29, 2006, 09:25:48 AM »

I would drill the vetn so the center is just ahead of the rear of the bore. You want to leave some room for the end of the cartridge and be able fuse into the powder.

Rickk · « **Reply #55 on:** June 29, 2006, 09:56:08 AM »

I to had to make a hole in a Hern barrel. Mine was a mortar. There is a dimple cast into the barrel where the hole is supposed to start. As near as I could figure it would have entered the chamber about .8 from the bottom. I was fraid that with realistic loads that I would be too far forward.

I had a machine shop EDM the hole so that the hole entered the barrel .40 from the bottom of the bore. This put it at an angle. A vent pick hits the bottom of the bore if inserted far enough in. That means that no matter how small a powder charge... even a little dinky one... will be hit by the vent pick.

For what it is worth, I probably could have aimed a bit further away from the bore bottom.

To figure out where the hole will enter the bore when drilled on an angle was an excersize in frustration. What the machine shop wound up doing is putting a length of 2.25 inch round bar into their EDM machine and adjusting it so that the EDM electrode ws aimed at a point that was .400 from the end. Then they slide the barrel over the bar to see where the goes-into hole was going to be. They played with the angle a few times untill it entered where I wanted it to enter the barrel and exited .400 from the bore bottom.

The hole diameter is .200 .

EDM was way less risky than a drill. They owed be a favor and did it for free. I have no idea how much they would have charged, but I suspect the novelty factor of drilling a hole in a cannon barrel and maybe a case of decent beer at the right machine shop might be somewhere near the right price. I guess some would work for good ole cash as well of course.

Let us know how you make out.