Cannon Project Questions

[GrifterGuru]

I'd part brass using HSS. Use a 0.5" stick out of the blade. 3/32" thick blade. Should be pretty easy, even on a 7x lathe. Using carbide on brass, strikes me as just silly. Make sure you are on center line and the parting should go easy.

Don't knock it until you try it. It cuts brass very nicely. Very nicely indeed!

Recently made a blind cap nut from 20 A/F CZ121 brass and using a carbide H01 (aluminium) insert, it cut through it like a hot knife through butter. Even parting off was without the usual stress.

Don't misunderstand me, I am not against HSS tooling, I just prefer carbide inserts because the angles are perfect and I do not, at the moment, have time to grind, shape, and stone an HSS tool for a so-called "quick" job where making the tool would take longer than making the part.

 

[k_millard]

Looks like The GrifterGuru has you covered.

 

[WobblyHand]

Don't knock it until you try it. It cuts brass very nicely. Very nicely indeed!

Recently made a blind cap nut from 20 A/F CZ121 brass and using a carbide H01 (aluminium) insert, it cut through it like a hot knife through butter. Even parting off was without the usual stress.

Don't misunderstand me, I am not against HSS tooling, I just prefer carbide inserts because the angles are perfect and I do not, at the moment, have time to grind, shape, and stone an HSS tool for a so-called "quick" job where making the tool would take longer than making the part.

Not knocking it at all. I don't doubt it works. But so does HSS. I can assure you that even clumsily sharpened parting blades work excellently on brass, aluminum and most steels. Really don't even need to hone it. If you set things up properly, you can part 1.5" steel using HSS on a mini-lathe. My point was that there's not much need to buy a $40 tool when a $2 blade will work similarly, especially when one is starting out. I'd reserve the carbide for difficult stuff. I'm not against building up capability, but I also don't want new people (not you) to think that expensive tooling is required to part brass.

Of course, if you mess things up like I did, 304 stainless will burn your HSS blade down to a nub if you let it work harden. That's a lesson you learn once!

HSS is just another tool. The ability to make your own tooling means you don't have to wait for it to show up (and be wrong!). It doesn't take that long to grind. Try getting a custom form tool - good luck with that. But you can grind your own in a short time. Far better than waiting two weeks. (Actually had to wait a lot longer than that during the pandemic. So I made my own tooling.).

Making tooling and or building up your infrastructure is part of machining... Especially if you don't have infinitely deep pockets.

 

[GrifterGuru]

Not knocking it at all. I don't doubt it works. But so does HSS. I can assure you that even clumsily sharpened parting blades work excellently on brass, aluminum and most steels. Really don't even need to hone it. If you set things up properly, you can part 1.5" steel using HSS on a mini-lathe. My point was that there's not much need to buy a $40 tool when a $2 blade will work similarly, especially when one is starting out. I'd reserve the carbide for difficult stuff. I'm not against building up capability, but I also don't want new people (not you) to think that expensive tooling is required to part brass.

Of course, if you mess things up like I did, 304 stainless will burn your HSS blade down to a nub if you let it work harden. That's a lesson you learn once!

HSS is just another tool. The ability to make your own tooling means you don't have to wait for it to show up (and be wrong!). It doesn't take that long to grind. Try getting a custom form tool - good luck with that. But you can grind your own in a short time. Far better than waiting two weeks. (Actually had to wait a lot longer than that during the pandemic. So I made my own tooling.).

Making tooling and or building up your infrastructure is part of machining... Especially if you don't have infinitely deep pockets.

Oh, I agree about grinding a specific tool, I have every intention of doing just that when I need a particular form tool, or a very particular shape tool.

I have a job coming up that requires multiple items all the same and with that, comes needing to grind a very specific tool in HSS. Yes, the fun of that job will be grinding the form tool.

 

[MaverickNH]

You could use one of those MGEHR1010-2/MGEHR1010-3 tools with an MGMN200-M H01 or MGMN300-M H01 Non-ferrous (aluminium) insert. A 2mm or 3mm wide tool would give you room to open the groove out to 0.16" (4.064mm) atool.s well as prove useful as a parting-off tool.

It also helps that you can get neutral/left/right inserts as well as round nosed inserts for them, so a multi-use

You can get 4mm wide MGEHR tool-holders, but I am not sure you would have much use for one, even as a parting-off tool. I acquired 2mm & 3mm MGEHR, but stopped at that since I can see no real use for a 4mm wide cut-off/grooving tool.

That said, I do have a 4mm cut-off/grooving tool, but have only ever used it once or twice at most.

Worth bearing in mind that the OXA tool holders can carry up to 13mm or 1/2" tooling, at least all my holders can. Worth checking your own tool-holders. Just remember to get the tools "on-centre", especially when it is a cut-off/grooving tool given the pressures involved.

Thanks for the advice. I'm not finding MGMN200-M H01 but see MGMN200-G H01 - which is sometimes listed for Al and Copper and sometimes only steels. I'll keep looking!

 

[GrifterGuru]

Thanks for the advice. I'm not finding MGMN200-M H01 but see MGMN200-G H01 - which is sometimes listed for Al and Copper and sometimes only steels. I'll keep looking!

MGMN200-G H01 will be fine. It is merely a difference in the profile moulded into the insert.

"M" is one type of profile "G" is a different type of profile.

Have a look at these inserts. See the difference in profile moulded into them between the "M" and the "G" designation?

 

[talvare]

I agree with @GrifterGuru
"For the tapers, swing the compound to the desired angle and feed the tool in, in multiple passes, to form the taper on the stock." You can cut the initial groove with a parting tool as you've suggested.

I recently finished building a scale model Civil War cannon and am starting to gather materials to build another cannon. Looking at your drawing brings some questions to mind and I am very curious about it's design.

Is this cannon a replica of an existing cannon and is it intended to be fired ? I ask because there are some unusual characteristics in the design. What you are calling the breech really isn't because the bore stops before it gets to that portion of the barrel. Also, the breech is typically the strongest and largest portion of the barrel and in this case the "breech" section is a reduced diameter. It may still be of adequate thickness, just a little unusual. Also, it appears that the bore has a taper. What is the purpose of the tapered section ? Will there be trunions on the barrel and how and where will they be installed.

Appreciate any feedback.

Ted

 

[MaverickNH]

I agree with @GrifterGuru
"For the tapers, swing the compound to the desired angle and feed the tool in, in multiple passes, to form the taper on the stock." You can cut the initial groove with a parting tool as you've suggested.

I recently finished building a scale model Civil War cannon and am starting to gather materials to build another cannon. Looking at your drawing brings some questions to mind and I am very curious about it's design.

Is this cannon a replica of an existing cannon and is it intended to be fired ? I ask because there are some unusual characteristics in the design. What you are calling the breech really isn't because the bore stops before it gets to that portion of the barrel. Also, the breech is typically the strongest and largest portion of the barrel and in this case the "breech" section is a reduced diameter. It may still be of adequate thickness, just a little unusual. Also, it appears that the bore has a taper. What is the purpose of the tapered section ? Will there be trunions on the barrel and how and where will they be installed.

Appreciate any feedback.

Ted

Brass Mini-Cannon - First Firing

My first test fire of the 5” brass mini-cannon I made on our Southbend lathe at our local Makerspace. The base is 3D printed from PETG, glued and bolted together, and I added a 1/2"x3"x6" steel plate for recoil. The 3" long bore is 0.28" widening to 0.42"over the last 2". The charge was 14grains...

www.hobby-machinist.com

The taper was designed to assure expansion out the bore.

 

[RaisedByWolves]

The taper was designed to assure expansion out the bore.

I was going to ask about this, what purpose is there?

 

[MaverickNH]

I was going to ask about this, what purpose is there?

Just a safety feature for abuse testing. A test unit survived fully packed with black power but 14 grains is enough for a pop. No projectile intended or tried.