Cannon Project Questions

MaverickNH

MaverickNH

H-M Supporter - Gold Member
H-M Supporter Gold Member
Joined
Nov 6, 2012
Messages
157
My 5" brass mini-cannon build, done on a SouthBend at our Makerspace, is a bit more challenging on my home 7x16 mini-lathe. I chucked a 7" 1-1/4" 360 brass rod in my 4-jaw chuck, set up a steady rest 2-1/4" from the end, and turned down the 0.9000" dia 1.8" long breach section. On the big lathe, our retired professional machinist shop instructor did the curved tapers by hand for us, turning both axes simultaneously. We practiced a bit but us newbies didn't have "the touch" yet. I'm looking for alternatives, given my minimal experience.

I figure I can cut that 0.16" wide 0.63" dia narrow "waist" depth with a cut-off blade, then file the back of the button-end down. I'm thinking to approximate the tapers by angling my compound rest to progressively cut angles and rounding with a file.

Advice appreciated! Again, it's a 7x16 mini-lathe and, while I appreciate thoughts on interesting tooling/fixtures I could make, I'm wondering what I can do with what little I've got already. I'll add those tools/fixtures I can make to the list. ;)


1729520633631.png
 
MaverickNH said:
My 5" brass mini-cannon build, done on a SouthBend at our Makerspace, is a bit more challenging on my home 7x16 mini-lathe. I chucked a 7" 1-1/4" 360 brass rod in my 4-jaw chuck, set up a steady rest 2-1/4" from the end, and turned down the 0.9000" dia 1.8" long breach section. On the big lathe, our retired professional machinist shop instructor did the curved tapers by hand for us, turning both axes simultaneously. We practiced a bit but us newbies didn't have "the touch" yet. I'm looking for alternatives, given my minimal experience.

I figure I can cut that 0.16" wide 0.63" dia narrow "waist" depth with a cut-off blade, then file the back of the button-end down. I'm thinking to approximate the tapers by angling my compound rest to progressively cut angles and rounding with a file.

Advice appreciated! Again, it's a 7x16 mini-lathe and, while I appreciate thoughts on interesting tooling/fixtures I could make, I'm wondering what I can do with what little I've got already. I'll add those tools/fixtures I can make to the list. ;)


View attachment 506583
Click to expand...
My chance to be a smart A... Get a small CNC!. Ok that aside get a groove tool for the .11 x .63 Dia., Turn all your Flat O.D.'s, kick your tool post and touch all your chamfers, Pre-drill the I.D. bore, then go to a tool grind/supply shop in your area with the print and have them grind a form tool to finish the bore net all in one shot. (turn any O.D. Rads into chamfers for simplicity)
 
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.

Do NOT rely on the "plastic angle guide" on the 7x compound. Use a protractor to set the compound angle. You will need to work out if those are "half" angles or full angles.

Re using a protractor to set the compound angle, even a cheap "mathematics set" plastic protractor is more accurate than the "guide" on the compound of a 7x.

MaverickNH said:
0XA QCTP from LMS.
Click to expand...

Same style tool-post I use (minus the square "foot). LMS Cat No. 3113 right?

Swing the compound, then use the face of the chuck, or the nose of the spindle itself without a chuck mounted, to square the (loosened) tool-post to the spindle, then re-tighten in position. (Fit an empty holder, trust me, you will need to as the wedge gib will push it of being square).
 
Last edited:
k_millard said:
My chance to be a smart A... Get a small CNC!. Ok that aside get a groove tool for the .11 x .63 Dia., Turn all your Flat O.D.'s, kick your tool post and touch all your chamfers, Pre-drill the I.D. bore, then go to a tool grind/supply shop in your area with the print and have them grind a form tool to finish the bore net all in one shot. (turn any O.D. Rads into chamfers for simplicity)
Click to expand...

A groove tool like this?



1729533158121.png
 
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.
 
Last edited:
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.
 
You must log in or register to reply here.
Back
Top