Pop can mortar

[freekforge]

the boring bar is 1/2" dia so with it being around 6" long it had WAYYYY too much flex and was bouncing an tearing up the bore. me and dad started a new larger diameter bar to keep it from flexing just waiting on it to cool off from annealing it.

 

[30calmachinegunner]

The chatter free solid carbide bars work nice, how large of a bar can you handle?

 

[freekforge]

right now the biggest holder I have is 1/2" but we are going to make a new T nut with two studs sticking out to bolt the bar directly to the compound. I am going to buy a qctp when I have the money so then I will be able to use 3/4" bars.

 

[30calmachinegunner]

What are you doing now to hold the bar, running it through the tool post holder ? You making your own boring bars?

 

[freekforge]

I am making a boring bar out of the drag link off a dodge ram. I cut a slot to hold my tool bit and will drill and tap it for 10-32 set screws. Dad said he has made them like this in the past so I hope it works. I am going to drill two holes in the bar to bolt it to the compound using a new T nut with two vertical studs

 

[IndyGunworks]

I have seen that exact same set up before. if I remember right it worked OK. didn't give the best finish, but they were turning fairly slow and using carbide, which could also be part of the reason for the poor finish.

 

[freekforge]

We bolted the bar straight to the compound at school when doing the more precision stuff except the boring bar wasnt made from old car parts and the lathe wasn't 69 years old so I'm not sure how well this will work.

 

[1911ly]

That's really clever! Let us know how it works!

 

[freekforge]

IT WORKED! my ugly car parts boring bar is cutting with very little vibration. I will post some pics of the progress in a little bit I will also post a few of the boring bar after i get it welded up for those interested.

 

[1911ly]

I could not resist

I want to see pics for sure! I love a fix under fire fix! lol Good job Ethan!

 

[freekforge]

Well here's the very little work I got done today. Normally I wouldn't take the part out until its finished but I had to due to equipment malfunctions so I'll just have to break out the dial indicator and redial it. but any way here's where I'm at

First pass taking out chatter from the previous attempt with the wimpy boring bar

the homemade boring bar on its test run it will be finished later today

just passed 2.5". I'll use a micrometer and T gauge when i get closer to final bore size

and here it is now with just a few passes left to take

 

[freekforge]

Oh and here is the boring bar it will be welded to the plate it was sitting on in the pics above. It is 1" dia x 10" long. I decided to go with only one stud to hold it on for no reason other than I didn't feel like looking for another bolt of the same size

 

[1911ly]

Hey it works and works great!!

 

[freekforge]

Well all that i need to do to the barrel is drill and tap for the vent liner. Here's where I'm at now.

got the bore to size

turning the OD of the breech plug to major bore size

turning the opposite end to minor bore size

test fit of plug

drilling and countersinking the trunnion

tapping with a taper tap

now a bottoming tap

test assembly

 

[IndyGunworks]

looks good. Assuming you are going to use the bolt/vent to secure the chamber? I think that's the way Double D's KISS mortar design is.

 

[Trigger Time]

Looking awesome!!

so for someone who has no machining knowledge ..... Why do you have to make it in 2 parts? The barrel

 

[freekforge]

yep its pretty much DDs design with the two cap screws in the back pulling the breech plug against the shoulder inside the barrel and the the vent liner bolt keeps it from rotating and reduces corrosion where the barrel and plug meet.

trigger time it just makes it easier and cheaper to make.

i am also going to round off the back end a bit but need to make a center plug so I can support it on the tailstock end. And im going to get another vent liner and chamber it for a .22 nailgun blank to use as a primer

I just drilled and tapped the vent liner.

cap screws that secure the plug to the barrel

 

[freekforge]

I was curious about how much the barrel weighed so I stepped on the bathroom scale with it and the barrel alone weighs about 17lbs....just enough to use it as a CC weapon

 

[Trigger Time]

LOL

 

[1911ly]

I want to see the holster :-)