How to machine the end of a 1.5" dia rod perfectly round?

[John O]

Check Brafasco and Bolts plus they should have threaded rod. Sometimes even lower prices.

 

[toysareforboys]

Check Brafasco and Bolts plus they should have threaded rod. Sometimes even lower prices.

I talked to Brafasco, the only grade they have above grade 2 is grade b7, which is $110 per 3ft or $440 for 12ft.

Stainless 304 (they didn't know the tensile strength) is $183 per 3ft.

I'll check with Bolts Plus and some other shops

-Jamie M.

 

[toysareforboys]

Fastenal has B7 - 3ft x 1in is $75 each. Finish: Plain Tensile Strength: 125000 psi Yield Strength: 105000 psi Sku#47683
Bolts plus: B7 , $50 ea.
CCS Industrials: B7, $26 ea., lots in stock.

Made CCS confirm twice it was the right stuff, nice price!! They have a great price on a cobalt 1" drill bit too, will pick that up for enlarging the holes

-Jamie M.

 

[Latinrascalrg1]

With the amount of adjustability you have with the current setup along with the expensive cost for the larger harder threaded rod you might be better off all the way around using a different cheaper but stronger material such as some pipe and hardened pins! I dont know if cost is a factor or not but im guessing pipe material is gonna be much easier to source then that hardened very expensive thread rod!

 

[toysareforboys]

im guessing pipe material is gonna be much easier to source then that hardened very expensive thread rod!

I can return all the threaded rods and nuts, etc. that I've already bought, and I don't mind the cost of $26CDN ($19.60USD) per 3ft rod and CCS industrials is just down the street from me and they have lots in stock, so I'll probably go that route.

-Jamie M.

 

[Eddyde]

The rim is pretty weak (2mm thick aluminum) but it should be strong enough to just press in the primer. I don't have a milling machine but I think I can build a thick tube that the case will slide into with enough room for the projectile to come out and the back cut out to allow the flame/pressure to go away from me. Thanks for the ideas


I'm used to having to keep black powder compressed, with smokeless I guess I can shorten the stem some then use some wadding to keep the powder in front of the primer.


Thanks for the great info. Princess Auto (local shop) sells grade 5 and grade 8 threaded rod and nuts but they are renovating or something and had zero in stock If I used four 1" threaded bars of grade 8 what could that take approximately?

Thanks again everyone, tons of great info

-Jamie M.

1" grade 8 would do it and give a nice safety to margin.

 

[Mitch Alsup]

To be technical correct, most smokeless powder (except for some propellants tried by the military) will not "detonate". That doesn't mean they won't blow you're gun up, but a detonation, in technical terms, is a very specific thing. A deflegration explosion is what you see in gun failures, when the gun breech or cylinder explodes in a few large pieces. This is due simply to the pressure inside increasing slowly (relative to a detonation) until the strength of the containment is exceeded. A true detonation produces small fragments due to the detonation wave propagating around the cylindrical body and producing rarefaction waves that tear the container apart, these waves bouncing back and forth inside the pieces and tearing them apart in turn, until there is not enough energy to further tear the pieces apart.

Powder is supposed to burn; this means the flame front is moving slower than the speed of sound (in that mixture at that temperature that instant).
This is known as a conflagration.

Detonation is when the flame front is moving faster than the speed of sound--this necessarily produces a shock wave and reaches pressures ordinance metals cannot withstand.

Then there is the secondary pressure spike. This happens if the projectile is pushed faster than the speed of sound, and then, while still inside the barrel, the projectile slows down (friction) and the conflagrating flame front reaches the back side of the projectile and reflects back through the original flame front instantly detonating (conflagrate becomes detonate) the unburnt charge remaining. This usually happens when insufficient powder is placed in the case before loading. This is why there is a lower limit to the amount of powder to put in a case.

 

[toysareforboys]

1" grade 8 would do it and give a nice safety to margin.

Sweet! I got it all ordered, pick it up on Monday. Thanks again.

-Jamie M.

 

[toysareforboys]

Finished off the final machining tonight of the smokeless 40mm inert prototype ammo

Second last step is cutting the bevel for the extractor and grip fingers (so when you push the ammo into the chamber/barrel, if you pointed it straight up without closing the barrel it wouldn't slide back out). Last step is cutting the 45 degree bevel on the front of the projectile.

And she's done and done!

Thanks again everyone for all your help plus safety tips!

-Jamie M.

 

[Tozguy]

Thanks for sharing and the good photography!