[How do I?] Lathe/mill A Converging, Internal Angle Deep Inside Part

Steve Shannon said:
Sometimes they are spun. Here's how Copenhagen Suborbital spins theirs, which is also a two wall design.
Click to expand...

This is exactly what I thought about when I read "rocket nozzle".

When in production, we had a few parts with similar features that we ran on CNC. They were a time consuming challenge. Seems like every other month we would experiment with some new wonder tooling, which was able to better cut such features.

On this piece you have above, I would start on the righthand side ID and drill, then bore straight into the other chamber. I would then use a boring bar with the compound to start the angle in the large chamber to the left. Before removing the workpiece, the external nozzle features would be finished.

Then flip the part and finish out the chamber.
 
mattthemuppet said:
I'd make it in two parts (cylinder and angled bit) with mating threads and whatever seals would hold up to whatever's going to happen inside it :)
Click to expand...
Once I looked into Copenhagen Suborbital's more recent YouTube videos I discovered that they are now on version 2 of their BPM 5 motor. It is now a weldment of three pieces, done on a sort of welding lathe adjusted to ensure penetration on the welds.
I've added it to the rocket nozzle playlist. Here is a link to just the one video:
 
Steve Shannon said:
Once I looked into Copenhagen Suborbital's more recent YouTube videos I discovered that they are now on version 2 of their BPM 5 motor. It is now a weldment of three pieces, done on a sort of welding lathe adjusted to ensure penetration on the welds.
I've added it to the rocket nozzle playlist. Here is a link to just the one video:
Click to expand...

Great. Thanks. Now apparently I need a welding lathe. I'm sending wifey to you to explain why.
 
A Tree Automatic Taper boring head is what you need.
2 are for sale on ebay, both have a asking price of more than what I paid for my mill.

 
That is one dangerous looking head.... looks almost exactly like what I need, but I was waiting for a hand injury in that video.
Well worth looking into (the price being a huge limit as I would personally have no use for it after this is done, my designs are typically 2x the size).

I also contacted Robert who has some similar designs from:
http://watzlavick.com/robert/rocket/

His response was rather simplistic and puzzling (I emailed him back for more detail and questions about how he keeps the bar and toolpost from hitting the chamber wall):

Zach,
I use a boring bar and then adjust the cross slide on the lathe at a 30
degree angle to get the converging section.

-Bob
Click to expand...

This makes it sound as if he simply has a boring bar at 30(deg) and feeds it using the cross-slide crank, but without a lathe in front of me, I cannot see how that possibly works....

No response from Jared from the previous link I posted....
 
knoq said:
That is one dangerous looking head.... looks almost exactly like what I need, but I was waiting for a hand injury in that video.
Well worth looking into (the price being a huge limit as I would personally have no use for it after this is done, my designs are typically 2x the size).

I also contacted Robert who has some similar designs from:
http://watzlavick.com/robert/rocket/

His response was rather simplistic and puzzling (I emailed him back for more detail and questions about how he keeps the bar and toolpost from hitting the chamber wall):



This makes it sound as if he simply has a boring bar at 30(deg) and feeds it using the cross-slide crank, but without a lathe in front of me, I cannot see how that possibly works....

No response from Jared from the previous link I posted....
Click to expand...
I assume he means that he sets the boring bar parallel to the lathe axis and sets the top slide to 30 degrees.
 
That.... could work!

I have a QTCP and rotating that is fairly easy.....
The angle of attack on the cutting face may be off, but I could get a HSS boring bar (ideally a blank) and grind that to the correct face.
 
start off with the left side first, so chuck the right side
drill the through hole and bore the chamber
roughly form the left taper
chuck the left side and with a boring bar turn the right taper
after that turn the left taper
there is enough room to use a thin boring bar to form the left taper
in alu with tiny cuts that should be no problem
 
You must log in or register to reply here.
Back
Top