Welding cones into the assembly

[hinote]

Here's a tip I've found useful for welding intake bells and transition cones into place: (generated by "Nanosoft" on the Valveless Forum):

I make the small end of the cone I want to weld to an assembly SMALLER at its minor end (but with the correct angle--so the cone is actually TALLER in its x-length than specified); then, weld the cone into place while an assistant is putting pressure on the cone-to-part joint (this forces the cone into circularity during the weld).

You'll end up with an assembly that has the minor end of the cone sticking into the part it's welded to; now, use a die-grinder to remove the excess metal on the inside of the joint.

If you have been liberal in adding weld filler material to the outside of the joint you can grind a nice radius between the cone and the part it's attached to--and that's probably a performance enhancer for your pulsejet project.

Hope this helps someone.

Bill H.
Acoustic Propulsion Concepts

[Rossco]

Bill,
I know that my engines are be no means "pretty" or even as neat as this method may produce bit i use a similar trick.
In some of the larger cones, such as a tail pipe piece, there would be difficulty in getting a diegrinder and your hand in there with any hope of seeing what you are doing.
What i do in this case is similar in preparation to yours.
I make the smaller section the correct size, with a very smooth and "sharpened" edge. This is achieved with a die grinder or file on the inside of this cone.
The larger cone is made slightly longer than needed by about 10mm (depending on the size of the cones). I flare the end of this cone back to the reqired length so that the flared section matches the angle of the smaller cone. A pic may be nessasary, ill scratch one up.
When these two pieces are pressed together with a substantial force, any imperfection of roundness are evened out.
I then tack with the weight on, release, make sure everything is straight and finish the weld up, flowing the overlap back nearly to the smallest section.
This seems to produce a neat and strong fit, with very little mess inside the weld.

Thankyou for your suggestions on such assembly process, this could turn into a very informative thread.

Rossco

[hinote]

Bill,

In some of the larger cones, such as a tail pipe piece, there would be difficulty in getting a diegrinder and your hand in there with any hope of seeing what you are doing.
What i do in this case is similar in preparation to yours.
I make the smaller section the correct size, with a very smooth and "sharpened" edge. This is achieved with a die grinder or file on the inside of this cone.
The larger cone is made slightly longer than needed by about 10mm (depending on the size of the cones). I flare the end of this cone back to the reqired length so that the flared section matches the angle of the smaller cone. A pic may be nessasary, ill scratch one up.
When these two pieces are pressed together with a substantial force, any imperfection of roundness are evened out.
I then tack with the weight on, release, make sure everything is straight and finish the weld up, flowing the overlap back nearly to the smallest section.
This seems to produce a neat and strong fit, with very little mess inside the weld.

Thankyou for your suggestions on such assembly process, this could turn into a very informative thread.

Rossco

Your method is similar to mine is some ways. Whatever works is good.

I feel that access to the inside of weld seams is a matter of planning; just weld enough parts together to keep the seams accessible. Of course you're eventually going to have hidden seams for the final weld-up---but if you plan ahead you will have dressed the most important areas to aid in smooth gas flow and not create tiny acoustic "mirrors" that contaminate your signal strength inside the engine.

I drew up a quick illustration to show what I'm trying to say. I also showed another trick--I make the transition cone oversized at the joint with the combustion chamber; then, during welding the excess material becomes the filler in the weld, and you don't have to add very much. A little pressure applied here during the tacking process closes-up any gaps you may have in the joint.

Bill H.
Acoustic Propulsion Concepts