FUEL ROD BUILD

I drilled the holes in the fuel rod and welded the end up. I decided not to use the ball valve to regulate the gas flow as we can just use the gas cylinder regulator.

TACKED TOGETHER

I grinded a few parts of the straight seems down and re-welded them slightly better. I intended to get all the circumferences welded today completing the main body of the Pulsejet ready for filling the fuel rod to and setting up.
However, the weather was terrible.. I've said in my risk assessments that any substantial amounts of welding I intended to do should be done outside to minimise fire risk and improve ventilation. Wind also makes welding more difficult because it blows away the shield gas making the welds of worser quality. This meant I couldn't do much more than tack the pieces together. This has made me miss the deadline date set for completion of my artefact. However, I intend to get it finished next weekend and in evenings instead. This shouldn't postpone the project and EPQ by too much and I therefore believe this isn't a huge problem.

These are the pieces tacked together:

FUEL ROD DESIGN 2

I've sourced a piece of hydraulic tubing that would be better suited as a fuel rod having a smaller diameter and thickness therefore impeding the gas flow less.

Here is the original design and the updated one:

STRAIGHT SEAM WELDS

I got all of the straight seams welded today (still on schedule). There are a few strips where the welds could be better so I'm thinking about whether it's worth grinding them down and redoing.

From reading that the surface of the metal has a large effect on weld quality, I looked at different ways of cleaning the metal in preparation for welding:
Sand-paper

Brush

Disk Grinder

I chose to use disk grinder as it cleaned the metal quickly and well:

I also found that parts where the metal joint had a gap didn't weld as well as when they were butted up tight.

FINISHED CONES

Managed to get all the cone rolling done today today just about on schedule.


To cut the inside radius for the combustion chamber flare 2, it was difficult to cut such a tight radius neatly using an angle grinder so I tried cutting it out using a hole saw on the advice of my dad but this wouldn't cut through the metal so ended up cutting a rough radius slightly smaller than the desired one and I can just flatten the top of the cone once rolled with a belt sander or something to give the desired diameter.




On the longer pieces such as the combustion chamber and tailpipes which I had my worries about being able to roll into a cone, to twist the metal in the rollers to ensure a cone is rolled, we slackened the rollers, twisted them, re-tightened them, and then rolled a bit more.
A fair amount of brute force was needed to marry the edges up.

All of the pieces are now tacked in shape; they just need the seams welding up and then all welding together and it'll be ready for fitting the fuel rod to.

CONE TRIAL 2

I looked at the option of adding a bracket guide to the metal roller but there seemed nowhere to mount it so that idea needs more thought. The man in the video also tightens one side of the top roller more than the other to achieve a tighter radius at one end of the metal.
I tried rolling the intake tube-the convergence on this cone isn't very great and it's very close to a standard tube-This was fortunate because of the length of the metal, there was a large amount in contact with the rollers making it very hard to twist straight to form the cone in the rollers. This wasn't too much of a problem because the difference could be corrected using brute strength and tacking the cone closed before putting it in the roller again to neaten it out.
This has worried me for rolling the exhaust pieces though as they are the longest pieces and have a greater convergence so will be difficult to make into a cone.
 The guide idea may need revisiting to help with this.

   

This piece also married up well to the intake flare (first test piece) which is positive sign. 

CONE TRIAL

I cut out the intake flare from the mild steel using an angle grinder; this seemed to work well enough even though it has a relatively tight inside radius. I also tried with tin snips but found this distorted the metal too much and was hard work. To roll the metal I put it in the roller and whilst rolling had my dad to keep the metal perpendicular to the roller.

The cone's dimensions are close enough to the desired measurements to make it feasible. The cone is slightly off-round in parts but with the metal being thin this can be altered by hand and welded in place. This cone looks reasonable enough to use on the actual pulsejet so i'm going to keep it; if the preceding cones are a similar sort of quality then I can use this, if they are better I can re-make it. 

When it was almost fully rolled I welded the come up so the edges met up well and put it back in the roller to improve it's shape. 

   

Also, if any of the cones have a tighter radius to cut, I can cut it roughly and once the cone is rolled sand down the top horizontally. 

The whole 2 person rolling job seemed quite a task so I looked on YouTube for tutorials and found one person who uses a guide clamped to the roller to turn the metal; I'm going to try this on the next cone.