Why the heck did my qu-bd mod leak?

I wanted to see what happened on why my mod failed.

This one I made the tube from scratch with a thinner ptfe liner. Notice the runout on the chamfer and the burr in the nozzle.

This one I made the tube from scratch with a thinner ptfe liner. Notice the runout on the chamfer and the burr in the nozzle.

This one didn't leak but had a clogged nozzle.  When I tried to disassemble I cracked the thin wall tube.

This one didn’t leak but had a clogged nozzle. When I tried to disassemble I cracked the thin wall tube.

Close up of the home made tube which caused the leak.. Notice the runout.

Close up of the home made tube which caused the leak.. Notice the runout and sharp jagged edges.

close up of the nozzle that leaked

close up of the nozzle that leaked

I had made  fixture to turn my blanks.  Basically put a piece of 3/4 bar in the collet chuck of my lathe and then single point bored it for concentricity.   I was checking it with pins and I noticed a few thou taper but  I bored it from both sides.    I then  the bored blanks in vblocks and then had tapped them in my lassey tapper….  The change gears on my lathe are inch and I don’t have cnc to single point the threads.   I did my best to make a nice fixture…  I thought it would be better to locate on the thread pd, plus I don’t have a 6mm 5c collett… That and I didn’t want to damage a collet clamping on a thread od.

I’m thinking there’s some slop between the fixture and the threads.   I held my blanks in place using a lock washer and a nut..  The front chamfer and the bore were done in seperate set up which accounts for the eccentricity.
I think I kicked up a bur in the brass nozzle caused by the sharp edges in the tube I made which resulted in the leak….   I’m thinking I need to loose the lock washer when I clamp my blank in the fixure and assuming that the od runs true to the PD. (no guarantees on that) I suppose I can try to indicate the thread od in…   I should also polish the end of the tube  and round off sharp edges to avoid creating another burr on the brass.

I’m going to see if I can salvage this tube by skin cutting the chamfer and front face…. Hopefully the run out is in the chamfer and not the bore.. If so I might stand a chance.   I’m thinking once done, I can heat the tube in the block without the nozzle and push some filmanent through to clean things up and get flush out any metal chips before putting on the nozzle.   I probably should lapp the bore to try to smooth out the tear marks that are probably in the bore from drilling.

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