Sage / Breville Dual Boiler - two problems - Page 2

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
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lancealot

#11: Post by lancealot » Oct 08, 2019, 2:28 pm

Re: sanding the valves. The process you are looking for is called lapping. Valve lapping. It is going to be challenging with such a small valve. Most of the information you will find online about valve lapping has to do with the intake and exhaust valves in internal combustion engine cylinders. I think it can be done with any valve, but like I said it may be hard to do because the valve is so small. I don't know, maybe you cannot do it with a needle valve. Good luck.

pcrussell50

#12: Post by pcrussell50 » Oct 08, 2019, 3:23 pm

I do know that this particular needle is not terribly "needly". It's thick and blunt. IMHO it's very much worth a try.

I'm surprised it works as well as it does for precise flow control for people (like me) who have done the "Slayer" mod.

-Peter
LMWDP #553

albionbrass

#13: Post by albionbrass » Oct 08, 2019, 4:01 pm

I put the valve back in the machine the other day, but from what I recall, the needle has quite a flat end, so I'm thinking rounding off the edges would be a good place to start. I'm thinking some combination of T-Cut, Brasso, G10 Finishing Compound or fine grade sandpaper. Planning to have a go tomorrow, so if anyone thinks any of those products are a big no-no, shout now :D

pcrussell50

#14: Post by pcrussell50 » Oct 08, 2019, 4:10 pm

I don't know which of those have actual metal cutting abrasives in them :( But valve lapping compound of any brand, does for sure.

-Peter
LMWDP #553

albionbrass

#15: Post by albionbrass » Oct 09, 2019, 9:55 am

Well, success in that it's stopped dripping, for now. I got it down as far as this

Image

but that nut towards the right hand side didn't want to come out. It just got tighter whichever way I turned it, so I couldn't open the valve to access the needle or seat. What I ended up doing, was attaching the knob whilst off the machine, and working it back and forward against the stopping point to try and bed in the needle a bit more. And so far, it's worked.

It may have been possible to do all this without opening the top and taking it off the machine, but it's not a big deal.

If anyone has any tips on how I could open the valve further in order to access the needle, do let me know.

Thanks all

Dave

pcrussell50

#16: Post by pcrussell50 » Oct 09, 2019, 11:51 am

Jake has done it. I'll ping him.

-Peter
LMWDP #553

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Jake_G
Team HB

#17: Post by Jake_G » Oct 09, 2019, 12:01 pm

If I recall correctly, the trick is to loosen the needle from its seat a little as you back that nut out.

Image

You don't want it to be closed or open all the way.

Cheers!

- Jake

albionbrass

#18: Post by albionbrass » Oct 10, 2019, 5:37 am

Thanks Jake. I'd already put it back in the machine unfortunately, and won't get a chance to fiddle about with it for a while, but it's really good to know what to do when I do. I'll run it for a bit to see if the (gentle) brute force re-seating has become more than a short-term solution.

Dave

albionbrass

#19: Post by albionbrass » Oct 11, 2019, 6:37 pm

I tried Jake's suggestion of loosening the needle from the seat, throughout the entire range of movement and the nut just doesn't want to come off. I'm wondering if it hasn't quite been put on straight, as it does start to come away from the body of the valve at a slight angle, before it stops completely. I don't really want to force it in case I strip the thread, then I'd be properly stuffed. So for now, I'll live with doing the knob up tight and stopping the leak that way.