Maker
Most folk just call me; Orange Joe
- Messages
- 10,633
- Location
- Keeler crater
I've finally had a go at this. I turned a plug to fit inside some 4" stainless tube so I could hold it in a chuck without deforming it, just to get clean, perpendicular ends and a tidy chamfer. The Perforated mesh was cut somewhere close with shears, then hot glued and pressed between two bits of plastic and machined to size, which absolutely ******** my last Seco insert.It turns out I didn't have the material thickness to get the bottle thread on the funnel but I thought it would work without it, the vacuum should pull the gasket tight.
View attachment 356697
View attachment 356698
Unfortunately when I drilled into the side for the vacuum line, the drill bit broke though the bottom, and also through into the middle hole, totally ruining it. I tried wedging bits of PVC tubing into it but couldn't get it to seal.
View attachment 356699
View attachment 356696
I think I'm gonna put it back on the lathe and turn the bottom off so its just a shallow funnel, then cut out another piece of plastic, machine the bottle thread* and drill it for the vacuum fitting, then glue it all together. I also need to find a big O-ring and machine a groove, to seal the stainless pipe to the funnel.
*I want it to fit an ISI cream whipper, the bottle has a 50x3mm trapezoidal thread, I need to grind a tool and remind myself how to cut metric threads on my lathe. I was hoping I could make it work without the thread but there's only gonna be any real force to compress the gasket (The white thing in the last image) when the filter is blocked, it'll be much easier to use if I can just screw it on, it'll save having to hold it in place and I won't have to worry about it sealing.
I spent a while this morning measuring the bottle thread, perhaps a bit big for this microscope, maybe I need to find an optical comparator?
I welded a 1/4" piece of HSS to some steel to save grinding an internal threading tool out from solid, works a treat.
Excellent fit. Turned it round and cut a register on the back face, and a matching step on the back of the funnel, the plan was to epoxy it but it's a solid press fit and air tight, so I probably won't bother.
There's a slight taper on the inside face, I was hoping it would stop liquid clinging to the surface and making it back into the vacuum line, but it didn't quite work, I'll probably just plumb in a trap between the filter and the pump.
Insulation tape because I haven't decided how best to seal the funnel to the pipe yet, probably make a custom O-ring. Finally found a use for these Melita filters, bought them years ago thinking they'd fit a V60.
It's brilliant with water, sucks it through faster than you can pour it, but I put a handful of sand in it and it got blocked. Hopefully once there's a better seal to the pipe it will build up a stronger vacuum and won't get blocked. I'll have to make a batch of coldbrew and test it properly.
I was also surprised at how long the 'temporary' strips of masking tape lasted; I haven't had to replace the tape strips yet, even after sanding about 40 feet of inside plaster board corners, although I suspect the tape strips will probably wear out faster when sanding harder materials such as setting-type plaster, etc.
