Member postings for Sean Taylor

One of my clients makes these on occasion, but I prefer these as being slightly more practical.

Sean

Looks very nice - mine doesn't need through chucks (I have my big lathe for that), I just need something to fit direct to the shaft of the stepper, which I can quickly clip tubing into and out of. I'll do a drawing nd stick it on a new thread in 'other hobbies'

Sean

Roger - exactly what I'm here for! I'm hoping someone here will be able to help me with some very simple chucks for a pair of steppers - but I need to draw something before I make a proper begging post. For the rest I'm looking at a v-slot assembly similar to a camera slide.
Neil - will do, ta.

Sean

Oops, Neil, I didn't see you post as the thread flipped on me.

Soda glass is much more difficult to work with than borosilicate - doesn't really get used in scientific work any more. Lots of use for 'pretty things' though - beads, marbles, sculpture, etc.

Yep, I'd happily write something for you - some idea of the common requirements for glasswork in model engineering would be useful, I have no idea how much detail you would need!

Sean

I seem to remember reading somewhere that it took many, many attempts to get a good cylinder/piston fit and arrangement - given the other challenges I see in this piece, I can well understand the price.
If people are interested, I'll happily post some videos and links around the subject of lampwork (that is, both scientific and artistic glasswork made at a bench or lathe), perhaps under a more appropriate heading? It's not really model engineering, so not exactly relevant, but I'm always keen to spread the word, as it were... what do you think?

Sean

Yeah, I've often looked at that video, and weighed my chances....
One day.

Sadly, I doubt they'd be worth anything - and you might even be charged for safe disposal! But yes, very interesting, even though not as jazzy as that rectifier thingy - that's a bit of a beast...

Hi Dave,

Yes, those will definitely be handmade - they look pretty 'historic' - certainly not something we would need to make these days. Very neat design, though! They will have been calibrated by repeatedly timing the return loop flow, and constricting a bit by warming the loop at the midpoint. Plainly part of a tip-delay circuit of some sort, but no idea whatsoever what it might be. Very interesting!

Sean

Mick, that would have been Gayle, I think - she had a spot on the One Show, I think it was. There are not many scientific glassblowers in the UK, so we pretty much know, or at least know of, each other, via the British Society of Scientific Glassblowers. They have a website, which I administer, at bssg.co.uk

Don't know about old glass - the thing about glass flowing isn't true, though, I'm afraid. Old window glass was made by dipping from a furnace and spinning out on the end of an iron - the windows were cut radially from the disc, which was thicker at the centre than the edges. Glaziers wisely put the thicker, heavier part at the bottom of the window.

The score in the glass is edged with microfractures which quite rapidly close and 'heal' if left open to the air. Wetting prevents this closure, and allows thermal expansion to complete the cut. I have found that scoring with a wet glass knife makes for an easier cut than scoring dry and wetting immediately afterward - so I suspect this 'healing' effect can be very quick.
There's a wee tutorial with pics Here, which shows several cutting methods. It suggests using a file; don't, it makes a horrid wide graze as opposed to a score line, unless very sharp. Glass knives are expensive and hard to come by, but B&Q sell a very cheap hand-held tile cutter with a very short, square-section carbide blade which I have used successfully many times (because I am, at heart, a miserly skinflint).

HTH,

Sean

Thanks George,

If you do a google image search for 'scientific glassblower' you'll see the kind of work I do - although most of those guys are a lot more experienced than me!

Sean

Hi all,
I'm new here, and have been browsing, and I noticed a few posts on the subject of cutting glass tubing. This is how it's done by glassblowers:

• Score with tungsten carbide, or diamond - the score should be on the line of cut, and min. 1/8 circumference - longer is better
• wet score with water (saliva works fine) to prevent 'healing'
• touch small, hot end of glass rod to one end of score
• wait, applying light pressure. the score will crack and run around the tube
• if tubing doesn't separate on its own, apply axial tension, with very slight bend away from crack (in the 'opening' sense)
• Voila! The cut edge will need grinding/fire polishing to finish.

Small diameters (up to about 10 - 12mm) can be cut by scoring and pull/bending, without the need for heat, as long as they are long enough to get a good grip. Otherwise, heat is normally applied to the score by heating the end of a small dia. glass rod to molten and white-hot (oxy/propane, although for very small dia. rod, propane alone will get there) and transferring quickly to one end of the score line. Soldering irons aren't hot enough, I wouldn't think, neither burning meths, although a petroleum lighter fluid might be worth a try. Also worth trying would be a small blowtorch - larger dia. tubing is often cut using a long score and a very small oxy/propane flame while the work is rotated in a glass lathe.

Hope this is of some use - happy to answer questions if you have 'em.

Sean

(Glassblower, of sorts.)

Hi all, my name's sean, and I'm a scientific glassblower, not a model engineer. I'm here to ask for a favour, but more about that elsewhere. Meanwhile, if anyone needs small, fiddly glass stuff, give me a shout

Sean