Member postings for Brian Oldford

IIRC LBSC's tender hand pumps tended to rely on nothing more that a few turns of graphite rope in a groove near the inner end of the ram. Simple but effective.

A risk associated with the casting of brass is the possibility of over-heating the melt and evaporating the zinc content. Even as a semi-retired pattern-maker it took me quite some time to find a non-ferrous foundry that would take on small volumes. Please feel free to PM me.

Brian

With small stuff that's OK but doing that with larger stuff creates dimensional errors due to shrinkage between solidus and ambient.

Looking at the unseen face the originals definitely look sand cast. Everyday stuff.

[grouse mode] IIRC they did something similar a year or so back at one of the Llangollen Railway's galas. Great fun, great showmanship but of little practicle benefit.[/grouse mode]

As a patternmaker I find no shortage of brass foundries. I'm always geting small runs of broadly similar bits cast. Once  polished they'd be virtually indistinguishable from the originals. PM me if it helps.

Edited By Brian Oldford on 16/05/2019 08:18:02

Edited By Brian Oldford on 16/05/2019 08:18:58

How many do you need to make?

Without knowing the full facts I think it wrong to be overly critical.

From personal experience I know well meaning companies have donated life expired machines to heritage railways.

If you have a lathe without a screw-on chuck try using an inverted tool and run the machine backwards. Or if it has a screw-on chuck use the tool in a rear tool post. The chips tend to be directed downwards and far less carbon/iron dust gets into the air.

Not silent from the top diving board.

More recent info on these boards here. **LINK**

Duncan

Is the 5v derived directly or from the higher voltage supply?

"Easyouts". . . . . .Invention of Satan.

There's a well documented issue with these inexpensive stepper driver boards., The fact is the designers of those boards did not follow the recommendations set by Toshiba for the power-up and power-down sequence.
There are other minor design faults but this is the one that can lead to total TB6560 failure.

In simple terms the logic (5v) supply onto the IC should be established and stable before the stepper drive voltage is applied to it and should be maintained until the stepper drive voltage is removed . These boards derive the logic voltage from the higher voltage via a 7805 (or similar) making this impossible as supplied.

There are mods that can be done to overcome this problem but they involve cutting of PCB tracks and the construction of a delay module.

The solution to the issue may be to hand by using spare pins of the Arduino, a MOSFET and a few more lines of code.

In depth discussion here. https://www.cnczone.com/forums/stepper-motors-drives/139306-can-tb6560-driver-design-violate-chips-specs.html

Good luck

Edited By Brian Oldford on 15/04/2019 16:08:56

You could use something removed from these perhaps? **LINK** 

Edited By Brian Oldford on 14/04/2019 11:30:50

Grind a groove and use a miniature circlip or similar.

As a complete aside, please can someone tell me why most horologists seem to use the cycloidal tooth form yet mechanical engineers mainly use the involute form? There's bound to be a simple reason.

That's the "putting on" direction.

There might some pearls of wisdom on the degree of temper here.

**LINK**

I'd bin it anyway. I can never get a good finish from non-drip paints.