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Peter, Laboratories use a magnet in a ceramic case - driven remotely by a further motorized magnet under the beaker - maybe a lash-up ? Correct - you don't want to entrain bubbles. The anode is obviously sacrificial but you can use heavy gauge copper wire quite liberally - I don't...

Peter, Looking great thus far - learning curves are a sod. Re previous comments on thief rings etc. You want to have a uniform current (amperes per square inch) all over by provision of anodes and "thief" cathodes. Alas practice is invariably a compromise on theory (AKA just not...

Hi Pat, Just for future reference - here's how I managed to cut glass disks for a Mendocino motor. I needed to make a couple of 30mm diameter glass disks for the end stops. All attempts with a diamond coated hole saw resulted in disks that could be done better by a Neolithic flint knapper...

K2, I agree with you on most points. You do not want the displacer to convey heat to the cold side - only to displace the hot air - the clearance obviously is a double whammy in that a smaller clearance will mean more energy lost to compressing the hot side and squeezing it through the annulus...

K2 - Refer my diagram post #8 I used 2mm diameter Viton "O" rings in a gap of 1.95mm - not much interference at all - the amount of force required to keep the tube in place is negligible. Using standard interference can make assembly somewhat difficult. Jonkman's original assembly instructions...

Can't really say - I've seen square ended displacers so yes it's probably more an aesthetic thing. I don't see any point in adding anything to the displacer - all it does is (mostly) move the air about - null mass and thermal capacity would be optimum therefore unobtainium would probably do the...

And then you find you need a fixture to make the tooling to make the part. Arrrrgggghhhh ! Sympathies - been there - done that. Regards, Ken

There are huge problems in gearing down from ultra high rpm's. Any kind of belt or chain drive can't handle the pitch circle velocities or centrifugal forces. Gear drives also cannot handle the pitch circle velocities without special consideration to lubrication. Lubrication and cooling for high...

Not bad for a first attempt - I haven't printed PLA only ABS and I normally "glaze" it in Acetone vapor - I once tired dunking - total failure as the porosity (and voids) in the print simply filled up with Acetone and proceeded to dissolve the part from the inside. You are probably going to have...

In a curiously related incident - I was having a foundation slab cast for a very large Chrome plating system - it had a number of PVC tubes set through it and also through the wooden box form. As soon as the concrete pour was hit with vibrators, the buoyancy lifted the box form - concrete...

Pete, Thanks for the progress report and the link - a useful resource. Looking good so far..... Regards, Ken

While fooling around with cylinder head design you also need to consider what the variables are related to fuel, octane ratings and a whole bunch of other stuff that might otherwise thwart your plans and damage your engine - link to an article I have posted previously which is germaine to this...

Here's a "Small Engine Dyno" that I built years ago and is still working - built as a "Rolling Road" braked dyno for testing slotcars and is capable of measuring from 0 to 300W output. I started with the idea of using a DC motor as a generator and loading its output - using motor parts...

I like to design or un-hand a design so that it is ambidexterous - like this laser cut part of a more complex welded assembly. The castellations fit into other laser cut parts for welding. The large hole is for a cable access - the "red" hole is redundant to unhand the part otherwise some dolt...

There are several tube bending tips and devices on the site - conduct a search. Here's mine - note bending of 1/8" NOS lines. Wire & Tube Bender The ACAD plans are available as a Zip file here :- https://www.homemodelenginemachinist.com/threads/wire-tube-bender.29079/ Regards, Ken

Doug - Spot on - lefties live in a right handed world and have to learn to cope. I began on an old fashioned drafting machine - it never even crossed my mind that working with my arms crossed was "wrong" - years later I was given a reversible drafting machine - I set it up left-handed and found...

Bob - slightly off topic - but you did say that statistics was your middle name. I once visited Fichtel & Sachs and queried a Vickers microhardness check which they had placed on a report as 1052.1 - I said that such accuracy wasn't possible. Turns out I was wrong - they calibrated each and...

Bob, This is the way I use a telescopic gauge :- Insert it deliberately skew and very lightly nip it up - then tilt it into alignment (going to be a bit more difficult with your "bent" gauge) - the telescope will collapse - when you feel it is a good fit - tighten more solidly. Re-check the fit...

Here's a video of spin casting. So you can see why a helical pattern can be formed. Normally used for hollow bar but solid is also doable :- Regards, Ken

I think you will find that defect is a continuous corkscrew and no slice will be free of it. Steelworks typically re-melt all scrap - they buy scrap - they don't sell it - but that doesn't stop them producing rubbish. I don't believe it is continuous cast - those longitudinal striations are from...