Member postings for Tony Jeffree

Rather late in the day coming across this...but my 2 pennorth:

I suspect what you are seeing is an inherent problem with the Hipp toggle - unless everything is precisely aligned, the trigger and notch are perfectly hard and have very sharp edges, there is always the possibility of the trigger "catching" on the edge of the notch rather than in the base of the notch as it is supposed to do. My version of the Wilding 3/4-second pendulum clock has always exhibited this behaviour, and I pretty much gave up on fixing it; the clock keeps good enough time so I ignore it. However, that is one of the reasons that eventually led me to build a pendulum with a similar drive mechanism but which uses Hall-effect sensors to detect the pendulum swing amplitude, which removes the problem altogether - see link. I am tempted to retro-fit a similar solution to the Wilding clock at some point.

I make no claims about how well or badly my clock performs - my intent was to build a pendulum that operated with no direct mechanical contact and the minimum of indirect mechanical interference, and to that end, I have succeeded. As it is currently set up, the clock runs for ~100 seconds between impulses; that interval, and also the choice of arc of swing, can be adjusted to tase by re-positioning the Hall effect sensors, changing the distance between the electromagnet and the pendulum bob, and changing the electromagnet current. With a sifficient supply of round tuits I'm sure all of the potential permutations could be investigated, along with their effect on the clock performance.

However, as John has observed, as the arc of swing is closely controlled, circular error shouldn't itself be a major problem.

Great idea.

Talking of which Neil...do you have an ETA for my most recent scribblings...?

Great posts Andrew!

Just a thought, but you could potentially fix the "house drift" problem by mounting the whole clock on gimbals. You would of course need to add sufficient viscous damping to the gimbal bearings and/or add mass to the structure so the pendulum oscillations themselves don't cause the whole contraption to swing, but it could be done.

Thanks Dave - I will take a look.

Answering my own question here...I've downloaded FreeCAD and so far it seems somewhat simpler to use from the GUI point of view than Fusion 360 - especially since the limits were placed on free use of Fusion - so I am going to persevere with it and see if the initial promise continues.

Has anyone any experience of FreeCAD? Is it any good?

It has been a tad draughty today ...

Skeleton unicyclist

Thanks for all the input everyone. I will probably be going with one of the R-Tech units - a bit pricier than some, but seems to be quite versatile and the online reviews are good.

Thanks - I will take a look.

Any views on inverter vs non-inverter units?

Thanks - that helps. I'm not expecting to go above 6mm steel, but I guess that is pretty much the limit anyway if I am using a 13A plug.

Edited By Tony Jeffree on 06/09/2021 19:08:45

A good point. I do want to be able to weld outside if need be, and that is one reason why the versatility of both gas and gassless would be useful. The other is that, because we live on an island, actually getting supplies of gas (even the disposable bottles) is difficult, as the postal regulations and costs are prohibitive. So re-stocking would only be possible on the rare occasions that we venture onto the mainland.

...because...?

I'm looking for a combo gas/gasless MIG welder that I can run off a 13A plug for light welding jobs. Any recommendations?

Edited By Tony Jeffree on 06/09/2021 15:45:48

He'#s a dead ringer for Dominic Cummings

The scarecrow competition on the Ropss of Mull this year led me to follow up on the "skeleton on a bike" project that was published a few issues back - this time the skeleton has mastered the art of the unicycle. A bit trickier to pivot this one - the whole contraption rotates on a pair of sealed ball races spaced by a piece of scaffolding pole, with seats for the races machined from scrap thick-walled brass tube. Also, because there's no gear reduction between the wheel and the pedals, and the wheel is a lot smaller, this one needs ~20 MPH to get it going. Not much of a limitation in these parts, mind!

Skeleton on a unicycle

I bought a cheap set of metric taps & dies once that was so safe there was absolutely no danger whatever of cutting a thread with them...

...and of course a simple approach that doesn't need the receiver to have any additional intelligence is to measure the transmission latency in your software and adjust what and when you transmit accordingly - the latency should be reasonably constant.