what are you doing ?

[pre65]

James, if it helps I have a hardwood disc 327 mm dia and 30mm thick. One side is flat and smooth, the other is less so but quite reasonable. There are no splits or cracks.

If you think it might be of use I can send it.

[JamesD]

Philip - Thanks for the offer but I have a laminated design in mind - laminated both vertically and horizontally. A checker board of different hardwoods horizontally on the top and layers of different materials vertically - so its going to be rather difficult to build and turn... I'm tempted to go for a polygon shape rather than circular with a thin round perspex disk on top of the hardwoods layer

Ant - Thanks for the offer - I may take you up on that later - I've got quite some way to go with thinking it through before I start building anything...

Mark - Neat idea and I regularly walk past my local garage... I had imagined using x and y strain gauges attached to a temporary spindle and measuring the wobble with a Lissajous on the oscilloscope as it turns - needs more work but might suffice... Of course I need to build a proper stable work surface to build and then measure it on...

Too many ideas and too little time - and I'm so slow at building stuff now-a-days... but I do love it

[jack]

Interesting thought, building your own balancer... Please excuse me while my mind runs away with this !

I would keep it simple - use an optical position encoder on the drive shaft and a 3-axis accelerometer on the bearing. Using slow motor (100 RPM or so) correlate rotation with accelerometer output using an Arduino or similar and store data in ram/eeprom - maybe just 60 points, i.e. every 6 degrees (all depends on encoder resolution) and just average out each value over a load of revolutions. Simple 2x16 LCD display. Then in playback mode, you can slowly rotate the platter by hand and adjust balance by drilling holes in the back, or inserting screws or whatever.
If you ran it with no platter in place, you could record the baseline data for the test rig and then just subtract that from the recorded data for a turntable - that would remove a lot of the error introduced by the test rig itself (sort of Heisenberg elimination). Natural resonance of the test rig is relevant too - might be worth trying a range of rpm to find one with low vibration.

Might be an idea to use polycarbonate rather than Perspex (acrylic) for the top, though both will build static like crazy.

Actually, once you've built that, you could offer balancing-as-a-service, complete with a USB stick with the before and after data as an xlsx file !

[Ray P]

Something based on ths technique would look nice;



or if you wan't a more 'coloured' sound;



Maybe the interface with the vinyl could be done by leaving a thin layer of the slow cure epoxy he pours over the stack, it would polish up well and modern resins are clear and resistent to discolouring.

[jack]

The problem is that both those would be a nightmare to balance.

For the crayons, you would need to vacuum impregnate at the very least to remove air pockets.

For the other one, differing wood densities would be a nightmare.

Wood has so many issues, including water content, absorption and loss - it moves. Even different samples of the same wood can behave differently over time.

And then there's woodworm

[ed]

That's such a cute thing that I just ordered one from Banggood. Amazingly cheap for something so powerful & easy to use. I want to play with one!

next question - who is the SIM from?

https://shop.ee.co.uk/preloaded-data-sims

[Ant]

Aha! Andy Philip
he does some utterly beautiful work
The pencil one was I think done using a pressure vessel to force all the air bubbles out of the resin.
The other interesting thing about the resin is that the dyes he uses means that you could cast a platter in resin in whatever colour you wanted.
I dont know wether a cast resin platter would have a uniform density, but I suspect that it would be more uniform than wood. Depends on how good the mix of the 2 parts is I suppose.
The original dual platter does appear to be balanced, there are holes around the periphery, on mine, some have weights in and some don't

[pre65]

I was just going outside to cut the grass, as they forecast thunderstorms at 2PM (66% chance), but the rain has just started.

Still, the ground does need a good soaking.

PS 13:07 first flash of lightning and thunder.

[Ant]

A boring day today
Got plenty done admin wise for work purposes, chasing parts, chasing suppliers and filling in forms for son no 1s new school, although I still have a couple of emails to reply to. That will have to go on the to do list for tomorrow.
I was going to swap the eroica onto the jvc in place of the Hana sl, that didn't get done.
I was also going to see if I could work out cable wise how to reconnect the big lenco and the jbe, that didn't happen either.
The system is so overcomplicated at the moment that things like that are difficult. I need to have a really good think about what to do with it all.
I did receive the soundsmith cart though so I do have that to look forward to when I get around to trying it.
Also connected up the graham slee phono stage, it's pretty nice, it's got the jvc running into it. So that's nice.
So a productive but boring day

[jack]

Bit of an odd day. Nice surprise with a delivery (in Nothing in Particular), but a bitch of a time sorting out why our son's Micra keeps losing power and stalling....

Decided to take out and clean the fuel filter & pump, but they're in the tank...

Took battery out of the car. No power tools, no torches/phones, doors open & outside.

Remove the back seat (2 bolts rear, 2 bolts front), undid the cover plate (3 catches), removed the pump/sender connector, unclipped the fuel pipe.

The lock ring on the pump is a total b******. I cleaned all the grot off it, hoovered out all the debris and tried to budge it. No chance. Note there is a white dot on the chassis and an arrow on the ring indicating how tight it needs to be... Solid. Solid as a rock (I feel a song coming on).

Soaked the joint in WD40. Went and had a cup of tea. And some cake.

Came back after 20 minutes. No change. Lots of ridges on the ring, so got a BIG screwdriver and a medium sized persuader (hammer) and spent the next 30 minutes tapping all round the ring until it eventually started to move. There are only 900 degrees/2.5 turns until it is undone.

Got the filter/pump/sender unit out. Siphoned out the fuel that was left (about 5ltrs). Remaining fuel removed with clean sponge until dry. Then used micro-fibre cloth to clean any remaining specs of crud. Tank now clean.

Allegedly, the filter/pump/sender is not user-serviceable, but there are three catches which can be gently pried off to get to the filter. See attached photos. These were cleaned and rinsed, then reassembled. Note that the filter can be gently removed from the main body of the unit to ease cleaning...

Getting the unit back in was a complete b****. The unit is spring-loaded and must be held down firmly and then the green gasket slipped under the rim - if its allowed to pop up even slightly, the gasket falls into the tank and you start again. And again. And again... Two man job - one person holds the unit down so the gasket stays in place, whilst the other desperately tries to get the lock ring to engage and tighten.

It took us an hour, and we're both professional engineers (not motoring ones, unfortunately). We had to have more tea half way through. And cake.

Put some clean fuel in it. Car now runs smoothly, but not taken it for a full road test yet.

[shane]

Took three calls yesterday from customers whose routers had been killed by lightning strikes. I’m one of about fifty taking similar calls so that’s maybe 150 routers. That’s just EE, and we have about 5% of the UK home broadband market. I’m making a few assumptions here but by any reckoning that’s a lot of dead routers.

[izzy wizzy]

Our router isn't dead but something drops out when it starts to rain but only momentarily and then you're back in business even if it's still raining. If on the PC at the time, which SWMBO is all day working from home, it's a sure way of knowing it's started to rain and get the washing in or whatever.

[pre65]

The signal on our Sky box dropped out a few times yesterday afternoon when it was raining reasonably heavy.

[pre65]

Had another mad moment on the tidy up job. I'm very bad at getting jobs done in one go, always have been. It's just the way I am.

Anyway, I ordered an M4 tapping set yesterday, cos I'd mislaid the set I knew was "somewhere". Well guess what, I've just found them.

The heatsinks I ordered came today (4 + 4) and the 4 biggest ones have had the locating pins removed, and that means 8 M4 holes need to be drilled and tapped. Good job I know where my 3.3mm drills are.

I've even got myself a smallish plastic toolbox to keep my hi-fi tools in.

[jack]

So, just had the first part of the greenhouse electrics signed off... All good. All IP65/66 and stainless fixings... I hate terminating SWA.

Also got confirmation from Keysight/Agilent that I can keep the nice meter they sent me in error. It was really intended for some bloke in Doha.

One big takeaway... Those plugin mains testers are crap at identifying faults. All three lights came on indicating a live/earth swap!!! What had actually happened was that live, neutral and earth were all ok at the greenhouse, but the neutral was still on the CU RCD... Quite dangerous as the moment any power drain happens in the greenhouse, the RCD tripped, disconnecting the neutral BUT NOT THE LIVE! (as the live had been moved to the non-RCD of the CU).

So the tester was showing a fault but completely the wrong one...

I moved the neutral across this morning and all is 100% now...