Mr H in Yorkshire

26 minutes ago, Carbon Brush said:

how much UV (invisible but harmful) gets through

As far as I know, no shortwave UV gets through because plastics and ordinary glass absorbs it. Longwave UV is not generally considered to be harmful, not energetic enough to break chemical bonds. PS You are a bit unfair on China, they only make the stuff because we consume, and we make the landfill when we chuck it away.

In view of the typical age group of this forum (I hit 70 on the 25th) I worry what the membership attrition rate has been during the change over! Should there be a roll call?

The diffraction effects would be to die for.

My experiences of North Wales have been more hydrocentric than heliocentric but that is fascinating.

Pyrite is possible but most likely a marcasite nodule (also FeS2 but different crystal system), the radiating crystal structure is typical. 

What a great thing to happen, and what an ingenious double f ratio design in the first place. Did your wealthy client make much use of it do you know? I only ask because it looks unused.

@Albir phil Glad to heat that. It fulfils my specific design ideas, including lightweight / portable. As Peter says about heartbeat, it is detectable but not unacceptable due to the low magnification. It would need a different design for anything higher. I have some ideas to eliminate the problem in my next project - a 'double' seat, the inner one suspended from the outer, and deep pneumatic cushioning for a start.

@Coco @Paz @DirkSteele

Thanks all for those very appreciative comments, I'm a bit surprised by the sudden recent interest.

I'm actually working on a trailer based successor to the fold-up lightweight version, and I had hoped to have some stuff to post but I'm having some problems with the az drive, so may be a while yet. As my wife says, this is about the journey, so what if the path is long!

Yes I have experienced that too, the brain definitely interprets that rolling effect as several too many.

2 hours ago, Steve Ward said:

Why was 10 chosen as the base?

Might that have something to do with our hands, though in the higher Dale up from my town I'm sure there's a bit of sheep DNA mixed in so maybe binary comes naturally to some up there.

To continue the derailed thread, I asked at my Butcher's far a 1/2lb of ham, the lad looked at me and said he didn't know what that meant. As he was young I assumed he had been through school in Metric, so I said so many grams. He looked blank, said he didn't know what that means and could I show him, so a quick thickness gesture (me not him?) and it was sorted. He's not the brightest but he played with our son at school so all is forgiven.

To be clear, do you mean 2.5mm on one end and 6mm on the other of the connector?

9 hours ago, Graeme said:

Gloves have been mandatory PPE for a number of years now.

The other benefit I find is that so often I'm using glues of one kind or another, or liquids with dark coloration. I used to happily bath in white spirit afterwards but now I let the gloves take the hit.

22 minutes ago, Graeme said:

That's sound advice Mr H

I meant something tougher than nitrile actually, mine are cotton with a rubber? palm/fingers. They are surprisingly sensitive so you can pick up really small items but they have saved me from several nasty cuts/abrasions

On 29/04/2023 at 08:25, mikeDnight said:

who couldn't wrestle me into submission within 60 seconds

Just where did your encounter these lady astronomers, in a ring?

22 hours ago, Graeme said:

every nick and scratch keeps bleeding!

I wear work gloves regularly these days, even two pairs on occasions. I used to tough it out, you know using my hands to remove rough wood edges! Not any more.

Can you ease something like a small screwdriver in between the bearing and knob and gradually tighten it in, avoiding misalignment as best you can?

That looks like a tiresome job, you will have to dismantle the scope till you can press the bearing (it's most likely brass) back into its housing socket. You must be careful about alignment before applying any pressure, I would use a good G-clamp probably as bearing presses are not common. Another possibility is if you back off the plastic knob you may be able to insert something behind the brass bearing and then tighten the knob bit by bit. By something I mean a thick washer with a bit cut out to fit over the spindle.

46 minutes ago, malc-c said:

stop rodents getting through.

Mice can get through a 10mm gap. Might I suggest stuffing stainless steel wire wool down all the gaps, I had a problem with plastic water pipes getting gnawed and stuffed every hole I could find, no problem since. The material I used was for pot cleaning, be careful if you do use it, wear gloves because a single thread will slice through your fingers if pulled on.

Thermowood - is that heat treated to make it inedible to insects etc? That build is a serious bit of woodwork and construction.

More of a wee dram than a bumper, but worth trying. As a retired ex-scientist, 20 years Mineralogy, 20 years Forensic Science, I am still just as curious and I still have 'Wow look at that moments'. One thing that disappoints me - I won't be around to read of the amazing discoveries of the next century or two, but I suppose Galileo, Newton etc felt the same, so who am I to complain.

13 minutes ago, Mark2022 said:

Yes, if there were an alternative but there isn't.

I obviously didn't express my thoughts well enough. I meant before you made the observatory shed and the false floor etc, test the inherent stability of the deck level that will hold the scope.

Before investing time, effort and money in the whole project, would it help to do a test run to see if the idea is even likely to yield a positive result? Use some slabs, a tripod sandbagged a bit say, and attempt a photograph. See what the results are.

Not sure about your pier but I had a similar flexing problem which I dealt with by shoving two removable props under a pair of joists in the centre of garage. If I wanted to house the car I just took out the props. Simple woodwork is all that's required, or a couple of scaffold poles. Merely loading the roof will deflect it but can't see how that will stop it being bouncy. From your post I can't tell if you can even put props direct to joists so I may be talking out of my Piers Morgan!

PS You might have planners on your back by putting something on top of the existing garage roof, just a warning.

Hope it works out for you, but don't rely on it, if a funny cat story or the likes turns up you might get relegated. I speak from distant experience from a whole weeks filming at the Natural History Museum - then nothing.