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Member postings for john carruthers

Here is a list of all the postings john carruthers has made in our forums. Click on a thread name to jump to the thread.

Thread: Microscope rack and pinion
23/03/2018 08:32:43

mic pinion done.jpg

I had to repair one of Flemming's brass microscopes with just this problem.
It was a straight cut rack and the pinion had lost 3 teeth.
I managed to build up the 12 tooth steel pinion with a tiny welding electrode, skimmed it true, then ground a profile tool to cut the teeth with the lathe as a shaper.

fleming microscope (2).jpg

Edited By john carruthers on 23/03/2018 08:33:48

Thread: Trouble finding brass H and I columbs and beams
23/03/2018 08:16:45

Try a glazing supplier, we used a lot of brass H and U for stained glass, as an alternative to lead cambs.

Thread: Telescope Laser Collimator
12/03/2018 07:59:33

Only 3 !!?
cheeky

I just gave a 12" Newt/Cas Fullerscope and an 8" SCT to Monkton Observatory, still have a shed full to take with me to Wales.
I should thin them out a bit more, but it's like choosing which child to leave behind .

Thread: Recommended blow torch?
11/03/2018 08:12:32

+1 for the Superfire 2.
I was kindly given a torch with several spare canisters of MAPP and propane.
It has done everything I need.

Thread: Repacking water gauge cocks
11/03/2018 08:01:45

I have used plumbers hemp and non emulsifying grease for glands. (less than £1)
Or ramin fibre, as used for bow strings, can be used but the mica tends to wear the faces.
**LINK**


Thread: Telescope Laser Collimator
11/03/2018 07:50:49

Telescope collimation, a can of worms with various opinions.
Do you Barlow it Neil?

I find it is possible to get a single laser spot to return to the origin but take a circuitous route so still be slightly off.

I get it as close as I can then use a star as the final arbiter.

09/03/2018 08:25:43

Very nice Neil.
I use 'keyring' red lasers for collimation. They fit in a 1.25" hoover tube with a few holes tapped round.
The green pointer in a 2" tube I reserve for the big refractors like Greenwich.
A mirror on the wall brings the spot back where you can see it and doubles the effective distance

Edited By john carruthers on 09/03/2018 08:26:15

Thread: Barometer help please
04/03/2018 09:15:07

When I worked at the local glass works I had to do dozens for local dealers .
Check the thickness, modern 4mm float is the usual substitute but they can be from polished plate or even drawn sheet.
You will eed;
A circle cutter (can be done freehand if you are good
A '0000' alox wheel, running in water to polish the edge and bevel. (glazier speak, polish = grind)
A cork wheel or rubber & pumice wheel to buff said bevel. (can be done on a linisher running wet with a cork faced belt)
A spear point drill to drill the centre hole to fit the needle.
Slowly grind the circumference and bevel until it is a 'click' fit in the bezel, if you over cook it, start again
If the needle is a bit floppy when finished a turn or two of silk will take up the slack. Some centres have a cork washer, but 100 year old cork washers are not very robust.

Thread: Bandsaw woes
21/02/2018 08:31:05

I used 2 layers of cycle inner tube to get my old saw running.
I put a slight crown on the wheel first to keep the blade running true.

Thread: What did you do Today 2018
14/02/2018 18:52:24
>That's a mighty serious looking camera! Any details for AP nerds?<

It's an SBIG STXL-6303E
FW-8G filter wheel and AO-X adaptive optics fitted to an LX2oo 16" at the remote operating obs at Monkton Nature reserve. (the smaller white dome).

**LINK**


 

Edited By john carruthers on 14/02/2018 18:52:56

Edited By john carruthers on 14/02/2018 18:54:35

13/02/2018 08:29:10

Sunday I unpacked the lathe and a few tools to do one last 'just job' before we move.
A mate bought a camera for his scope, the guys in the states got the adapter wrong so it wouldn't fit.
Bored out the adapter to 3.5"
Now packing tools away again.


monkton camera.jpg

Thread: Blue steel screws
06/02/2018 08:19:24

don't step on them

Thread: Seig sc3 'ticking over'?
01/02/2018 18:50:37

Thanks everyone, puts my mind at rest.
I always hit the stop switch before handing the work or chuck.
I shall get a sparky mate to check it over.

01/02/2018 08:30:32

My sc3 mini lathe has started trying to creep round when the speed pot is at zero.
Not really spinning, just trying to, and not all the time.
Anyone else found this?

Thread: Oiled hardboard.
01/02/2018 08:27:04

Old conveyor belt makes a superb work top and shed floor covering, (doesn't like hot weld spatter)

Thread: Hi from South Wales
23/01/2018 07:22:03

Hello Nigel and welcome. I am looking at buying a place near Port talbot.
I will have to build a decent shed/shop too.

John.

Thread: Ten Useful Things
16/01/2018 08:04:52

Eleven, eleven useful things, Blue Tac. wink

Among our useful things are.........

Edited By john carruthers on 16/01/2018 08:06:53

Thread: What did you do Today 2018
04/01/2018 08:51:31

Speak not of Sinclair, grrr.
I spent several summers picking black currants to fund the purchase of some Sinclair hi-fi modules, none of which ever worked.
I assembled them as per the instructions, even had a sparks check it over for me, nothing...

Decades later I mentioned it to Clive at a mensa dinner, no reply

03/01/2018 08:03:24

Yesterday I did the first little job of the year, a thrust washer in brass, 77mm ID, 103mm OD, 1.1mm thick to go on the bottom end of a mate's polar axis shaft....
polar shaft assembled.jpg

Thread: Recommended lathe outside protection?
20/12/2017 08:04:09

In tropical humid conditions we used RIG (rust inhibiting grease) on weapons and vehicles, good thick tacky jollop that lasts ages. Try a local shooting supplier.

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