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4mm (M4) Grub screw required

Andrew*

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Andrew*

Andrew*

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I am trying to figure out a way to squeeze out some back-focus for my Speers-WALER eyepiece on my 16" dob. Using the standard 1.25"-2" adaptor (which has about 12mm profile) it doesn't come to focus. Another adaptor (with only 2mm profile) has the set-screw on the 2" barrel, and is designed to be used with focusers/extenders with a little cut out to allow the set screw to be accessed. I can use this other adaptor exclusively for this eyepiece if I used a grub screw in the M4 thread instead of the thumb screw. Get me?

So basically, I require a 4mm (M4, I assume) grub screw with a hex bolt "head", preferably with a non-marring tip such as delrin.

Anyone happen to have one or know where to get one?

Or any other ideas on how to get more back focus on a newt?

cheers

Andrew

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Andrew*

Andrew*

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Could you adjust your main mirror to have it further up the ota?

Had to do that to get my camera in focus or are you a fair bit away from getting it in focus?

Hi S5, Yes, I have pushed the mirror as far up as I reasonably can.

I have found 'ONE' 4mm Allen grub screw! It is 5.5mm long and takes a 2mm Allen key

That sounds fantastic! I only need one, and 5.5mm is more than long enough. I'll PM you. :hello2:

Cheers

Andrew

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Psychobilly

Psychobilly

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Oops :oops: :oops: knew I should have checked in Zeus before making such a ... :withstupid:

Yep Sorry M4 is 0.7 pitch which ties in with your pic 5 threads in 3.5mm

Billy...

8-32 UNC would be too big as its 4.17 diameter with 0.79mm pitch

6-32 UNC would be too small as its 3.5mm again with 0.79mm pitch...

To get 0.63mm pitch you would need a x-40 thread

Goldilocks and the three bears of screws...

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DIYASTRO

DIYASTRO

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If you have a look you will see that they do sell metric grubs etc. Admit link title is missleading.

As for BA they are wonderfull! Good pitch available in 0-10ba from lots of places and fit good quality older equipment. They have proved very valuable to me when converting webcams for long exposure and fitting peltier heat elements. I tend to use BA in most of my constructive 'inventions'!

Boyd

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Andrew*

Andrew*

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Well thats the end to this thread........ :p:hello2:

:D

Not quite: On the same theme, I have realised that my adaptor is actually more like 5mm in profile. I could have the "lip" shaved down to 1 or 2mm. However, I don't have any tools to do this. Could a local firm do it for me and would they charge for it?

Andrew

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saturn5

saturn5

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Its times like these i'm glad i'm a turner to trade,if i need something then i can make it myself or adapt something to make it work and all for free,if its electrical or instrumentation however,then i'm a complete doughnut :withstupid: :hello2:

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Psychobilly

Psychobilly

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Its times like these i'm glad i'm a turner to trade,if i need something then i can make it myself or adapt something to make it work and all for free,if its electrical or instrumentation however,then i'm a complete doughnut :withstupid: :hello2:

Oh yes its great to be able to make mod things...especially in this hobby...fairly handy with a soldering iron as well.... :p

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PhillyDee

PhillyDee

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Its times like these i'm glad i'm a turner to trade,if i need something then i can make it myself or adapt something to make it work and all for free,if its electrical or instrumentation however,then i'm a complete doughnut :withstupid: :hello2:

Heh, me too . . . Except im pretty good with anything electric/electronic too and pcs. Keep meaning to make some dovetails on the milling machine . . . Just need some Ali.

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saturn5

saturn5

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I'm in the process of making a dob mount,was milling the aluminium base

on the cnc mill when a drive went and the motor started to produce lightning :hello2: So come on up and fix my drive. :p Seroiusly,i think its going to somewhere in Worcestershire to redo the drive panel,one big mass of electrical bits and bobs.It does something with the electricity to the motor but stopped doing so which caused the lightning in the motor,thats as technical as i get with electric tricity :D

More important....are you getting it sorted out Andrew?

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