Diving in a SM40 for modification

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DSobserver
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Diving in a SM40 for modification

Post by DSobserver »

After Mark advices and Joe (Vanter) help, here a summarize how to upgrade a SM40 double stack with a PST in my case.

The idea is to remove the front ERF glass not needed for DS.

Here the starting point

First difficulty was to remove Tmax ring that in my case fixed with glue that I manage with a collegue to unscrew it after many tries :evil:


Next step is to unscrew the brass blocked with a 0,9mm allen stud (not 0,7, not 1!)




After, as said by mark :"You will see a small hole that is filled with black silicone seal. Pick this out with a needle [strike](this is the most time consuming bit!)[/strike], when you do this it reveals a really small allen stud - maybe 0.7mm. This is a retaining screw. Loosen this off, you do not need to completely remove as is a pain to get back in! Now, make sure you are doing this on a table or bench etc... Hold the knurled black ring at the base of the unit in one hand and the brass in the other and carefully unscrew. This will reveal the etalon that is housed inside - Be ridiculously carefull with this! Then look inside the brass housing and you will see the ERF is held in place with a reatining ring"


As you can see in next picture, in my case the reatining ring was blocked with a type of epoxy glue making impossible to unscrew it as in my SM40 the ERF glass is tilt


Using this handmade tool

I manage to unscrew all the reatining rings :blink:


thanks to joe advice, using a burning blade I could melt and remove this epoxy and unscrew everything :silly:

Last picture from fabry perrot before to screw everything together again


and that's it!


Last step is to protect again from dust the optic. For the moment I only order an adapter ring for our 2" filters
[ebay]200714881984[/ebay]

The question is which one? a simple red filter, an IR cut, a skyglow one bit more selective or a Ha one? any advice?

I think that an IR would be interesting as I will replace the mini ERF with a KG5 that I think will be good enough once stacked with the front baader IR cut, don't you think?

Optically I couldn't saw from the moment a huge difference in brightness but yes a slight improvement in faint details

Hope this help you guys! B)


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swisswalter
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Re: Diving in a SM40 for modification

Post by swisswalter »

Hi Francois

great job :bow: I like your hand made tool ;)


Only stardust in the wind, some fine and some less fine scopes, filters and adapters as well. Switzerland 47 N, 9 E, in the heart of EUROPE :)

from 7 am - 7 pm http://www.nanosys.ch

from 7.01 pm - 6.59 am http://www.wastronomiko.com some times vice versa ;)
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Re: Diving in a SM40 for modification

Post by DSobserver »

Hi Francois


My name is vincent.... ;) still not available for our 1st of may party?


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Re: Diving in a SM40 for modification

Post by marktownley »

A result! Excellent! B)


Image
http://brierleyhillsolar.blogspot.co.uk/
Solar images, a collection of all the most up to date live solar data on the web, imaging & processing tutorials - please take a look!
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Re: Diving in a SM40 for modification

Post by colinsk »

I love the home made pin spanner! I will have to make one myself.


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Re: Diving in a SM40 for modification

Post by swisswalter »

Hi vincent


thank you


Only stardust in the wind, some fine and some less fine scopes, filters and adapters as well. Switzerland 47 N, 9 E, in the heart of EUROPE :)

from 7 am - 7 pm http://www.nanosys.ch

from 7.01 pm - 6.59 am http://www.wastronomiko.com some times vice versa ;)
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