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M31 with Redcat 51

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Posts Made By: Craig Colvin

November 28, 2003 05:30 AM Forum: Equipment Talk

What type of finish?

Posted By Craig Colvin
Thanks for all the great replies! I've learned alot from this thread and have some ideas now on what I've been doing wrong.

I'll post the results when I'm done.

February 29, 2004 01:24 AM Forum: Telescope Making

Accuracy of f-ratio on Discovery mirrors

Posted By Craig Colvin
My 8" Discovery mirror had the focal length written on the back of the mirror with black marker. It wasn't exact but I don't recall how far off it was.

March 6, 2004 04:25 AM Forum: Telescope Making

Specialty Tools for TM'ing, Part I

Posted By Craig Colvin
I have one more tool that I made for my most recent scope. I was very concerned about balancing the final scope. So instead of calculating the the COG I decided to measure it. I built the following jig to try out various positions for the altitude bearings. I use roller blade bearings the altitude bearings rest on. This gives me a lot less friction than the final rocker box design so if I can acheive balance with this jig then I should have no problem with the final design. This theory has yet to be tested as I haven't built the rocker box yet.

March 6, 2004 04:54 PM Forum: Telescope Making

Upper cage clamping problems

Posted By Craig Colvin
Seems to me it is just mounted backwards. If the semi-circle mounting plate was turned around then it couldn't rotate.

It wouldn't work for the scope in your example because the truss poles get in the way, but if the truss poles were on the outside you could attach it either way without detaching the truss poles from the mounting plate. Would just depend on how you flipped the poles during setup. Seems like it would be easy to setup the wrong way if you weren't careful.

March 9, 2004 11:48 PM Forum: Telescope Making

question about fully racked in focuser height

Posted By Craig Colvin
you should use 3

However if I were in your situation I'd probably mount the focuser out 1/4", either by adding 1/4" of wood to the outside of the focuser board or using other spacers. This assumes that in doing so you don't have any vinetting problems or have to bump up to the next larger size of secondary.


March 15, 2004 04:41 AM Forum: Telescope Making

First light 8" String Scope

Posted By Craig Colvin
A couple more pics

March 21, 2004 05:45 PM Forum: Telescope Making

Ebony Star Question

Posted By Craig Colvin
That's strange, I've never had a problem gluing ebony star. Perhaps it's the type of glue you are using. I've always used Titebond II wood glue (available at Home Depot) for all my gluing and it works great.

I've also never really had a problem with ebony star being that stiff. It shouldn't be cracking when you bend it.

March 21, 2004 05:48 PM Forum: Telescope Making

My version of the Turret Telescope

Posted By Craig Colvin
That's very interesting but I have one question. Why?


What's the advantage of a scope like this over a standard newtonian design?

March 23, 2004 06:27 AM Forum: Telescope Making

Are shrouds unavoidable?

Posted By Craig Colvin
I'm not sure you could baffle enough at the focuser or with a filter slide without adversely affecting the light path from the primary.

BTW what did you use to create that drawing? It's very nice.

June 15, 2004 03:04 PM Forum: Telescope Making

First (second) Light?

Posted By Craig Colvin
A couple more pics

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