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Astro-Physics Focuser

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#1 bremms

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Posted 21 February 2013 - 03:05 PM

Just picked up a used greasy AP focuser. MAN! I forgot how nice these are. This beauty will go on my 6" F12 D&G when the lens is finished.

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#2 plyscope

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Posted 21 February 2013 - 04:04 PM

Nice! I have a similar second hand one on my home built D & G 6" f15.

#3 bremms

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Posted 21 February 2013 - 07:27 PM

I was going to put it on my 5" F12 D&G, but I modded the old 2" Japanese made unit, and took out all the play. The D&G is sooo nice though

#4 bremms

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Posted 21 February 2013 - 07:29 PM

I was going to put it on my 5" F12 D&G, but I modded the old 2" Japanese made unit, and took out all the play. The AP focuser is sooo nice though. Now I can build the OTA for the 6" F12.

#5 StarStuff1

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Posted 22 February 2013 - 05:55 AM

Even though I have had very little use with that AP focuser I remember from those few times at star parties that they were robust and smooth. From your pic it screams to me "Larger focuser knobs!" :D

#6 bremms

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Posted 22 February 2013 - 07:37 AM

I was kind of thinking about larger knobs. Those are so nice. They are pretty big but look small next to that beast.

#7 Jim Curry

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Posted 22 February 2013 - 07:24 PM

Yes, the stock knobs are kinda wimpy. These focusers look much better with a 3" knob. Here's a 4" refractor, 5" tube.

Jim

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#8 Jim Curry

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Posted 22 February 2013 - 07:29 PM

Here's a 6" refractor, 7" tube.
Jim

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#9 Happy-Idiot

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Posted 22 February 2013 - 07:50 PM

Jim,

Did you make those on a Mill and lathe? Very nice!

#10 Jim Curry

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Posted 22 February 2013 - 10:13 PM

Brian,
You nailed it.

Jim

#11 bremms

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Posted 22 February 2013 - 10:17 PM

I have knob envy. :rimshot:

#12 Happy-Idiot

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Posted 23 February 2013 - 08:39 AM

Marc, I had a AP focuser that I wanted to use on a 6" ATM but I had one with internal threads. Great focuser but impossible for a lightweight like me to mount it. Im guessing you bought the D&G focuser plate for your external thread focuser? Sadly I ended up having to sell my AP focuser and ended up using an old D&G focuser(much easier to adapt to the OTA tube size), I am happy with it but would rather of had the AP like yours. :bow:

Jim, I love the knobs, maybe a tutorial/recipe post on how you made them(tooling and steps)would make for a incredible post for the amateur cellar machinist like me. HINT HINT ;) Also don't forget to post a picture of those incredible knobs HERE.

#13 Jim Curry

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Posted 23 February 2013 - 08:51 AM

Brian:

Great idea about the thread. Let me pdf some drawings for attachments and I'll see what I can do this weekend.

In the meantime, here's a lineup for ya'....

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#14 bremms

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Posted 23 February 2013 - 10:51 AM

Mine is the threaded version. I will either machine a plate with threads at work or just get the plate from D&G. I may use a 6" tube with a reducer. I have some nice 6061 6"tube. Iwas going to put it on my 5" D&G but I got the old one working really well. It has the Japanese made focuser he used in th early 90s. It's nice because it keeps the weight down on the 5".

#15 bremms

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Posted 23 February 2013 - 11:02 AM

Weight was a concern. The 5 " D&G is on the edge for the GP mount and my home built 1.5 " shaft is not very far along. The extra 5 lbs of the AP would be too much for the Vixen mount.

#16 Happy-Idiot

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Posted 23 February 2013 - 09:22 PM

Brian:

Great idea about the thread. Let me pdf some drawings for attachments and I'll see what I can do this weekend.

In the meantime, here's a lineup for ya'....

More of a tease. I could only wish. ;) I only have a tiny set up with a 4" Atlas and a small Grizzly Mill. About all I can do is knobs. :lol: I am looking forward to the thread. Thanks again I have lots to learn.

#17 plyscope

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Posted 23 February 2013 - 10:41 PM

Mine came secondhand with a six bolt adaptor. I think it was originally fitted to a cassegrain. I believe A-P supplied other manufacturers with these focusers as well as D & G.

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#18 Jim Curry

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Posted 24 February 2013 - 09:35 PM

Brian
Sorry, no pics of that work and I can't lay my hands on my digital drawings today. I'll probably make more this summer as I get back into atming and document things better.

Jim

#19 Happy-Idiot

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Posted 25 February 2013 - 08:58 AM

No problem Jim, I have an idea how to do the fluted sides of the knob, I think its more of a lack of confidence issue with me. I need to play with the machine and crack some eggs. ;)

#20 Jim Curry

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Posted 25 February 2013 - 09:44 PM

Brian,
I used a ball end mill with the knobs mounted in a rotary index. Several other ways come to mind.

Jim

#21 Happy-Idiot

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Posted 28 February 2013 - 07:26 PM

Im wrapped up in buying a plasma cutter right now but when I free my brain from this compulsive have to have clot I will give the ball end mill another try. I cant chew gum and walk at the same time. :tonofbricks: I am determined to make a nice set of knobs with the hunreds of dollars I put into my mini machine shop. But then again it isn't the destination it is the thrill of the chase. ;) Thanks for the tip Jim

#22 Jim Curry

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Posted 02 May 2013 - 10:08 AM

I found a drawing of my 3" focuser knob. Not worth an extra thread at this point but I've attached it as a pdf for those inclined to machine a set. No dimensions are critical, just a guideline. Hogging this out of 3" stock can be a drag....:>)

Jim

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