
How Do I Build A Focuser Out Of PVC/ABS
#1
Posted 23 March 2008 - 08:36 AM
Any suggestions would help.
Anthony
#3
Posted 23 March 2008 - 11:53 AM
#4
Posted 23 March 2008 - 08:46 PM


Best,
Mark
#5
Posted 23 March 2008 - 11:57 PM
#6
Posted 24 March 2008 - 12:07 AM
You'll find them at Loew's and Home Depot in the plumbing section.
I believe that those sold in cardboard boxes at Home Depot are the best as they allow you to open the box and pre-inspect the two parts for close tolerances. The fit does vary from box to box. Obviously, you want the combination of the two parts that has the least play.
If used as is, the focuser is ready for two inch eye pieces. If you wish to use 1.25" EP's you'll need to make or purchase an adaptor.
A helical focuser from a flush valve will cost you about $5.oo
Art
You need to cut away everything to the left of the red spacer and throw away the black rubber seal. What's left is the large "nut" and the threaded body.
#9
Posted 24 March 2008 - 02:56 AM
#10
Posted 24 March 2008 - 08:19 AM
You need to cut away everything to the left of the red spacer and throw away the black rubber seal. What's left is the large "nut" and the threaded body.
What the best item to use to cut this?
#11
Posted 24 March 2008 - 08:43 AM
You need to cut away everything to the left of the red spacer and throw away the black rubber seal. What's left is the large "nut" and the threaded body.
What the best item to use to cut this?
Several tools come to mind. One of those fine tooth razor saws used in model making would make a nice clean cut (check out your hobby shop). A band saw with a fine tooth blade would make a very neat cut. If nothing else is available, just use a hack saw. A dremel with a cut off disk will work too, but these sometimes MELT plastic rather than cut it.
#12
Posted 24 March 2008 - 09:05 AM
Is there any kind of paint or dye that will "take" to the plastic. This looks like a perfect solution for a 3.5" newt project I have using one the surplus shed red tubes they have. I'd like the focuser to be red or black.
Generally for a nice spray finish use acrylic paint as used on model car plastic bodies. For something that will last a bit longer enamel paints are the way to go as used for old airfix kits. Enamel is also good for coating aluminium too.
You could always buy pvc pressure pipe. It comes in black and with lots of adaptors and stuff with screw fittings. Way better than your run of the mill plumbing fittings. Mostly used for garden pond filtration, ie koi carp.
How about the valve in the attached pic as a focuser body? that inside pipe diameter is 2 inch so there's a heckuva chunky body for running your focus adjuster bar through the side of it...
Toe.
#13
Posted 24 March 2008 - 09:05 AM
Any paint applied to the threads will interfere with the smooth movement. I tried it.
I did paint the top surface flat black so as to minimize any chance of reflections.
I am not aware of any dye.
Art
#14
Posted 24 March 2008 - 09:10 AM
I did mine on my band saw, leaving a short stem. Then I used a 12 inch disk sander to grind it flush.
Bear in mind that the geometry of the valve and stem design differs from one manufacturer to another. That's of no consequence.
Most of the plastic will be cut off and thrown away.
Here you see the Flush Valve focuser fitted with an EP adaptor and an EP.
#15
Posted 24 March 2008 - 09:40 AM
I'm not expert on anything, but have got in the habit of overcoating "pretty" paint jobs with a few coats of Rustoleum crystal-clear enamel. It dries very quickly, is nice'n'shiny, and seems to protect a finish.
Non-scope-related experience re durability of the clear enamel-- Out old house has ancient glass-knob doorknobs, but the metal parts were not brass, just some kind of plated alloy that had got very grungy over a half-century. We wire-brushed em down to the metal, hit em with metallic-brass Rustoleum, and overcoated with clear enamel. They have been in use a few years, and still look good, and even close inspection looks like brass.
#16
Posted 24 March 2008 - 04:16 PM
Best,
Mark
#17
Posted 24 March 2008 - 09:50 PM