My first refractor assemblage - using a short length of poly pipe, an Meade SCT visual back - interference fit into the tube. A WO SCT focuser attaches to that. The business end is a SuplusShed 80x400mm objective pre-mounted in a cell. I've used three short tech screws to hold the objective on to the tube. Length of the tube was determined by lying all the components along a board which I then aimed at a very distant object, and moved the pieces around until I thought I had focus. I measured the distance between the end of the cell and the back of the SCT visual back to determine the tube length.
It is not able to be collimated, which is a pity, but it is still pretty sharp. I have flocked the tube with self-adhesive flocking paper to keep internal reflections off the otherwise white tube to a minimum. I've also attached a Vixen-style dovetail by using short countersunk bolts and bolting straight through into the tube. The nuts and end of the bolts on the inside are not long enough to enter the light path. I've also mounted a WO red dot finder.
Views are good - but being achromatic the scope suffers typical colour - which is virtually cancelled with a minus violet filter on all but the brightest objects (Sirius, etc).
The stainless steel object on the end of the objective cell is the cover off a thermos flask's cup - and is used as a cap, not a dew shield. I plan to make a dew heater to combat the obvious.
Received the package this morning, so got right into it.
Did a bit of searching around town for suitable pipe, but nothing available apart from truck exhaust pipe (too heavy) so settled for 100mm PVC.
Its 1mm too big in OD, but an hours work with a coarse file and some emery cloth brought it down to size.
The objective has 3 screw holes for holding it in place, beware, they are not evenly spaced. If you drill through, mark one hole and the tube so it goes back the same way if you remove it.
Turned next to the focuser. Its spigot diameter is 95mm so had to bush the inside of the tube down to suit. The Pad Repair Fitting to the rescue again. These fittings are tapered inside and out. I cut it off at the shoulder and found that the ID at that end was narrower. It also wasn't a real tight fit inside the 100mm. As you can see in the pic I cut right through it lengthwise, the focuser spigot slipped inside and it expanded the OD enough to make it a snug fit in the tube. The focuser spigot has 3x4mm tapped holes in it so marked them driled and fitted 3 salvaged screws to hold it in place.
Tube was initially cut purposely too long, lots of taking off tools here, not many puter oners
Tried it with only eyepiece, too long, cut of 100mm. OK
Tried with 2" diagonal. too long, cut off 80mm.
Dust cover is off a 50 pack of CD's, perfect fit.
Made rings from 100mm pipeclips, used the redundant plate from the 80mm to mount it up and ready for first light
Tube has still to be flocked inside, fine tuning of length and find something for a dew shield, but essentially all done.
Time taken 8 hours, including running around looking for "bits that fit".
Great scope Bill! Looks like that PVC tube really works well.
OK, since Chris asked, here is my main scope. I took the light shrouds off for clarity in the photos. Key features are:
- 35cm F/4.6 Suchting mirror
- Mirror box is a ply/foam board/fibreglass resin composite structure, lined with the ProtoStar flocking material
- It has a cooling fan in the back, suspended with 'scrunchies' (= elastic hair ties from the $2 shop), so vibration does not transmit to the scope
- Cell is a 6-pointer designed with PLOP
- Now has Dave Ek's encoder system fitted (that's the disk & wires on the side)
- Six-tube truss; the tubes are bolted together, so they stay together as a unit when you disassemble it (three nuts top & bottom)
- Wire spider made from a 0.016" guitar string. It tensions up with wingnuts, one of which is just visible in the photo
- Filter slide; has a click stop made from a bathroom cupboard catch
- UTA has foam board in place of kydex. Total weight of the UTA is 2.2kg (it's designed for wimps, i.e. me).
It balances with eyepieces around 500g. If I use very light eyepieces I have to hang a weight on the front.
Most of you have probably seen my scope in the articles section but I'll post it here again. The top end now has been reinforced with aluminium tubing bent into a ring (not seen in the picture) to stop the secondary from moving from horizon to zenith. I have also added a drive but I am still waiting for some software issues to be sorted out for it to work.
Received the package this morning, so got right into it.
Did a bit of searching around town for suitable pipe, but nothing available apart from truck exhaust pipe (too heavy) so settled for 100mm PVC.
Its 1mm too big in OD, but an hours work with a coarse file and some emery cloth brought it down to size.
The objective has 3 screw holes for holding it in place, beware, they are not evenly spaced. If you drill through, mark one hole and the tube so it goes back the same way if you remove it.
Turned next to the focuser. Its spigot diameter is 95mm so had to bush the inside of the tube down to suit. The Pad Repair Fitting to the rescue again. These fittings are tapered inside and out. I cut it off at the shoulder and found that the ID at that end was narrower. It also wasn't a real tight fit inside the 100mm. As you can see in the pic I cut right through it lengthwise, the focuser spigot slipped inside and it expanded the OD enough to make it a snug fit in the tube. The focuser spigot has 3x4mm tapped holes in it so marked them driled and fitted 3 salvaged screws to hold it in place.
Tube was initially cut purposely too long, lots of taking off tools here, not many puter oners
Tried it with only eyepiece, too long, cut of 100mm. OK
Tried with 2" diagonal. too long, cut off 80mm.
Dust cover is off a 50 pack of CD's, perfect fit.
Made rings from 100mm pipeclips, used the redundant plate from the 80mm to mount it up and ready for first light
Tube has still to be flocked inside, fine tuning of length and find something for a dew shield, but essentially all done.
Time taken 8 hours, including running around looking for "bits that fit".
Not much to see picture wise as I didn't do the step by step thing. Plus it is like most any other truss newt.
The new 16" f4.5, to "replace/supplement" the good old 10".
Built between November last year and January this. Truss shroud is a work in progress, mainly catching the Chief Sewing Officer on the machine.
Gary
Been posted before but here is my 8" F5 fo F16 refractor on alt/az mount. Hoop-pine ply with Oregon legs.
Ian - both of yours are wonderful I musy have missed mention of it before - but your refractor has adjustable ratios - f/5 to f/16? I notice the helical objective mount - so how do you change the f/length in relation to its diameter? Are you moving a flint & crown in relation to each other or something?
Most of you have probably seen my scope in the articles section but I'll post it here again. The top end now has been reinforced with aluminium tubing bent into a ring (not seen in the picture) to stop the secondary from moving from horizon to zenith. I have also added a drive but I am still waiting for some software issues to be sorted out for it to work.
Tim - I love your rocker box. I'm thinking of using its overall design to base my binocular on. I have already made the basic rocker box and it's very shallow too. I like the bearing extensions on yours - similar to the new Obsession ultralight. Do you have any close-ups of the box/bearing design?
Ian - both of yours are wonderful I musy have missed mention of it before - but your refractor has adjustable ratios - f/5 to f/16? I notice the helical objective mount - so how do you change the f/length in relation to its diameter? Are you moving a flint & crown in relation to each other or something?
Hi Chris,
The objective lens system is actually the optics from an ex NASA satellite tracking camera. "MOTS". There appear to be 6 or more elements contained within the 500mm long lens cell. In the centre of the cell is an adjustable iris diaphram just like a normal camera lens - just that this one is on steroids. The objective cell is 220mm diameter, 500mm long and weighs 26kg if I recall correctly. Mounting it was a significant exercise. I have attached some additional images that hopefully show how it works. The whole scope weighs more than my 407mm F4.5 Dob!!
While it was designed to deliver a 200mm diameter flat and orthoscopic photographic image, it is not much as a visual instrument and I don't use it. Great fun to build though .
In order the images are:
Objective cell prior to mounting after I had fitted some mounting rings to firtinside a 250mm diameter tube.
Next 2 from the front showing iris partly closed and fully open.
F/Ratio Change Knob below focuser F5 - F16.
F/Ratio change drive gear.
Internal collimatable diaginal mirror.
good idea chris ...nice looking scopes guys a couple I hadn't noticed before ..I not long did mine and its still currant on this page a few posts down so more pics of the same seems a little overboard .
heres a finished pic .. [strange I was hopeing to remove this pic from its original post but can't seem to edit that thread ?]
Its has a 12 f5 gso primary
2.6" protostar pyrex secondary and 4 vane spider.
kineoptics hc 2 focuser
moonlite connecters top and bottom
And a homebrew velcro mounted mirror cell
Just an Adendum to the 102x900.
Painted the tube to day, inside Black, Outside White.
A word of caution to those who have not used it before.
When painting PVC the tube has to be cleaned inside and out with PVC primer or the paint will flake off due to the release agent used in the manufacture of the tube. Hence the pink colour.
This liquid is composed mainly of Methyl Ethyl Keytone. This is nasty stuff. Use it outside, don't breath the fumes and don't get it on your skin (use gloves and eye protection). Its safe if you follow the rules, but otherwise......
Here are some pictures of my 12 inch F5 telescope. I made the mirror several years ago and originally had it in a very heavy mount that I rarely used. The current mount is a 'flex rocker' designed to be compact and light - and gets used regularly. The mirror sits on a 4 point mirror cell which can be adjusted by two collimation knobs located at the front of the mirror box. Like Phil's the secondary is supported by a wire spider.
It's great to see everyone's instruments on one thread.
