Widefield Triple Imaging Rig

[Gina]

Made a mistake with the last focus plate - motor is driving the wrong lens   Back to the drawing board for a small redesign

[Gina]

New design - I think it's right this iime

[Gina]

Should have the focus motor mounting frame done soon - just finishing the second plate print now.  This afternoon I cleared the way through to the lathe and expect to start on the threaded lens to camera adapters soon - maybe tomorrow.  And I have been looking into mounting the whole caboodle.

I plan to take my earlier widefield triple imaging framework and adapt it for the turret.  I'll take the ADM mounting plate off the bottom and turn it 90 degrees so that the turret runs alongth the length rather than individual lenses across the width on the base plate.  The end plates will be made of wood as before but the front end will need a bigger piece of wood.  The back end will want a number of holes to allow airflow to the cameras as well as a hole for the axle bearing.

[Gina]

This was my previous widefield triple imaging rig.

[Gina]

Focus motor plate completed - printed and glued together.  Whole turret roughly assembled with stepper motors screwed on.

[Stu]

Looking very good Gina :-)

Sent from my iPhone using Tapatalk

[Gina]

Started the turning - parting off a section of tube and turning down the camera end ready for external thread.  The second photo is failing to upload in spite of trying three times and even after re-editing

[Gina]

Upload has worked now

[Horwig]

Nice one Gina, nothing like generating a bit of swarf 

Huw

[Gina]

Thanks Huw

[Gina]

Now finished turning to size ready for thread cutting.  As a result of reading and replying about Baader filters I have turned a ledge to take 36mm unmounted filters as I have the set of 3 NB Baader filters for my debayered DSLR unit.

[Gina]

Next turning job is something I haven't tried yet - thread cutting   Wish me luck

[Horwig]

Nice looking turning job Gina, looking forwards to your thread cutting with interest. I've not tried it on my lathe, too much of a coward. 

Huw

[Gina]

Thank you Huw

[Gina]

Having had a look for suitable wood for the turret mounting I've decided to go for printed plastic.  So here is the design for printed parts to implement turret supports.

This is the back end mounting for a ball bearing that takes the axle.

And this is the design of the front support parts showing the initial 2D design and 3D versions of the bottom and one side bearing mount.  The other side is just this side flipped - a mirror image - along the red axis.

[Gina]

Slight change in design - the plastic lugs were not strong enough with the way the front upper bearing mountings were printed, in order to fit them on the print bed, so I've changed to holes with bolts to hold the bearings.

I'm wondering though whether I'm overdoing the ease of rotating the turret.  It's only a preset option to frame the DSO the best way on the camera sensors.  Once set it will not need or even want to move so I'm wondering if supporting the turret on 4 ball bearings - 3 at the front and one at the back - is really the best way to go.  With the three 200mm lenses the whole thing weighs well over 2KG so it does need a substantial mounting.  It isn't necessary to rotate it remotely as I can see the laptop from the scope room (or if I use the no. 2 pier I can use the laptop or netbook outdoors beside it).

[Gina]

I've done a test of printing some support structure that fitted the front end plate and propped up the axle at the back.  The turret could be turned quite easily by hand   So the bearings are going

[Davie]

Hello Gina! 

If you haven't done your screw cutting yet can i suggest you find a bit of scrap to practice on first? I sometimes have to screw cut at work but it had been a gap of almost 20 years since I'd done it previously so I practised a little first

Remember and keep your speed low as the feed is pretty fast even on fine threads

[Gina]

Hello Gina! 

If you haven't done your screw cutting yet can i suggest you find a bit of scrap to practice on first? I sometimes have to screw cut at work but it had been a gap of almost 20 years since I'd done it previously so I practised a little first

Remember and keep your speed low as the feed is pretty fast even on fine threads

I haven't started yet, no.  And I think you're right - I have several odd bits of aluminium round stock that I've used for practicing other things so could use one of those.  I shall probably turn the chuck by hand, at least at first, though this lathe will turn as slow as 12RPM in bottom gear.

Thank you for your advice

[Davie]

I forgot to mention that depending on how much meat you have left you're better off having an undercut at the end of where the thread stops.

Good luck when you get going :-)

[Gina]

Thanks   Yes, I will be having an undercut.

[Gina]

I expect to try thread cutting today

I have bought  a 55mm f2 Super Takumar lens to go with my two 55mm f1-8 lenses.  Should be a good enough match.  Annoyingly, not long after buying that on ebay another came up at £5 cheaper   Still, I think the £30 I paid was fair enough   Amazing how often that sort of thing happens.  I also have an offer in for a 105mm f2.8 lens in the auction section.

I have nearly finished printing the parts to make up the support framework for the turret.

[Stargazer33]

Looks like you are single handedly rebuilding the British manufacturing industry Gina! Great project and looks like you should get it sussed really soon. Will keep watching with interest.

[Gina]

Turret front support framework.

[Gina]

Turret with 200mm lenses on support frame and base.  Not fastened together yet.

I think the guide camera and lens is going to have to go underneath.  Have yet to design stuff for that.