Mountings and Controls For Widefield Imaging Rig

[Gina]

Printing the camera supports.  1:26 printing time and 10m filament.  Without the extra holes it was and hour and a half (a whole 4m less ) and 11m (a whole metre ).  Hardly worth the effort but so-be-it

[Gina]

Slight mistake on the camera supports - insufficient allowance for the oversize printing due to filament width.  I'll fix that ready for re-printing.

[Gina]

Clear skies forecast for tonight so I'm getting ready for imaging.  Going over to 105mm lens as I want slightly bigger FOV than the 135mm so printing new lens support and focus gear.  The lens support is for the fixed rotation system I have now as the rotator isn't ready yet.  The focus gear will fit the rotation rig too.

[Davey-T]

Don't mention the forecast or it'll change in an instant  I just hope the humidity drops a bit, been nearly 100% the last few "clear" nights equating to high level fog.

So far out of 24hrs of HA  I've salvaged 4hrs.

Good luck with the printing.

Happy New Year and look forward to lots more projects this year.

Dave

[Gina]

Thanks very much Dave   Happy New Year to you too

 

[Gina]

Just realised I haven't got a dew shield for this lens and I haven't got a suitable bottle to adapt so it'll have to be 3d printed.

[Gina]

No chance of printing a dew shield - need the laptop for imaging.  If I can get it to work out in the observatory!!

[Gina]

Two thoughts for the design of the wheel mounting for the objective end of the rotation rig.

[Gina]

Printing the dew shield for the 105mm lens this evening.

[Gina]

[Gina]

Printed the new camera supports and they fit perfectly

[Gina]

Now printing the ring that runs on the rubber tyred wheels to allow rotation.

Looking now at the front support and decided to go for four support wheels on a ring somewhat larger than the running ring.  I was originally thinking of using one fairly thick ring but I'm now thinking two rings with the wheels between would be stronger and stiffer.

[Gina]

Here are models of the two sides of the wheel support ring.  The thick one encloses the wheels (except for one side) and the thin one will be glued to the thick one, probably with M8 bolts to hold the wheels.

[Gina]

I might add some pegs and matching holes to help align the two parts for gluing.  I also need to sort out how this part will connect to the base.  Depends on the base of course.  If I use an ADM dovetail bar I could bolt it on.

[Gina]

Running ring printed and offered up to the cage and it fits perfectly   I shall glue it onto the bigger cage section or more precisely - solvent weld with acetone.

[Gina]

Here's a photo of the rotation rig with 135mm lens.  I think I shall be able to use this for the 105mm lens too with a 3D printed adapter.

[Gina]

Here is a screenshot of model of 105mm lens supports.  These will fit inside the cage.  I think focussing can be handled by mounting the stepper motor on the outside rather than the inside so that the pinion is inside and in the right position to operate the focus sleeve on the lens via gear sextant.  The 105mm lens is a fair bit smaller than the 135mm and I think it will fit inside the 135mm lens support hole with sufficient room for the dew shield.

[Gina]

Printing now  - 1hr 10m and 9m of filament.

[Gina]

Camera end main support.  I have yet to sort out fixing holes - depends on dovetail bar holes.

[Magnus_e]

This is really impressive work Gina! I do believe a 3d printer with my name on it exists somewhere in the future

Something I have been wondering. If you need a hole that is smooth and of exact diameter. Could you print the hole slightly tighter and then drill it out with a drill bit of correct size?

It's really impressive that you can print parts that is strong and rigid enough to make parts like these, but will the material be too brittle to manipulate with tools, or can it be drilled and grinded, aso?

[Gina]

Thank you Magnus

Yes, you can drill out a hole with a drill bit - I do that sometimes.  It is also possible to tap threads in holes by printing the hole slightly small and running a tap through.  I find a battery drill handy for this - easy to hold in line with the hole and the variable speed makes control easy.  Reverse drill to remove tap, being careful to maintain alignment.

I use ABS filament which is sightly flexible - it bends rather than breaks.  It can even be used to make springs.  It is easily worked with drill or file.  Also, ABS is soluble in acetone which can be used to solvent weld parts together.  Wet surfaces with acetone, wait a few seconds and press together.  Hold together for a few seconds more until the bond has dried.  ABS can also be painted though I've never tried this.

The other main type of filament used in 3D printers is PLA.  This melts at a lower temperature than ABS.  But it is insoluble in acetone or most solvents so can't be solvent welded - I believe it is difficult to glue but not sure on that.  It is said that it won't take paint.  It's more rigid than ABS and will break rather than bend.  It also doesn't fair well outdoors.  It's usually the same price as ABS.  There are other types of filament for special purposes - Google if interested or get back to me and I'll explain a couple of others.

[Gina]

Some photos showing the 105mm lens fitted into the cage with the support pieces (printed in yellow).  There is a small problem - the supports for the lens end fixing for the cage interferes with the small lens support plate so I shall have to modify the design slightly and re-print.  Not a problem.

[Gina]

Here is the new design for the 105mm lens support.

[Gina]

That piece goes in nicely   When I looked further I thought there might be a problem with the focus motor but it's fine.  There is room to put the focus gear on the outside after all and this makes things far simpler.  The larger 105mm lens support is a nice close fit in the cage but the smaller part will need some double sided sticky tape to hold it in position during assembly.  I'm pleased with this cage design - it will take at least two lens options

[Gina]

Found a suitable dovetail bar on the abandoned 400mm triple imaging rig - an 11" ADM.  This should be about right for the present rotation rig