3D Printers

[Thalestris24]

1 minute ago, Merlin66 said:

A blatant plug....my book “Astronomical Spectroscopy for Amateurs” covers most of the design bases.

Some very helpful links also on the Webpage (see below). 

Yes, I have your book!

Louise

[Thalestris24]

Um, I know it's late in the UK but... Anyone about who knows how a 3d printer will print across a sideways T2 sized hole? Clearly I'm asking this because I didn't switch on supports... When I started printing I didn't actually mean to print the whole thing - just the base really. Then I thought - nya might as well just let it go on and on ha ha. It actually printed across a smallish aperture ok - 9mm dia. But will it cope with the larger one? I was thinking as it curves gradually it might be ok since all circles are similar (in a geometric sense)? It's not near to halfway up a T2 hole yet but will be whilst I sleep. Fingers crossed...

Louise

[upahill]

Sideways holes usually come out ok for me. If it gets chance to build up the sides (eg cylindrical holes).

 

[JamesF]

I think it should be fine.  I've printed 40mm diameter holes in vertical sections without a problem.

James

[Thalestris24]

15 minutes ago, upahill said:

Sideways holes usually come out ok for me. If it gets chance to build up the sides (eg cylindrical holes).

 

Oh good, thanks for the reassurance! What's the chance something will go wrong overnight?

It should look something like this (without the internal components):

Louise

Edit: Changed to more up to date image

Edited November 5, 2019 by Thalestris24

[Thalestris24]

4 minutes ago, JamesF said:

I think it should be fine.  I've printed 40mm diameter holes in vertical sections without a problem.

James

Thanks, James  

[upahill]

Assuming you are printing with side facing us being the top then I can't see any issues with that.

[Thalestris24]

5 minutes ago, upahill said:

Assuming you are printing with side facing us being the top then I can't see any issues with that.

Yeah, it's top view. I just edited to show a more up to date design, though it's essentially the same case. I'll let you know how it goes!

Thanks

Louise

 

 

[Stub Mandrel]

The top of the T2 hole may need some manual tidying up.

[Thalestris24]

It's printed out ok! Yes, the top of the slightly bigger than T2 holes do need a little emery papering But this was only meant to be a rough print though it does actually seem quite good.

Thanks everyone for all the support and advice

Louise

[JamesF]

That doesn't look too bad at all.

Where there are a few bits of "stringiness" I have occasionally used a hot air gun (one I use for warming heat-shrink insulation) to get them to shrivel up and disappear.  A hair dryer might work equally well.

James

[Thalestris24]

2 minutes ago, JamesF said:

That doesn't look too bad at all.

Where there are a few bits of "stringiness" I have occasionally used a hot air gun (one I use for warming heat-shrink insulation) to get them to shrivel up and disappear.  A hair dryer might work equally well.

James

There was some 'gossamer' but easy enough to remove manually Looks like some things don't quite fit together so will need some shaving or maybe a reprint with a slightly reduced size.

Louise

[ejp1684]

That print looks decent enough to me, very similar to how mine came out. I went for shaving/filing to get the bits to fit together.

Eric.

[Gina]

Nice print.

[Thalestris24]

I'm looking at the collimator lens holder which I think had its design changed. Ken was saying last night about how the collimator lens focal length (lens specified at 125mm but measured distance = ~115-120mm) should match the distance between it and the slit. The collimator lens holder has the aperture stopped down to F10 - I'm assuming that's to achieve the match? It seems a shame to discard the lens aperture but must be necessary? Eric?

Louise

[JamesF]

Surely stopping down the aperture won't change the focal length?

James

[ejp1684]

I'm not fully conversant with the theory of the optics, but when I first used it with the full aperture for the collimator the spectra were distorted at either end. Someone suggested I step down the aperture to f8 or f10. I tried both and f10 works best.

My understanding is this design works best at f10 so I've stayed with that.

Eric.

[Thalestris24]

1 minute ago, JamesF said:

Surely stopping down the aperture won't change the focal length?

James

No, but as with cameras, will change the depth of field.

Louise

[ejp1684]

2 minutes ago, JamesF said:

Surely stopping down the aperture won't change the focal length?

Correct.

Eric.

[Thalestris24]

1 minute ago, ejp1684 said:

I'm not fully conversant with the theory of the optics, but when I first used it with the full aperture for the collimator the spectra were distorted at either end. Someone suggested I step down the aperture to f8 or f10. I tried both and f10 works best.

My understanding is this design works best at f10 so I've stayed with that.

Eric.

I assume it was a post-design change. Wondering whether it might be as well to use a smaller lens but I suppose, in that case, probably couldn't get the longer focal length. When it comes to it, I'll experiment with a few things. I need to find a source for the 1" mirror but with the smaller collimator aperture, maybe a smaller one will do.

Louise

[Thalestris24]

3 hours ago, Thalestris24 said:

I assume it was a post-design change. Wondering whether it might be as well to use a smaller lens but I suppose, in that case, probably couldn't get the longer focal length. When it comes to it, I'll experiment with a few things. I need to find a source for the 1" mirror but with the smaller collimator aperture, maybe a smaller one will do.

Louise

Oops! It's actually the 0.5"/12.7mm diameter (guide) mirror that Thorlabs don't have. Edmund do a similar one which is half as thick and is nearly £13 + shipping... Seems a lot for a tiny mirror! If anyone knows of an alternative source, that would be good to know

Louise

[skybadger]

Surplus shed ?

 

[Thalestris24]

47 minutes ago, skybadger said:

Surplus shed ?

 

Nah, they don't do mirrors, and cost with shipping would be silly for just 1 x 0.5" mirror. It probably doesn't have to be particularly high quality either - it's just for guiding (via the reflective slit). It needs to fit the 0.5" holder but perhaps an odd bit of mirror tile might do... If only I had one and the skills to cut it ha ha. 

Louise

[Stub Mandrel]

Try Astromedia for small front-silvered mirrors:

http://www.astromediashop.co.uk/Components.html

22 x 15.5 for £2.45 + postage.

[Thalestris24]

10 minutes ago, Stub Mandrel said:

Try Astromedia for small front-silvered mirrors:

http://www.astromediashop.co.uk/Components.html

22 x 15.5 for £2.45 + postage.

Nice try but wrong size and shape!

Louise