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Thalestris24

3D Printers

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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

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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

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

 

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

James

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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):

LowspecTopNew.JPG.356aaca0e68e5f3ef311cde78f478af1.JPG

Louise

Edit: Changed to more up to date image

Edited by Thalestris24

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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 :) 

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

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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

 

 

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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.

Side.jpg.b9911565113692d01174c1e45ebb8c43.jpg

Top.jpg.a4c54fa14d981b554f261d31b715c063.jpg

Thanks everyone for all the support and advice :)

Louise

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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

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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

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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.

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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

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

James

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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.

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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

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2 minutes ago, JamesF said:

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

Correct.

Eric.

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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

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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

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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

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