First Spectroscope finished… (well, mechanically).

Hi Guys,

Greeting from 20 year old Angel land.  Here’s a quick update for anyone interested in the Paul Gerlach DIY spectroscope..

First one finished in PLA (the second is being printed as I type and a new spool of black ABS has just arrived for what I hope will be the ‘final product’).

It’s mechanically sound and the component fits are very good.  Tolerances from the design are superb and Paul has done an amazing job.  I’ll be spraying (see below) and fitting the optics for V1 over the weekend.

I know orange is the worst colour for a spectroscope (apart from white) but I’ve sprayed a few test parts with dark grey acrylic primer and black matt acrylic (both automotive) which seems to ‘completely’ address the transparency issues. I’ll find out when I mount the optics.  Actually orange has been great for hacking, sorry “modifying”, the components to fit different optics etc.  You can see measurement/cutting marks easily.  I’ll be experimenting with different optics and gratings from the ‘Ken Harrison magic box’ asap.  (I’ve ordered a ‘proper’ optical bench to play with).  

I printed using thick walls and high density infills so the PLA is quite machinable and is much stronger than I thought it would be.  A Dremel/Draper does wonders by the way.  As does a good set of needle files.  

Despite the reasonable mechanics I’m adapting the second ‘print’ to have standard metal scope/camera adapters (drilled and grub screwed) to ensure good interface strength.  In addition I’ve cut/drilled aluminium bars to brace the body ‘mecanno’ style.  I’m hoping that will help mitigate the thermal expansion issues.  Again, the proof of the pudding…  I’ll tidy the final build.

That, by the way, is the way I think this kind of project will go until “wonder materials” are available for printing.  A hybrid design of printed and metal parts to maximise each’s best attributes.

I’ve a calibration unit already on the bench for V2.  Electronically similar to Alpy but bolted to the underside like the focus unit with bulbs placed inside the slit compartment.  The ‘screen’ is manual push through and ‘flood everything inside the slit-holder compartment’.  Only enough room to work for the Alpy slit.  But I think it’ll work as a first pass to mess around with on a test bed.  My (very) old electrical engineering days haven’t helped prevent a few small soldering iron burns :0(  Things will improve.

So, onward.  And remember, ‘you can’t tell a fool he’s wrong’.  Now I’m learning 3D CAD as quick as I can and printing for all I’m worth.

A friend at Newcastle Astro talked about meteorites the other day and got talking about reflection spectroscopy.  Anyone know what/where I can read up on that?  And any designs?

As soon as I’ve bench/scope tested V1 I’ll update if anyone’s interested.