I ordered some Borofloat blanks from Germany and looks like I won't be getting them until July. I wanted to make a start on the primary before then, so I dug up an old school Pyrex blank from my collection and spent several days machining it down to 25mm thickness. Actually I overshot the mark by half a millimetre.
I just have to generate the front radius and I can start pushing glass. I already have a thick Pyrex tool that I made for re-grinding an ODK10 primary.
The radius difference is very small and I will fine tune it with a metal ring tool.
Cool Stefan, Guessing it should be easier to grind than my 10 inch?
I 3D printed the secondary baffle using expensive ($90 for 750g) carbon fibre loaded filament. This stuff produces such a nice matt finish that I'm not sure whether it can be improved with black paint. And it weighs 26g.
Finished the mounting rails.
I opted for system 20 (2080) extrusions, rather than a solid bar - as I see on many commercial instruments. These extrusions have superior stiffness to weight ratio, compared with solid bars. The end caps are 3D printed ABS.
Another advantage is that the dovetail plate can be moved along the long rail for optimum CG, and thus it does not have to be extra long (and heavy).
I 3D printed the secondary baffle using expensive ($90 for 750g) carbon fibre loaded filament. This stuff produces such a nice matt finish that I'm not sure whether it can be improved with black paint. And it weighs 26g.
I had no idea you could 3D print CF filaments. So how does it work and holds together? Heat? Glue?
I had no idea you could 3D print CF filaments. So how does it work and holds together? Heat? Glue?
CF filaments contain only up to 20% short strands of CF and print like any other filament, although slower. The result is nowhere near as strong as laminated CF. I'm waiting for graphene reinforced filaments to hit the market, but that may not happen for a while.
Making the necessary jigs and fixtures is more work than making the actual parts.
For the primary, I made a new wedge error tester, from an old tooling plate, that allows me to also measure the concentricity of the inner diameter.
For making the dovetail plate, I had to make a fixture for cutting the 60 degree angle of the dovetail.
Next I have to figure out a way of setting up the primary on the lathe to cylindrically grind the inner diameter to the required specs.