So the previous top piece for my gauge cluster didn't last long. Turns out black PETG just can't hold up to dashboard temperatures without warping over time. So now we are onto ASA (a UV resistant variant of ABS). The key thermal property of the plastic I have to worry about is
heat deflection temperature, or at what temperature a test part will bend under a given load. Apparently PETG has one that is too low for the dash board, even in winter.
The downside of going to more heat tolerant and stronger plastics like ASA, ABS, Nylon, and Polycarbonate is that they get harder to print. Difference in temperature across the part will cause it warp while printing and once you get to Nylon and PC upgrades to the printer are necessary
to hit the right nozzle temperature. So I had to play around with settings, build plate material, and get an enclosure to make sure the temperature remains constant around the printer.
My printer isn't big enough to print the whole thing in one go so I did it in two pieces, super glued them together, and filled any imperfections with a thin coat of body filler. Then I'll glue some vinyl down to it using contact adhesive. That should cover the layer lines and the bondo.
Up until now I've been using the rear door handles off of a 144/145 on my Amazon as the original handles were falling apart (foam/vinyl overmolding had detached from the metal frame). I found a model online someone had made of Amazon door handles. Since these parts are not on the dash and are significantly thicker warping if they end up hot enough should be negligible to nonexistent.
Two 17 hour prints later I have a set of new door handles.
To continue with the 3D printing kick the stock round air filters on the HS6 carbs always bothered me. I personally prefer paper over the oil and cotton or foam. Also the stock filters are $30 a piece.
I was also running into issues with the crankcase breather nozzle on the filter housing. Two bolt carbs had a weird little part that fit between the filter and the carb that the hose attached to. I preferred the three bolt SU arrangement where it just has a fitting on the filter housing. Fewer parts to mess with.
To get the best of both worlds and not have extra holes in the air filter plates I decided to print my own plates to fit paper filters that met the right dimensions.
The filters I ended up with are Wix part number 42032, which I think is for the stock air filter housings on a Pontiac big block with a Tri-Power setup. Now the cost to change the air filters is $20 instead of $60.