I was thinking at least ABS. From the little research I did PLA ducts would become soft and deform with the car sitting on hot pavement on a hot day. These ducts are to be used for track day applications after all. It might not be 300 degree engine compartment heat, but less than 12" off of hot baking asphalt can get pretty hot in the summer.

Even standard ABS will be pushed to its upper temperature range. I was wondering if anyone has the ability to try Nylon or Polycarbonate, even High Temp PLA?

Even if the first ones are PLA just to see if it can be done, it would be great to see some pictures!

PLA glass transition temp is 60 deg C = 140 deg F
ABS glass transition temp is 105 C = 221 deg F

Using PLA brake ducts on a 100 ambient day is usually closer to 120+ track surface temps and would concern me. I would go with ABS just to be safe if you plan to leave it on for a while.

Any update on the GV lip version Madjak?

in for 3" r package ducts

Whoa if this is still a thing I would totally love to get my hands on a set of GV 3" ones, I'll be doing a ducting job this spring when we get the car in the garage. In for a set!

Sorry guys, been away on a motorsport weekend and had to spend last week getting ready. I gave the GV lip version to another mx5 owner to test fit and haven't heard back yet. He has been busy too. I will find out soon if it needs modifications.

If anyone wants the 3d models pm me for a link. They aren't final but you can do a test fit if you have access to a printer.

So my buddy who is willing to print this for me sent me this information. What do you guys think material wise?


"I could print it out of ColorFabb XT (PET) co-polymer which has similar thermal properties to ABS ColorFabb - XT Co-Polyester Filaments produced from Amphora 3D? Polymer by Eastman Chemical Company. I don't have any on hand but it usually ships within a week and I get a 10% discount so a roll would be about $40.

Otherwise he could try Alumide (nylon powder mixed with aluminum powder) from shapeways https://www.shapeways.com/materials/metallic-plastic. It would have similar thermal properties but would cost around $80."

I don't care what it's made of as long as it fits the gv lip and has 3 inch outlets

I have no idea why you felt the need to answer my post with an answer that had nothing to do with the question. Thanks for the :2cents:

Does he have both an SLA and a FDM printer? I've never heard of the alumide one but one of the material characteristics says it can be brittle which is no bueno.

I'd go with the ABS type stuff.

I have had dozens of hollow parts FDM printed. If you go that route you will want 3mm wall thickness and an acetone vapor bath to help bond each layer together as one surface.

I have been going back and forth with him trying to pick out a good product. We spoke about using the Carbon option. XT-CF20
ColorFabb - colorFabb XT-CF20

This has a higher temp resistance, closer to an ABS option. However, this also means that I am picking up SS Nozzles for his printer. I am not sure if this is overkill. Maybe I would be fine with a regular XT option???

Would you still have 3mm thick walls with the XT-CF20?

:werd:

Or just use a squirt bottle with acetone and wet the entire part and let it air dry. It takes some practice to learn how much is the right amount of acetone to smooth out the part nicely. My vapor bath just takes way to long to heat up and I'm impatient so I often use this method.

I have tried that several times but I always get delamination and surface cracking. I think the rapid change in temp as the acetone evaporates causes the ABS to warp on the surface. My parts have always been rough sanded to ~220 grit before doing anything with the acetone, that might contribute to the surface weakness.

Really? I haven't had any issues like that yet. It might have to deal with the quality of ABS your using. I had a roll once that was terrible and always seperated and was

What setup are you using the vapor bath? My decision to use a crock pot was a terrible one.

I have an electric hot plate (I do this outdoors) and two of these aluminum stock pots:
16 Qt. Standard Weight Aluminum Stock Pot

I epoxied a flange onto one of them to make mating them together easier. The other pot is used as a lid and has a hole drilled in it so I can run a string and suspend the parts. The trick is getting the part out very carefully and hanging it somewhere to dry. The ABS stays soft until all the solvent evaporates out.

My neighbors are very tolerant of seeing me in the driveway with elbow length gloves and a respirator.


Edit:
On the crockpot issue. I am guessing it doesn't get hot enough. I have had the best results with the vapor bath when the acetone is very hot and making a lot of vapor. Better results from a lot of vapor and brief exposure than a little vapor and long exposure. Did your part in the crockpot start to deform?

Thanks for the info. I might have to switch to one of those.

It gets hot enough. It just takes a very long time to heat the very thick (3/4" or so) ceramic pot up to temperature. Like 1+ hours. I've found freezing the part helps the acetone vaporize on the surface alot easier too. I've had abs bead up and run from excess acetone and leaving it in for too long of a time when I first started experimenting with it. I'm sure if the parts were large enough I'd see deforming.

Brake duct test print. I'll try and fit these later today.

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Those look much prettier than the fiberglass blobs I just made. I'll post pics when I am done. I only have 2" ducting and got impatient waiting for 3d goodness

They need a bit of work. Madjack. Let me k ow if you need measurements or anything. If you could pm me a 2.5 inch version that would he great too.

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