Disclaimer: This model comes without any guarentee of fitness for use with your engine - use at your own risk of engine failure.
Material: A word of caution first! For a permanent solution a strong, high-temperature filament with chemical resistance to petrol should be used.
- Nylon may be a suitable material (although I did not test it myself). It has a high melting point and is chemically resistant to petrol.
- PETG is chemically resistant to petrol, but the carburettor may become too hot and cause the PETG to deform.
- ABS/ABS+ may be a suitable short-term solution since the choke is at the air in-take side of the carburettor. However, the petrol vapour when the engine is not running may degrade the ABS material over time and cause it to fail.
- PLA is NOT SUITABLE. It is neither temperature nor chemically resistant and should be avoided.
Layer Height: 0.2mm
Nozzle size: 0.4mm
Line width: 0.4mm for all layers
Do not print the assembled model! It is only to show the final assembly. The layer adhesion is too poor when the shaft is printed up-right. Print the two separate parts and assemble it after printing.
Head [1of2]:
- Print with the top facing up
- No supports needed
- Wall loops: 2 (*important, otherwise bridging doesn't work properly)
- Infill: 100% (it's a small part)
- Bridge infill direction: 45deg (*important, otherwise bridging doesn't work properly)
Shaft [2of2]:
- Print it lying flat on the build plate for longitudinal strength. Layer adhesion is too poor if the shaft is printed standing up-right!
- No supports needed
- Brim: outer only (use a brim, otherwise the shaft may warp and lift off from the build plate)
Assembly instructions:
- Lightly run some fine sandpaper (200 grid+) through the slot of the shaft if it is too tight for the butterfly to slide in. The butterfly must be moderately tight and should not fit loosely in the slot. Do not force the butterfly in if its extremely tight - the shaft may crack.
- Use a trimming knife to scrape off the brim edges and use fine sandpaper to smoothen the shaft - clean the dust off after sanding before inserting it into the carburettor (you don't want sanding dust in there!)
- Use superglue to join the two parts.
- Make sure the shaft is perpendicular before the glue sets.
- Make sure that the shaft goes in all the way into the head, the rectangular key should be flush with the bottom of the head.
DMT_ZA
