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So I'm working on my '73 that's getting a Mercedes V12 and I needed to replace the cable driven gauges with ones that are electronically driven. However, I really wanted to keep the classic gauges and mechanical Odometer. So I built a 3D printed, servo driven tach and speedometer conversion that allows you to keep the mechanical odometer functioning like it should as well as the trip meter.
If anyone is interested in a step by step I'd be more than happy to go through a full build description, and the 3D .STL files are linked below. I'm also not quite finished writing the code yet, but I'll have it up in a few days. I started this on Monday so It's been a bit of a busy week.
The full video is linked below, but here's a short clip of them working.
Link to CAD files: https://www.thingiverse.com/thing:4619065
First video is the long one, second one is the 20 second version of just them working.
I bought a cable to electronic tach conversion from ZIP. The servo drive was very nice looking, but unless the servo drive is powered, the needle points straight down due to gravity. It will only read 0 rpm if 12 volts is applied to the servo motor. Doesn't look good if the engine is off.
I'm interested in more details of what you had to do to the existing gauge mechs, the video was a little light on details.
Also, how fast are the servos? Can they respond with the same speed and smoothness as an analog gauge?
Essentially I had to fix the input shaft to the needle shaft and remove the stop for the disk. I did this with superglue. The speedometer is the same, however you also have to drill out one of the existing holes to 1/4". I'll post pictures at a later date.
Speedos can turn 60 degrees in .12 seconds. That means it can go from 0 to 7000 RPM in .4 of a second, plenty fast for an engine.
Originally Posted by 68/70Vette
Here!
I bought a cable to electronic tach conversion from ZIP. The servo drive was very nice looking, but unless the servo drive is powered, the needle points straight down due to gravity. It will only read 0 rpm if 12 volts is applied to the servo motor. Doesn't look good if the engine is off.
As soon as everything gets cleaned up, I'll get in contact! These behave just like a normal gauge.
Electronic Speedometer and Tach Conversion
