Multiturn Trimpot Knob

Multiturn Trimpot Knob

This is my first model, I've created it on FreeCAD.

Back story:

I am making a Bench Power Suply with a 300w Buck converter I had laying around. Problem was it has small trimpots for adjusting Voltage and Amps. These are tricky to adjust by hand, you'll need a small screwdriver to do so. 

So I looked online and big Trimpots are very expensive. I searched the internet for somthing that can be attached to small trimpots and somehow make it big enough to be able to adjust by hand without any tool. I coudn't find anything, so I spend a whole day just to make these.

These are not perfect as I am very new to 3D printing. But It got the Job done. 

I am attaching a YouTube video link, its not about this knob, but how to modify an ordinary single turn knob to a multi turn one. WATCH IT. and you will understand how to prepare this after printing.

Basically you will have to place a thin(~.5mm) and very small piece (about 2mm x 1.5mm)  of tin or plastic sheet (check, it sould be able to turn the small screw of trimpot).  Insert the sheet into knob inner slotted part and test it.

I have also added FreeCAD file, if you want to modify it.

Hopefully I will create a Video about how to do it step by step. Till then Have fun!

Just for Reference: