Cap head thumb screws

Overview

These thumb screw adapters can be attached to any standard metric bolt to turn them into ergonomic thumb screws. This particular model still allows you to use the drive of the bolt. There are pre-made sizes for common bolt sizes from M2-M10.(Check table below for sizes). Optionally use this public OnShape Document to create a thumb screw adapter for non-standard sizes. 

Printing Instructions

Print in high infill (20-70%) and high perimeters (3-5). Suitable for most filament types (PLA, ABS, PETG, etc) however brittle or flexible filaments (TPU, resin, etc) are not suitable.

Assembly instructions

To assemble the bolt and thumb screw adapter slide the thumb screw adapter down the bolt ensuring it is in the correct orientation (see image above). Then thread a nut down the bolt until you get to the adapter. Using the correct size hex key for the bolt and a wrench for the nut, tighten the bolt until the adapter will go no further. The head of the bolt should not stick out past the adapter and the friction of the bolt should keep the adapter on. Remember these are still just plastic parts and over-tightening will lead to the adapter breaking. 

Common screw sizes (mm)

If you want to use the pre-made adapters use the table below and check if your bolt will be compatible. Use the diagram below to see the parts of your bolt you need to measure.

When you have selected the correct sized adapter the bolt head will not stick out past the adapter. The adapter should not slide into position freely but will reach its final position when compressed by the nut. 

OnShape configuration 

Click here for the OnShape document here.

To create an adapter for a non-standard bolt size use a pair of callipers or a ruler to measure the bolt diameter, cap diameter (ØD) and cap height (H) and enter the values in the configuration tab at the top left of the features tab. A tolerance is automatically added to the size entered. If the adapter still doesn't fit correctly adjust the values until it does.