Hand-guard for masonry chisel or other such tools. Because whacking your hand with a hammer hurts. Model is adjustable to fit any tool with a round or oval shaft of any measurement.

The files included fit snuggly on my chisel that has an oval shaft with a major diameter of 17mm, a minor diameter of 11mm, as printed on my printer.

HOW TO EDIT:

You can easily modify all measurements to fit your chisel and hand in the OnShape configurator by following this link! No CAD skills required. Just change the values up in the left hand corner of the screen to your hearts desire. You might have to drag the "features" panel out of the way. When happy, click "export" on the toolbar along the bottom of the screen, and choose your favorite file-format (STL if you're unsure).

There is also a sizing-test available here (or by switching tabs at the bottom of the screen), to easily find that perfect fit.

Print settings

Print in an impact resistant material (duh), flat side down, no supports. I recommend a soft material like 95A-shore TPU, with several mm of solid bottom thickness. A tight fit that you have to hammer home will prevent it from slip around during use.

Nitpicky details

I haven't set any limits to input measurements, so the configurator is easy to break by inputting nonsensical values. Especially avoid zero. If the model breaks when you think it shouldn't, please send me a PM with the values you tried. If you want to get back to an unbroken state, simply reload the link.

If you want to use a cylindrical shaft, simply set the Major Diameter to a value equal to or smaller than the Minor Diameter. If cylindrical, the sizing-test will output weird geometry, but still works on the holes along the center diagonal where the measurements are equal.

The top of the shaft-hole tightens a bit towards the end, in an attempt to stop it from slipping along the shaft. This feature can be suppressed.

The bottom of the shaft-hole is very slightly flared, to make it easier to insert the shaft.

Note that the sizing test uses it's own minor and major diameters, so you have to set them separately from the values in the HandGuard tab.

OnShape uses meters internally, but can take mm, in, feet, etc. as inputs. My brain uses mm internally, and so does the sizing-test; your chosen input should be accurately translated to mm.

"Oval" is poorly defined, which is fine as the fit doesn't have to be precise in this case. Wikipedia calls this exact shape a Stadium (geometry).

Creative Commons Public Domain Dedication

Anyone is free to use this as they see fit: I created this for my father and simply wanted to share in case it comes in handy for someone else. I'd appreciate attribution, but don't demand it.
Using the Export function you can import into another CAD package in your choice of file format, or any OnShape user can freely copy the workspace.