Lathe Chuck Spider for 7x11 Mini-lathe

This is not something you will want to use for precision work, but these are quite useful if you keep their limitations in mind. These devices are used in a 3-jaw lathe chuck to hold flat work-pieces at an even distance from the chuck face.

The benefits of 3D printed lathe spiders are as follows :

• Cheap and easy to make
• Easy to customize size to a specific requirement
• Very usable for non-demanding work

The drawbacks of 3D printed lathe spiders :

• Not as precise and accurate as a (well made) metal spider
• Wear more readily, and more likely to pick of metal chips (which reduces accuracy)

Of course the first question to ask about these is - just how accurate are they? To answer this question I made measurements on my surface plate (see photos - note that a 1 on the instrument dial corresponds to 0.001 inches). I placed a test disk (measured parallel to one ten thousandth of an inch) on the spider to average out surface roughness, and found that the spider was parallel to well under one thousandth of an inch. Of course this does not mean that it will be that accurate in actual use, but it does show that the spider is reasonably accurate as made.

For my intended use (cleaning up some brass gear blanks - see photo) I believe these spiders will be quite adequate. I am sure I will find other uses for them as well.

I made the spiders in three styles :

• 20mm center with 10mm wide arms, 12mm height
• 10mm center (no hole) with 5mm wide arms, 12mm height
• 10mm center (with hole) with 5mm wide arms, 12mm height

I found that it is better to leave a hole in the center, because otherwise the print ends up with a small blob in the center - not good for accuracy. Note also that the spider height can be easily changed by scaling the print.

Although I made these for my mini-lathe, they can probably be scaled up to work on larger lathes as well.

The OnShape 3D CAD files for this are here :

https://cad.onshape.com/documents/161da41beebcf941415f7bc7/w/438d3806cc0ead1e3cbceb94/e/d6b0ff31f89465ff103565af

Print instructions

Print in PETG using the 3mf files provided; otherwise :

• perimeters = 2
• infill = 15% rectilinear

These will probably also work in PLA as well.

Note that some of the included prints are scaled in the Z direction (for example, Z105 in the file name means 105% Z scaling).