Low Profile CNC Table Vise

I often need a way to clamp small parts on my CNC bed without using clamps that hold them down from the top.  In the past I've been able to use a manufactured vise borrowed from my drill press table, but it is rather tall and my CNC doesn't have a lot of Z axis clearance.

This prompted me to come up with this low profile vise:

All the wood parts were cut out on my CNC from 1/2" (12mm) and 3/4" (18mm) baltic birch plywood. The bottom plate that holds the moving jaw down is from a scrap of old 3/16" thick plywood.   Follow-up procedures included drilling pilot holes for screws that hold the main parts together, and tapping threads in a drilled out 5/16" hole for the 3/8" x 16tpi threaded rod I used.

I've added some 100 grit sandpaper to the jaw clamp faces for more friction than the plywood edge itself has.  In use it now holds anything tight enough that when being cut by the CNC it doesn't move. The four bolt holes were spaced to align with the t-track slots in the bed of my CNC.  At the moment I use a box end wrench to turn the end where two nuts are jammed together.  I embedded a vertical steel post in the moving jaw for the threaded rod to push against.  It also helps keep the plywood from splitting.   Brass screws were used to hold all the parts together, as well as to keep the individual plywood parts from splitting.  The CNC will just mill through the brass screws should it accidentally encounter them.

I've posted a file that includes all the vectors I used in .CRV (Vectric's VCarve) format on their forum site:  http://forum.vectric.com/viewtopic.php?f=2&t=24361#p189439.  Direct download link: http://forum.vectric.com/download/file.php?id=53303

If you are interested in making your own feel free to use my file as is or modify it to fit your CNC's bed mounting/clamping system.   I know I'll get considerable use out of mine.

The software I used to cut the parts out is Aspire from Vectric.com.  Aspire is their most expensive and full featured product, but they do have lower priced options that would have been fine for drawing up and cutting out this project.

Speaking about Aspire, it was recently upgraded to version 9.  Version 9 has enhanced drafting features, and a much improved rendering engine to show how your parts should look after being cut.  below are two images of the base plate of the vise, all done in one file and once rendering.  The new and most appreciated feature is being able to show what 2-sided cuts would look like together.

Bottom side.

Top side.

4D

2/18/2018 - Update for the bed vise:   I've taken it apart and re-assembled it so there is no more conflict with the hold-down bolts.   I also CNC'ed a slot for a 3/8"-16tpi square nut and the nut slid in there tight.   I drilled out the wood threads and now am confident the vise won't strip out in use. Steel threaded rod through a steel nut now.   I found that square 3/8"-16 tpi nut in a coffee can full of assorted hardware living in my garage shop.  Now it has a home.