New Updated CNC Bed Vise

My low profile CNC vise gets regular use,  It's only "flaws" are the limited opening, the slow movement of the jaw using a 3/8"-16tpi threaded shaft, and the moving jaw isn't attached to the shaft when backing out.  

This new vise design has a push button release for quick action, and a 19 inch opening for larger project boards. The jaws hold on to the shaft as it pulls back with a rare earth magnet. 

I made two bases using up-cycled 12mm thick baltic birch plywood with walnut veneer on the bottom side salvaged from an old coffee table top. 

Thickness of the jaws had to make room for the push button and conical spring below it. Button travel is close to 3/16" to push down an open 3/8" hole for the shaft threaded shaft. All vertical parts are a stack of assembled  layers. End jaw is two 12mm layers atop the 12mm base. The bottom layer that the shaft runs through is actually two 6mm layers.  Top 12mm layer on all pieces.  

Push Buttons

For the button I ordered a 3/4" diameter 12" length of aluminum rod to make the buttons from. The button shape was cut on the end with the aluminum rod clamped vertically. Next I clamped it horizontally and the CNC marked where to drill the 5/16"d hole and the bottom edge. My benchtop drill press cut the 5/16" hole.  I threaded the hole with a 3/8-16 tap with the rod held vertically in my bench vise. Then back on the CNC clamped horizontal to open up the 3/8" through-hole.  I hacksawed the button off the long aluminum rod, then put it back on the CNC to mill flat that rough end. It took a little filing and finagling to make the buttons slide easily.  

Button and Spring

I cut all the jaw and button end  parts from small pieces of 12mm and 6mm thick plywood. Alignment holes for 1/4" dowels were be added to each layer. 

The center hole for the threaded shaft needed to be perfectly placed. It was more precise to cut that center layer as halves from 6mm plywood.  A 3/8"d ball end bit cut the shaft slot in each. 

Rather than a stepped slide I chose a 14 degree dovetail slide. I used Teflon as the slide.  The center slot for the slide doesn't have to cut all the way through except in one spot where the slide can slip in to be attached to the jaw.  That spot was cut from the bottom side. Two flat head screws attach the Teflon to the moving jaw. 

Teflon Dovetailed Slides

The Teflon slides I cut at my router table with a 14 degree dovetail bit.  1.5" wide sections were cut from a longer strip. First test fit of each showed the slides were too wide.  I used my small hand plane to trim material off the edges until the slides slipped in and slid easily. 

Two 1.25" long flat head drywall screws attach the slides to the moving jaws. Action is smooth up and down the slot.  

The 1/4"d x 1" long rare earth magnets work to keep the sliding jaws attached to the threaded shafts.   

Rare Earth Magnets

Lastly sandpaper was glued to the face of the jaws for a much better grip on wood parts that are held in the vises.  Handles were CNC cut from a small scrap of dense white oak. 

White Oak Handles. 

These new vises will hold larger pieces of wood that will have the top surface carved/pocketed on them.   I can easily clamp the vises to my CNC bridges.

Comments encouraged!

4D

Variable Height Coffee Table

18 Inches Tall

This coffee table raises and lowers. The height adjusts from 14.25" to 18". 

The table is 16" wide and 42" long. The top of leg frames move in and out.  The bottom edges simply rotate in place. An intersecting panel maintains support of the top as it moves up or down. 

14.25 Inches Tall

A hand crank raises or lowers the table height.  The top of the leg frames remain attached to the underside of the table top as they slide. A HDPE slide in a T-slot connects to a barrel nut embedded into the top of the leg frames does that job. 

HDPE sliders

Inserts that pivot with an embedded square nut on one side, and two lock collars for the other side hold the ends of the hand crank shaft. 3/8-16 threaded rod. 

I haven't yet made or found a hand crank. I may make a nice one from hardwood.  The threaded rod  stays registered through one leg, and threads through the other leg. Spinning the shaft clockwise pulls them together lowering the table top. I used lock collars on either side of a pivoting insert. 

To allow the pivot panel to pivot I made four blocks like the block below. Twin tapered tenons wedge tight even without glue.  Adding some glue prevents them from ever dropping out. A nylock nut embedded in the pivot block keeps the screw from rotating/unscrewing as the leg rotates around it. 

Twin tapered tenons

In place and set back from the top sides this pivot bracket discretely does the job.

In place

Square blocks with 5mm pins inserted into their sides pivot in the leg panels as the 3/8-16 threaded shaft pulls them together or spreads them apart. Lock collars keep the shaft in place on the crank end. 

Nut Pocket Revision

With the nut dropping in from the top of the block, it can't come out if the threaded shaft it running through it. I made a plug to glue in over the nut, and another plug to fill the square hole in the other block. 

Test Pocket for Pivot Block

Two small blocks with a hole for the pivot pins, inset next to the hole.  They are 5/8" deep with the pin hole centered 3/8" down from the top:  

Pivot pins are trapped in place.

Thin plastic washers were needed to keep wood from rubbing on wood. I had to make my own as I couldn't find any the right thickness this size.

Plastic Washers

The steps needed to make the washers I've documented here: Making Plastic Washers.

I needed a link between the sliding slots to synchronize the movement of the leg panels.  I drew up and outline of the needed link plate and sent a DXF file to SendCutSend.com.  They sent me 2 copies of the stainless steel link plate I designed.  Just under 1/16" thick. The plate won't scratch the wood as it pivots as Teflon tape has been applied to the side between the plate and the underside of the table top

I chamfered the edges of the leg panels. I 3D printed end stops so the slides won't pop out.  Simple 1/2" diameter cylinders with a chamfered hole for a 1/2" long wood screw.   

3D Printed End Stop

Installed into the slot.

There remains a small danger potential. Over-cranking past limits may stress and break something.  I need to work on a way to indicate when to stop.  If the shaft was motor powered I could install limit switches. Adding a motor and Up/Down switches was considered.

The table was stood up and the top edges were profiled using a ball end bit and a roundover bit.   

15.5" tall.

The table can be set to any height including and between 14.25" and 18".  I don't anticipate changing the height frequently.  This table was more about solving the engineering to make it work than contemplating how it would be used. I leave that for the eventual owner to figure out. 

4D