I'm a big advocate of push button releases on machines and hand tools. The push button depth stop on my bench drill makes setting the depth simple and quick. The push button release on my CNC bed vises make opening/closing the jaws quick over 19 inches of jaw travel.
 |
| Push Button Adjust Clamp |
I have a couple of classic hand screw clamps, inherited from an Uncle. Both are rather slow to open or close the jaws for what needs to be clamped. This project is my quest to make my own version that uses push buttons to release the 3/8"-16tpi threaded shafts for quick opening or closing. The jaws are 1" thick, just enough thickness for push buttons and the spring below them.
Making this work with standard all-thread rather than left/right threads on the shafts was the tricky problem. To control the space between the jaws both screws needed to stay attached to both jaws. The threads can only be in one jaw though. The push button side is the threaded jaw. I needed to trap the thread in the other jaw so it can spin but can't come out. I also needed to allow the trapped ends to pivot. It passes through a 5/8" HDPE rod that has #6-32 machine screws 90° intersecting the 3/8" hole where the grooves on the shafts are.
 |
| HDPE Inserts and #6-32 Screws |
I drilled the 5/8" holes through the jaws using my drill press. I cut the taper to the end on each jaw using my band saw. My band saw removed most of the wood against the line I drew. Then my disk sander sanded them down to the line.I used the rotary axis on my CNC to make the grooves around the threaded shafts. The bit used was a 1/8" diameter milling bit (4 flutes). I offset the bit by 3/16" and set X, then set Z on the top of the threaded rods, then set Y where I wanted the groove to be. I turned on the router (set to its lowest speed), stepped Z down .01" then spun the rotary axis 360°. Stepped down another .01" and repeated the 360 rotation until I was down .19" (a bit below center). I checked the inner diameter which should have been .25" or a bit less. First try and the groove was a little too shallow I jogged in .005" and repeated the above steps until the groove was deep enough. Once I had a good groove on one shaft I repeated the same process on the second shaft.
 |
| Groovy! |
Sloped slots for the threaded rods were cut using the fluting toolpath in Aspire. The shafts can pivot up to 30° either way.
 |
| Sloped Slots |
For the push buttons I started with an aluminum rod that was .76" in diameter. I trimmed the ends square with my metal cutoff saw. Next I clamped the rod vertically in my CNC frame, and then trimmed the rod down to .75"d. Next step was to mark where the 5/16"d hole needed to be, as well as where the bottom needs to be cut. Both were done with the rod clamped horizontally in my CNC table vise. I then removed the vise (with the aluminum rod still clamped tight) and took it to my drill press to drill the 5/16"d hole through the aluminum rod. Then I clamped the vise vertically in my bench vise and used a 3/8-16 tap to cut threads through the rod. The last step was to open up the intersecting 3/8" hole next to the threaded hole using my CNC and a 1/4" end mill. The toolpath started in the center of the threaded hole, then moved over to profile around the 3/8" hole. No plunging into aluminum needed.
 |
| Aluminum Buttons and Conical Springs |
Once all the details of the buttons were done I cut them off the ends of the aluminum rod. That was done at my cutoff saw.  |
| All the Parts |
With all the parts done I assembled the clamp. Conical springs in a centered recess below the push buttons keep the threads tight against the 3/8" shafts. Push the buttons down to release the threads and slide the jaws where you want them. Release the buttons to lock the jaws back onto the threads. It sometimes it takes a 1/2 turn of the handles to register the buttons to the threads and get the buttons to pop back up.
 |
| Closed Tight |
 |
| Wide Open |
The sloped slots allow 30° of tilt in either direction.
 |
| Angled Open |
 |
| Angled Closed |
This project was another interesting design challenge. Allowing the threaded shafts to pivot relative to the jaws took a few iterations, some research, and some creative CNC vectors to solve. I've already been using this clamp. It delights me with how quick it is to adjust. The handles were left overs from my CNC Vise design and may need a few iterations yet. These work fine but a variation may be needed if I want to use the clamp flat on a table/bench.
Comments and questions are encouraged and welcome.
4D
