Introduction: PanaVise Junior "Big Mouth" Mod

I love my PanaVise Jr. But about half the time I go to use it I find its just not wide enough to hold what I'm working on. At only a 3" opening, it only holds the smaller of my projects.

After disassembling the vise to see how I might be able to extend the opening, I discovered it was very doable. This Instructable documents how I was able to extend it to a 7¼" opening for only $7 in parts! The end result is a product that looks as good and works better than the original.

Important Notes:
  • This will make the vise more unstable since the wider it opens the more its off balance. But it works great for me, and a homemade base would solve most issues (EDIT: or one of their own bases here
  • The wider you make this, the more screwing you will need to due to open and close it that far.
  • You will need a tool to cut 1/4" steel rods (hacksaw/miter saw/etc)
  • You will need a grinder or dremel to make a delicate cut in one of the steel rods.

Step 1: Planning

Below are the original plans I drew up for the mod.

The parts that will need to be replaced are the two outer glide shafts, and the inner threaded rod. The new length for the replacements will obviously determine your new vise opening.

You can decide on your own vise opening size, as long as you follow these rules (ensure your own vise does match up with this):
  • The vise opening = Shaft Size - 1¾in. This accounts for the 7/8in arms on either side.
  • The threaded rod should be 3/16in longer than the glide shafts. This accommodates the threading into the knob.

I chose to use a 9in shaft, which means my vise opening will be 7¼in wide. It also means that my threaded rod needs to be 9 3/16in long.

Note: While a very wide opening is nice, because of the design of this vise it will start to tip over the wider you go with a load in it. A bigger base addition would fix this though.

Step 2: Parts

You will need the following parts:
  • 1/4in steel rod (Lowes 30302 | McMaster-Carr: 6061K101)
  • 10-24 threaded steel rod (Lowes 10305 | McMaster-Carr: 90034A410)
The Lowes version is nice because both rods come in 3ft lengths, and are cheaper than what I found at McMaster-Carr. If you go with McMaster-Carr note that I just picked some random lengths, so make sure you buy the right ones.

Step 3: Disassembly

1. Remove the plastic endcap (opposite side as the knob). I did this by simply expanding the jaws of the vise until it popped off. Save this cap as you will be re-adding it.

2. Unscrew the threaded rod all the way out, and pull the assemble apart.

3. Remove the knob from the threaded shaft. I used a pair of vise grips to hold the threaded rod while I unscrewed the knob.

4. Pull the threaded rod from the jaw. Make sure you save the hard fiber washers for reuse.

5. Remove the retaining ring from the threaded rod. Note the notch it was clipped into. This will be referred to in the Fabrication step.

6. Remove the glide shafts from the jaw. They come out with a punch and hammer, or similar tool.

Step 4: Fabrication

1. Cut your two glide shafts and threaded rod to length (lengths determined in the Planning step). I used a miter saw with a metal cutting blade, but with some effort you can use a hack saw. I cut mine to 9in and 9 3/16in respectively. Use a file to cleanup the threads on the rod.

2. Now for the tricky part. If you look at the original threaded shaft you removed, you will see one inch from the end where PanaVise removed one thread, this is where the retaining ring clipped into place. I used a bench mounted grinder with a stone that had a fresh sharp edge to it to gingerly grind away a narrow ring. I couldn't get it only one thread wide, mine ended up two threads wide, but works fine like that. Maybe someone has a better suggestion for this part.

EDIT: User Spokehedz and Redleg had a great suggestion for the above step. Put the rod into a drill and spin it while using a dremel to carefully cut the thread. See their comments for more details.

Step 5: Assembly

1. Insert the glide shafts into the jaw. You can just hammer these into place.

2. Clip the retaining ring onto the threaded rod (where you removed the thread).

3. Slide the threaded rod into the jaw (with the hard fiber washer first) until the retaining ring fits into the recess.

3. Thread the rod into the knob. I used channel locks to grip the rod as close to the jaw as you can. Try not to mess up the threads any more than you have to, but this close to the jaw you should be fine. (Maybe someone has a better suggestion here?)

EDIT: User fubal19 had a great suggestion for the above step. Thread two nuts onto the rod, tighten them together, then use a wrench on the nuts as leverage to thread the knob on.

4. Push the glide shafts into the opposite jaw, and thread the rod into place.

(Queue the Jaws music) You did it! Rate it if you like it!