Motorized Big - Mouth Panavise Jr. Modification




Introduction: Motorized Big - Mouth Panavise Jr. Modification

Overview: The Panavise is a very common tool for electronic hobbyists. In this project I made a few mods:

1) Increased maximum jaw width from about 3 inches to 6 inches

2) Motorized jaw opening and closing (about 40 mm/sec). The motion is smooth and quite, and like power windows in your car - you get spoiled real fast. Manual operation using the standard knob is preserved.

3 Added a weighted base so attachment to workbench is not needed for most electronic applications.

View YouTube video to see it in action



Panavise Model 201 PV Jr. was used for this mod.

Panavise Model 201 Specs

Jaw width increase. This basically just requires replacing standard guide and screw shafts with longer ones as per contributor "Croy9000." Details in the steps that follow.

Motorized jaw opening. Since the vise screw is a 10-24 thread, it takes 48 revolutions and about twice as many knob-twists to move the jaw 2 inches - that takes a while to do manually. The motor can do it in about 12 seconds. In this mod, a gear motor ($10) is attached to guide shafts opposite the standard knob and drives the vise screw shaft via a DIY flex coupling.

Weighted Base. Four C cell batteries along with the jaw open-close rocker switch are mounted to a 7 by 6 inch wood base which also helps stabilize the vise. Motor current draw is about 60 mA, so the batteries should last a long time.

Step 1: Parts and Tools


One each unless otherwise noted

McMaster-Carr 6mm shaft collar 57485K66

McMaster-Carr ¼” shaft collar 9414T6

McMaster-Carr 1/4 OD Alum spacer 92510A305.

McMaster-Carr 7/16 ID, 9/16 OD, ¾ lg. Tygon tube 5552K33 (2 feet long, you only need 1 inch)

McMaster-Carr Tight - tolerance rod 0.2500" diameter 8893K204

McMaster-Carr 10-24 threaded rod 90034A410

McMaster-Carr 3 mm threaded rod 98861A040

McMaster-Carr 3M hex nuts 90591A121 (pack of 100, you only need 9 nuts)

McMaster-Carr 3M flat washers 91166A210 (pack of 100, you only need 6 washers)

(3) 1/4-20 x 3/4 lg. Flat head screws - hardware store

(3) 1/4-20 x T- nuts - hardware store

(4) rubber feet - hardware store

small tip-ty hardware store

(2) small 1/2" lg wood screws (for mounting battery holders - hardware store)

(2) Two "C" cell battery holder - Radio Shack 270-385

(4) "C" cell batteries

JST-PH Battery Extension Cable - 500mm - Adafruit ID: 1131 or similar

#19285 MD Gearmotor from

#30187 SW DPDT Rocker Switch, On/OFF/ON from

[it would be better if the switch was the momentary type, but I couldn't find one at a reasonable price]

1/2" thk. plywood 6 by 7 inches

(2) 1" square wood bar by 6 " lg

3/4 thk. by 2" wide piece of hardwood about 2" lg. (This will be the motor mount)

Loctite "Red" stud and bearing mount thread locker


Drill Press. Drill bits 5/16, 1/4, 7/32, 5/32

2 mm hex key, 3/32 hex key

Soldering iron

Wood saw, Hacksaw


Metal file

10-24 tap and tap holder

Step 2: Expanding the Jaw Opening

1. The basic idea is to follow the method Croy9000 described -

Croy9000 Instructions

With a few exceptions -

a) The screw shaft needs to be extra long to accommodate attaching the gearmotor, here are the shaft lengths needed:

Guide shafts: 9", Screw shaft: 9 3/4"

b) You won't need to keep the 3-hole black plastic end cap as it will be replaced by the motor mounting block (described in the next step). Because the mounting block is quite wide, the net jaw opening will be about 6 inches wide - still much larger than the 3 inches of the standard Panavise Jr.

Step 3: Make Motor Mount, Flex Coupling, Install and Test

1. Fabricate the motor mount from 3/4 thick hardwood per drawing A (PDF file). I recommend using a drill press for better precision. I taped the drawing on top of the wood block to use it as a drill hole pattern. Optional - paint the mounting block.

Test fit the block over the two vise guide rods - the fit should be snug, while keeping the rods running parallel to each other, check by fully opening and closing the vise using the manual knob to assure there is no binding.

2. Cut about 1/4 inch off the end of the gearmotor shaft - this will allow the coupling arrangement to be shorter overall. Put the 6mm ID collar on motor shaft and tighten the set screw.

3. Cut three lengths of 3mm all-thread rod, each about 55mm long. Thread the 55 m long sections into the lower three holes on the motor mounting face (do not use the threaded hole nearest the motor's drive shaft), and secure each section to the motor with 3mm hex nuts.

For the follow steps, please see the illustration: Gear Motor and coupling arrangement

4. Thread 1/4 aluminum spacer using a10-24 tap. With the motor mount block still installed, screw the space onto the end of the vise 10-24 threaded shaft and secure with Loctite "RED." Then install the 1/4 ID collar over the spacer an tighten the set screw. Allow the Loctite to cure at least 8 hours

5. Thread hex nuts and washers about 1 1/2 inches onto the three, 3mm shafts already attached to the motor (step 3 above).

6. Using a 3/4 inch length of Tygon tubing, connect the two collars OD together while simultaneously inserting the 3 mm studs into their holes in the motor mounting block. Then add hex nuts and washers to the very end to each 3mm stud so that the motor mount block is clamped on both sides by nuts and washers. See photos.

7. Use the manual knob to assure the vise screw shaft and motor turn together without binding.

Step 4: Wiring DPDT Switch, Batteries and Motor

1. There are plastic barrier walls between the switch terminals that need to be removed using a Dremel or something similar so that you can solder the "X" pattern wires between top and bottom pairs of terminals. See photo.

2. Follow the wiring diagram for battery holders and switch connection.

3. For connection to the motor, I used a junk box male and female connector pair - a better choice would be a JST connector since that's what the motor comes with already. I suggest JST-PH Battery Extension Cable - 500mm - ID: 1131 or similar.

4. Install 4 C cells and test the wiring to make sure the rocker switch powers the motor in both directions so the vise can both open and close. Note - you don't have to worry about which side to the switch drives the motor which way because you can just rotate the switch 180 degrees relative to the base plate during final assembly.

Step 5: Fabricate Base and Mount the Vise

1. Make the base plate from 1/2" plywood per drawing B (PDF file), pound three T-nuts into the underside as shown, and glue 1" square rails to each end. Optional - paint the base.

2. Mount the two battery holders to the underside with small wood screws, slide the switch into its slot, run the motor lead out its access hole and attach the vise to the base with 3, 1/4-20 flat head screws.

3. Install batteries, connect the motor lead and secure with small tip-ty. Test operation, and - if needed, swap the switch around in its slot.

4. Attach 4 rubber feet to the two bottom rails.

That's it. Enjoy !

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