ACCURATE MILLING VICE

I have experienced numerous difficulties when using my conventional type vise  to hold workpieces during milling.   The movable jaw tilted upward  slightly as the jaw was tightened causing the workpiece to shift upward.  The  parallels  could be  moved freely, even though the workpiece was tapped down as the vise was tightened.  This is a common problem with conventionally  designed vises, and obviously, introduces an error. 

I found a design for a vise that promised better performance.  This design is sometime referred to as a "screwless vise" even though a screw is used.  This design differs from the conventional design in that the movable jaw is pulled downward as the vise is tightened.    

Screwless vises  are commercially available, but I thought that the design was within my machining capabilities, so I decided to make my own.  

My vise  is 60 mm wide, 130 mm long, 50 mm high, and has a maximum opening of 75 mm. The material is mild steel.

   
<< Drawing is here >>

Mild steel is used throughout, except for the brass inserts. 

Accurately aligning the angle plate on the mill table.  See Article Number 28 for additional information on the angle plate.


Precisely squaring the body edges.  

A precision trysquare was used to set the right angle.  Fine adjustments were made with taps of a small hammer

After milling, the workpiece  was checked to assure that it did not shift during machining.

Cutting the first side guide slot.  The overall width is 10 mm and the depth 15 mm. Cuts progressed in 0.5 mm steps using a roughing end mill.  

After completing the first  slot, turn the workpiece over without changing the setup to retain symmetry.  Second slot cuts also progressed  in 0.5 mm steps.  

Unfortunately, a locking screw  of the mill loosened and led to running off track.  The ruined piece was saved for another project and a new piece was selected for a fresh start.    


Marking out the side holes after machining the two guide slots.

Drilling the holes, 50 mm deep -- a key process in making this vise calling for precise drilling -- the  holes must be straight and positioned accurately.  

The hole positions were indexed using a
dial indicator.  The marking out lines served for double-checking to avoid careless errors.


The holes were drilled to 7.8 mm and reamed to 8 mm.  

Since hole accuracy is critical for smooth  operation of this vise, each hole was inspected using a mandrel and trysquare.  All holes passed.

Cutting the slot in the underside of the base. The slot depth extends to the centerline of the cross-drilled holes. 

The end mill 12 mm.


Completion of the underside slot cutting.

A slot has been cut  through from the underside of the base.  A 12 mm end mill was used, with depth increments of 0.5 mm.
Initially the fixed jaw was mounted  with robust machine screws set into  counterbored holes. 

Eventually two tight-fitting dowels were added to fix the jaw and provide additional rigidity. The dowels were set with Loctite, high strength.   

Machining the moving jaw while held in a drill press vise.

The drill press's lack of precision makes it difficult to machine  parallel surfaces on the mill.  As shown, shims were  added as packing under the vise.

Drilling the hole for the vise's tightening screw, starting with a center-drill.

Machining slot for tightening screw.

The clearance space in the moving jaw is made as shown in the figure.

The white area is the clearance space.

Reaming the cross-hole in the moving jaw to a diameter of 12 mm.



This is the tightening system.

Drilling a brass jaw plate while held in partially finished vise.

All the finished parts.

View of the underside of the vise.

It is complete.
The jaw plates are made of brass.