Dual Screw Wooden Vice

 Dual screw wooden vices were often used in carpentry workshops before steel vices became common. A variant of these is the so-called Moxon vice that is portable and can be attached to an existing workbench or in fact any reasonably stable table or trestle. This vice gets it's name from a book published by Joseph Moxon, 1703 , apparently the first book published on English on woodworking. Amazingly the vice is still available but with steel screws, eg. Axminster Tools, although Lake Erie Toolworks in USA still make a wooden screw version.

My idea was to try and make a dual screw vice that could be attached to a workbench permanently or used as a portable vice. The big advantage of the vice is the wide gap between screws that allow the clamping of long boards, e.g when doing dovetails on cabinet sides. Another advantage that when it is clamped on top of an existing bench, it raises the work height a little making joinery easier on the back!! I will be using imperial measurements mainly because the thread cutters and brace bits are made to imperial sizes. However, I do revert to metric occasionally.

I made the vice using kiln-dried beech. The main stock was two pieces measuring 20 x 3 3/8 x7/8 inches for the front of the vice and 23 1/2 x 3 3/8 x 1 1/2 inches for the rear plate. These were cut and planed to get square edges. The threads were put in the rear plate and oval holes in the front plate. The screws were made from 1 1/2 inch beech dowel so the holes in the front were 1 1/2 inches and made oval by filing. Making them oval allowed the front to angle a little. Gaiters were not used, again to allow more flexibility in clamping varied shapes of wood. The holes in the rear plate were 1 3/8 inches to allow threads to be cut with a 1 1/2 inch box thread cutter. 

I started on the rear plate and drilled holes 15 3/4 inches apart (to permit boards of up to 14 inches between the jaws). I didn't have an auger drill for my brace of that size (I have 1 1/4 and 1 1/2 inches and don't know even if they made a 1 3/8 inch size) and so had to resort to a 35 mm Forstner bit that I'd bought in a Chinese store in Spain (after sharpening this did do the job). The threads did take some effort to cut even with oiling. I needed to release the cutter a few times to ease the cutter and remove waste. I found the best method was to cut say half a turn and then reverse a little to free the cutter and then turn forward again. I also removed the cutter several times to clean the threads. 

From top to bottom (1) the rear plate with the holes drilled and threaded, (2) the front plate with the 1 1/2 inches holes made slightly oval, (3) a handle turned to a dash under 1 1/2 inches diameter for the screws and 1 inch section for a larger handle to attach.

The front plate was easier as I had a 1 1/2 inch bit for the brace. I made the holes oval with a round rasp file. The front plate is a tad wider than the rear plate to make it easier to align with a work bench if it is sit on top of the bench.

The handle before threading. All components made from beech apart from the stoppers on the bar which are oak.

The handles were made from beech dowel (1 1/2 inch diameter) and some beech left over from other projects. The beech dowel was 12 inches long and divided into 8 1/2 inches for the screw and 3 1/2 inches for the handle itself. Firstly, the diameter of the dowel was adjusted to fit into the screw threader box (it was too wide and needed coarse sanding to get to a comfortable size to get through the box). The handle section (3 1/2 inches) was turned down on the pole lathe to 1 inch diameter. The main handle was sawn to 5 inches long and 2 1/2 inches square and then planed to an octagon cross-section (2.69 cm sides). A 1 inch hole was then drilled down the centre to a depth of 6.0 cm to accommodate the spindle. This would be glued into the handle (I used polyurethane glue for this) with an oak bar passing through the main handle and spindle to secure the joint further. Finally a beech bar (3/4 inch diameter) was located though the main handle (a hole 13/16 th inch was drilled to allow free movement of the bar) and fixed with 3/16 inch toggles on the ends of the bar and the end of the handle shaped to a dome to make handling more comfortable. 

The next step was to cut the threads on the spindles. The spindles were first soaked in "Butcher's Block " oil for 2 days and then cut (since then I have cut threads in beech with only 5 hours soaking). This worked well as shown below. The threads allowed a jaw opening of 6 inches.

Threads cut on the 1 1/2 inch beech spindle after soaking the wood in oil.

Finished dual-screw vice after waxing the threads and treating the beech with linseed oil.

Vice clamped to the bench and in use. 

Showing details of the handle and screw. The so called Moxon vice is traditionally mobile and clamped to a bench. However, this one can also easily be permanently attached to a bench with coach bolts.

Finally some thoughts on the construction. The problem I had anticipated was cutting the long threads on the spindle without tear-out on the threads. In fact the threading was easy after 2 days soaking in oil and no tear-out. I can't say how soaking effects the threading but it is not difficult given some planning. Joining the spindle to the handle is tricky and needs care. This is because of the long hole needed in the handle and getting this central in the handle needs practise when using the traditional brace and bit. It would be easier to turn the spindle and handle from one piece of wood. Also in retrospect, it is better practice to drill the holes in the front and rear plates with a 1 3/8 inch bit with the plates clamped together. I didn't have a drill of that size so compromised by marking centres and drilling separately.  Having oval holes in the front panel makes fitting easier if there is a slight mis-alignment and of course this also allows the front panel to clamp at at an angle. 

I noticed that when clamping narrow pieces that only contacted the top of the jaws that the bottom of the jaw was pulled in. To stop this I later added an additional screw in the middle of the jaw and near the bottom that allowed the bottom part of the jaw to be held in place and not swivel. This I made from some green ash wood, turned on the pole lathe as one piece and then threaded with the 3/4 inch threader. This addition is shown below.

Ash screw added in the lower middle of the jaw to prevent the jaw swivelling when clamping narrower pieces of wood. This can be unscrewed in normal use on wider pieces.

Finally, after using the vice I decided that the front plate was too thin so I doubled the width and this worked perfectly. Since then, I have made two other vices similar to that described above but with thicker back and front plates and slightly longer threads but otherwise identical. I improved the alignment of the holes by being careful to get two reference faces planed correctly and marking the hole centres carefully to allow drilling from both side if necessary. This is particularly important for the back plate where the holes must align exactly to allow threading. My Forstner bit was too short for a direct bore-through so I needed to bore from both faces of the back plate. I haven't been able to get 1 3//8 inch brace bit and found modern auger bits are unsuitable. 

Since the first vice, I have made another two for family but the third one didn't go well because the threading tool cutter broke. The cutter blade in these tools is I believe made of mild steel and seems quite fragile. It can be sharpened but it is more difficult to repair when the edge or edges break off. Also the positioning of the blade in the tool is crucial to cutting a good thread that matches the female thread cut with the die. The spindles I cut were too tight and so I deepened the cut and in doing removed too much wood. Anyway, this gave me an opportunity to make new spindles from greenwood ash. This is the first time I have used greenwood to make 11/2 inch threads. I have done so with 3/4 inch threads in greenwood and this worked fine. I am concerned about the wood movement during drying even though the ash had been felled for several months.

 This time I planned to make the spindle and handle in one piece and use a new cutter to make the threads.

The starting ash log was split into four ready for sectioning and preparing for the pole lathe and turning a spindle and handle in one piece. The log had been felled in the previous spring and had been on the woodland floor all summer and autumn.

The wood was axed and ready for the drawing knife.

Turning to size on the pole lathe. The handle is on the right (about 8 cm diameter) and the spindle for the threads is on far left (1.5 inches in diameter). The remaining part of the spindle needs to be turned to 1.5 inches. The diameter is adjusted so the spindle passes through the bottom section of the threading box.

Ash spindle and handle after turning on the pole lathe and ready for making the threads.

After threading using a new blade in the threader.

Close-up of the threads. 

Initially the threads were cut in the top 10 cm and I found that they were too shallow as they were too tight in the threading box. It is difficult to judge the position of the blade accurately but I pushed it out a little and this seemed to do the trick. I checked the fit on the first vise and it worked well without problems. I have noticed that the exact shape or depth of the thread is more critical when threading through  thicker wood.

Finished vice. This is a smaller and lighter vice than the others. 

The second thread was cut without problems and checked in the vice as shown above.

PS. This is a copy of a note 77A32 given by Woodcraft in USA.  This is useful but the reinstallation method that is given didn't work for me. I had to adjust the cutter deeper so that the cut thread passed through the alloy threads without binding. I know if you go too deep the crests of the threads are damaged and produce a loose fit that cannot take hand pressure when tightening with the vice. If the cut is too shallow, the thread binds in the box i.e. the fit in the alloy is too tight and can bind very tightly and possibly get stuck in the box. 

 From Woodcraft literature:: Sharpening/Cutter Adjustment The thread box is sharpened and adjusted at the factory and should work well as taken from the box. With use, the cutter will need sharpening, which will require removal and subsequent readjustment. To sharpen the cutter, remove the guide by unscrewing the two brass screws which secure it. Undo the acorn nut and remove the cutter and cutter holder. Sharpen the cutter carefully, holding all the angles and bevels true. Use a fine grade, high quality, oil stone such as hard or black Arkansas. Reinstall the cutter and align the bottom of the "V" of the cutter with the crest of the inside thread. Tighten the acorn nut, replace the guide, and try the box on a dowel which is as true in size as possible. If it binds and breaks the thread as the box is withdrawn, the cutter is out too far and must be moved back. If it cuts thread with a sharp V crest and a shallow, rounded root, the cutter must be moved out.

A perfectly formed 60 degree thread with proper root depth and easy withdrawal from the box indicates a properly adjusted cutter

Further notes

The important part of the description above is ""..align the bottom of the "V" cutter with the crest of the inside thread" is crucial because if the blade is further in, the cutting will be too shallow to go through the box and possible bind if forced and cause problems. If it adjusted too far out, it will cut too deep into the dowel making it a smaller diameter and too loose. The ideal is somewhere between with the bottom of the "V" near the crest. When I placed at the crest, the dowel was too tight in the cutter and couldn't be turned. When I pushed the cutter a fraction further in, maybe 1/16 inch, it formed a tight fit but turned OK. I noticed that in this position, there was no play when the dowel was passing through the cutter. This seemed to work OK in the vice but it is all quite difficult to get right.

The correct position for the cutter as viewed from the bottom of the box with the guide box removed. Placing a small ruler along the thread, the bottom of the "V" protrudes slightly. Moving the cutter further out will loosen the dowel in the cutter and make the "V" deeper but if taken too far will cause the crest of the threads to be removed and the diameter of the dowel reduced and produce a spindle that is too loose in the "nut" and will slip under pressure. The cutter position is even more crucial with wide nuts.

Great care is needed when trying to alter the cutter further out after the threads have been cut once. I found the best method was to view the cutter position when engaging the thread and turning with the cutter in one hand and the spindle in the other. At the moment I think it is important to ensure the cutter is a symmetrical "V" shape and also sharp. I use a fine diamond file for this. Another trick is to adjust the cutter and check it's position using an existing threaded spindle that screws well.  Carefully screw the start of the threaded rod into the threader box and observe the cutter through the waste hole to see how the cutter aligns with the existing thread.