Conrod Vise – How To Build.

How many times in the past have you been guilty of clamping a con-rod in the bench vise to undo or tighten the rod bolts, or to carry out some other operation.

You more than likely took some care while you did this, but did you take a really hard look at the con-rod after removing it from the bench vise?

Chances are you didn’t, and you may not have noticed the metal bruising that took place where the jaws clamped onto the con rod, well perhaps you were careful enough to use copper, or aluminium soft jaws to protect the con rod, that’s good workshop practice, but it also means having to juggle everything while you clamp the con-rod, and I think you would agree they are not the easiest of things to hold.

The chances of damage caused by a bench vise (Minus the soft jaws) is quite high, the bruises and marks left in the con rod metal from the jaws are the very points at which stress and fractures will emanate, not the kind of thing you want in your new engine rebuild.

So What Is The Best Method To Hold A Con-Rod In A Vise?

You may, or may not have noticed the various con rod vises being offered by various engine accessory shops lately, they are designed to clamp any type of con rod without bruising or leaving marks on the con rod, commercial vises can be had from about $80.00 to $206.00US

They are considered an essential item to have in your engine building tool box, if you enjoy small DIY engine building workshop projects, a con rod vise can be built for a very low cost.

You Should Build Your Own?
If you have a reasonably equipped workshop with the right kind of tools and gear, why not make most of what you have, it is possible to build a quality con rod vise to for a fraction of the retail cost. Yeah, sure, you’ll spend a few hours on the project, so what, it might even help to keep you sane.

The photo below pretty well illustrates the quality of DIY vise that can be built in the home workshop, the materials cost less than $16.00 (Not including the con rod) from the local engineering steel merchant.

The vise was constructed from 3 lengths (170mm) x 1″ x 1″ (25 x 25mm) 1045 carbon steel, which is commonly called bright mild. The 5/8″ Dia outer rods that hold it all together are machined, drilled and tapped from 4140, but 1045 MS would be totally satisfactory, the pressure screw rod is machined from 1045 – 5/8″MS hex  machined to 9/16″ Dia and the lathe cut thread is 9/16″ UNF. A small spigot with a locking groove is also machined onto the end of the screw rod which locates into a drilled hole in the middle bar of the vise, the valve springs (Discarded Twin Cam Inner) keep the jaws open and ready to insert a con rod.

Construction is really just basic machine shop practice, and a very rewarding project to complete for your workshop.

This con-rod vise is designed to clamp and hold all Ford Kent push-rod and twin cam lotus rods, and if you wanted to make a vise for other types/sizes of rods then just alter the dimensions to suit if required.

Photo illustrates the parts custom made for the con rod vise, note the counter bores for the 5/8″ Dia rods, which are held with 1″ x 5/16″ x  UNC cap screws.

Some factory made con rod vises have a quick action over centre lever to do the clamping, the writer chose to go the traditional screw thread to apply the pressure and it works a treat, no need for anything else really, a 5/8″ AF ring spanner or socket and handle is used to apply pressure or to undo.

The con rod vise is normally held in the bench vise at the normal upright position, or it can be turned sideways (L or R) and clamped. To prevent marking and bruising the MS metal, make sure to use soft jaws. Some con rod vises have a lug attached under the lower vise rail in which to clamp into the bench vise, that is an option, but hardly worth while, just remember to always use the soft jaws when clamping the con rod vise in the bench vise.

This is not a difficult project to make, but you will have to decide whether you want to make or purchase… your choice.

But it is actually damn good therapy making things your self, and helps to keep your fitting and turning and general machine shop practice skills up to scratch.