Zero Adjustable Dials with Rotating Handles
for the Taig Lathe

Even if you are not planning to do these modifications, this section could be useful to you. Sooner or later, the leadscrew backlash will become excessive and need tightening up. Here's one safe way to get it apart.

Taig uses a little Loctite to secure the factory settings of the dial and it's not always easy to loosen it. The photos show how a hole drilled in the leadscrew allows a tommy bar to counter the force used while freeing up the locknut and dial. This is a #53 (.0595") hole which is just big enough for an .050 Allen key. This key offers some safety in that it will bend before you can put too much torque on the leadscrew.

Once the Allen key is in place, the brass acorn lock-nut can be removed with a 5/16" socket. Then the dial can be unscrewed. Sometimes they come right off and sometimes heat is needed to soften the Loctite. A small butane torch works very well. In any event, if the key starts to bend, back off and apply a little more heat. Take it easy and it will ultimately come free.

Cut an 11/16" long piece of 1 1/4" diameter 12L14 steel. Dial indicate it true in the 4-jaw chuck leaving 1/2" exposed for machining. Face off the end and turn the axle part to 9/16" diameter for a length of .410 inches. This length is based on a Taig dial thickness of .404" and thus allows .006" for end play. Taig dials from different production runs may vary from this dimension so you should check yours and adjust if necessary.

Turn the circlip groove 1/16" wide, .024" deep and .051" in from the end. A standard 9/16" snap ring is .039" thick so this gives an additional .024" or so for its spring action.

Lightly chamfer the end. Center drill, then right through with a #35 (.110") drill for the 6-32 thread. Counter bore the end #28 (.1405") about 1/10" deep.

This completes work on this end of the arbor. Wear is reduced on the tap by leaving the actual threading until after the nut recess is bored from the other side.

Reverse the arbor and hold it in the 3-jaw chuck by the 9/16" diameter section. Take enough off the 1 1/4" diameter to clean it up and face it off to 1/4" long. Chamfer the end to about the same as on the Taig dial. Drill 3/8" .410 deep and then bore the bottom flat with a 3/8" end mill.

Tap the spindle hole 6-32 and try the new arbor on for size. The only remaining job is to drill and tap the 8-32 crank handle mounting holes. Some people like two handles, others just one. Providing two holes now allows either configuration later.

There is nothing special about these crank handles. The plans show a common design used in this particular instance. But the only requirement is the 8-32 thread. Otherwise, the shape and size are strictly a matter of personal preference.

The stock is fed through the headstock and held by either a collet or the 3-jaw chuck. Starting with 1/2" or so projection, turn the .164 diameter for the 8-32 thread. Use a 1/16" parting tool to provide a groove next to the shoulder for the die to run into when threading. Move the stock farther out of the chuck to turn the 3/16" shaft. Finally, thread the end 8-32. A tailstock die holder works best but any way that gets the thread reasonably square is fine.

Set this part aside for the time being. Before it is parted off, it will be used as a headstock arbor to hold the handle while turning the taper.

Cut off a piece of 3/8" brass a little longer than needed for the handle. Face the end, then drill through 3/16". Counter bore the end 1/4" diameter, 1/8" deep for the head of the axle screw. A 1/8" HSS drill blank can easily be ground to make a great mini boring bar.

Cut off a piece of the same brass about 1/4" long. Face the end, drill it 3/16" diameter about 1/16" deep, then drill and tap 8-32. This is a sacrificial nut that will be used to hold the handle on the arbor while the taper is turned.

Reverse the handle in the chuck and face off to a length that gives just a little end play when put on the arbor. Thread the sacrificial nut on the end and tighten it with pliers to hold the handle fairly tightly.

Mount the top slide and set it to the 4 degree taper angle. Turn the taper right through the sacrificial nut using light cuts of .005" or less and slow feed. Brass is pretty easy to turn but the holding power of this arbor setup is not very great.

Reverse the handle on the arbor and use a file to lightly round over its butt end.

The last operation is to part off the arbor and slot the screw head. This completes the handle and arbor set which can now be attached to the crank arbor. A little light grease is probably not a bad idea.

Reverse the soft jaws on the 3-jaw chuck. Grip a 1" washer right next to the chuck base and bore a recess in the jaws about 1/4" deep and to a diameter of about 1 1/8". Open out the jaws, remove the washer and grip the 1 1/4" Taig dial. This technique gives all the accuracy required for this operation. The jaws can later be reversed back to normal and nothing has been lost.

Chuck the dial with the micrometer graduations toward the tailstock. Drill it to 1/2" and bore out to 9/16"+ using the new arbor as a plug gauge to get a nice easy rotating fit.

Measure the actual distance from the arbor shoulder to the snap ring inner face. The circlip recess in the dial should be bored to leave the bearing surface about .010-.015" less than this but still ending within the range of the circlip groove. In this case, the distance was .323". The final dial bore should be .323 - .015 = .308". The dial thickness of .404" less the .308" bore leaves .096" to be bored for the 13/16" diameter circlip recess.

If the dial is now put on the arbor and the snap ring put in its groove, the dial will just spin without much friction. But if the snap ring is first bent as shown to make a kind of spring, it will press on the dial and make its movement somewhat restrained. This is the intended effect.