Sunday, February 3, 2019

Quick Change Tool Posts for Vintage Lathes

My recently acquired Logan 400 9" lathe was originally equipped with and currently uses lantern-style or rocker-style toolholders. While effective, they are a pain to work with because they can be awkward and difficult to adjust properly, and by properly, I mean that the cutting point of the tool must be at the centerline of the lathe. This is because the cutting geometry must be correct to be not only efficient, but capable of producing a good finish.
The top picture is the toolholder (and wrench). The long serrated piece of metal is the rocker that is used to adjust the vertical angle of the tool that holds the cutting bit. The bottom picture is a threading tool inserted in the toolholder. Of course, the toolpost is intended to be held in the compound slide of the lathe.

The benefit to this style of toolholder? They are usually included with vintage lathes when you buy one. The downside besides the inconvenience of adjustment? The tools themselves are about $30 each and only accommodate one size of HSS bits.

Enter the Aloris-style toolholders. They come in two basic types: piston and wedge, with the wedge being believed to be superior. Several sizes are available that are scaled to be appropriate to the height of your spindle centerline above your lathe bed. The two most popular hobbyist sizes are 0XA for mini-lathes and AXA for 9-12" lathes.

There are also several different types of toolholders that attach to the QCTP (Quick Change Tool Post), depending on the cutting tool you want to use.

Little Machine Shop offers a good discussion on the choices available. It also lists the swing heights appropriate for the toolpost size.

Imports version are available on eBay and Amazon and, of course, directly from Aloris. It all depends on the money you want to spend and the precision and reliability you need.

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