Four-Jaw Chucks

[pennview]

There have been a few questions recently about using turning chucks on the Shopsmith so I'd though I'd post a few pictures that may help clarify a few things regarding scroll and independent 4-jaw chucks.

Here is a Nova 4-jaw scroll chuck that is almost 20-years old. The four jaw move simultaneously via two tommy bars or levers that tighten the jaws. Other models use a chuck key similar to those used with drill chucks. The jaws come in various lengths and clamp to a tenon you turn on the end of your stock or bite into a dovetailed recess in your turning. The jaws also can grip turning square or dowels.

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Here is an independent 4-jaw chuck. The four jaws move independently so you can do off-set or off-center turning, enabling you to turn something like a crankshaft with multiple centers. If you're mounting turning square or round stock, centering your work can be tedious, however.

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The Nova chuck is universal and can be mounted to a wide variety of lathes. The chuck itself is threaded 1 1/2" x 8 Threads Per Inch (TPI) and uses adapters or inserts that have male threads matching the chuck threads and female thread that match your lathe's spindle, or in the case of the Shopsmith a 5/8" smooth bore. Here's the Nova with the Shopsmith adapter mounted in the chuck and a 1" x 8 TPI adapter beside it.

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I'll add further details additional photos in another post.

[pennview]

Here is a Penn State Industries adapter (their model #L5818) that is used to mount my independent 4-jaw chuck to the Shopsmith. The adapter mounts to the Shopsmith spindle and has 1" x 8 TPI male threads that match the threads in the chuck.

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Here is the independent 4-jaw chuck mounted using the PSI adapter.

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[pennview]

Here is the Nova chuck mounted using the manufacturer's adapter for the Shopsmith.

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And here is the Nova mounted using the manufacturer's 1" x 8 TPI adapter plus the PSI Shopsmith to 1" X 8 TPI adapter. As you can see, it doesn't make a lot of sense to mount the Nova this way as it would put additional stress on the bearings by moving the chuck further away from the headstock. So if you're going the Nova route or using one of the other universal 4-jaw chucks like the One Way, I'd get the proper adapter from the manufacturer of the chuck.

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One other point I just noticed in the past few days after I saw some questions on the Yahoo group regarding the use of chucks on the Shopsmith. I reread the Nova operators manual (carefully this time) and saw that they say not to exceed 600 RPM when using the Nova chuck. Here's the on-line manual -- http://www.teknatool.com/products/chuck ... Manual.pdf . When I looked at my hard copy of the manual today, it said not to exceed 500 RPM. Nevertheless, I've use it on the Shopsmith as have a number of others.

[algale]

Thanks, this is helpful. I'm actually contemplating a 4 jaw chuck right now....