3 Jaw Chuck Runout

I’m getting significant 3 jaw chuck runout on my Warco 240B lathe. Although ok at first I’m now finding the chuck as delivered with the lathe is rubbish.

warco 240b lathe

As delivered the Warco 240B lathe and the 3 jaw chuck were brilliant, but over time the runout on the 3-jaw has increased.

I’ve even marked the location that the 3 jaw should be fitted, but still it’s not great. It might be that I’ve been a gorilla and over-tightened it.

I set up a digital dial gauge and measured total runout for a few different sized bars and using the inside and then outside jaws.

warco 240b original 3 Jaw runout

Runout Measurement

Material Diameter mmRunout mm
22.350.140
41.300.120
1000.234
Warco 240B original 3 Jaw Chuck

Comparing this to my Hobbymat MD65 I measured a runout of 0.054mm at 22.35mm diameter. A much more acceptable runout than the Warco even though it’s a much older lathe.

A really good runout is zero, 0.001″ (0.0254mm) is good for normal use, 0.003″ (0.0762mm) is workable. If you want an accurate chuck then use a collet chuck or a 4 jaw independent chuck.

warco 240b spindle runout

Spindle Runout

Just to be sure all was well with the base lathe headstock I removed the chuck so that I could measure the runout of the spindle.

Radially I measured a runout of 0.006mm and axially 0.004mm.

This is a tiny runout and nearly down to surface roughness.

My work around has been to either mark the work piece and the jaw so that I could rotate it and align the part with the same jaw. Or if looking for high accuracy to use the 4 jaw chuck. The problem with the 4 jaw is you need to dial the work piece in.

This got me wondering what the options were for a replacement 125mm 3-jaw chuck.

Bison

Approximately £420

Looks like prices can vary across the net, but expect to pay between £300-400. 2-piece jaws and 32mm pass-through diameter.

If you go for a precision steel body chuck from Bison then the prices are roughly double.

Pratt-Burnerd

Approximately £220 for std

~£300 for the precision chuck.

An old name in the word of lathe chucks and a phenomenal reputation, the latest reviews though are a mixed bag.

Soba

Approximately £110

This is the lathe chuck I’ve chosen. I have some Soba tools already and they are rather good, eg optical centre. Front mount, inside and outside jaws.

This chuck has now been fitted with a backplate and tested on the lathe.

Vertex

Vertex 3 jaw lathe chuck

Approximately £150

30mm through hole on the 125mm chuck.

Warco

Approximately £80

A replacement Warco lathe chuck might be ok, but will it fail in the same way.

If nothing else a change is as good as a rest.

What I’m not sure about with any of these lathe chucks is who actually makes them and who just re-labels them?

About Nigel 338 Articles
I've been making models since I was around 7 years old and using a lathe from the age of 11, a self taught engineer with a passion for making model engines.

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