Router guide bush thread dimensions

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gcusick

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I want to make - 3D print - a router baseplate that will take the threaded guide bushes (like the Leigh, AUK or Katsu ones) without needing the separate locking ring.

Does anyone know the dimensions of the thread? Best I can do by measuring is 30mm diameter and 1.2mm pitch, but I’m not that confident in the measurements.

Thanks
Geoff
 
I am under the impression that the common name for that design of guide bush is 'Porter Cable style'.

Try this thread:

https://www.routerforums.com/threads/guide-bushing-thread-size.140835/
It says 1 3/16" x 20tpi.

Being of US origin, they are unlikely to be metric.

1.2mm pitch is extremely non-standard in the metric world.

If you have one to hand, measure it in both sets of units using a caliper and with a proper thread pitch gauge (Draper 51072 is a good set - technically it is the wrong thread form for US imperial, but it will identify the correct pitch).

Edit:

Having just gone to my cold garage and retrieved my Katsu ones (imperial and metric), the securing ring is interchangeable between the sets.

They measure 1.176" or 29.9mm OD and both 20 tpi and 1.25mm pitch gauges fit.

On that evidence, either M30 x 1.25 or 1 3/16" x 20 as above would be a good starting point.
 
Last edited:
I am under the impression that the common name for that design of guide bush is 'Porter Cable style'.

Try this thread:

https://www.routerforums.com/threads/guide-bushing-thread-size.140835/
It says 1 3/16" x 20tpi.

Being of US origin, they are unlikely to be metric.

1.2mm pitch is extremely non-standard in the metric world.

If you have one to hand, measure it in both sets of units using a caliper and with a proper thread pitch gauge (Draper 51072 is a good set - technically it is the wrong thread form for US imperial, but it will identify the correct pitch).

Edit:

Having just gone to my cold garage and retrieved my Katsu ones (imperial and metric), the securing ring is interchangeable between the sets.

They measure 1.176" or 29.9mm OD and both 20 tpi and 1.25mm pitch gauges fit.

On that evidence, either M30 x 1.25 or 1 3/16" x 20 as above would be a good starting point.
Thanks for that - just what I needed.

Geoff
 
A follow on from this.

I've successfully printed sub-bases for both my routers that work perfectly with the Katsu threaded bushes I'd bought. Then I needed a second 30mm bush so that I could use both routers on the same job (making t-slots). A search for just a 30mm bush led me to Trend Screw-On Style Guide Bush for Precision Routing, 1 3/16 Inch, GB/US/30 - £8.20 from A*zon, but still substantially less than a complete set. And, I thought, I'll get a spare locking ring into the bargain!

But when I try to screw the Trend bush into the sub-base, I discover that the thread is the same diameter as the Katsu/Leigh/Porter-Cable ones, but a different pitch! Why, in the name of all that's holy? Why? Thanks Trend.
 
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