Making a 3/4 x 16tpi lathe spindle thread protector?

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Making a 3/4 x 16tpi lathe spindle thread protector?

This topic has 10 replies, 6 voices, and was last updated 13 March 2021 at 12:43 by Roderick Jenkins.

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12 March 2021 at 16:52 #533446
jon hill 3
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@jonhill3
Recently purchased a Coronet 2 wood lathe and want to make the above for when I am using a drive centre in the headstock. I had thought of adapting a spare chuck adaptor so that the morse taper tools will fit.

Or I had heard of a technique using a smaller tap of the same tpi and pitch held in a block in the tool post.

Any sugestions?
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12 March 2021 at 16:52 #28041
jon hill 3
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@jonhill3
12 March 2021 at 17:05 #533450
old mart
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@oldmart
3/4" X 16 happens to be a UNF thread, maybe you could get hold of a nut and modify that.
12 March 2021 at 17:19 #533451
Ian P
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@ianp
If its purely to cover the exposed threads when you are using the Morse socket then something as simple as a short length of PVC tube or even a turned wooden sleeve could just be a push fit.

Unless I've misunderstood the requirements.

Ian P
12 March 2021 at 17:45 #533455
Roderick Jenkins
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@roderickjenkins93242
On my Coronet Minor lathe, also 3/4"x16, the nose protector is also used as an extractor for the drive centre since the mandrel is not hollow all the way through. The drive centre has a flange for extraction.

HTH,

Rod

Edited By Roderick Jenkins on 12/03/2021 17:54:27
12 March 2021 at 18:07 #533457
jon hill 3
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@jonhill3
Hi Roderick, do you have a pic of your nose protector perhaps I could make a copy?

Jon
12 March 2021 at 18:53 #533469
Roderick Jenkins
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@roderickjenkins93242
Here you go:

Rod
13 March 2021 at 00:54 #533519
Dr. MC Black
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@dr-mcblack73214
I just spin a nut onto the mandrel thread. That can also be used to release the fixed centre (locking the rotation) when necessary.
13 March 2021 at 11:53 #533570
Howard Lewis
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@howardlewis46836
What is the thread form?

As already said, 3/4 x 16 is UNF, which is 60 degree form. If the form is Whitworth, it will be 55 degree, which may accept a UNF thread, (I know that a female UNC will not happily accept a Whitworth thread despite being the same pitch ).

If it is 3/4 x 16 Whit form, the thread is a special, with a finer pitch than either 3/4 SW (10 tpi ) or 3/4 BSF (12 tpi ) and will need to be screwcut. Although Tracy Tools offer 3/4 x 16 Taps and Dies (The Autumn / Winter catalogue lists Taps at £10 and Dies at £12 ex carriage and VAT. )

Howard
13 March 2021 at 12:39 #533585
Dr. MC Black
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@dr-mcblack73214
Posted by MC Black on 13/03/2021 00:54:56:

I just spin a nut onto the mandrel thread. That can also be used to release the fixed centre (locking the rotation) when necessary.

Apologies I should have mentioned, the nuts are 3/4 x 16 UNF.

I believe that's one of several standards for woodworking lathes

MC
13 March 2021 at 12:43 #533588
Roderick Jenkins
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@roderickjenkins93242
I used a UNF tap to make a couple of wedge chucks which work ok. The register is also 0.750". Always tricky to determine thread forms on these late 20th century British machines. Industry seemed to make the move briefly to Unified threads before embracing Metric

Rod
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