why spider?

[mick70Participant @mick70]

Making a spider for lathe and my 7yr old asked why its called a spider.

Says should be tripod as 3 legs.

Can anyone help?

Thanks

[mick70Participant @mick70]

[Michael GilliganParticipant @michaelgilligan61133]

Seems a bright lad

[KWILParticipant @kwil]

Thats strange, most lathe spiders I have seen have 4 alignment screws! Just like a miniature 4 jaw.

[Clive HartlandParticipant @clivehartland94829]

When a surveyor uses a Tripod on a smooth surface he uses a 'Spider' to stabilize the three legs to stop them splitting apart on the smooth surface. So a 3 legged tripod needs a spider that the points of the legs lock into to fix them.

Clive

[Michael GilliganParticipant @michaelgilligan61133]

I presume you are making something like this … In which case the name may derive from its similarity to the 'Spider' in some loudspeaker suspensions. [which is an equally daft name, albeit very long-established]

MichaelG.

[egaParticipant @ega]

The late Clifford Bower showed a design for a device similar to Michael Gilligan's link in his invaluable manual Aids to Workshop Practice, with the refinement of a detachable centre plug to control the length of the jaws' grip. He called it a "Chucked-Work End-Stop"; I think I prefer spider!

The creatures of the same name are very plentiful in the garden at the moment. More to the point, naughty boy could have invited his child to look it up – COD has "any object having radiating spokes".

[Gordon WParticipant @gordonw]

May be from the spider web, ie. as in the picture books with radiating lines. OED says it is from old english for spinning. Hard to explain to a 7 yr. old tho'.

[Mark CParticipant @markc]

I think they call them a "cats paw" in America, also a type of knot i think?

Mark

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Gordon W on 04/10/2015 11:26:23:

Hard to explain to a 7 yr. old tho'.

.

Isn't everything ?!

… Mine is now a 33year old; but we still fondly remember some of his difficult 'How?' and 'Why?' questions.

MichaelG.

Edited By Michael Gilligan on 04/10/2015 11:36:40

[AjohnwParticipant @ajohnw51620]

I saw an interesting gadget that can do something similar on youtube. Just a ball race on a piece of metal in the tool post. Lightly tighten work in the chuck and run the ball race against it while moving the saddle or compound to true the work up. The poster also mentioned using the same idea for an edge finder.

John

–

[Michael GilliganParticipant @michaelgilligan61133]

See Fig. 3 in this Patent … Ling Dynamic Systems adaptation of an audio loudspeaker

MichaelG.

[JAParticipant @ja]

As a person who named things at works, names frequently make no sense at all. If the name sticks and is memorable that is all that matters.

By the way, what is a lathe spider?

JA

[davebParticipant @daveb17630]

Posted by John W1 on 04/10/2015 11:50:22:

I saw an interesting gadget that can do something similar on youtube. Just a ball race on a piece of metal in the tool post. Lightly tighten work in the chuck and run the ball race against it while moving the saddle or compound to true the work up. The poster also mentioned using the same idea for an edge finder.

John

That is the deluxe version of the method I use, I have a bit of 3/8 keystock fitted in one of the toolholders, used the same way, works very well.

Dave

–

[BazyleParticipant @bazyle]

This is a similar case to that of dead, live and revolving centres where misconceptions of the correct name propagates and is now appearing incorrectly in lathe manuals.

A spider is the device, 3 or 4 screws at the rear end of a mandrel to centralise and steady long stock. It has a number of thin screw sticking out so if detached and left in the tool box the analogy is obvious. Only a nit picking arachnologist is going to care about the number of legs. The one linked by MG above is not a spider, just a good idea needing a better name than 'spacer' but shouldn't nick something else's name.

well I'm blowed a little red arachnid has chosen this moment to crawl across my laptop screen.

[David Clark 13Participant @davidclark13]

A spider for the lathe usually has three bolts placed radially so soft jaws can close on it to be bored to suit the work. The article linked to above is just a flat back stop with slots cut to clear the jaws.

[Michael GilliganParticipant @michaelgilligan61133]

… Best wait for 'naughtyboy' or his Son, to tell us what he's making !!

MichaelG.

[mick70Participant @mick70]

Mg as in your link but not as fancy and edges are bit wobbly as young man did cutting.

Its to hold stock forward for some collets to go on my ml6 lathe.

[KWILParticipant @kwil]

Google lathe spider and they appear in all shapes and sizes, 3 and 4 screws

[BazyleParticipant @bazyle]

lots of references in the ME index.

 

 

Edited By Bazyle on 04/10/2015 16:07:43

[mickParticipant @mick65121]

David is right about the three screwed spider being used to hold soft jaws apart. Multi legged spiders are used for supporting large diameter tubes while being turned, the more screws the less the chance of distorting the tube.

[BazyleParticipant @bazyle]

1997, 179, 4051, 374, MJ Dwyer, three jaw spider

[AjohnwParticipant @ajohnw51620]

Posted by daveb on 04/10/2015 12:45:52:

Posted by John W1 on 04/10/2015 11:50:22:

I saw an interesting gadget that can do something similar on youtube. Just a ball race on a piece of metal in the tool post. Lightly tighten work in the chuck and run the ball race against it while moving the saddle or compound to true the work up. The poster also mentioned using the same idea for an edge finder.

John

That is the deluxe version of the method I use, I have a bit of 3/8 keystock fitted in one of the toolholders, used the same way, works very well.

Dave

–

I'll probably make the delux version. What I usually do is place some packing behind the work and press it firmly home while tightening the chuck then pull the packing out which might be a parallel strip if I have something suitable or what ever i have to hand if not.

John

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[Neil WyattModerator @neilwyatt]

I often use a wooden dowel or similar, one end between the shears of the lathe, as a lever to get awkward things running on centre. Works well for things with relatively small gripping surfaces.

Neil

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