Cannot let this pass without comment

Well I wanted to post this video of a bidirectional thread cutting exercise. Not sure if it has been seen before, apologies if it has, but I thought it clever

You tube thread cutting

Edited By Sam Longley 1 on 19/12/2020 22:18:01

Neat. Gotta love the Russians. They are masters of innovation born out of years of necessity to do everything with the almost nothing they had available.

I taught English to Russian refugees back in the late '80s and they regaled us with endless stories of how they fixed their Russian motorbikes and cars and tractors with no parts available. Stuff like pulling the springs out of leaking garter seals and shortening them to make the seal work again, or cutting dead car batteries open, scraping the sulphide off the plates and putting them back together by using the collective farm's plastic irrigation pipe welder to seal up the casing. Or climbing up lamp posts to steal the street light reflectors to make nice stainless leg shields for winter riding on their Jawa 350 motorbikes.

Using a hand held router in the toolpost to do thread milling comes right out of that school. Great stuff! And the double thread takes it to a whole new level. Not sure what you would use it for but a great conversation piece.

That's a nice chunky one

Fishing multipliers have a similar system where the "nut" changes direction when it reaches the end, it all runs back and forward on a single milled thread, clever stuff, and very reliable too

They call it a level wind mechanism

You can see it from 2.37

Edited By Ady1 on 19/12/2020 23:30:06

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Déjà vu ... but thanks for posting a clickable link 

**LINK** : https://www.model-engineer.co.uk/forums/postings.asp?th=169837&p=1

MichaelG.

Edited By Michael Gilligan on 19/12/2020 23:37:40

I am a bit slow-- I will try & keep up next time

It’s good enough to get mentioned twice, Sam !

MichaelG.

Thanks for the link to that intriguing video - once more with feeling - the author puts his heart and soul into turning on that nice-looking lathe.

I very much liked the Plug-It style lead to the router he was using.

Bi-directional threads are used in a wide variety of applications needing constant-speed reciprocation with minimal reversing time at each end.

I have seen it on an offset-lithographic printing press to oscillate pairs of water and ink rollers against each other for even spreading. The screws were little more than helical cams as they had only two or three turns.

A big version of the fishing-reel mechanism Ady1 describes, is used to drive the fairlead back and forth on special winches for handling items like sonar towed-arrays (a long string of hydrophones in a hose), that must be wound accurately to avoid "birds-nesting" that would damage the item. The screw pitch is the diameter of the item being wound on.

' ' ' '

Level-winding can also be done with a fairlead operated by a cam, and I can remember when very young, being fascinated by the action of the level-winding spool-filler on our Mam's sewing-machine. As the fairlead swings on a single pin at radius R through an angle A, I would guess the cam's heart-shape is of, or is based on, (R, sin-A).

' ' ' '

YouTube videos are inaccessible to me now, but I can certainly vouch for Russian ingenuity from some I saw a while back. The machinists were making sizeable conical screws with sharp ridges and wide roots, like wood-screws. In fact they were wood-screws - for splitting logs! The lathes, of uncertain vintage but clearly rugged and effective, appeared to have their power-feeds geared together to allow taper-cutting (threads an' all) by generation rather than followers. (Holtzappfel describes a fitting resembling a taper-turning attachment on the cross-slide, for generating short threads.)

Given the low RPM of the lathe and (presumably) low torque then the ingenious use of a high speed rotary cutter makes sense.

+1 for ingenuity

The atomic kettle was a novel idea ! Does it boil on demand, or constantly and be plumbed into the water system ? How many decades do the fuel rods last ? Noel.

The connector is a Neutrix powerCON
https://www.neutrik.com/en/products/power/powercon-20-a
Nery nice connectors, twist engagement with large area wiping contacts I use the similar speakON
https://www.neutrik.com/en/products/audio/speakon
for high current low voltage power connections.

Robert G8RPI.

Robert Atkinson 2:

Thank you for the links which I will pursue.

My mains electric power tools mostly have pluggable leads but I was not aware of the Neutrix brand.

Our local woodman has a log splitter with a big spiral "Woodscrew" the splitter is tractor mounted so there is a lot of hp behind the screw, Due to the tractor PTO standard direction the Screw and the mounting thread is left handed,and these screws really get tight on their mounting screw so I get the job of fitting a new screw,in excchange for firewood. As the screws cost around £90 I was asked if I could make new screws ,I tried to cut the thread on my universal mill but could not get a fine enough lead with standard gearing, I really needed a short lead attachment or make another reduction pair of gears, and it was not commercially viable due to cost and time invoved,so I still get the occassional request to get a stuck one removed, I saw on you tube a car wth the rear axle jacked up and a Log splitting screw attached to the axle flange and the operator was working away on his hands and knees splitting his firewood.

For a crazy wood splitter try youtube "red necked log splitter". Noel