'Make a lathe and scroll saw from rubbish' (Motors etc)

[Yorkie]

I'm a member of the EPE 'Chat Zone' and there's a debate running at the moment about speed control of induction motors - in particular for lathe speed control.

http://www.chatzones.co.uk/discus/messag...1390751903

As happens, the debate has broadened out (I haven't engaged in the debate as I have no such applications in mind), and it led to others topics which might be of interest on here about what Americans tend to use the term 're-purposing' - that is adapting stuff for purposes for which it wasn't originally intended to be used. A more apt and descriptive word than 're-cyling' I think, which often simply means tearing things to bits that would otherwise have gone to landfill, and recycling the scrap materials (copper, steel, aluminium, plastic etc) from the destroyed item.

For what it's worth, though some of the info below has previously been discussed at length on this forum, nevertheless, it might still be of passing interest. Here are some links:

"Make your own Lathe from other people's rubbish":

http://www.floweringelbow.org/projects/m...d-control/

"From Sewing Machine to Scroll Saw, step by step":

http://www.floweringelbow.org/projects/f...croll-saw/

Also:

Electric Motors for Home Workshop Practice:

http://www.amazon.co.uk/Electric-Motors-...g_b%20book

Book Description:

Publication Date: 30 May 1996 | Series: Workshop Practice:

The author's earlier book Electric Motors (Workshop Practice Series No. 16) described the basic principles of operation and methods of application of the wide range of motor types likely to be encountered in small scale engineering. This book provides additional information about popular workshop applications for motors. Detailed advice is given on how to identify and make good use of discarded and surplus motors from both domestic and industrial sources and also how to operate three phase motors from single phase supplies. Examples are given of actual workshop applications and conversions, and on battery supplies for the use of motors in mobile projects.

Three-Phase Conversion Workshop Practice:

http://www.amazon.co.uk/Three-phase-Conv...=pd_cp_b_1

Book Description:

Publication Date: 29 Nov 2010 | Series: Workshop Practice:

A practical guide to running three-phase equipment on single-phase electricity supplies. Often, model engineers buy industrial workshop equipment, such as lathes, drilling machines and milling machines, which usually require a three-phase electricity supply. Although ready-built phase converters are available, they can often cost as much or even more than the equipment purchased. This book provides an invaluable source of practical guidance on how anyone can find out the type of electrical equipment they have, and how to convert it to run on a single-phase supply. The book provides calculations, step-by-step instructions with photographs and diagrams and covers electricity supplies in the UK, North America, Europe and the rest of the world. Finally, it also advises on which equipment cannot be converted at all.

Hope that's of interest.

[Retired]

Hi,

WOW David what a lot of information to wade through and I'll be looking at the sites later with great interest. Many thanks for adding the information.

Regarding 3 phase motors; the very old 415V Star wound motors found on our vintage machinery are unsuitable for conversion because the "Star" connection is usually buried too deeply and trying to locate it usually destroys the winding. The more modern 3 phase motors though have the leads running to a terminal block giving excellent access so these can quickly be re-connected in "Delta" in fact many motors are supplied already fitted with three links which are simply re-arranged as required to give either Star or Delta connection.

VFD's (Inverters) are now available quite cheaply; these are becoming increasingly popular for home workshop owners who wish to run three phase machinery at home and I can confirm these VFD's are an absolute bargain given the technology involved.

An interesting thread David; I hope it attracts lots of replies.

Kind regards, Col.

[Alan Douglas]

You could use a 415V motor as an idler to generate 3 phase for another one. That's what I did to run my 550V 3 phase mill from the 240V house service. The 240V is stepped up to 480V with an autotransformer (obtained free) and then runs a 2HP 230/460 3-phase idler connected for 460V. The 550V mill runs fine at the slightly reduced 480V as I don't do heavy work on it anyway. Changing the mill motor is impractical as it is a 4 and 8-pole machine with the switching built into the mill.

[camallison]

In the time of the rolling power cuts during the miners' strike, our little company did the ultimate in repurposing. Excuse me if some of the detail is slightly inaccurate, but here is the account:

We took a slip ring motor (bought as scrap from ICI), brought the star point out, and used it as an alternator, excited by a car battery. That motor was driven by a Morris 1000 car engine, converted to run on towns gas, with suitable flame arrestor between the engine and supply. Cooling water was circulated through the central heating radiators in the factory and offices with the car radiator still attached and cooling fan also. Switch over of mains supply was done manually.

That kept us going 7 days a week, recharging the battery when running and also from the mains supply when power was restored.

It was later sold to a local farmer who had frequent interruptions of supply, and we converted it to run off LPG for him.

Colin

EDIT .... PS - electrical output was 11kVA or thereabouts.

[singlepentode69]

I heard model engineer magazine did an article on making a lathe in wartime using concrete to make the bed I do not know how true this is
Regards
Robin

[Retired]

Hi,

Most interesting David; I've finally had a look at the links you kindly supplied.

It shows what can be achieved Colin through desperation; thanks for sharing your story.

Sounds like you made a "Rotary converter" Alan D? These work but are expensive because the idler motor really needs to be much bigger than the motor being used? I've mentioned this previously; A guy in Wales wanted to power two big heat exchangers (30hp) to his two farmhouses and having been quoted over £17,000 to have 3 phase 415V laid on; he contacted Doug at "unique3phase" and Doug in turn put the guy in touch with me. I suggested he wind a big transformer using Doug's transformer method which I had already done but instead he went the rotary converter way. The rotary converter proved so noisy in operation it was keeping the family awake at night and once again this guy contacted me asking for advice. I suggested he build a dedicated out-building to house the converter but have since not heard from him.

My home made 3 phase transformer continues to work very well and at idle only ticks over at 0.8A which disappears once it is loaded. It gives full power to the motor and has always impressed visitors whom I've demonstrated it to.

I converted my big Startrite combination woodworking machine using a start and run capacitor allowing it to run from 240V single phase; this machine has three 3hp 3 phase motors installed and because all motors are identical in size I got away by using a single start and single run capacitor connecting each in such a way that the switching diverted these to the required motor; this was over twelve years ago and the machine is still reliable having the same capacitors still installed so they have held up well for a long time.

I'm not electrically trained but I did find this work most interesting.

Kind regards, Col.