Dewhurst Switch

This topic has 8 replies, 7 voices, and was last updated 19 February 2016 at 08:59 by Eugene.

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4 March 2015 at 13:55 #7501
Jacob Williams
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@jacobwilliams59811
Advert

4 March 2015 at 13:55 #182112
Jacob Williams
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@jacobwilliams59811
Hey folks, does any one have a Dewhurst reversing switch for sale? I need one for me myford 4inch precision lathe.

cheers
4 March 2015 at 16:05 #182125
JasonB
Moderator
@jasonb
Jacob this would be better placed in the classified wants section rather than a forum item.

Having said that there is one on Home Workshop at the moment, be quick before Johns Stevo buys it
4 March 2015 at 16:14 #182129
Harry Wilkes
Participant
@harrywilkes58467
Hi Jacob

I use one of these link as you can see lot difference in price Dewhurst go for around £40 on ebay. Some folks shy away from this switch because it leave the neutral connected in the off position but a lot of electrical items in the home have the neutral connected when left in a 13 Amp socket outlet !

H
4 March 2015 at 16:20 #182130
John Stevenson 1
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@johnstevenson1
Posted by JasonB on 04/03/2015 16:05:05:

Having said that there is one on Home Workshop at the moment, be quick before Johns Stevo buys it

.

Only so I can bin it before it injures someone.
5 March 2015 at 09:08 #182200
Lambton
Participant
@lambton
Dewhurst switches are 1950's technology and do not conform to present day good practice or safety standards. I have repaired several all of which had badly burned contacts due to being used as on/off switches. They will of course work in this mode – but not forever. If you find a good one I urge you to use it in conjunction with a normal direct on line starter (DOL) using the Dewhurst just to select forward/reverse before pressing the start button on the DOL. This will ensure a long and satisfactory life for the Dewhurst switch. You will also benefit from the motor protection and No-Volt Release safety feature of the DOL.

Alternatively buy a modern push button type of F/R starter as fitted to the last Myford lathes made in Nottingham. however these tend to be a bit expensive.
18 February 2016 at 17:08 #225951
CHRIS WOODS 1
Participant
@chriswoods1
Was the original question asked by Jason ever resolved? Can Harry advise if the Chinese green reverser switch he linked to is O.K. for single phase & if so, was wiring it done readily?
18 February 2016 at 21:31 #225998
Harry Wilkes
Participant
@harrywilkes58467
Posted by CHRIS WOODS 1 on 18/02/2016 17:08:21:

Was the original question asked by Jason ever resolved? Can Harry advise if the Chinese green reverser switch he linked to is O.K. for single phase & if so, was wiring it done readily?

Hi

I used the reversing switch up until Oct last year without any problems the only reason I removed it was to fit a 3ph motor and VFD. I have recommend and fitted the same type of switch to a couple of my friends Myfords and they to are pleased with the switch.

H
19 February 2016 at 08:59 #226024
Eugene
Participant
@eugene
The Dewhurst drums particularly those with long operating levers, when used without any other isolating protection are potentially very harmful.

I demonstrated this to my self by leaning across my Myford M type to adjust the countershaft belt and brushing the lever with my hip. The motor started and I was briefly in contact with the moving chuck with my fingers close to the rotating belt.

It was demounted straight way and a modern NVR reversing switch fitted in it's place. Given the hazard potential a Dewhurst drum (on it's own) isn't worth any money at all; you'll be buying into harms way.

nvr-switch—with-forward-reverse-switch-5761-p.asp …. about twenty quid.

Eug

Edited By Eugene on 19/02/2016 09:03:14

Edited By Eugene on 19/02/2016 09:14:48
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