Guillotine Problems

Never mind number of posts, the real task today was to try and find out why my guillotine has stopped working.

Last time I used it things were fine until the guillotine only clicked when the foot switch was pressed, but the blade didn't move. I suspected the foot switch as the wiring isn't in good condition - the rubber insulation is perished. I've put off looking at it for a week or several but now I really need to use it.

On starting up today the darn thing worked for a couple of cycles and then stopped. So that eliminated the foot switch as being the problem. Next I wondered about the limit switch not working. But, having examined it, it was clear the guillotine was overshooting at the end of the cycle. That turned attention to the electromagnetic brake, which did seem rather easy to turn when it was supposed to be on, the default. So I had a go at adjusting it to be properly on, and give more clearance when off. Still nothing when the foot switch was pressed, just a click. The motor was running with no problem so the only other electrical item was the electromagnetic clutch. In this picture it's the silver coloured disk bottom right, in front of the worm gearbox:

According to the manual it runs on 90VDC, so think brushes. The brushes are held by the green bracket immediately to the left of the silver disk. Sure enough they looked quite worn, and one wasn't making any sort of contact. There are four brushes in two parallel pairs. So even if one brush isn't making contact things should still work. Following the manual I decided to check whether I was getting 90VDC on the clutch. So round to the front of the guillotine and take the cover off the electrics box:

The circuit is pretty crude, basically just a rectifier. It can just be seen bottom right of the box - old school selenium with more fins than Helsinki. Being careful with the measurement, as there is 415VAC floating about, I measured 90VDC on the output to the clutch. And blow me down, the guillotine worked. And continued to work.

All I can think of is that fiddling about with the brushes has made the clutch work again. At least for the time being.

The clutch is made by Warner, who are still in business. According to a supplement in the manual the clutches were PC type, which even more surprisingly are still made. I've found them online and you can order spares in general from the parent company in the US. But minimum value and payment terms are somewhat onerous for overseas orders.

So the question is do Warner have an outlet in the UK? And if so am I likely to be able to get spare brushes for the PC range of clutches? If not I have found a couple of companies that might be worth calling as they claim to be agents.

Andrew

What is that machine? What does it do?

Ignorant yank here....

Pete

Andrew

As soon as I looked at the second picture I thought that's it the selenium rectifier has gone phut ! Then I read further in your account and realised how wrong I was . If I remember correctly we used to strip selenium rectifiers apart, heat a plate till the coating melted then wipe the surface to obtain a very rudimentary solar cell/light sensor but that is over half a century ago.

Regards

Martin W

Edited By Martin W on 06/03/2017 00:31:03

.

Originally used for chopping of naughty peoples heads with. ( as recently in france as 1977 it seems ) But in 'industry' the same principle for slicing metal, paper, leather. etc although with more of a shearing type of cut than for lopping off naughty garlic chewing frogs heads.

Nick

Ahhh, what dumb yanky sheet metal workers call a shear...

Thanks!

Pete

Andrew

I have a quantity of brushes for Warner clutches if you get stuck

Cripes, selenium rectifiers still working!

You would have known if they had gone pop, you woudl have been able to smell it half a mile away.

Neil

**LINK**

UK agent for Warner Electric clutches & brakes.

Nigel B

Sorry for jumping straight in without setting the scene. As explained it's a sheet metal cutter. Made by Edwards in the UK, probably in the late 60s. Capacity is 4ft by 1/8" mild steel. Small by industrial standards, but about as big as I could fit in. It's still built like a battleship though; the frame is welded from 3/4" thick steel plate and the flywheel must weigh over 200lbs. Shear is probably a better name, as that is what it does.

Nigel: Thanks very much for the link. Once I've identified the exact type of clutch I'll give them a call. Looking at the information I've downloaded from Warner it looks like my clutch is the smallest, the PC500, going on diameter. But it would be nice to find a label to confirm. There is a label on the brush holder, but it's just a generic manufacturers label with no indication of model number.

Ian: Thanks for the generous offer, I may contact you if the result of contact with Warner is "HOW MUCH?" and a need to sit down.

Andrew

According to Wikipedia (tat always reliable source of information!) the beheading guillotine was actually first used in Halifax UK

**LINK**

Yet another British invention pinched by those pestilential foreigners

Supposed to have been invented by a Scotsman and used in Halifax. Must have been cheap. Andrew- if brushes are v. expensive can you not get some larger and file them to fit, are they some exotic material ?

Duncan. There used to be a replica in Gibbet Street, Halifax, last time I was there ( early 90's )

Roy

I had the same problem with my Edwards Trucut some time back, replaced the rectifier with a modern

bridge rectifier and a series diode to take care of the back emf.. works perfectly

That's plan C, not exotic as far as I'm aware.

Andrew

Edited By Andrew Johnston on 07/03/2017 10:37:24

Would love to have one of those machines,no better way to cut sheet steel.

Apart, of course, from laser or water cutting

AndrewJ, am certain I read a thread on here some while ago where somebody asked for obscure brush availability and was recommended a company, South coast way, that would make up brushes to your spec and they indeed came up with the goods - can't find it on initial search but perhaps someone can remember ?
DaveD

DaveD,

Is this the company to which you refer?

http://carbonbrush.co.uk

Thank you John, that is indeed the one I was thinking of !
DaveD
(now book-marked)