Love of lathes.

[Joe]

It was the math part that was Greek to me. Still is, but I didn't have to design them, just repair them.

Sounds horribly familiar.
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- Joe

[ex 2 Base]

It was the math part that was Greek to me. Still is, but I didn't have to design them, just repair them.

Sounds horribly familiar.

- Joe

Hello Colin and others, I have worked on repulsion motors,we had them on small compressors.To change direction of rotation we moved the brushes to a point passed the neutral position, usually marked by the manufactuer.On the more common type of repulsion motor the brushes are short circuited, some had a centifugal brush lifting arrangement so that when the motor was up to speed the brushed were clear of the comm.We never under cut their comms it was deemed not necssary, but did on other DC motors/generators. All comms were skimmed between centres, we had a machine made by Martindale for big motors/generators but smaller one was done by hand using a ground up hacksaw blade in home made holder.We had a tail stock rotating chuck for those motors which didn't have a centre both ends, such as starter motor. I made myself one as they were expensive, but I notice they are now advertised in the model engineer for about £70.Don't forget to carry out an insulation test on the motor as the lead insulation is often rubber covered with cotton and it rots and become brittle.Very interesting brings back a lot of memories, best of luck with the lathe.Ted

[Retired]

Hi,

Thanks for the information and for your good wishes Ted; much appreciated.

I've polished the com up in the lathe but not under-cut the slots only cleaning the slots out with a blunt instrument to remove dirt.

I am concerned about the insulation because as you rightly point out Ted it had turned extremely brittle with age and is breaking away in lumps so hopefully I can re-sleeve as much as possible; the moving brush holder plate was also rubbing the leads which I found strange because they should have been well clear so I'll sort this out whilst the motor is in pieces. The motor ran OK but it was exceptionally noisy which I hope to cure by installing a pair of new bearings which are paid for and should arrive shortly. After dinner I plan to clean the motor a bit more and have a good look at it getting it ready for reassembly. I'm intrigued as to what will happen when I operate the moving brushes via the lever once the motor is powered up? I'd like to re-use this motor if possible.

Kind regards, Col.

[Retired]

Hi,

The new bearings arrived at dinner time today so I've spent the afternoon in the garage playing with this motor.

Assembly was straightforward and I connected directly to a 13A plug for test purposes. At switch on the motor burst into life but operating the brush control lever made no difference; I switched on and off a couple of times trying the lever in its three positions; the middle position did nothing but I then found this is a reversing motor by simply switching off and moving the lever from one outer position to the other outer position; as I've previously stated I've never worked on this type of motor before and never seen one so this came as a surprise to me.

The new bearings have quietened the motor considerably as expected but it has a dull rattle which I've so far been unable to trace. Just before knocking off I had the motor under power giving it a close visual inspection and I noticed a spring operated device at the com end; not understanding this kind of motor; whilst I had it in pieces I noticed the spring but didn't understand it's function; it appears to be some kind of centrifugal switch because a shielding plate abutting the spring moves outwards immediately upon powering up? I think it is this mechanism generating the noise? The motor runs well enough though.

This now begs the question of why this motor has been installed in the first place and why would the lathe need to rotate in reverse? The lathe is flat belt drive with an idler pulley located in the base of the head-stock; I've not yet had time to study this but idler pulleys are usually located in a certain position on the drive so reversing would throw this out? The lathe has a threaded mandrel so reversing could very well throw the chuck and I'm not always quick at ducking?

Next session I'll pull the end cover off the motor once again but this time to inspect what the spring loaded mechanism is and to see if I can detect any wear? I sleeved the leads after removing the hardened and perished rubber.

This is interesting to me because its something new which I've never come across before?

Kind regards, Col.

[Alan Douglas]

For the usual repulsion-induction motor, there is a centrifugal mechanism to short-circuit all the commutator bars, to make the rotor a squirrel-cage. Normally the brushes also lift, to reduce wear, but they don't have to. In a straight repulsion motor they are always in contact. The fact that the operating the brush-shift has no effect while running, suggests the commutator is shorted and the brushes aren't doing anything during that time.

Small lathes here commonly have threaded chucks and they always reverse. I wouldn't take a heavy cut in reverse, but I've never had any problem with the chuck coming loose. My Logan has a 2 1/4-8 thread, I recall, and takes 5C collets natively. It came with a three-phase motor which can be reversed "on the fly" though I changed it to single-phase.

[AlanBeckett]

The lathe has a threaded mandrel so reversing could very well throw the chuck and I'm not always quick at ducking?

I'm pretty damned quick when I'm frit young Col, but I still wouldn't risk it. I simply don't think it's worth it.

Alan

[Retired]

Hi,

Thanks Alan D. Yes the brushes on my motor are in constant contact and as you say operating the lever once the motor is running has no effect whatsoever.

I share your views Big Al when it comes to running a lathe in reverse; this is obviously safe if the mandrel has a tapered nose and locking ring but for a straight threaded mandrel I too won't risk it. I can't see a reason I would want to run the lathe in reverse anyway.

I need to resume work on the lathe proper cleaning it and getting it ready for new paint; I can sort the motor out later and I still haven't excluded the idea of installing a top quality Brook 3 phase motor hooking up to a new VFD which would give increased power and variable speed? This brush motor is not standard equipment so I wouldn't be losing anything regarding originality or character and the motor is mounted out of sight. It wouldn't hurt to modernize all the electrics because the starter currently installed is of the old dash-pot style and the old steel conduit looks a mess.

Kind regards, Col.

[Retired]

Hi,

I've spent a bit of time in the garage today playing with this brush motor and I'm far from happy with it. The new bearings have quietened it down considerably but it's still running too roughly for my liking. Its possible a previous owner has tried to use excessive force in order to remove the stepped double pulley and distorted the shaft causing the rough running? Next session I'll clock the shaft with my DTI just to check it. Everything appears OK and it starts without problem also it reverses as it should but it's not going back on the Lorch unless I can get it to behave.

Out of curiosity I've just been browsing eBay looking at electric motors because a top quality Brook cast iron motor would do justice to this lathe. What a shame it is now that I came across the following;

http://www.motors-direct.co.uk/index.php?_a=category&cat_id=77&gclid=CNLC_sD10LwCFazHtAodjlgAhA

When Brooks were in full production here in Huddersfield "lead" time for a special could easily be six weeks but now it appears even standard motors are being severely delayed no doubt due to being made in India or Poland these days? How sad it is for me to see a notice like this appear from a stockist. So many British manufacturers dumped England as a manufacturing base thinking it would be much cheaper to manufacture abroad because of very cheap labour but now is it coming back to bite them?

I used to work the "Link shift" and occasionally would receive a late panic call from a company wanting a stock motor because of a breakdown; I would visit the warehouse and request a motor to be issued without correct paperwork then I would fill in a manual consignment note allowing the motor to be loaded that night and despatched for the customer to receive next day. The correct paperwork would then be issued and everyone was happy. Progress department staff always had urgent motors for me to despatch leaving me details (motor serial number) during the normal shift hours then when the production lines shut down I would cruise the JIT cells on the fork-truck mopping up these urgent motors; each motor was logged through assembly stages and could easily be tracked on the computer. In 24 years at Brooks I never ever knowingly left a motor on the shop floor which had been completed and was ready for despatch. How times have changed?

Kind regards, Col.

[camallison]

The other thing that happened when production moved offshore was that overseas companies were allowed to manufacture under licence for their domestic consumption only. Gradually, they showed the company that granted that licence that their production could be done cheaper in the overseas plant. Fast forward a decade and the UK company has significant lead times with their official product, but knock-off product starts to trickle in to fill the vacuum left. This happened to a sister company of mine in the 90s who produced large actuators for the water industry. These were large electric motors with beefy gearboxes. Licensed manufacture was allowed in China and India on condition that no production was exported. Sure enough, knock-offs appeared and, on a visit to Shenzhen to check our licensee of electronic products, I happened to call in at the other (actuator) plant only to see the knock-off product being assembled on the same line as the original.

This has also happened with small generators - Kipor is the knock-off of a Honda generator, but certainly doesn't have the quality.

Colin

[Retired]

Hi,

Thanks Colin. Whilst at Brooks I always considered Brook Motors the best production motors in the world and was proud to be part of the team. I don't know what quality is like these days now the motors are made abroad and I don't know many details as production was just being transferred abroad at the time of my retirement in December 2000.

I did however see many consignments arrive by shipping container into the export department these then transferred into stock. What was surprising though was that these were stock motors only so it meant any deviation involved extra work on the motors by the modification team which really didn't make sense to me; ship production abroad then import the motors only to strip them down again?

Its just sad how our once mighty manufacturing base has been allowed to decline the way it has; our departed great inventors would shudder if they could come back to see what goes on these days?

Kind regards, Col.