Sick Unimat

Lindsay G
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Sick Unimat

Postby Lindsay G » Sun Jan 19, 2014 10:22 pm

This is a thread I’d rather not be posting as I’m fearing the worse. However, let’s see what responses it might bring.

I have a rather sick Unimat 3 on my hands. I’ll describe all the symptoms in case it might help pinpoint the problem and prognosis. When problems first started appearing, it was when the motor was started on the fast speed as it would occasionally trip an RCD. It then started tripping the RCD every time on the fast setting and then occasionally when switched on at the slow speed. The motor would turn for part of a second before the RCD kicked in. If it got passed switching-on without tripping, the motor would run fine. I think it may have tripped the RCD whilst running once or twice. After a night or so the motor then started running erratically, but only sporadically. However tonight it started running very erratically then slowing right down before tripping the RCD.

The motor spindle is moving freely as is the live end spindle. There’s been no smoke or smell but the motor housing was warm (it might have heated up to the same extent before the problems started for all I know). The motor has been run in line with the 8 minutes max on, 2 minutes off warning, and was at no time put under any extreme workload.

The problem is obviously in the drive unit. Per the exploded parts list, the drive unit incorporates the switch and per the exploded parts lists doesn’t break down any further. I haven’t got round to taking this off the lathe to see if it can be dismantled further.

Obviously, a new drive unit is one option but the most expensive. Can anyone identify the problem from what I’ve described, and offer any solutions?

Lindsay

Terry Bendall
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Re: Sick Unimat

Postby Terry Bendall » Mon Jan 20, 2014 7:26 am

I don't know the answer personally Lindsay but you might try these sites where Unimat problems are listed.

http://www.woodworkforums.com/f65/emco- ... or-174830/
http://unimat.homestead.com/
http://groups.yahoo.com/neo/groups/unim ... topics/292
http://madmodder.net/index.php?topic=2859.0

http://www.emco.or.at/index.php/downloa ... -manual-en

The last one is a scanned copy of a manual which may be useful.

Terry Bendall

beachboy
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Re: Sick Unimat

Postby beachboy » Mon Jan 20, 2014 3:02 pm

Lindsay,

If it helps. My experience with high reving motors that become erratic, and suddenly die, results from a carbon brush breaking apart.

Steve.

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Tim V
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Re: Sick Unimat

Postby Tim V » Mon Jan 20, 2014 4:37 pm

Original motor? Have the brushes been replaced? If not, they're probably worn out. Extra sparking could cause the RCD to trip.

New brushes occasionally come up for sale these days, but when I had to replace the brushes in mine, there were no replacements available. I took the old brush and found a similar arrangement of spring but too big in the Hoover range of brushes. I just filed down the brush to fit, and hey presto, motor back in good condition.

I also bought a new motor, convenient to leave on the vertical column, I have the 3 by the way.
Tim V

decauville1126
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Re: Sick Unimat

Postby decauville1126 » Mon Jan 20, 2014 5:32 pm

You may find the Unimat brushes have worn down to their limit - always worth checking.

They are restrained in the brush holders and have a braided wire connection which pulls off to allow for removal.

If worn there are two options: replace (new ones are available but are pricey) or my dodge (usual disclaimers) is to take a spare set from an angle grinder or similar, file to profile and a suitable length, then pop down the brush holder tubes with the originals behind. Not good practice but quick and it works.

The motors are not ventilated and are easy to strip AFTER removing the brushes! You'll find all the carbon dust from the worn brushes nicely contained and distributed throughout the interior so a blow with an air line is useful.

Also, due to age, the cover part of the brush holder cap will probably disintegrate - I just stick a piece of duct tape over when done.

Spare motors do come up on ebay and there is also a chap in Cambridgeshire who does a replacement which is worth considering if your motor goes permanently kapput.

New motors are not available, even as spares.

Hope this helps,
Peter (3720)

Lindsay G
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Re: Sick Unimat

Postby Lindsay G » Tue Jan 21, 2014 3:53 pm

Many thanks for the replies.

Brushes seem to be the likely problem which was my first thought (but only because I hoped it was - it seemed the only user-serviceable option, and the least costly). Brushes also came up on a couple of threads that I came across or Terry supplied - one suggests not proceeding with motor dismantling unless you're experienced, but the Unimat is just going to sit in a corner with that advice.

Once I get around to it, is there anything I should watch out for in dismantling or assembling? (e.g. Peter, what do you mean by "the motors ...are easy to strip AFTER removing the brushes").

Lindsay

decauville1126
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Re: Sick Unimat

Postby decauville1126 » Tue Jan 21, 2014 5:49 pm

(e.g. Peter, what do you mean by "the motors ...are easy to strip AFTER removing the brushes").


The motor can easily be stripped: remove from lathe, drive out pint securing pulley and remove, remove mounting plate, remove brushes as they can catch on the end of the armature, undo the two long screws which go into trapped nuts on the brush-endcase cap, gently tease the endcap away and watch for the link wires and tags which have to be detached - make a note of their 'bendy' layout other wise the cap can be a b.....r to put back on, remove armature.

The inside coil and armature will be a mess with all the carbon dust - best clean with air.

Takes about the same time to get to this point as typing this reply! Practice makes perfect - and usual disclaimers about H&S, PPE, etc.

The exploded view in the manual will help make sense of this. There are a couple of useful forums (or is that fora or forii?) for Unimat users

Peter (3720)

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Tim V
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Re: Sick Unimat

Postby Tim V » Thu Jan 30, 2014 7:46 pm

Tim V


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Tim V
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Re: Sick Unimat

Postby Tim V » Thu Jan 30, 2014 9:40 pm

Way to go on that one Keith, that will go for a lot more....
Tim V

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jayell
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Re: Sick Unimat

Postby jayell » Thu Jan 30, 2014 10:32 pm



Trouble is that is a Unimat 3 and not a Unimat SL and I don't know if parts are interchangeable. I was bidding on an SL a few days ago but dropped out when the price went over my self-imposed £100 limit, I doubt if I will ever get one for that sort of money as fully equiped ones go for £200 plus :cry:

Johnebay

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grovenor-2685
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Re: Sick Unimat

Postby grovenor-2685 » Thu Jan 30, 2014 10:43 pm

Trouble is that is a Unimat 3 and not a Unimat SL

This topic is about a Unimat 3. ??
Keith

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jayell
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Re: Sick Unimat

Postby jayell » Thu Jan 30, 2014 10:50 pm

grovenor-2685 wrote:
Trouble is that is a Unimat 3 and not a Unimat SL

This topic is about a Unimat 3. ??
Keith


Oooops! I knew I should have re-read the original posting, so the one being used as a saw bench would be quite a good buy if you could get it at current price but I bet it will go much higher

John

Lindsay G
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Re: Sick Unimat

Postby Lindsay G » Thu Jan 30, 2014 11:21 pm

I saw that replacement motor and coughed. They're also available from Pro Machine Tools but they're sold out presently.

I've order brushes from them, awaiting arrival at present. One brush in the motor was worn to perhaps half way, the other worn virtually all the way down and a small cylindrical shaped piece of graphite had been inserted and might be the suspect item. Time will tell.

If we could find a source for the motor that drives the item on Ebay, the rest of the gubbins could be put together and I bet that motor in isolation will cost a lot lot less. We'd then have a cheaper solution for anyone with Unimat motor problems. Might anyone recognise the motor?

Lindsay

Terry Bendall
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Re: Sick Unimat

Postby Terry Bendall » Fri Jan 31, 2014 7:07 am

Lindsay G wrote:a small cylindrical shaped piece of graphite had been inserted and might be the suspect item. Time will tell.


Quite often motor brushes are rectangular or round in cross section and then have a smaller round section at the end to slot into the spring. It might be that part that you found, in which case the brush had worn down a lot.

Terry Bendall

decauville1126
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Re: Sick Unimat

Postby decauville1126 » Fri Jan 31, 2014 12:59 pm

Lindsay G wrote:I saw that replacement motor and coughed. They're also available from Pro Machine Tools but they're sold out presently.

I've order brushes from them, awaiting arrival at present. One brush in the motor was worn to perhaps half way, the other worn virtually all the way down and a small cylindrical shaped piece of graphite had been inserted and might be the suspect item. Time will tell.

If we could find a source for the motor that drives the item on Ebay, the rest of the gubbins could be put together and I bet that motor in isolation will cost a lot lot less. We'd then have a cheaper solution for anyone with Unimat motor problems. Might anyone recognise the motor?

Lindsay


The motors used on the Unimat 3 are no longer manufactured, hence their non-availability. Secondhand on ebay expect to pay £50 - £100. Sometimes the speed switch fails too, often noted as 'only works at one speed'. I got a very tatty-looking one which actually works fine for £85, ready for when my original one finally goes.

Depending on usage, the replacement motor sold on ebay could actually be a wise investment as it is a more modern unit which is vented. There is also one available from the USA but with the potential risk of duty + vat + Royal Mail handling fee being levied on import.

And with apologies for going off-topic a tad, as somebody also mentioned SL types, they are best treated as a world apart! Very few accessories are interchangeable. This is mainly because they use an M12 x 1mm spindle thread, the Unimat 3 (and 4) using M14 x 1mm. But the SL does have, particularly in the USA, a cult following to the extent that new accessories and parts are manufactured.

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jayell
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Re: Sick Unimat

Postby jayell » Fri Jan 31, 2014 5:30 pm

decauville1126 wrote: But the SL does have, particularly in the USA, a cult following to the extent that new accessories and parts are manufactured.


That probably explains why they sell for silly money, I made a bid this morning for a 'broken' one that had a current bid of £67 and put in my £100 max only to find it was immediately trumped by an auto bid

John

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Tim V
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Re: Sick Unimat

Postby Tim V » Fri Jan 31, 2014 7:55 pm

I would not expect to get a SL for that kind of money....
Tim V

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grovenor-2685
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Re: Sick Unimat

Postby grovenor-2685 » Fri Jan 31, 2014 8:27 pm

Way to go on that one Keith, that will go for a lot more....

Remarkably, exactly the same price as the new motor, and you would have got the saw table and a few other spares thrown in.
Keith

Lindsay G
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Re: Sick Unimat

Postby Lindsay G » Thu Mar 13, 2014 7:42 pm

I've finally got round to fitting the new brush that was obtained from Pro Machine Tools. Didn't want to fit it before going on a recent holiday in case it didn't cure the problem as I'd have spoilt the holiday fretting over what to do next!

However, I shouldn't have delayed fitting everything back together as it seems to be up and running again (altho' singular swallows and summers do come to mind). The new brush from PMT didn't fit into the housing and had to be sanded down until it slid in easily. Apart from that, taking apart and putting back together wasn't too onerous. The brushes can in fact be replaced through the 2 apertures when the plugs are prised out avoiding the need to dismantle the motor. However, in my case I may have assumed that one brush had worn right down and not noticed the other small piece of graphite that had been inserted and becoming dislodged was possibly the cause of the problem.

The graphite dust within the motor wasn't for moving with air alone and I ended up resorting to cleaning everything out with Isopropyl Alcohol.

Fingers crossed for a trouble-free future. I will, however, keep an eye out for possible replacement motors - episodes like this make one aware how vulnerable Unimat owners are should a motor die.

Lindsay

beachboy
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Re: Sick Unimat

Postby beachboy » Fri Mar 14, 2014 9:53 am

Good news Lindsay, your 782 turnings looked really good.

I have often considered the possibility of adapting worn down RSU carbon probes for make shift brushes ( ? ).
Its worth checking / cleaning up high rev'g motors like drills etc regularly. Prevents damage to the commutator.

Steve.

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Tim V
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Re: Sick Unimat

Postby Tim V » Fri Mar 14, 2014 4:04 pm

As I said previously, I found a similar, oversize brush with the same spring arrangement in a Hoover spares shop, filed it down, still going umpteen years later.
Tim V

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jayell
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Re: Sick Unimat

Postby jayell » Sat Mar 15, 2014 2:23 pm

An even sicker one is currently on ebay, 'shorted' motoer and apparently missing the 3 jaw scroll chuck and price has already gone beyound £75

http://www.ebay.co.uk/itm/Emco-Unimat-S ... 461c6e1a40

From comments made here getting a replaement motor will be expensive.

john lewis

decauville1126
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Re: Sick Unimat

Postby decauville1126 » Sat Mar 15, 2014 4:11 pm

As with all Unimats, it's the tooling and accessories which are included that can dictate the value. A lifetime of adding such extras will make it more desirable for a new user.

But going back to the original subject of this thread, it sounds as if someone may have already tried packing back the extant brushes. As to the suggestion of filing down oversize brushes, I've done that on other motors and the mess it makes of files is awful, the carbon dust spreading everywhere. Only as an emergency fix methinks.

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Tim V
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Re: Sick Unimat

Postby Tim V » Sat Mar 15, 2014 6:23 pm

Sandpaper does just as well!
Tim V


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