Seig SX2P mill cutting out

[Ches Green UKParticipant @chesgreenuk]

Andy,

No noise that I can detect –  my hearing is decent. That’s not to say there isn’t a quiet noise happening inside the circuit board box, but my ears don’t pick anything up

When the fault happens, the spindle gently stops rotating in about a second or two. Occurs both when cutting and rotating idly.  Been milling again today for about 1 hr …no issues.

My mill otherwise behaves as your lathe does….works fine for a day or a week then the spindle just stops rotating. The power remains On. I turn the speed dial down to zero and then back up to the 2 o’clock position, say, and everything is back to normal.

A ‘clonk’ from your lathe could indicate a relay activating? Also your lathe (…I have the same one) has a micro-switch on the guard. I wonder if that switch is positioned such that a slight movement of the guard activates it?

I could live with the issue but I worry that one day I’ll be using a large cutter taking a decent sized cut and the mill stops … that could cause damage to the workpiece, cutter or whatever else is nearby.

I’ve ordered a new speed control potentiometer which should be here in a week or two – I’ll advise if that fixes the issue.

Ches

 

[andy198712Participant @andy198712]

Yeah yours does sound different to mine. Mine was sound like a belt flipping or jumping a tooth and stopping with a sound and feel of a clunk.
mans like you say, would effect the work piece sadly.
Have you found any links to the axeminster spare board? Might be a phone up job.

I think I’m going to go the sewing machine motor and controller route (motor is actually fine but I’m not sure I want to go down the speed controller route and use the stock motor just as I don’t know enough about 240v electrics to mess with it.

 

if it were my 2.7L mill I would just replace the board or controller though

 

because interesting to see how you get on !

[Ches Green UKParticipant @chesgreenuk]

I would just replace the board or controller though

I don’t have the knowledge or inclination to fault find at companent level so spoke to Axeminster Tools this afternoon.

As Kevin from Arc advised, Axeminster do stock (or can get) spares for most of the Arc kit since lathe/mills across both companies were essentially the same.

I bit the bullet and ordered the mill control board from Axeminster. If I don’t use it immediately I at least know I’ll have it at hand for a rainy day.

Axeminster don’t list all the spares they hold on their website. As you say, a phone call is necessary, but they were very helpful.

Ches

[andy198712Participant @andy198712]

Can I ask how much it was? Good to know though!

[Ches Green UKParticipant @chesgreenuk]

Andy,

£218….not sure if that included P&P. Not cheap but I could spend weeks trying to fault find rather than enjoying the hobby. So in that respect good value for money.

Just finished reading your own thread on your lathe – quite the journey! The lathe control board ‘looks’ identical to my mill one.

Like you I’m a (retired) Mech Eng. Good luck with the problem.

Ches.

[andy198712Participant @andy198712]

Not too bad, I’d pay that for my milling machine should it ever need in a heart beat given the mills cost and quality ect it’s worth it

 

my lathe is pretty old, maybe worn and didn’t pay much for it so going the cheaper modding route. Thanks, fingers crossed!

[Ches Green UKParticipant @chesgreenuk]

Update: A new motor has cured the problem, fingers crossed. This was not a cheap exercise, but the main thing is I can now continue with the hobby.

The symptoms of the SX2P mill had been intermittent stopping of the spindle, sometimes accompanied by a clicking sound towards the top rear of the mill. Over a few weeks the problem got worse.

Parts replaced…

– Speed control potentiometer, supplied by AliExpress – no difference made

– Main control board, supplied by Axminster Tools – no difference made

– On/Off switch, supplied by Axminster tools – no difference made

– 500W brushless DC motor, supplied by Axminster tools – Fault now no longer apparent. Mill has been test run for about a total of 1hr over a few days without issue.

Some pictures follow of the old motor being disassembled trying to spot where the issue may have been….

Below – The top of the motor showing a small circuit board with FETs and Hall sensors? I haven’t (yet) extracted this since it seems potted. It looks like the board can be slightly rotated to find the optimum position for the Hall sensors in relation to the windings?

 

Below – The case + windings next to the rotating shaft. The shaft magnets are strong and took a decent (careful) tug to get the shaft out.

 

Below – The shaft assembly – magnets, bearings (they run smooth) etc. There appears to be some blue plastic material added, I guess for balancing.

 

Below – A close-up view of where the cables are attached to the windings.

 

Below – The bottom end of the motor where the gear would be mounted that drives the belt

Nothing seemed out of order anywhere in the motor, but I am no expert on these matters. I believe there may be 3x bimetallic sensors embedded in each motor winding to sense over-temperature conditions. Or perhaps the sensors are of the Thermistor or Silicon sensor type? I suspect the clicking I heard was a relay in the main control board being activated by a sensor in the motor.

The other thought was that perhaps one of the FETs or Hall sensors was failing.

Fitting the new motor took a couple of hours mainly due to making sure each new connection went to it’s proper mounting place.

Also the plastic conduit, that protects the two motor cables as they route to the control box, is actually permanently captive. The conduit is pushed in to a plastic connector ring which has double-sided barbs – the outer barbs fix the ring into the plastic connector; the inner barbs dig in to the conduit grooves. So I had to carefully cut off the conduit from the barbed rings at both ends of the conduit. This meant, when reusing, the conduit was now about 50mm shorter, so more cable protruded in to the already tight control box.

Feeding the two cables back down the conduit was also a fun job!

I’d order fresh conduit next time.

So, for now, the mill appears to be working. I’ll update if that changes. I’ll also have a go at checking the resistance of the motor windings.

All for now,

Ches

PS: Axminster and others sell the Main Control Board plus Motor as a pair, and at a lower cost than as seperates. This kinda tells me that it is a chore to identify where fualts such as mine may lie. So the quick, likely-to-be-successful, but expensive solution is to replace both at the same time.

 

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