Go make yourself a tea or coffee and settle down in a comfy chair.

About 14/15 years ago, around the time of my retirement, I bought an SX2P mini mill to supplement my lathe bought a couple of years earlier.

I could not have been happier with my purchase as it has done everything I have asked of it.

It has been modified with gas struts and cheap scales on all axis.

All was going well until recently, when I started to have problems with the SX2p not starting, stopping intermittently and the dreaded ‘clunk’ which a few others have commented on, and blowing fuses.

Eventually it stopped altogether, forcing me to investigate further.

I have my SX2P bolted down to the workbench on two wooden blocks to raise it up a couple of inches for ease of use.

Now! I am not the worlds tidiest person (understatement!) so I now have to find a home for all the clutter around the mill so I can unbolt it and turn it round to get at the main circuit board in the box at the back. Home for all the clutter was found (just moved else ware actually!) and I gained access to the main board.

Initial look didn’t find anything obvious, so put my glasses on – low and behold I have a one legged IGBT ( it also has a big hole in its body). This is IGBT number 5 (U phase).

There are 6 IGBT’s which work in pairs, it’s partner looked ok so had a look else ware for obvious damage which led me to the plug in processor board which has 6 white opto isolators on (one for each IGBT), two of them had opened like clams, obviously to let out the magic smoke.

Further inspection led to IR2110 DIP14 IR FETS DRIVER 14 pin dip package which showed signs of distress, the gate resistor of the blown IGBT had also burnt out.

Testing all the other IGBT’s showed that No. 6 (number 5’s partner) had also gone.

So, armed with a list of required components, I ordered them off FleaBay.

Parts arrived and duly replaced the dead components, switch on and Poof, more magic smoke!

Oh dear! What a shame! Never mind.

Could it be the motor me thinks, phase coil check looked ok, could be the hall effect switches (probably most likely.)

So went in search for a new board and motor, my god! How much!!!!

new boards are anything from £260 to £500 and the motor isn’t much better, I am reluctant to spend that sort of money so looked for alternatives.

I could buy a new BLDC drive control panel for about £60 (China of course.) but the exact motor proved more reluctant.

I did though find lots of adverts for BLCD servo motor + control panel at reasonable prices.

I wasn’t sure if these would fit the bill so went online to do a bit of research and found an article on some forum where this nice chap had replaced his brushed lathe motor with one of these units (actually advertised as a replacement sewing machine drive!)

These seem to come with a variety of spindle options but all from China, I wanted something nearer to home so looked on FleaBay, lots of options from China but less options from UK suppliers (not many), so I though I would try Amazon.

Low and behold, I could get a 550W package for £100 or 750W for £110, delivered next day.

Go on, guess which I went for?

I did check the spec and thought it would fit reasonably well as the motor mounting holes were the same as the original.

Well they got one over on me there!

Package duly arrived, box marked as lathe drive motor so looking good, took it out of the box and plugged it all together and it works!!!, it looks well built, the motor has a fan housing on top to aid cooling, all I have to do now is make it fit.

Now this is where it gets interesting, on the original motor it is bolted to a bottom plate with tapped holes, the new motor has tapped mounting holes, hmm! Didn’t expect that, so I now need to drill out the threaded holes in the mounting plate, these holes also need countersinking as new countersunk screws are needed to sit flush with the bottom of the plate, The original cap head screws would prevent the plate sitting flush.

The old motor had a 60mm boss which fitted into a 60mm hole in the mounting plate, the new motor had a 65mm boss, no problem, mount the plate in the 4 jaw with jaws reversed and bored to the new dimensions,

This job done and the motor with mounting plate now sit properly on the top of the mill.

The next job is the drive pulley, the new motor has a 15 mm shaft the old one was 14 mm, the shaft is also longer as it has a 12mm threaded section.

I had two options here, buy a new drive pully or modify the original, I chose to bore out the original as this one is the right length to mate up to the toothed belt driving the main spindle.

The pully now fitted onto the motor shaft(it is keyed like the original) but still leaves the extra length to deal with,

A 12mm nut is supplied with the motor, I suppose to keep the pully on the motor shaft, the original motor had a shorter shaft (no threaded part) with a 6mm tapped hole for a washer and 6mm countersunk screw.

I attempted to drill and tap the new motor shaft but managed to break the tap!(B****R!) so had to resort to using the supplied nut.

This nut is too thick so reduced it on the lathe to about 3 to 4 mm and when fitted the shaft does not bottom out, so all fine.

Motor fitted to the mill, nothing fouling, things turning smoothly so onto fitting the control box.

This item is stand alone but does not have any safety features such as a no volt switch.

So I decided to keep the original control box and no volt switch but move it back about 6 inches and mount it on the box at the back that held the main board. I also decided to keep the mains filter board, can’t do any harm, and wired the mains cable from the new unit into the rear box and connected the wires to those from the no volt switch.

Now I only have to mount the new control box somewhere convenient, some searching on Bambu labs site produced a bracket that I could resize to suit the new control box.

I intend to mount the bracket where the old no volt switch was located, drilled some holes in the bracket to mount the control box and looked for some suitable screws.

Now! Would you believe it, I had thought that the mounting holes at the back of the control box would be 6mm, well they looked that size….. no way would 6mm fit, 5mm too small (B****R once again), so what ‘expletive deleted’ thread have they used?

I suspect it is an American thread ( I don’t have any at all) so a search through my ‘might come in handy one day’ box and found that 1BA fitted perfectly, I have not done any research but I am sure someone on hear will tell me what the thread is.

The bracket was fitted to the mill via a couple of 5mm screws into new holes tapped into the side of the mill where the no volt switch used to be.

Everything connected together, switched no volt switch on, switched new unit on and….. nothing. Oh! Dear.

Silly me had not put the fuse in, low and behold I now have a working SX2P with more power than the original, for a very reasonable amount of money and a little bit of work.

Not a one for one replacement, but life is never easy.

Now! Having sorted the SX2P out, do I now replace the brushed lathe motor with a similar sized brushless unit? It is about 17 years old now but still going strong.