Strip-down
and rebuild

Coming apart

Before a spanner touches anything, the machine gets looked at whole and turned over by hand where that is safe. Free play, tight spots, a rough feel through one part of a revolution: those tell you where to look, and they are gone once the thing is in pieces. Then it comes apart in a written order, because that order read backwards is the rebuild.

Fasteners stay with the holes they came out of. Mating faces are marked before they are parted, so a cover goes back the way round it has worn in. Shims are counted and stay in their stack. Seals are noted for which way the lip faced and springs for their free length. Grease and oil come out over clean paper, where swarf, bronze glitter or a broken shell can be seen instead of washed away.

Sub-assemblies that nothing points at stay shut. Opening a gearbox to satisfy curiosity introduces a risk the machine did not arrive with, and it buries the fault you were sent under three more jobs.

Measuring, and what the measurement decides

Each part that matters gets a figure put on it before any decision is made about it. A micrometer along a shaft at more than one point and more than one angle, because wear is rarely round and rarely even. A bore gauge in the housing it runs in, since a shaft inside tolerance in an oval housing is still a short-lived drive. A dial indicator for run-out and end float. Feeler gauges for clearance. A straight edge and a light for a face that should be flat.

Those figures are read against what the manual or the drawing asks for, and the gap between the two is the decision: refit, rework or replace. Where nothing survives in print, the fit is taken off the mating part and off what the material will stand, and that reasoning is explained before it is acted on rather than after.

1. AInside toleranceClean it, refit it, and say what it measured so the next person knows.
2. BWorn but recoverableSkim, sleeve, re-cut or bush, and bring the mating part back to suit.
3. CPast the limitReplace with the part, or with one made to the same fit if nobody sells it.
4. DPast the machineWhere the figures say replacing beats repairing, that is what gets said.

Parts, bought and made

Bearings, seals, belts, chain, fasteners, contactors and cable are bought to the size and rating that came off the machine, or to the nearest equivalent still in production. Where the equivalent differs in width, clearance class, rating or material, the difference is named, because a bearing of the right bore and the wrong width is how a machine ends up back in the shop.

The rest gets made: a shaft turned from bar to suit the bearings that do still exist, a keyway cut on a fresh angle with a key made to fit it, a bush pressed and reamed in position, a bracket or guard fabricated because the original cracked where it always would. Making a part is often the difference between a machine with another decade in it and a machine that becomes a space on your floor.

Going back together

Everything is cleaned before assembly, and cleaned again where a bearing or a seal has to seat. Old sealant comes off properly. Threads are chased so that a torque figure measures the joint rather than the drag of damaged metal. Bearings go on with heat or a press rather than through the balls, and seals go in square with the lip the way it came out.

Fasteners go to the published figure in the published pattern, and by feel only where no figure was ever published. Shims return as counted unless a measurement says the gap has moved. End float, backlash and belt tension are set, then checked again when everything around them is tight, because tightening moves things. Coupled shafts are aligned, not assumed: a motor flat on its feet is not the same as a motor running true.

On the electrical side, terminations are made up clean and to torque, bonding and glands go back as they were designed, cores are identified rather than guessed, and insulation resistance and continuity are checked before anything is energised.

Run-off

A rebuilt machine runs here before it runs anywhere else: off load first, long enough to get properly warm, with bearings felt rather than glanced at and current draw read against the motor's own rating. Then under load, doing the thing it came in for. The fault it arrived with should be gone, and everything that worked when it arrived should still work. Both of those are checked, because they are different questions.

It leaves with the plain version of what happened: what was worn, what the figures were, what was replaced, what was made instead of bought, and what is worth watching next time it is open.

The same stages, on your floor

An installation reverses the journey. The machine is set out where it has to sit, levelled on its feet, anchored or packed to suit the floor, connected, and then aligned to whatever it drives or is driven by. The drive arithmetic matters here more than anywhere: a pulley changed on site changes the speed of everything downstream of it, and the ratio and belt figures on the front page are the same three formulae we use standing on your floor.

Electrical repair often has to happen in place too, and the constraint stops being the measuring and starts being isolation, access and the window the line can be down. That window is agreed before anybody arrives, with MAHAKALI ENGINEER SERVICES LTD reachable at workshop@mahakali.work.

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