For a while now both the belt sander and the lathe have needed a flick to get them started. I suspected the run capacitor in both cases. Both are small AC induction motors that only have a single capacitor (bigger motors have a separate big start capacitor and a run capacitor). It's difficult to test a capacitor without a specialist meter, some convoluted and cunning measurement* or testing by substitution (or similar) on a live machine.
I happened to have a spare 6uF capacitor but was reluctant to try wiring it in or dabbing it across the terminals and switching on. The lathe motor had been getting increasingly noisy and I'd replaced the bearings recently so I wanted to fix it.
The lathe capacitor is 8uF and I thought if I put the 6uF across that in parallel it would give me an indication if the old one was shagged. I held the cap' in place with one hand with the two wires touching the appropriate terminals (not easy) and switched the lathe on with the other hand... It purred into life, great! That proved that the capacitor was the problem.
While I was on a roll I dismantled the belt sander to see what size cap' was in there so I could order a new one for that whilst I was at it. It was 6uF, ha! (old one is pictured). That's what my brand new spare was, I fitted that and it now starts without a flick. Whilst the belt sander was apart I noticed a lot of fibrous dust had collected in the bottom of the belt guard/case and it was covering the lower half of the motor pulley.
I thought a small hole in the bottom of the guard would be a good idea so that the dust would fall out or could be picked out. A couple of minutes with tin snips, hammer and file made a nice small hole which can't trap a British Standard Finger, but should do the job (indicated by yellow arrow in pic). Note, the underside of the sand belt doesn't have a guard... that's because it is a right pain to remove one when changing belts... (anyone who thinks that this is a hazard should consider that it's no more of a hazard than the top of the belt!)
I ordered a couple of capacitors from Ebay an 8uF and a 9uF just in case a bit of extra oomph was needed. It's not a simple case of more is better and the manufacturers recommended size (+/-10%) should be used. However capacitors are notoriously poor tolerance components so I thought going up to 9uF if necessary should be fine.
While I'm waiting for those to arrive I might add the old tired 6uF in parallel to the old tired 8uF and see how that runs.
I'm keen to get the lathe to start up when switched on, as it almost caused a fire last week!... The switch had been knocked to "on", the lathe cover was over it and the motor sat there stalled humming quietly... I'd noticed the hum and thought it was the central heating pump. It wasn't until my mate JT, who was there, said can you smell something? (Other than my usual farting) that I investigated further.
The motor was too hot to touch and the film of oil and dirt on it was smoking lightly! It was this incident that led to me dismantling the motor and replacing the bearings. Getting it starting correctly should avoid a repetition. Note:- The switch is easily knocked because it is positioned to be accessible for emergency switch off. Of course a fancy latching switch with big red button would do the trick and be less likely to get switched... but IMO the solution is to cure the fault rather than just add more complexity (and cost). If the lathe had actually switched on, it would have been obvious.
I've also been doing more to the bow weighing rig, adding some angle ali' at either end which will provide a way of clamping it to a table. It also adds some extra rigidity.
* For those who are interested I suppose you could measure its capacitance by charging it up to a known voltage and plot how it discharges through a known resistance over time using a digital voltmeter and work it out from there.
I've been asked for more detail about the Archer Automaton, so I've done a video here:-
I've had a bit of a break from bows as I've been modifying my Mini Mill (a Clarke CMD10, which is the same as a Sieg X1) to make it belt drive which should make it smoother and quieter. The pic shows the small stepped motor pulley standing on top of the big one which is still work in progress, centre hole being bored with a boring bar.
JT came round and he did a good deal of work on the bow under my watchful eye. There was the usual panic as the spoke shave or plane dug in and started to tear, but careful use and resorting to the rasp kept things under control.
For a while now both the belt sander and the lathe have needed a flick to get them started. I suspected the run capacitor in both cases. Both are small AC induction motors that only have a single capacitor (bigger motors have a separate big start capacitor and a run capacitor). It's difficult to test a capacitor without a specialist meter, some convoluted and cunning measurement* or testing by substitution (or similar) on a live machine. 
I happened to have a spare 6uF capacitor but was reluctant to try wiring it in or dabbing it across the terminals and switching on. The lathe motor had been getting increasingly noisy and I'd replaced the bearings recently so I wanted to fix it.
The lathe capacitor is 8uF and I thought if I put the 6uF across that in parallel it would give me an indication if the old one was shagged. I held the cap' in place with one hand with the two wires touching the appropriate terminals (not easy) and switched the lathe on with the other hand... It purred into life, great! That proved that the capacitor was the problem.
I ordered a couple of capacitors from Ebay an 8uF and a 9uF just in case a bit of extra oomph was needed. It's not a simple case of more is better and the manufacturers recommended size (+/-10%) should be used. However capacitors are notoriously poor tolerance components so I thought going up to 9uF if necessary should be fine.
