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mike 109444
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Why can't I get this out of my head while reading this post ??
So I decided to check the speed of the lathe now it has got a working coupling. The gearbox had been modified selection wise to give just two speeds by restricting the select lever to be moved forward or rearwards. The gears that are selected must include reverse as one powers the chuck clockwise and the other anti clockwise looking at the chuck from the bed end. So in clockwise rotation it spins at approx. 460 rpm and at 374 rpm in counter clockwise rotation. Does it matter much which way the chuck turns as regards the cutting?
Gritineye
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Turning towards you the tool has to be at spindle centreline on the front of the workpiece, away from you it moves to the back, but upside down, same height.
Be interesting to find what the other speeds are, are your headstock bearings white metal or ball/roller bearings?
Is your chuck a screwed on type, if so a positive locking method is desirable for turning in reverse.
Be interesting to find what the other speeds are, are your headstock bearings white metal or ball/roller bearings?
Is your chuck a screwed on type, if so a positive locking method is desirable for turning in reverse.
Bill Edwards
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The common (normal) method of turning has the tool on your side of the work piece and the metal turns into it - try it the other way and it'll just rub and won't cut. That's anticlockwise when you look at the chuck from the tailstock end.
Headstock bearings are white metal and I will have to check the chuck fitment. The couple of actual cutting jobs I have done have been with the chuck rotating ccw towards me so the speed was 374rpm. Is that the sort of speed you would consider normal for cutting mild steel? I have not attempted to use the other direction yet. I might remove the top home made cover off the select lever and see what else is available.
Spark plug
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374rpm is purity mutch a good general speed but for material over say 30mm but for smaller stuff you would be if it from a bit more speed. Maybe try for 2nd, if you could get say 600rpm as well it would make it mutch more useable but your always going to be limited by your white metal bearings.
mike 109444
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It is not good practice to cut with tool mounted at rear as you are "lifting" the cross slide and any slack in the slides will alter the center height of the tool.
It is usually seen on capstans and a parting off tool is at rear as last stage of process.
It is usually seen on capstans and a parting off tool is at rear as last stage of process.
Pete.
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It's a minor matter to put a dial indicator on the slide and lever it up to measure the lift, then set the tool height accordingly. Really though, there should not be much lift on a well-maintained machine. If you can't adjust it out the ways need attention.
