The Craftmans Shop > New from Old

Making-A-Taper-Gauge

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millwright:
I enjoyed watching the surface grinder, it seems to have a hypnotic effect, spent many a happy hour on the Jones and Shipman over the years

John

David Jupp:
Andrew,

In the past I've seen 'Go, No-go' gauges for 'Grayloc' hubs - the hubs have female tapers (rather like the back of your chuck).

The interesting point is that whilst for smaller sizes the gauge is round, as the sizes get larger the gauges are made from flat plate having curved / tapered ends.  Imagine the plate as a 'thickened diameter' across the hub.  Presumably the plate is mounted in a 4 jaw chuck to turn/grind  the conical faces on its ends.

This approach both saves material, and keeps the larger gauges to a manageable weight to handle easily.

awemawson:
David I can well see why they'd want to do that - things get unwieldy rapidly as they get bigger !

As I had the 20 mm plate my plan is to fettle the taper to fit the rear of the chuck when I eventually take it off, leaving the taper long and concentrating on getting the correct engagement of the smaller end. This of course is critical as the O ring seals for the hydraulic actuation need to be properly squashed but not too much.

Once that's achieved I can measure how much of the big end protrudes with a depth gauge, and remove a small crescent to that depth as a tell tale for the gauges final use making a recess in the adaptor.

I spent this morning chasing my tail and going down the rabbit hole setting the lathe for the correct taper - it's dead easy at a theoretical level - applying SOHCAHTOA tell me that the sine of my angle times the travel that I can achieve on my top slide gives me the offset. Tap over with a dial gauge and Bob's your uncle. When I came to actually doing it I found that my tailstock wasn't dead nuts 'on' and had to dig out my setting bar and do a few adjustments.

I might actually get something done this afternoon !

awemawson:
So I did indeed rough out the taper on the lathe this afternoon using the top slide.

I emphasise that this is roughing out, although I can set a pretty accurate angle using trig on the lathe top slide it is at least an order of magnitude worse than I can set on the J&S 1300 cylindrical grinder as after all this is what it's intended for.

My top slide gives me a comfortable travel of 90 mm, which by applying trig gives an in feed at the smaller end of 11.1627 mm. Now 90 mm of top slide travel is 45 turns of the knob. This rapidly becomes a pain - I did three (or maybe four) iterations and got the displacement down to 11.171 mm. Perfectly adequate for a roughing cut - this is just to reduce the amount to grind off. Fairly arbitrarily I just let the taper take half the width of the disk .

Once mounted on the cylindrical grinder I'll take the diameter down to the major dimension of the taper (106.358) before putting on the taper.

The J&S has a table intentionally designed to swivel in a precise manner and is equipped with a racking screw to make the setting rather more precise than whacking the top slide with a soft mallet !

(I borrowed the measuring equipment dedicated to the cylindrical grinder !)

awemawson:
I did actually skim off a bit more from the disk this morning - still left a generous millimetre for the grinding, talking of which, time to re-commission the J&S 1300 EIUR cylindrical grinder:

Poor thing has been neglected for ages, infact I'm not sure that I've used it in earnest since I moved here - I probably have as there was still coolant in it which remarkably was in good condition. I had sprayed it with Shell Ensis preservative years ago before moving, and the table was still thick with it. A bit of elbow grease and a rag soaked in white spirit and it cleaned up OK. I obviously had missed the swivlling table clamps and tailstock release handle as they showed a bit of corrosion, but that was soon cleaned up.

So far I've proved the hydraulics are OK, and that the controls all work - the fine infeed dial was stuck but that was just dried up oil. The coolant pump works, and the coolant clarifier seems to work. This is the type where the used coolant discharges over the back of the machine through a weir falling onto a paper roll filter that sits on a mesh conveyor belt. As the filter draws particles from the coolant it gets heavier, weighs down the conveyor tripping a microswitch that advances the roll dumping the contaminated bit into a bin. I'd tried poking the switch to prove that it worked (it did) but I've left it pumping coolant round the system as I type this, and it's just tripped of it's own accord  :thumbup:

I've yet to check the alignment of the powered swivelling headstock (MT3 test bar job) and the swivelling table (parallel bar between centres job) but I now have other duties to perform, first lambs having been born this morning.

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