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| taper problem. |
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| John Hill:
--- Quote from: wheeltapper on September 06, 2011, 04:23:53 PM ---Haha, as far as I can see they describe a very large circle. :lol: what I might do is strip the thing down (again) clamp the slide part onto the mill table and run a D.I. along the dovetails to see if they are straight. I haven't got as far as working out what to do if they aren't. :bang: :bang: if I do this I'll let you know the result. Roy --- End quote --- It does seem a bit odd though, if the dovetails are a bit squirely one would expect the slide would bind at some part of its travel. :scratch: |
| hopefuldave:
Quote: It does seem a bit odd though, if the dovetails are a bit squirely one would expect the slide would bind at some part of its travel. /Quote Depends whether the wear's at the ends or in the middle, and whether the gibs are taper-with-adjusting-bolts (which would bind) or parallel and adjust from the side with a bunch of setscrew and nuts (which could be adjusted to fit the worn curve)? Assuming that the wear would be in the middle of the pressure face where it has done the most work and the gib is adjusted to match, it'd give the deviation the OP described... How much deviation, if not extreme it could probably be scraped out? A good test would be to put a known bar (uniform diameter. ground silver steel or HSS blank?) in the chuck and run a tenth-thou" DTI along it, would at least indicate how much needs to be taken off to straighten it. Luckily it sounds like the error's in the topslide, so there's not the same criticality - unlike the topslide, it doesn't need a fixed 90-degree angle to the ways - you'd be swivelling it anyway :) Dave H. (The other one) |
| wheeltapper:
Hi the lathe isn't that old so I wouldn't expext much wear in the topslide dovetails. most of the time the topslide is in a cupboard and I have a chunky toolpost that goes directly on the cross slide. I only fit the topslide for tapers. Roy |
| hopefuldave:
Ah, so it was made that way... Damn. If it were mine, I couldn't leave it as-is, I'd be in with the Prussian blue and a scraper (assuming it isn't grossly curved) - how much of a bulge did you get when cutting the 2 Morse taper? It doesn't take a lot to make them rock in the socket, I know! Dave H. (The other one) |
| John Hill:
Of course a taper can be cut without using the top slide but by using centres and offsetting the tail stock (which I understand is quite easy if one of those boring bar holder thingies are used instead of actually disturbing the tail stock position). Bit hard to do an inside taper that way though.. :scratch: |
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