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Home Model Engine Machinist > The Tools and Tips > Machine Modifications > Lathe bed regrinding

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Old 09-28-2017, 07:25 AM   #11
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Jon,

It seems like your measurements are way out. going by yours, the saddle and tailstock would jam up solid if you tried to move them at most a 1/4 of the lathe bed length.

There are also a few ways that you can get a taper when turning, and bed wear is the least probable one.

If your machine has the removable headstock, like mine was, then the position of the headstock front to back and side to side in relationship with the bed can easily give very excessive tapered turning.

With regards to getting your bed reground, don't even consider it. The cost of it will not add one penny to the value of your machine, and I can see later, in a year or so, you will be looking for a larger machine, so keep the costs if at all possible down to zero.

Anyone with a good strong milling machine should be able to (with a couple of hours setup) skim across your bed with a flycutter, giving you surfaces that are plenty good enough for the type of machining you will be doing.. The same goes for the saddle and cross/top slide as well. In fact, you might find, if it is the head causing the tapered turning, the bed might be plenty good enough for what you want to do.Just keep it well lubricated with the correct grade of oil, ISO 68.

John


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Old 09-28-2017, 09:22 AM   #12
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Hi John,

Yes it's got the removable headstock, I think I'll need to buy a test bar, or the very least get a magnetic base and dial indicator, mount it to the headstock and dial in a 1" test bar to in the four jaw, then proceed to see if the bar runs parralel to the bed, by measuring chuck end and far end of the bar, with the dial indicator mounted to the saddle.

My theory is the spindle is fixed so if I can dial the bar in parralel to the head stock (and spindle) then I can use that as a reference to dial in it's position relative to the bed. What would be really handy for setup is a double ended MT1 taper bar, as this would help align the tail stock too. Whilst also useful to align the headstock. Which if I can get to 1 thou taper over 3" i dont think os too bad for now.

Then comes measuring the cross slide square to the bed. For that I intend to use a faceplate with a dial indicator attached and take a measurement of the cross slide travel.

Just need to get a dial indicator, oh and I've got my eyes on a ML10 next which I've been informed about so your quite right 😀


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Old 09-28-2017, 09:35 AM   #13
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Ah but there is the question of the headstock spindle NOT being at right angle to the ways so that the lathe will face slightly hollow and then the work will ring together. I'd sort of forgotten that amongst the plethora of often irrelevant information.
I'd been doing a classic series of tests using my J blocks on what of these extremely cheap super market verniers that everyone seems to possess.

Of course, the next interesting thing is not to lean on the tailstock or whatever one does whilst watching the wheels turn.

As the Glaswegians rudely comment-- Is that a fact?

Ooops

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Old 10-12-2017, 07:04 PM   #14
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I set up a rather odd (according to lathes.co.uk!) 'Wandess' lathe by adjusting the head across the bed, looking to make it parallel by boring holes until they were no longer taper. But boring to a nice finish on a small, knackered lathe can be tricky anyway, and tools can be a bit bendy.

Then I set over the tailstock until it turned a straight bar too.

It made something terrible into something merely rather worn. I also coloured two of my jaws on the 3-jaw, since a bit of beer can here (but not on the third) made things a whole lot more concentric

Then someone gave me a Boxford, with everything keyed to v-ways, which is either right or it isn't. Well, for me it mostly is, but perhaps that's just by comparison from where I've come from!


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