Thread: lathe alignment

Whats rhe procedure with turning without a gap close to the chuck?
Ive though about selling it but at the moment im not ready to give up on it.

Originally Posted by brendanh

Whats rhe procedure with turning without a gap close to the chuck?
Ive though about selling it but at the moment im not ready to give up on it.

Chuck with maximum overhang, for example fitted with a thicker than normal "spacer" backplate? And/or use long overhang tooling. Or/and maybe make a toolholder offset towards the headstock (overhanging the cross slide)? Neither solution is ideal, all do trade-in rigidity to bridge the gap. Thereby reducing depth of cut. But at least it gets you to use the machine.

Ahh didnt even think of that. Yeah thats a great idea, like you said not ideal but usable.

Hi Brendan,

I don't see the gap as an issue ! It is there so that you can turn work with a diameter that would otherwise foul the bed, like pulleys. As CBA said, my Myford has a permanent gap. I think I've only had need to take advantage of it two or three time since I got the lathe, nearly forty years ago. Even with a nose collet, I can't get the cross slide to overhang the gap by more than a couple of millimetres. However having said that, I wouldn't want to be without the gap because the face plate wouldn't fit on the spindle nose.

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Ive attached a couple of pics. Show the saddle right before the gap. Pic 1 is compound centralalised. Pic 2 shows the compoud at max travle. Being new to lathes im not sure what is and what isnt accetable practise.

I feel given the info avaiable we might be jumping a little to quickly to 'glue the damn thing in' or 'throw it out'. Many lathes have had there gaps pulled out and replaced with no issue(though not mine as yet). I know of a $26k(1984$at least I think that was the number) Mazak lathe that the boss said the gap was not to come out.

I've pulled my gap out several times and replaced after a thorough clean with no problems. For normal tuning the saddle barely gets on the gap piece anyway, unless you are using a faceplate.

The problem with replacing the gap is not unlike truing the headstock. I had ocassion to realign a headstock a few years ago. I would line everything up nicely but the moment I did the final tightening of the headstock bolts, it moved. In the end I sat down and looked at it critically. The next day, using a file, I smoothed the area under the bolt heads, removed all extraneous fittings that were in the way, modified a tension wrench to fit and worked out a final tightening sequence. Not sure all these steps were necessary, but they certainly didn't hurt.

It's not unknown for taper pins to be bent or damaged either - buy some new ones. Mechanics feeler gauges - wouldn't be without them either. Given the difficulties experienced so far though, once the gap is in place and lined up, I'd think twice about removing it again, then again, practice makes perfect.

I have read by those that know the threaded bolt holes should be countersunk to a small depth... What happens is you tighten the bolts and the metal around the threaded hole moves such that it ends up only a small round area around the hole ends up touching hard up against the mating part... If you countersink by three threads deep or so, the force is moved into a more general area...

Originally Posted by casjon

The problem with replacing the gap is not unlike truing the headstock. I had ocassion to realign a headstock a few years ago. I would line everything up nicely but the moment I did the final tightening of the headstock bolts, it moved. In the end I sat down and looked at it critically. The next day, using a file, I smoothed the area under the bolt heads, removed all extraneous fittings that were in the way, modified a tension wrench to fit and worked out a final tightening sequence. Not sure all these steps were necessary, but they certainly didn't hurt.

It's not unknown for taper pins to be bent or damaged either - buy some new ones. Mechanics feeler gauges - wouldn't be without them either. Given the difficulties experienced so far though, once the gap is in place and lined up, I'd think twice about removing it again, then again, practice makes perfect.

That was the trouble i was getting, i had it perfect then did the last tightening and it moved, is using the compound at max travel an acceptable method to help reach closer to the chuck without going over the gap? thinking for now i might leave it out due to the trouble i was having and other more important issue to sort out with the lathe first.

Once the tool is further to the left than the saddle ways than you are into very unstable cutting territory. All downwards force is trying to lift the right side of the saddle rather than being transferred straight down into the bed. Sure you can cut with the tool out there but it is less than optimum, and i would definitely keep the cuts small. Before anyone says something about the way plates, think about how flimsy these often are. They won't stop much when the saddle wants to lift under force.

Originally Posted by Ueee

Once the tool is further to the left than the saddle ways than you are into very unstable cutting territory. All downwards force is trying to lift the right side of the saddle rather than being transferred straight down into the bed. Sure you can cut with the tool out there but it is less than optimum, and i would definitely keep the cuts small. Before anyone says something about the way plates, think about how flimsy these often are. They won't stop much when the saddle wants to lift under force.

yeah obviously its all a compromise and you work around it all, what about tightening the saddle lock, that surely would help stop the lifting?

Originally Posted by .RC.

I have read by those that know the threaded bolt holes should be countersunk to a small depth... What happens is you tighten the bolts and the metal around the threaded hole moves such that it ends up only a small round area around the hole ends up touching hard up against the mating part... If you countersink by three threads deep or so, the force is moved into a more general area...

This is what I was trying to say to Josh when he was talking about his cubes. You're said it much better.(well I think)

Stuart