Cross slide travel

Hi all,

I have a Myford ml7 and the problem I seem to be having at the moment is that when facing off or parting off, it does the job but the cross slide seems to get very tight when getting to the centre pip.

what id like to ask is if your an ml7 owner how much travel do you get and also does it start to get very tight when your almost at centre.

how far is the cross slide supposed to travel past the work you are cutting.

any ideas or suggestions as to why this would be happening on my lathe.
the cross slide is the long length one by the way.

Thanks

chris m…..

Sounds more like you may have a tool height issue, does it travel OK when the tool is just clear of the face of the work or does it become tight all the time in which case gibs may need adjustment on a worn cross slide dovetail.

The cutter should be adjusted to avoid a centre pip. Actually, for making heavy cuts on larger diameter bars, the cutter will be deflected to below centre height by an amount depending on how rigid your set up happens to be. With an old fymord, I expect it could well be a few thou. There should be no (or minimum) deflection when at the centre of the bar.

Remember that at the centre, the surface cutting speed is actually zilch.

If you are using carbide, travelling beyond the centre may cause the cutter surface to be damaged (by reversing the cutter direction).

Yes with you there Jason, sounds like it’s too high.

Might also be worth checking that the cross slide end plate isn't misaligned. A problem I had when removing the lead screw to use the taper turning attachment and the re-installing it.

Rod

Hi,

the cross slide moves along fine, but as I’m getting nearer the centre of the work I becomes very tight.

any other ideas.

thanks

chris m….

So it moves fine when you are not cutting even when moved as far across the lathe?

If so look at tool height particularly if it is leaving a conical bump in the middle as tool is too high

This always happens on my set up. The parting tool is correctly positioned.I never have a pip after parting off, but you need to use more force to cut the pip off. I always put this down to the almost zero cutting speed on the last bit of the cut.

Andrew.

Hi,

even when I’m not cutting and moving the cross slide it still gets very tight at the same point.

the cutting tool is level to the centre and cuts well leaving hardly any pip, but as I said it’s very hard to turn at about this point.

thanks

chris m…..

In that case gibs of what Rod said. I would think you could remove the leadscrew so the slide can be moved back and forth by hand, this will show if it's the gibs getting tight. If it moves freely then the screw position or nut may be the problem.

I'll leave it to a Myford owner to suggest how to do this

Disconnect the end plate from the cross slide. remove the Cross slide screw fully from the lathe.

Push the cross slide back and forward. If it is tight at any point then adjust the gibs on the cross slide so it slides easily. Make sure that you have properly lubricated the cross slide with a suitable lubricant, I use an MDS grease.

When you reassemble the end plate with the screw back to the cross slide only tighten the 2 end plate screws when you the cross slide screw in ad far as it will go.

Only when you are certain that the cross slide is moving freely then try cutting and see if you still have the issue then we know you are dealing with a tooling or cutting issue.

Peter

Make sure that you have properly lubricated the cross slide with a suitable lubricant, I use an MDS grease.

The proper lubricant for a cross slide is slideway oil - NEVER use grease in this application.

Nigel B.

If the tool is on centre height, it may be that (very likely in an older machine, ) the Saddle and Cross Slide, and probably the Leadscrew,  are worn, and although the gibs are set for the worn areas, things tighten up over the less worn parts.

This can be alleviated by scraping the dovetails, but as a newbie, you would be well advised not to do it, for fear of doing more harm than good.   Scraping surfaces, particularly dovetails, is not easy.  It is a hard to acquire skill.

Howard

Edited By Howard Lewis on 01/09/2022 14:45:53

Howard have you ignored what the OP said

"even when I’m not cutting and moving the cross slide it still gets very tight "

Jason,

I don't think so!

I thought that I took account of that by saying, in the first paragraph, that If there is wear in those components, and the gibs are set for that wear, things will get tight when the less worn areas make contact.

The problem with living with that state is that the Leadscrew and the Mazak nut are likely to wear.

At least a worn nut is easily replaced!

Howard I was going by what you said in your unedited reply

Jason, Ah!

In that case, your response was valid.

Then I realised what had been sent about not cutting, and the tool now being on centre height.

Howard