Myford Super 7 Crossslide Woes

[DickDastardly40]

Gents,

As this is the machine modifcations board, also apologies, it is posted elsewhere if you've read it already though no replies there yet

I'm having a recurring problem with my super 7 (non-power cross feed) where the crosslide leadscrew binds on the housing where it passes through, the lock nut is on one side and the 'friction' graduated dial is on the other. The steel of the leadscrew collar is wearing away the pot metal casting of the housing and the flakes are working their way into the bearing.

The cross slide goes tight and the handle spins in the spindle as the taper 'securing' it is not man enough to grip.

The only means to free it up is to strip it down and and ease it all up which is a bit of a pain when when screwcutting or a particular cut is applied as it obviously only happens in the middle of an all-important process.

Has anyone else encountered this and what did you do to alleviate it, I am considering surgery of some sort and would like to go with a previously successful operation.

Is just liberal lubrication and installing a grease nipple the answer?

ARC Eurotrade have on their website a project for a ML7 but the bearings for the different sized Super 7 are not available.

http://www.arceurotrade.co.uk/projects/MYF001/index.html

Any pointers or input appreciated, unfortunately changing for a different lathe is not an option.

Al

 

[John S]

Sounds like you may have a slighly bent screw.

John S.

 

[deverett]

Sounds like you may have a slighly bent screw.

John S.

Once you get it sorted out, ArcEuro Trade do a very good ball bearing mod to the X slide lead screw (and main lead screw) that removes much of the screw friction.

Dave
The Emerald Isle

 

[DickDastardly40]

Sounds like you may have a slighly bent screw.

Well I finally had some time to look since you suggested a bent screw.

It rolls along my granite plate without a wobble, so next thing to try is set it up at various places on the thread in a 3/8 collet and clock the journal portion.

I'm thinking of making a T shaped brass bush to fit into the housing to act as a bearing due to the housing and front face being a bit chewed. The only slight fly in the ointment is that I need the lathe to make or adjust the bits to repair the lathe.

Fingers crossed and an opportunity to do it.

 

[John S]

Dick,
Last week I converted a non powered cross feed S7 as a project for Arc so they can do the kits for both S7 and ML7's.

It can be done on the lathe with a bit of a bracket and the 4 jaw, you need a boring bar that can open the 1/2" hole up to 3/4" and be able to back cut.
all the work is done on the bracket, the rest, screw and dials etc are un touched.

Once adjusted it silky smooth and absolutely no backlash from the bracket.

I still have everything handy so if you want your bracket doing give me a shout and I'll do it and fit the bearings.

John S.

 

[DickDastardly40]

John,

That is a very kind offer, thank you very much. The gent I spoke to at Arc said that they couldn't source the correct bearings for the S7, ??? obviously he wasn't in the know.

I'll PM to discuss how to send the bracket and payment, will you need the leadscrew also?

Al

 

[rezgaras]

Yesterday I encountered the same problem. The cross slide went tight and I am not even able to turn it! After removing the dial I can hardly turn the spindle by fixing it in a chuck! I do not even understand, how the ring on the inner part (red arrow) can be removed. Does it have a fixing screw in the side unvisible now? What to do if this screw is unaccessible?

Thanks

 

[bambuko]

...Does it have a fixing screw in the side unvisible now?...

Good guess ;D

Alternatively some other

might be jammed there? (although I doubt - grub screw is best bet)
As for what to do about it - I would try to rotate by gripping "adjusting collar" (to stop damage to leadscrew).

Chris

 

[rezgaras]

Thank you for the help. I have managed to turn the ring and loosen the setscrew. Still it was a hard job to push out the jammed leadscrew. But the ring-bushing assembly still sits fixed. To push out the bushing from the rear side would require a pushing rod with collar. Easy to turn one with a lathe... But without?

 

[bambuko]

It is threaded (that's why it is "adjusting collar") - so you have to unscrew it, not push it

Chris

ps I hope you haven't had a go at it with a hammer ...

 

[MachineTom]

The locking collar is threaded onto the crossfeed screw. It is a RH thread the same as the crossfeed screw. The grub screw locking the collar bears on the threads, over time it gets loose, next time you feed in the screw rotates, the collar doesn't it, then locks up. Another of the poorly designed parts on an overall nice tool.

Yes, I own one.

 

[rezgaras]

It is threaded (that's why it is "adjusting collar")

Thanks, too late I also discovered this - after pushing the spindle for a while. Actually I was wondering why the "copper pad" was there below the setscrew. It makes only sense if there is a thread (or something sensitive) below...

Now I have managed to take the assembly apart and put the crossslide together.

I think there is a basic design flaw in this construction. If the setscrew gets lose the collar drives and tightens itself abrasing the aluminium body of the endplate. Perhaps it would make sense to put there steel washers on both sides. And regularly check the setscrew. Well, it is easy to be clever afterwards...

Thanks for all responses, they've helped a lot.

 

[rezgaras]

> Another of the poorly designed parts on an overall nice tool.

Sorry, I have read your remark later on. I fully agree with you.