Thread: Show us your Hercus

Richard,
Your best reference is page 13, Text Book of Turning.
Finno

Originally Posted by Finnowa

Richard,
Your best reference is page 13, Text Book of Turning.
Finno

Downloaded 1970 copy is cutting tools and their uses.

Nothing to do with what I'm seeking.

Probably your best advise is what Steve Durden advised.
Backlash should be minimal,you need some but not a lot,desirable would be I think .002/.005".
Depending on your experience you can live with a fair bit of backlash as long as you remember to take it out before starting your cut.
In regards to End Float of your Cross and Compound Slides prefferably none.
You have a Gib Key on both of these slides as well as adjusting screws,the slides should move freely but not be loose.
You can set them by feel or if you like use a Feeler gauage to set them,you will only be able to set the outer ends with the Feeler gauage then adjust the centre ones by touch.
Would suggest to initially set with a .001/.0015" Feeler and see how that goes and work down or up from there.
If you have excessive End float you may have a problem with wear in your Compound or Cross slide,or even the Gibs maybe worn.

Here are the JIS specs

Originally Posted by pipeclay

Probably your best advise is what Steve Durden advised.
Backlash should be minimal,you need some but not a lot,desirable would be I think .002/.005".
Depending on your experience you can live with a fair bit of backlash as long as you remember to take it out before starting your cut.
In regards to End Float of your Cross and Compound Slides preferably none.
You have a Gib Key on both of these slides as well as adjusting screws,the slides should move freely but not be loose.
You can set them by feel or if you like use a Feeler gauage to set them,you will only be able to set the outer ends with the Feeler gauage then adjust the centre ones by touch.
Would suggest to initially set with a .001/.0015" Feeler and see how that goes and work down or up from there.
If you have excessive End float you may have a problem with wear in your Compound or Cross slide,or even the Gibs maybe worn.

Thanks pipeclay,
Perhaps i have not described correctly what I am referring to as endfloat.
When pushing either slide, backwards and forwards in its longitudinal plane, there is a distance of 0.120mm endplay. This relates to .12mm of freeplay on the rotating dial before the slide moves.
If this measurement is excessive, how may it be adjusted out ? Steve Durden said that new Acme nuts would be unlikely to improve.

The condition you have described is what I would refer to as side play, not endfloat. There is no detectable sideplay at either end, the slides move beautifully smoothly in their ways.
What I am trying to describe is ( I think ) what you are refering to as backlash. If this is the case, then how may I reduce that backlash ?
I have checked the " endfloat " at each end of the slides travel as well as points inbetween, where one could expect wear on the spindle thread through use. The " endfloat " is the same, suggesting little wear on the spindle thread, or the nut.

Being new to this, I could have this nomenclature thing all wrong. Please correct me where necessary. Thanks for the asisstance and patience.

cheers
Richard

The measurements that you indicate are not excessive in my opinion and the machine should be quite serviceable.
There will be a reasonable amount of backlash or end float from new.
I cant tell you what that should be,if you can find on the net the classes of fit for ACME threads this will give you a better refference point,you can also find the specs in the Machinerys Handbook.
If you feel the movement is excessive you could try and source new nuts as there are the typical wear areas,as they are bronze.
There is a temporary fix you can do if the wear in the nuts is excessive,it repqires you to remove the nuts ,split them HALF WAY through the thread,drill and tap for small screw, to pull the nut together reducing the amount of clearance on the screw.

Removing end-play from Feed Screws..
is the title of page 13 of Ed 4 Text Book of Turning
"Wear on the thrust faces of the cross feed and compound rest screws will produce end play which makes up one of the three components of backlash in the slide movement. The first two components, wear in the nut and wear in the screw can only be corrected by replacement of nut or screw."
It goes on to detail use of a shim to reduce the remaining backlash to 0.03mm
Are we getting close?
Finno

Hey finno I think your book is newer than the pdf book most of us have ,I dont suppose you feel like scanning you book for us? Not sure if it would be a copyright issue after all this time.
Darrell

Originally Posted by Finnowa

Removing end-play from Feed Screws..
is the title of page 13 of Ed 4 Text Book of Turning
"Wear on the thrust faces of the cross feed and compound rest screws will produce end play which makes up one of the three components of backlash in the slide movement. The first two components, wear in the nut and wear in the screw can only be corrected by replacement of nut or screw."
It goes on to detail use of a shim to reduce the remaining backlash to 0.03mm
Are we getting close?
Finno

Now we're cooking with gas finno.
Can't seem to locate this info on the PDF version.

I have checked the backlash at both ends of travel, as well as five points between the extent of travel, the backlash measurement does not vary, on both slides.
I've looked at the condition and they don't look worn. Heck the machine has hardly been used even though it spent 27 years in two institutions. Well, really only one owner, the buildings and name changed.
0.03 is what I'd like to aim for.

Is it possible to email me a copy of that page of information ?

Thanks

cheers
Richard

Originally Posted by pipeclay

The measurements that you indicate are not excessive in my opinion and the machine should be quite serviceable.
There will be a reasonable amount of backlash or end float from new.
I cant tell you what that should be,if you can find on the net the classes of fit for ACME threads this will give you a better refference point,you can also find the specs in the Machinerys Handbook.
If you feel the movement is excessive you could try and source new nuts as there are the typical wear areas,as they are bronze.
There is a temporary fix you can do if the wear in the nuts is excessive,it repqires you to remove the nuts ,split them HALF WAY through the thread,drill and tap for small screw, to pull the nut together reducing the amount of clearance on the screw.

Thanks, there's more info from finnowa now, stating the backlash as being 0.03mm.
I'm four times that.
Another bloke suggested to me the same method of splitting the nut.
Steve Durdon suggested the new Acme nut would be unlikely to improve my current lathe. Perhaps, given the specification by finnowa, there is room for improvement after all.
It's tough sometimes as an anorak.
Thanks for the assistance. Maybe there is a market for the nuts rather than the change gears, or indeed complemented by same.

cheers
Richard

The 260 has the exact same crosslide screw arrangement as the later 9" models with the bigger dials. If you really want to get all the end play out of these you should consider modifying it by putting thrust bearings in as Southbend did in their later models.

Check this excellent thread on converting a Southbend to larger dials with proper thrust bearings.

"http://www.practicalmachinist.com/vb/showthread.php?t=150571"

IMHO, without thrust bearing, attempting to reduce the backlash below 0.1mm is a waste of time. It's probably a waste of time anyway. They would have had that amount of backlash when brand new. There's documentation on the web saying Southbend had roughly that amount of backlash between the feed screw and nut from new.

BTW, if you're going to mess about with this it could be worth making a special screw driver for the nut which holds the ball handle on. If you can't do that nut up properly you can't get rid of any play.

Originally Posted by 12teethperinch

Hey finno I think your book is newer than the pdf book most of us have ,I dont suppose you feel like scanning you book for us? Not sure if it would be a copyright issue after all this time.
Darrell

Hey Darrell,
Yes it is, 1990 4th editon and good for the 260 lathe.
I would not post a copy because Hercus still sell the book and they are very good in answering questions. I would hate to jeopardise that (or breach copyright!)
Finno

Originally Posted by blackfrancis

The 260 has the exact same crosslide screw arrangement as the later 9" models with the bigger dials. If you really want to get all the end play out of these you should consider modifying it by putting thrust bearings in as Southbend did in their later models.

Check this excellent thread on converting a Southbend to larger dials with proper thrust bearings.

"http://www.practicalmachinist.com/vb/showthread.php?t=150571"

IMHO, without thrust bearing, attempting to reduce the backlash below 0.1mm is a waste of time. It's probably a waste of time anyway. They would have had that amount of backlash when brand new. There's documentation on the web saying Southbend had roughly that amount of backlash between the feed screw and nut from new.

BTW, if you're going to mess about with this it could be worth making a special screw driver for the nut which holds the ball handle on. If you can't do that nut up properly you can't get rid of any play.

Thanks for that information and link.
I have already modified a screwdriver for that purpose precisely. Uselss now for anything else !
cheers
Richard

Originally Posted by Finnowa

Hey Darrell,
Yes it is, 1990 4th editon and good for the 260 lathe.
I would not post a copy because Hercus still sell the book and they are very good in answering questions. I would hate to jeopardise that (or breach copyright!)
Finno

How about detailing the information on the shim please ?

Crikey, we're only trying to improve and repair a product no longer sold new. Don't post it on the internet, send an email, it is a backup copy.

cheers
Richard