# LMS 5500/Sieg SX2.7 Owners take Note: Y-Nut PINNED to Saddle!



## harrzack (Jun 19, 2017)

I'm currently attempting to install the DRO I got from the UK (links in another post).  I got the Y axis installed and moved on to the X axis.

Turns out (as with my LMS 3960) you have to remove the saddle to drill 2 holes for the read head attachment plate.  WARNING Will Smith!!  It turns out the saddle lead screw nut is not only bolted to it, but is also PINNED.  Not a bad idea - unless your mill is bolted to the table...   Also the pins are very long and even though the Y-Nut dropped off as soon as I loosened the to socket-head screws - the pins remain, and are so long they prevent the saddle from sliding off from the front.  This strikes me as a moderate design flaw as the mill should NOT have to be turned upside down to remove the saddle.  Sheesh!

To properly unpin the saddle you have to turn (all 210 lbs!) the mill on it's side and drive the pins out from below.  This was just not an option for me as I couldn't turn the mill over even if it wasn't bolted to the table.

So I drilled them out and will now have will have a bit of an extra chore when I re-assemble.


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## ronboult (Jun 19, 2017)

Hi Harrzack
Thanks for the report.
I do not have a SX2.7 but have a SX3 and wonder if I have the same problem. Have seen nothing on the web to suggest such with either a SX2.7 or SX3. 
I was wondering if you can drive the pins out from the bottom, why you could not drive the pins down a little so you can slide the saddle off. Sounds like your pins were higher than normal.
Please excuse my ignorance if this is not possible.
Ron


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## harrzack (Jun 19, 2017)

Ron - It turns out they are TAPER pins - driven in from the top - most likely for easy manufacturer.  I called LMS and the tech called back and said he was able to just "turn the mill over and tap them from inside....  Sad to say "just turning the mill over" was NOT an option for me!   They don't seem super important but must help square the nut to the screw.   I'll find out when it goes back together!

You will only notice this if you have to fully remove the saddle.  Check your exploded parts list in your user manual - they are shown in mine so if they are there should be identified on the parts list. Since the SX2.7 is moderately new maybe the pinned Y-axis nut is just a "feature" of that machine.


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## harrzack (Jun 21, 2017)

IT GETS WORSE!

During re-assembly I've (re) discovered the mill has a set of 2 black plates  (not shown in exploded view parts list) with rectangular cut-outs that slide along the Y axis. I  believe this is an alternative (to bellows) protection for lead screw.  When the Y-nut is attached to the saddle, it must go THRU these openings so they can be moved back and forth to cover front & back of screw.

As if it were a big enough PITA to attempt to get the nut mounting screw holes lined up from above (assuming the mill is mounted, and you can't turn it over to work from the bottom - GAK!), you have to be sure to put the plates back on the saddle, then bring the nut up thru and attempt to locate the threaded holes in the nut - peering down the thru-holes in the saddle...  And naturally I forgot to note the order of the 2 black plates and now I have to search the web and hope I can find an image of the mill that shows these plates - which can be hidden under the bellows...   What a freekin' nightmare this 'simple' job has become!

LMS5500/Sieg SX2.7 Owners take note:  DO NOT REMOVE THE SADDLE unless you absolutely have to - and then photograph every step along the way so you can reassemble it.  A very strange design from our friends across the sea....    :-( 





harrzack said:


> I'm currently attempting to install the DRO I got from the UK (links in another post).  I got the Y axis installed and moved on to the X axis.
> 
> Turns out (as with my LMS 3960) you have to remove the saddle to drill 2 holes for the read head attachment plate.  WARNING Will Smith!!  It turns out the saddle lead screw nut is not only bolted to it, but is also PINNED.  Not a bad idea - unless your mill is bolted to the table...   Also the pins are very long and even though the Y-Nut dropped off as soon as I loosened the to socket-head screws - the pins remain, and are so long they prevent the saddle from sliding off from the front.  This strikes me as a moderate design flaw as the mill should NOT have to be turned upside down to remove the saddle.  Sheesh!
> 
> ...


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