LMS 5500 (Seig 2.7) Cross Slide Teardown with QUESTIONS

[Clif123]

I started a DRO/scales upgrade on my LMS 5500 and decided to completely tear down the cross slide to make it easier to drill/tap and to solve some issues. I cleaned the mill when I got it without doing this so I figured it was time to see how the cross slide was constructed, adjusted, and what goop was still hiding in there. First some pictures for those who have not taken one apart.





First question: What are the 2 holes on front and back of the Y-slide used for? (The front 2 holes have grub screws to cover the hole and appear to serve no purpose as the holes are blind.



I'm curious if it is for some accessory.

Second Question:
The X-slide (looking at the front) has the lock nut attached to the left side of the Y-slide.
When I would crank the X-slide all the way to the LEFT, the table would go to the very end.
When I would crank the X-slide all the way to the RIGHT, it would bind about 2 inches from the very end.
My suspicions that the slide screw was out of alignment was confirmed when I removed it and the slide would go all the way to both LEFT and RIGHT.

*** Has anyone had this issue? If so, what did you adjust to line things up?
The blue end plates have alignment pins and lock nut has little movement range with the 2 bolt holes.

Third Question:
Before disassembling, I decided to indicate the X-slide. As I cranked, I saw visible movement. I tightened the jibs until it went away.
What didn't go away was a little more than 0.003" movement toward the front with the indicator located on the RIGHT side of the mill Z-column.

*** When tightening the gibs (they tighten on both ends), can then cause mis-alignment if not not tightened correctly? Also, could this movement just be a symptom of the 0.003" deflection is question 2?
I'm still relatively new to this and just know that they should only be tight enough to stop movement and no more. Feel free to educate me.

 

[higgite]

First question: What are the 2 holes on front and back of the Y-slide used for? (The front 2 holes have grub screws to cover the hole and appear to serve no purpose as the holes are blind.

I used the front ones on mine to mount the the auto stop for an LMS X-axis power drive. I wasn’t aware that there are two similar holes on the backside, but I suspect if they are there, they’re covered up by the rear way cover mounting bracket.

Second Question:
The X-slide (looking at the front) has the lock nut attached to the left side of the Y-slide.
When I would crank the X-slide all the way to the LEFT, the table would go to the very end.
When I would crank the X-slide all the way to the RIGHT, it would bind about 2 inches from the very end.
My suspicions that the slide screw was out of alignment was confirmed when I removed it and the slide would go all the way to both LEFT and RIGHT.

*** Has anyone had this issue? If so, what did you adjust to line things up?
The blue end plates have alignment pins and lock nut has little movement range with the 2 bolt holes.

Sorry, can't help as I haven't had that problem.

Third Question:
Before disassembling, I decided to indicate the X-slide. As I cranked, I saw visible movement. I tightened the jibs until it went away.
What didn't go away was a little more than 0.003" movement toward the front with the indicator located on the RIGHT side of the mill Z-column.

*** When tightening the jibs (they tighten on both ends), can then cause mis-alignment if not not tightened correctly? Also, could this movement just be a symptom of the 0.003" deflection is question 2?
I'm still relatively new to this and just know that they should only be tight enough to stop movement and no more. Feel free to educate me.

I suppose it could. You do know the gibs are tapered. (Note gibs with a “g”. Jibs are found on sailboats. ) To adjust the X-axis, you loosen the left gib screw and tighten the gib with the right screw and then lock it in place with the left screw. Not gorilla tight or you can bend the gib. I set mine by centering the table in the X-axis, locking the Y-axis, grabbing both ends and trying to twist the table back and forth horizontally, pushing one end while pulling the other end. You can feel even the slightest movement. I then adjust the gib until I can feel no movement. Then I repeat for the Y-axis with the X-axis locked.

Tom

 

[Clif123]

I suppose it could. You do know the gibs are tapered. (Note gibs with a “g”. Jibs are found on sailboats. ) To adjust the X-axis, you loosen the left gib screw and tighten the gib with the right screw and then lock it in place with the left screw. Not gorilla tight or you can bend the gib. I set mine by centering the table in the X-axis, locking the Y-axis, grabbing both ends and trying to twist the table back and forth horizontally, pushing one end while pulling the other end. You can feel even the slightest movement. I then adjust the gib until I can feel no movement. Then I repeat for the Y-axis with the X-axis locked.

Tom

Thanks. I corrected my spelling to help with search and keep away sailing enthusiasts.

 

[Clif123]

I've cleaned everything and started the re-assembly. I saw this thread and was initially troubled, as I had no intention of turning my mill over to remove the Y-axis feed nut. https://www.hobby-machinist.com/thr...wners-take-note-y-nut-pinned-to-saddle.59977/
First, I removed the Y feed screw and then I removed the 2 bolts from the Y saddle. Then, I put both bolts in a few turns and lightly tapped them, which caused the nut to drop out of the 2 pins and fall away. Next, I just took a straight punch and drove the 2 pins through the hole. That is much easier than taking a drill to them.

When putting the Y-axis saddle back, this is the sequence:
1. Put the small black chip guard plate on top of the larger one, with the thin walls to the rectangular openings aligned.
2. Place the Y-axis saddle over the chip guard plates with the milled square that mates with the Y-axis nut inside the chip guard rectangular openings.
3. Carefully put everything above onto the dovetail which is on the mill base.
4. Carefully insert the gib. It only will go in one way. It gets tighter as it moves toward the back, so use the front/back screws to tighten/loosen the travel respectively.
5. Put the Y-axis nut in your hand in the proper orientation, and position it from the back side of the Y-axis saddle. It is a bit of a pain but it gets easier if you do it multiple times like I did coming up with this sequence. If you have good light, you can see the Y-axis nut bolt holes align while looking at the saddle bolt holes. Bolt it in loosely and tap the pins back in if you want them.
6. Re-install the Y-axis screw assembly.
7. Tighten the Y-axis nut bolts. I found that if you just lightly tighten the bolts first, then get the Y-axis screw in the backlash zone before fully tightening, the travel works a little better.

Once I got this far, I indicated the Y-axis and found that it drifts a couple of mils over the full travel of the Y-axis, similar to the X-axis. :-(

 

[Clif123]

UPDATE
I think that I answered my questions and I fixed the binding on the X-axis.
Taking the cross slide apart was very useful and educational. After putting the X-axis back on, I removed the 4 taper pins from the two blue end-caps that hold the X-axis lead screw. I also left the 2 bolts from the 2 blue end caps and the X-axis lock nut slightly loosened and cranked the table all the way to the right (X-axis handle was furthest away from the Y-axis. This was the bind point and would lock up about 2" from the opposite end of the X-axis to the crank on the right side. The left blue end-cap was close to the lock nut. I tightened the bolts for both the lock nut and the blue end cap next to it. Next, I cranked the table all the way to the left so the crank was closest to the Y-axis. I then tightened the 2 bolts on the blue end cap with the X-axis crank. No more binding. Bottom line: I believe the 4 pins (2 in each blue end-cap) were out of alignment when drilled so I no longer used them so I could use the slop in the bolt holes to align things as described above.

As for the run-out on the X-axis, it was much worse now but I now understand what is going on. There was little pieces of metal from manufacturing (specifically tapping the holes for the gib screws) and gunk on the gibs, etc. After cleaning things up, there was more space around the gib. I used WD40, rags and a toothbrush to clean things up. After assembling things, I indicated the X-axis and found that I had around 0.006" of runout. The problem was that the gib loosening screw was not long enough now to accommodate the amount that the gib had to stick out on that side. If I removed that screw and carefully tightened the gib, the runout was minimal. The solution that I've come up with is to replace the loosening gib screw with a new M6 flange bolt that is 30mm instead of the original 25mm so there are enough threads to hold that bolt.