Table of contents

• MHATT-CAT Kappa Y1 and Y2 damage noted May 2001
• Visite of Jacques Bosse from Microcontrole

MHATT-CAT Kappa Y1 and Y2 damage noted May 2001

During the May 2001 run, we found out that some damage had occured to the
crossroller slides on the table vertical motor Y2. Essentially the crossroller
plastic holder broke and a large portion of the slide on its right hand side 
does not have rollers anymore (see Fig. 1). It was difficult
to move Y2 during the first experiment of the run.

On May 23, 2001, Paul Evans and I noticed further damage to the slide Y1 (see Fig. 2).
As seen in the picture, the cross roller on this slide is now also broken thus
both Y1 and Y2 slides need to be repaired. I will try to get someone at Newport
to come and repair the slides. A peculiar problem arose during the second 
experiment in the run in 7ID-C. We tilted the axis connecting Y1 and Y2 by more 
than 1.4 degrees and we simply could not get back the Kappa table flat. After 
consulting with Peter Eng, he right away pointed out that we must have reached 
a tilt limit. For several hours, we had been afraid that the slide were stuck 
and would not move anymore... 

Peter helped us to identify the problem further. The Kappa it turns out is
equipped with tilt angle limit switches with a +/- 1 degree range thus we tilted
the table too much today. Why did the limit not work though? It turns out they
were installed improperly, and were inverted. This explains why we were allowed
to go further than a one degree tilt. It explains also why we could simply not
raise back Y1 or lower Y2 (either one would have fixed the tilt).  Peter suggested
to remove the cover, and switch the limit switches next to Y1 (see Fig.3 and 4). 
The latter picture shows the two limit switches and the paddle connected to the
frame which closes the limit switches. Two bolts attach the limit plate to the
frame. Paul and I performed the repair and move the yellow cabled limit switch to
the bottom position. We were then able to level the Kappa table again.
The limit were switched physically, but the travel will need to be carefully
adjusted at a later time. There is about 3 mm of travel on each side of the
paddle at the moment. Because the limit switches were reversed, it is possible
that the Kappa slides Y1 and Y2 suffered damage which would have been prevented
otherwise. 

Peter also mentioned another problem when you home the Y1-Y3 motors.  Because 
the homing is done on a per axis  basis, the tilt limits interfere with the
homing process. He's put the level of the tilt limits on the slide covers so
that he first gets closed to the limits before homing them.


I wish to thank Peter Eng and Paul Evans to help identify and solve this problem.
For now we will keep the Kappa table levelled until the repairs have been 
performed.

Eric Dufresne

P.S. On 5/24 Ron Pindak and Bob Macharrie commented on this problem report. 
From Ron: 

Eric, we discovered the damage to BOTH Y1 and Y2 during our run - sorry
that this was not more clearly documented. It is highly likely that
overtilting the kappa resulted in the damage. We noticed that the jack
motors stalled when the kappa was tilted. This should be made clear to
Newport in getting them to repair the translation stages. Please
continue to document your findings. Ron.

From Bob:
Eric,

We have been aware for some time that when when moving Y1 relative to Y2 more
than 6mm(approx.) that we get a limit condition in the other motors opposite 
direction.  I.e. if we move Y1 negative more than 6mm from Y2 (after zeroing
them first) we get a positive limit on Y2.  But, this is the first time that
I have even heard of a tilt limit spec, let alone a tilt limit.  Is it the
case that the tilt limit is wired in parallel to these Y1/Y2 travel limits?
Because their is no input into the MM4005 for extra limits. I'm glad you found
this out, as it must be the reason for the damage to the slides.

-Bob

Fig 1. The Y2 slide showing the damage.

Fig 2. The Y1 slide showing the damage.

Fig 3. The Y1 slide showing the tilt limit switches before the repair.

Fig 4. The tilt limit switches once unbolted from the Kappa Y1 frame.

October 2001 visit of Jacques Bosse from Microcontrole

Jacques Bosse arrived last Thursday for repairing the Y1 and Y2 axes. He wasn't
able to start working at MHATT-CAT until last Friday because of the 7ID PSS
revalidation in progress. On Friday, Jacques repaired the sample X home switch,
and took apart the Y2 stage. Unfortunately, not only are the roller cages 
broken , but one of the cross-roller V on the slider is broken and Jacques does 
not have the spare part. On Friday, Jacques also upgraded the firmware on the 
two MM4005 controllers but ran into a problem in one of them, the bottom one.
He needs to reprogram an EPROM on the bottom controller because the firmware 
upgrade software is flaky.

On Friday, Jacques and I were surprised to notice that one of the limit switch
was not physically mounted on the Y2 slider block (see Fig. 5 and 12). Should there be
a tilt limit also installed like in Fig. 3? We need to ask France if there are
any reasons behind this.

Fig 5. The Kappa Y2 slide assembly. Note that Jacques and I found that not tilts limits were installed
on this axis, although it is provided.

On Monday October 22, Eric Sailleau wrote to us that they shipped two rails, 
and also two larger rails on the slide part of the slide assembly. By the way, 
Peter Eng mentioned that many of these pieces were available commercially from
www.scheenberger.com, i.e. the cylinder cages and some of the V-grove cross-roller cages.
Unfortunately, the slider part is costom made at MicroControle. It is hardened
steel, difficult to fabricate, withtight flatness tolerance. Some of the damage
on the slider V-groove is shown in Fig. 6, 7, and 8.
Fig. 9 shows where the broken rail goes, i.e. on the slider.
The remaining figures from Fig. 10 to 14 show the slide Y2 taken apart. Jacques is waiting for the slider parts to 
come in by UPS.

Fig 6. The broken Y2 slider V and cage assembly. The broken part is W 1665 A2,
called "RAIL VERIN Z Lg: 100 mm."

Fig 7. The broken Y2 slider V and cage assembly. The broken part is W 1665 A2,
called "RAIL VERIN Z Lg: 100 mm."

Fig 8. The broken Y2 slider V and cage assembly. The broken part is flipped.

Fig 9. The broken Y2 slider with its V-groove removed.

Fig 10. The broken Y2 slide.

Fig 11. Another view of the broken Y2 slide.

Fig 12. The unconnected Y2 limit switch. Why is isn't it installed?

Fig 13. The gear on the Y2 slide.

Fig 14. Second view of the gear on the Y2 slide.