Dan Edmunds
	
Nov 9 (4 days ago)
		
to me
Hello Dean,

Notes about your CMX Stiffener Bar project:

 - Goals:

     Provide prototype stiffener bars for the 2 "Mechanical
     Only" CMX cards that we are currently making.

     Provide models of the stiffener bar parts to be sent
     to the Machine Shop when we ask them to make the
     production run of real bars for the real CMX cards.

     Think about such questions as:  is there some better
     way to stiffen the CMX card   and   are there other
     mechanical issues about the CMX card that should be
     integrated into the design of the stiffener bars,
     e.g.  heat sink or front panel component mounting.

     The prototype bards will be aluminum.  The real bars
     will likely be stainless steel.  Thus the prototype
     bars are not expected to be exactly like the production
     bars.  For example the prototype bars will not be as
     thin at the top  and  they do not need radiused corners.


 - CMX Mechanical Only cards:

     We are making 2 Mechanical Only CMX cards.

     One of them will go to CERN in the next couple of weeks
     to verify that we have the correct overall physical
     layout and explicitly to verify the correct location
     of the backplane connectors.

     The mechanical only cards  may  also be used to verify
     such things as the air flow rate past the card  and  the
     heat dissipation vs temperature rise that we can expect.

     They can also be used as "toys" to help develop the
     front panel layout and other mechanical aspects of the
     real CMX cards.


 - I'm Not wetted to the current stiffener bar design:

     I'm not wetted to the current CMX Stiffener Bar design.
     Better useful ideas are welcome.

     Intent is to make it relatively easy to manufacture the
     production parts in the Machine Shop,  e.g. the top and
     bottom stub brackets differ only in the last step,  the
     top horizontal bar can be made from a bottom horizontal
     bar.

     I'm perfectly happy to abandon some current holes and
     poke new addition holes in the Mechanical Only pcb
     if it becomes clear that my current layout of the bar
     mounting holes is not what we want.

     I'm mostly using  4-40  screws in the stiffener bars
     themselves  and   M2.5 in the Euro-Card components e.g.
     the front panel insert/eject handles.  I did this mixed
     setup because the 4-40 screw heads looked bigger  (there
     is no room for washers on the back side of the card)
     and I thought that it might be easier for the Machine
     Shop to tap 4-40 in stainless.


 - Web Pages:

     The general MSU information about the CMX card is on
     the web at:

       http://www.pa.msu.edu/hep/atlas/l1calo/


     Most of the component level information is in a tree
     starting at:

       http://www.pa.msu.edu/hep/atlas/l1calo/reference/other/


     To understand the location of the drill holes in the
     current Mechanical Only CMX pcb   please see the following
     2 files on the web:

       http://www.pa.msu.edu/~edmunds/scratch/

       cmx_0_mech_only_instructions.txt    and
       cmx_mech_only_drill

     These locations are  abc.xyz mm  in both X and Y.
     0,0 is the lower left-hand corner in standard orientation.
     You are mostly interested in "tools"  i.e. drills  4, 5, 6.

     Probably not for immediate use in this CMX work but for
     your general back ground I have put 2 more VME mechanical
     documents on the web where you can grab them.  They are in

       http://www.pa.msu.edu/~edmunds/read_pdf/

       vme_1101_1_specification.pdf      and
       vme_1101_10_rev_1996.pdf

     You need both of these to have the current full "1101"
     mechanical specification.

           Thanks,  Dan