At 06:15 PM 3/25/2010, you wrote:
>If it is truly cumulative, you can fix it by adjusting the scale. If
>you gain or lose 0.002" for every inch you travel, just change the axis
>scale by that ratio.
>
>You might want to invest in something like this:
>
>http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=320505470762
>
>These sets were used back in the day on jig-borers. There was a
>v-groove
>in the saddle, running parallel to the table travel, and another groove
>in the knee, parallel to saddle travel. At one end of each groove was a
>sensitive dial indicator. A boss on the table or saddle moved along
>the groove at the other end. Say you wanted to locate the table at
>7.923
>inches. You'd set the micrometer head so that it was 2.923 inches, then
>put it in the groove. Then you'd add 4" of spacer blocks (a 3" and a
>1").
>Then move the table toward the indicator. The table boss pushes the
>entire stack, and when the indicator reads 0.000, you know you are at
>the
>right place.
>
>There were two sets of rods and two micrometer heads so that you could
>set both axes of the jig borer. Nothing stops you from using all the
>rods on one axis. For your purposes, you don't need the micrometer
>heads.
>In fact the best deals on such sets are the ones missing the heads.
>
>Most sets, like the one in that auction, have two 12", two 6", two 3",
>two 2", and two 1" rods. That lets you build stacks up to 48", in
>precise
>1" increments. Rig a temporary V-groove down the length of your table.
>It can be as simple as two strips of stock clamped down with a gap
>between
>them. Fasten a block to the table at one end, and attach an indicator
>to
>your gantry. Touch off and zero the indicator against the block.
>
>Then move 1" away from the block, insert a 1" rod, and write down the
>indicator reading. Move another inch, replace the 1" rod with a 2" one,
>write down the reading. Move another inch, etc. You can use various
>combinations of rods to take a reading every inch over 48" total.
>
>Once you have 48 readings, you can plot the error vs distance. Fit a
>straight line to the data - the slope will tell you the scale error.
>The residual after you correct the scale error might be random, or it
>might be cyclic, once per pinon rev, or whatever.
>
>If you are really dedicated, get a few gage blocks in the 0-1" range,
>and
>you can make measurements more frequently. A half-inch block will let
>you measure every half inch. A set of 0.1, 0.2, 0.4 and 0.8, or 0.1,
>0.2
>0.3, and 0.5 blocks will let you measure every 0.1" - although that
>would
>get incredibly time consuming over 48".
>
>If wind up with errors that are non-linear but repeatable, EMC2's screw
>error compensation can help. You can enter up to 256 points along the
>length of the machine. That would let you correct every 0.2" if you
>really wanted to.
>
>John Kasunich
>--
> John Kasunich
> [email protected]
John,
Funny you should mention the inside mic sets. When my Dad
passed away recently, I was digging through his tool chest because my
Mom wanted us kids to have some stuff from Dad before she gave the
rest to the grandkids, and I came across a smaller set of Starrett
inside mics with the extensions. Not quite as many as the set shown
above, but a good starting point if I decide to go that route. I'll
look into the screw error comp if I need too. Does that show up in
the user or integrator manual?
Thanks,
mark
------------------------------------------------------------------------------
Download Intel® Parallel Studio Eval
Try the new software tools for yourself. Speed compiling, find bugs
proactively, and fine-tune applications for parallel performance.
See why Intel Parallel Studio got high marks during beta.
http://p.sf.net/sfu/intel-sw-dev
_______________________________________________
Emc-users mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/emc-users
