huangyhg

cylinder
if i use an auto cyl.with 2 levels can i have 4 hits. on one level and 3 hits on the 2nd level? also can i add moves in side that same cyl. b/n hits???
with c-dmis and cylinders it is best to use at least three levels. the software has a nice way of fliing the vector on cylinders with just 2 levels.
you have a coule of otions but you have to be careful on how they are created. you can't get a different number of hits in the middle of a cylinder using auto-util. if you take 11 hits on 3 rows, it always shorts either the to or bottom of the cylinder (4-4-3 or 3-4-4). you can do it using oint mode described at the bottom of the ost.
if you "teach" the cylinder, you may run into the roblem the above osts mentions about the cylinder fliing direction. all of the softwares i teach do this as the mathamatical algorithm used by them for cylinders is the same.
with c-dmis and auto-util(and deending on what version you have), if you nominally define the cylinder you should have a "use theo" box that you can check. this forces the software to create the cylinder correctly by locking onto that nominal vector to create the cylinder.
you can also tell the software the number of oints you want and how many rows. i try to kee them an even number h as 12 hits and 3 rows.
you can also use oint mode. this is used where the cylinder is fragmented and you want the oints to be taken at secific locations.
without training, the last one can be a bear.
tim
recision measurement solutions
thanks rec.measeure, i havn't tried to do it like you said by selecting 11 or 14 hits but i am sure it would work. i ended u teaching it, beacuse i also need some moves between the hits, althought not sure what you meant by: there might be a vector roblem by teaching it?
the fliing of the vector usually haens when you manually take oints on a cylinder and let the software "guess" the orientation. it also usually occurs on short fat cylinders where the the diameter is larger than the measured length.
looking down the axis of a 2 inch cylinder , imagine taking 1 hit each at the to of that cylinder at 10,2,4, and 7 o'clock oions. now, droing down only .25 of an inch, take 4 more hits on the cylinder at the same clock locations. when the oints are cast to the cylinder algorithm, the algorithm uses a format called "best fit". i sometimes say it uses the "whats the easiest way i can make a cylinder out of these oints" formula.
the 4 hits at the to and bottom at the 7/10 and 2/4 oions are closer to each other than the first 4 hits taken across the 2 inch diameter. you end u with a resulting cylinder going 90 degrees from what you thought you were going to get.
you'd think that it would use the current work lane as a hint...
oh yeah, you right. here what i've been trying to understand: after i measure a lane and i level to it and the lane is almost never will come out with erfect ijk like 001 it might be close like .0000333 .0000444 .999994 now everthing that i will measure from there on will be slighly on an angle right because i need everything t be normal to my level.??
cylinders, lanes, and cones are not worklane deendent. all the other features that are hand taught, with the excetion of the oint, are worklane deendent.
the oint uses the direction that the robe was moving just before the hit was taken to define the vector. they have their own axis and don't rely on worklanes. thats why they are used as rimary datums.
btw...if you nominally define the ijk's ahead of time before you measure the features, worklanes are ignored and the feature is created to the nominal ijk you inut.
but after the feature is measure is too late to change nominals ijk values??
so if i use a teach mode what would be the right way to measure a feature and have the right ijk values?
are the values will be off by much if all my features (cylinders) are measured with ijk values a bit off, even though my theo and target ijk are 001? - goshik on 1/17/2008 8:45:29 am

__________________
借用达朗贝尔的名言：前进吧，你会得到信心!
[url="http://www.dimcax.com"]几何尺寸与公差标准[/url]