On Tuesday 18 August 2015 10:11:31 John Kasunich wrote: > The test you described would tell you if the spindle axis is not > parallel to the Z axis (the column). It would not tell you if the > column is tilted relative to the table. I don't know which type of > error you suspect - I'd think the latter would be more likely. > > Update: I went and looked at some pictures of a G704. It looks > like the head can be tilted sideways? So you are worried about > that adjustment? If that is the only thing you care about, then > you could test it with a straight rod in the spindle and an indicator > on the table. But again, that test will NOT tell you if the column > is tilted. > > There are three things you might want to check (and each one > needs to be checked in two planes, XZ and YZ. > > A1) Is the spindle axis parallel to the quill travel > > A2) Is the quill travel parallel to the Z-axis (column) > > A3) Is the column perpendicular to the table > > If the quill is locked, you can reduce it to two items: > > B1) Is the spindle axis parallel to the Z-axis (column) > > B2) Is the column perpendicular to the table > > Note that traditional tramming tells you if the spindle axis > is perpendicular to the table, but that is NOT the same as > knowing A1-A2-A3, or B1-B2. Imagine that the column is > tilted 10 degrees to the left. You could tram the spindle to > be perpendicular to the table by tilting the head 10 degrees > the other way. But the Z-axis would still be totally screwed > up. > > You either have to measure all three (or two) items, or trust > the chinese that the castings and machining are correct and > the only problem is mis-adjustment of the head tilt. I wouldn't > trust them and would try to measure everything. > > > I don't see any need to remove the fixture and workpiece and > indicate to the table. You should be able to indicate to the top > surface of the work itself. > > You really want to mount an indicator to the spindle, with as much > reach as you can get (2-4"). Then zero it in one location, turn the > spindle 90 degrees, take a reading, turn another 90, take a reading, > turn another 90 take a reading, and turn once more to get back to > the original position. That will tell you if the spindle is > perpendicular to the surface you are indicating to, whether it is > table, fixture, or workpiece. > > What is your biggest collet? 1-1/8" I think, but no precise rod in bigger than the 1/2" A2 stock I bought to make #209 nipples out of. > Can you stick a chunk of 3/4 rod in a > collet and then stick a mag-base to it? Or C-clamp a V-block to it > and then mag base to the flat surface of the V-block? Seems like > you should be able to improvise something. > > There is absolutely no need to use a 0.0001 indicator. If you get > it trammed to 0.001 over a 4" span (indicator tip 2" from spindle > axis) you are going to be more than good enough for even the > finest woodworking project.
The artifact I seem to ge getting could come from either spindle miss-aligned to the post, or the post isn't square. The QC sheet says the post is well aligned and I haven't laid a wrench on those bolts other than to determine that they were 1/8 turn from broke. I wasn't able to move them with reasonable wrench force. I did have the head off to reduce the weight I had to man handle while installing the Z ball screw, so that is where I suspect the major error is. The outer sides of the head, and the Z sled, are painted as cast, so a miss-match by using them for alignment purposes is well within believable. So I'll go and "get to it" & see if I can learn anything. [...] Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
