On Tue, Aug 18, 2015, at 12:53 PM, Gene Heskett wrote: > On Tuesday 18 August 2015 12:32:30 Ken Strauss wrote: > > > I haven't closely followed this thread but what is wrong with the > > traditional method of sweeping a DTI attached to the end of an > > L-shaped rod secured in the spindle? Simple, time tested and very > > accurate. > > The table is currently occupied by a large holding jig I don't want to > move without first installing some keys on the ends of it to re-align it > with the table when I put it back on later. > > I wouldn't trust the jigs top plane for absolute square and flat as its > been a year since I made it. It was machined flat, to that toy mills > version of flat then, but that 2" thick block of white ash has now had > another year to dry since. It was 10+ years out of the weather seasoned > then & should be fairly stable. > > I should reflatten the area where the boards get clamped to it, with a > fresh 2 flute upspiral SC mill, taking off perhaps 10 thou.
Yes, you should :-) Since Z won't be used when you flatten that area, any Z errors won't matter. The newly flattened area will be by definition parallel to the XY plane of the machine. Which makes it the perfect spot to use when tramming the spindle perpendicular, using the traditional bent rod as an indicator holder. > But this > error looks like 5 thou or so just in the 0.760" thickness of the board, > so a jig level error would have to be truly huge to make that big a > difference. It sounding like you probably do have head tilt. The columns of those chinese machines are rarely perfectly plumb, but they are also rarely if ever off that much. In your shoes, I would flatten the board clamping area of your fixture, then adjust the head tilt with a spindle mounted indicator sweeping the largest practical circle on the newly flattened area. Having done those two steps I bet you'll get nice joints on your project. -- John Kasunich [email protected] ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
