Hi Keith,
Your wm18 is similar to my hafco unit and if I'm guessing correctly you are trying to set up the surface of the table in the x & y axis to be square to the spindle or quill – aka tramming .
If so you need to pay attention to some minor things that I found were causing a similar problem to my mill.
As it is a dovetail column machine make sure the gibb adjustment on the column are snug as the head can hang down on the column if they are loose and tighten the locking bolts/knobs on the side as well.
Check the mating surfaces between the column and the base as mine had some swarf under there that knocked the column out of wack and also the surfaces between the two mating surfaces for the head swivel and nip the nuts / bolts up but not so tight that a light tap with a rubber mallet won't move it ( you fully tighten after tramming and re check for any movement that may have occurred when tightening the nuts – it happens and is annoying but that's life !
Make sure the table is locked down( x&y axis) so it takes up any play and once you have the dial gauge lowered into position lock the quill
Make sure the indicator mounting is not moving as the adjustable types of indicator bases can move and that's why I use a simple piece of 6mm dia rod with a 90deg bend on one end ( goes in the chuck)and the other end is turned down to fit through the mounting hole on my dial gauge and threaded for a locking nut – simple and rigid .
You can now tram the head to your hearts content !
If your problem is with the x axis not being at 90 deg to the y axis then check the gibb adjustments on the table then mount up an angle plate on its end so one face is parallel to the x axis and tram this to read zero on your dial gauge /indicator as you wind the handle back and forth.
Once this reads as close to zero movement as possible simply adjust the dial gauge / indicator so it can read the other face and you should have zero movement of the gauge or close to it .
If there is something wrong here there could be a burr somewhere on the dovetails so you would need to strip the table down and check it over.
Another thing that can happen is table climb and to check this simply use a nice thick parallel set it up on the axis you wish to check ( by eye is good enough but you can use the dial gauge to get it perfect if you want ) then run a dial gauge mounted to the head across the top by winding the appropriate handle ( x or y ) and there should be zero movement of the dial gauge .
Fixing table climb or the x/y axis not being at 90deg I think would need some experience with scraping and unless you can track it down to a burr or small high spot I would not attempt it without expert guidance as you can make matters worse very easily .
Have a look around on youtube and look for tubal cain or mr pete 222 (same person) I'm sure he did a few videos of mill tramming .
And by "close to zero I mean .002 inch or less – preferably less !
Ian
P.S i had to edit 3 times to kill the pesky winking smiley face that I did not put there !
Edited By SLOTDRILLER on 13/02/2014 01:07:46
Edited By SLOTDRILLER on 13/02/2014 01:08:45
Edited By SLOTDRILLER on 13/02/2014 01:11:51