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ptjw7uk
09-08-2006, 06:43 AM
Hi Folks,
Over the weekend I thought I would turn a chunk of metal into a rear toolpost for my lathe. All went swimmingly until I tried it on the lathe and it rocked ie the part I milled is not flat!!!
So this has me thinking as to how one sets up and checks a mill for truth!
Its only a micro mill that I want to cnc eventually but it has movements in all directions even the column will tilt. I've got several dial guages but do not not know what to check them against.
So far I am puzzled as to how the mill is not machining level my first thoughts are taht a horizontal mill is better at doing what I am attempting with an end mill after all I am only removing a 1/4" thickness to leave a 1/4" strip to fit in a T slot on the lathe cross slide.

Any ideas as to how to proceed or what am I doing wrong!!
Probably all wrong!!

John Stevenson
09-08-2006, 07:14 AM
Sounds like the head isn't what is called 'trammed in' correctly.
Tramming in means that the column has to be exactly vertical or the cutter is describing an arc.

Usual method is to get a flat plate, usually ground flat or even a piece of thick glass, lay it on the bed and with a dial gauge mounted on an arm held in a collet you sweep the gauge round in a circle on the plate. Do this by hand NOT under power.

Looking from the top of the machine, any errors between right and left, we will call them east and west can be equalised by adjusting the tilt of the head or column depending on design.

There should be no difference between north and south as there is no adjustment in this plane [ on this machine ]
If there is a lot of difference then the column will have to either be scrapped to fit or shimmed to get the same reading as you spin the gauge.

You can do this without a plate but you have to be careful as the plunger can catch in the bed slots.

.

ptjw7uk
09-08-2006, 07:46 AM
Thanks will give that a try
Peter

A.K. Boomer
09-08-2006, 10:22 AM
John, is there any merit to hogging out most of the internal mating material on a tool post holder? (just skin deep) i was thinking of doing this on mine and just leaving 25% of the material on the outer parimeter to avoid the "rocking" and potentual "chip trapping" factor...

Ed Tipton
09-11-2006, 03:55 PM
Going on the principal that a picture is worth a thousand words, you might try going to this site...http://www.jjtrain.com/vms/library.html
There are many good training tips there including the "virtual machine shop" where they have short videos showing how to do things. They have one on tramming a vertical mill head. Pretty basic, but...