Spindle to table alignment

[emj]

What tool does one use to make sure the spindle is perpendicular to the table, say, side to side and front to back? My Maxmill is like a turret BP but the little degree plates have become loose on one end due to missing rivets. I would like to try and do some cylinder head machining(valve guide reaming/honing and valve seat cutting/grinding) but need to check the alignment. I purchased a few same sized chucking reamers for the guides but would rather have a piloted reamer like a step/taper reamer I have seen at work. For the seats, I was thinking about getting a set of used Winona Van Norman 3 Angle Seat Cutters if a vertical mill is OK to do this operation. All help appreciated, emj

[macona]

Use an indicator attached to the spindle. Ideally use an indicol type holder. Its called tramming the mill. Heres a good tutorial:

http://www.jjjtrain.com/vms/mill_mov...t_head_07.html

[SGW]

Just to reiterate, in case it's not obvious: Don't rely on the degree marks for precision alignment. Unless you're uncommonly lucky, it will never be close enough for precise work. Put an indicator in the spindle, and sweep left/right and front/back on the table surface (or some flat surface on the table), adjusting alignment until the readings are the same, as described in the link macona gives.

[Carld]

If you do a search I think you will find a huge volume of ways to tram or sweep the head of a mill in. It seems everyone has their favorite way.

[emj]

Thanks for the information. Much appreciated. Looking for an indicator and holder right now. Thanks, again!

[hornluv]

A few things that aren't really made clear in the link:

When tramming the head, only loosen the bolts for the axis that you are working on at the time. If it is a Bridgeport clone, you should have four on the front for aligning the x axis and three on the side for aligning the y axis. If you loosen all seven, you won't get good readings on either axis and you'll be chasing your tail.

Also, snug the bolts up after you loosen them. If they're too loose it will be very hard to move the head consistently and it will move a lot when you tighten the bolts back up. At the local community college, I went to use my usual mill, only to find that one of the basic machine shop students had loosened all seven bolts, didn't snug them up, and left it like that after his class ended. When I tried to teach him how to do it right, he just spaced out and walked off after a minute or two.

Lastly, the article mentions tapping the head with a rubber mallet to align it. If your mill is a Bridgeport clone, then you should have two worm drive bolts, one for each axis. Turn those to move the head. If you don't have them, use the mallet.

Just as an added tip to make everything move smoothly, I always draw a pencil line across each axis using a ruler so I can put the indicator stylus in the same spot every time.

[dp]

Something interesting popped up on a link given earlier and that relates to a post made here some time back. Here's the current link: http://www.jjjtrain.com/vms/mill_mov...t_head_08.html

And here's the post nheng made earlier:
http://bbs.homeshopmachinist.net/showthread.php?t=30323 and which led to yet more testerone-filled posts .

I bought a VW rotor and have used it since reading this post and it works great with my coaxial DI.