Tramming a mill head using angle plate

[Blueskys]

I use my mill head at different angles quite a lot.
So I was wondering; to get a reasonable 'back in tram' could
I use an angle plate on the table and and a dial indicator?
And then run my quill up and down. A couple thousands over
the 5" length of my quill should be all the accuracy I would need
for my normal jobs. Just wondering if there's a reason why this
doesn't work. Thanks.

[Lew Hartswick]

Sounds like it may work but WHY not use the table?????
...lew...

[Blueskys]

Sounds like it may work but WHY not use the table?????
...lew...

I guess reading up and down seems easier to me then reading round
and round. I turn the head quite often so if I can save a few minutes
that helps.

[rockrat]

If I have pictured this correctly, you would use one angle plate to verify one direction of the head?

I'm going to make a major edit here. Still sleepy and not thinking correctly.

I guess on further thought that this method is not bad by any means, just different than a norm. The only error that I can see being duplicated is any error in the angle of the plate being anything other than 90º, any clamping forces on the plate that might change it or something similar to that.

rock~

[Blueskys]

rockrat:
I see what you mean. I wasn't considering the interaction between
the two arcs of the head. Might be more trouble then it's worth
going back and forth between axises with the angle plate.

[rockrat]

See my post, I made an edit due to lack of following through on my thought logic. But is does seem like a bit of extra work moving everything around trying to capture the true alignment.

rock-I need more coffee-rat

[Black_Moons]

'around and around'? you don't tram the table with the spindle running, you manualy move the spindle with a wrench on the drawbar nut or something with a TDI mounted into the spindle, its very quick an easy.

[oldtiffie]

I use my mill head at different angles quite a lot.
So I was wondering; to get a reasonable 'back in tram' could
I use an angle plate on the table and and a dial indicator?
And then run my quill up and down. A couple thousands over
the 5" length of my quill should be all the accuracy I would need
for my normal jobs. Just wondering if there's a reason why this
doesn't work. Thanks.

Bluesky.

You are on the right track.

If your angle plate is square, stand it on its end and put a good piece of say 3/8" precision-ground HSS tool-steel in your 3/8" collet.

Spin the spindle at say 200RPM - quicker if you like - and bring the angle plate up to the tool bit. Align the collet face to be just above the top face of the angle plate. Get a close as you can. If you have a strong light on the opposite side to you (back of the mill) you will soon see if the tool bit is "running out". If the "run-out" is the same from the top to the bottom of thermopile bit you are OK (amount of parallel run-out doesn't matter). If run-out varies from top to bottom of the tool bit you have "conical run-out" - change the collet and/or the tool bit combination until you eliminate the conical run-out.

Now, with the spindle either running or not - your choice - bring the angel plate up to the tool bit.

If the gap is the same top to bottom of the tool-bit (your eye is VERY accurate with this) you are OK.

If not, adjust the tilt of the milling head until the gap is the same.

Adjust "X "tilt" and "Y" "nod" similarly.

This should be good for say 0.001" (easy) gap over the say 3" length ("stick-out") of the tool bit from the collet.

A cylinder square works just as well (I bolt mine tom the table with a single bolt through the cylinder bore).

If you can get hold of a good (USA-made or an Asian clone) "Co-axial" indicator (see separate thread) - you will do OK.

http://bbs.homeshopmachinist.net/showthread.php?t=38994

Here is a video courtesy of "dp" (Dennis):
http://www.youtube.com/watch?v=ZfioLDhBNBQ

[Boucher]

The SPI instrument that ENCO is selling that has two Dial indicators mounted in a holder with a Pin that installs in the Quill looks like it would be another good way to get back in position. It is a little pricey but if you tilt your head frequently the time savings could prove to be worth the cost.

[oldtiffie]

Sorry about the bad spelling in my previous post - tired and in a hurry - not a good combination.

The "3/8" HSS tool-bit in the collet" method works both ends of the tilt and re-tram the spindle process.

Put a good protractor or bevel guage on the mill table (parallel to the table slots as "compound error problems" need to be avoided). Put the protractor/bevel-guage blade on the tool-bit and adjust the tilt as required.

Easy and quick too.

A vernier or digital protractor is good for 0.1 degree (0.0017" per inch).

A good set of angle guages is good for 20 arc seconds (0.0001" per inch).
http://www.cdcotools.com/index.php search for item 35116 - US$22

Forget about the sine bar and slip guages as they are expensive, awkward and a total PITA unless really needed.

My cylinder squares:


Angle guages:


Bevel guage and angle guage combo:


Cylinder squares in use to square up my angle plates - very successful!!