[wcarrothers1]

Just wondering if anyone could give me a best description of how to keep your head possition correct (on a round pole mill) between height changes (for when changing from a drill chuck to collet)..

Thanks.

b.

[9 1/2]

As far as I know, you can't.

Normally, I anticipate this sort of move ahead of time. To work around this issue, I mark my work peice zero with a center drill before I begin any machining. This mark is on a waste section of my stock. In that way, I can raise my head (or lower as needed) move my table to zero / zero (via my control software) and adjust my head (left or right from the swing induced by the raising / lowering of the head)

Its not dead balls on, but i've had reasonably good luck. I'm now in the process of installing a liner slide table to prevent the rotation of my head.

[FlyingIllini]

Can't you just move the table to clear the workpiece for tool changes, then return to zero? I do that sometimes even with a square column mounted head... heavy bugger.

[wcarrothers1]

Well I'm talking about drilling some holes then swaping in another device like a Tapmatic to do the taping later which would be longer and such thus need a different height.

Should probably add my round pole mill is converted to CNC so I'd be using a program to center my self on each hole for drilling and then tapping..

But guess I will figure some sort of refference of some type. Figured I would take a stab at asking.

Was at wholesale Tool today druling over the ZAY dove tail pole mill they had... only 1500 bucks.. Maybe some day..hehe that is the real way to solve this problem..But anywho..

[kentavv]

With a laser edge finder mounted in the spindle, zero on a reference point on your workpiece. Raise/lower the head and zero again on your reference point (watchout for backlash). Lower the quill as low as you can to put the edge finder close as possible to the reference point to avoid the inflation of the point. A polarization filter will help with that as well.

Here is an example of one such edge finder:

http://www.lasercenteredgefinder.com/

[Bubba]

The answser is: "Plan ahead" so you don't have to move the head up or down!
I use an ER collet extender to handle the short tools and set up things so I don't have to move the head up or down. I have a routine to clear the part to an area where I can change tools and keep going.
So far it has worked for me and I use tooling from a 1/2" drill down to a 1/32 EM in some jobs.
One key is to :"elevate" the work piece so you can have additional headroom to make the necessary tool changes. In my case, this might be the use of my 6" vise or an "elevated" table to hold the work.
If you plan ahead, most of the time, you will not have to move the head.

Bubba

[BobWarfield]

With a laser edge finder and polorization filter zero on a reference point. Raise the head and zero again on your reference point (watchout for backlash). Lower the quill as low as you can to put the edge finder close as possible to the reference point to avoid the inflation of the point. The filter will help with that as well.

Close.

Now consider this idea. Spot the laser on a wall 20 feet away. Place a mark on that wall, and make sure your laser is lined up on that mark whenever you use the mill. If you raise the head, check the mark and bump in the head until it is aligned before continuing. Longer distances can be even more accurate in restoring the alignment. If the point is inflating, simply target the center of that point on a circle and check the edges of the circle align well with the edges of the laser spot.

Do the trig on this based on your distances and how well you can align the spot. Tolerances ain't too bad. You're not going to do tenths though. If you need real accuracy, you gotta plan ahead as Bubba suggests. There are two things to plan ahead for:

- First, plan not to have to raise/lower the head as Bubba suggests.

- Second, plan for how to save your pennies and replace the round column mill with a square column or knee mill! (Sorry, couldn't resist!) (chair)

Best,

BW

[Geof]

Close.

Now consider this idea. Spot the laser on a wall 20 feet away.....

If you don't have a large space take Bob's idea a few feet further, bounce the laser off a mirror on one wall across to a spot on the other. Or mount the laser on the wall and a little mirror on the machine. And if your mirror is a partial cylinder you can enhance your precision because the reflection is off a curved surface. The beam does spread but it has a narrow point right on center.

[SORCHEROR]

all you have to do is buy one thomson linear rod and bearing,make a mount for top and bottom and a bracket to hold the bearing attched to the movable head stock to keep the head from rotating,works great if take time to do it right
steve

[kentavv]

Spot the laser on a wall 20 feet away. Place a mark on that wall, and make sure your laser is lined up on that mark whenever you use the mill. If you raise the head, check the mark and bump in the head until it is aligned before continuing. Longer distances can be even more accurate in restoring the alignment.

Sorry, but doesn't this only help if you are returning the head to the same height again? I guess I had in mind that the original poster needed more space to accommodate a large tapping head.

Not to mention you better have Chuck Yeager eyesight or a pair of binoculars nearby

[BobWarfield]

Sorry, but doesn't this only help if you are returning the head to the same height again? I guess I had in mind that the original poster needed more space to accommodate a large tapping head.

Not to mention you better have Chuck Yeager eyesight or a pair of binoculars nearby

Just means you have to line it up against a line if you want full range. RE the binocs, either take a few steps or use the mirror Geof mentions to put the spot back nearby. The main issue is the amplification the distance gives.

There's folks over on the HSM board using this method today.

Best,

BW

[omegaghost]

this might be of help this is what i did to mine with the lase dot on a wall http://www.cnczone.com/forums/showthread.php?t=30244 when the head moves 0.001 the laser dot on the wall moves 0.050 so it is easy to get really close to where you was at. i did use a craftsman laser level to make sure that the ruler in the pic was stright. if you have any questions about this just ask