Thread: 90° with a transit

What would be a good procedure to align a long part in a horizontal mill 90° to the spindle


thanks

Mount a dial indicator on the arbor or vertical face and traverse the table.

- Leigh

Originally Posted by Heavey Metal

What would be a good procedure to align a long part in a horizontal mill 90° to the spindle

If there were some reason it had to be done with a transit, it would be pretty straightforward (but time consuming) to do it. A mirror on the spindle would determine when the transit (or autocollimator) were perpendicular to it. Once that relationship had been established, moving the mirror between several locations along the long bar would determine when it was aligned along the same axis as the transit. Once the transit has been aligned perpendicular to the spindle, and the part aligned parallel to the transit, the part now would be at 90-deg. to the spindle.

Originally Posted by Heavey Metal

What would be a good procedure to align a long part in a horizontal mill 90° to the spindle


thanks

refer to the manuals. how depends on equipment you have.
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Product Manuals and Publications
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bucking in to spindle you could do. but if spindle is checked with a dial indicator to side of table and is within 0.001" per 10" you might want to consider setting a long part parallel to the table. buck in to table slide and set part parallel to table side.
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optical instruments are often used to setup long lathes and mills for doing parts over 10 feet long

I like the responses above, but I like a surface gage or keys locked in the "T" slot. You also don't say if you're boring, slotting, milling or combinations?

You can determine "X" parallel by traversing the table & indicating if the table front & slots are good with the ways, they should be "0" on a machine in good condition. If not, then note any deviation and adjust to it (it's scary fast using a surface gage with the pins down).

For checking the spindle to table-"X" ways for square, sweep the table slot or table face rotating the spindle with an indicator rig. I have a 3/4" tubular rig that allows up to a 6' dia sweep (at max dia it's really a 2 man job). Also note any out of square deviation from spindle to table & adjust to it. (there is a note here - if after finding the table is true to the way travel above you then find the spindle is not square to the table you have a problem... You will not be able to bore a hole square to any feature you have just milled without adjusting the part).

Squaring the "Y" or column/spindle to table face requires a square if you want to sweep with a simple indicating rig, but it's the same as above, note the deviation and adjust to it. (The same caution applies to an out of square indication of the table top) Another note is I am NOT GOOD with traveling the spindle out on a HBM to check "Y" square to table top.

Once deviation is noted & recorded then simple tools like a surface gage & square can be deadly accurate.

I have a K&E and a Fennel transit (both are considered 3 arc/sec instruments), and for use around machine tools I would consider their use very subjective. While good at distance up to several hundred yards dividing the foot, the crosshair lines at 10-20ft. will completely cover the .005" wide division line on a good scale.

Good luck
Matt

I'd question how straight the long part may actually may be.

It could undulate a bit over its length as long = squirrel-ly

Mike

Part is a trackhoe boom 22' long.

Machine is a hbm.

Hole is wallowed to much to pick up with a dial indicater.

Will bore with an arber.

Prior method was a string and a carpenter square.

Please explain how to do this:

''A mirror on the spindle would determine when the transit (or autocollimator) were perpendicular to it.''

Originally Posted by Heavey Metal

Please explain how to do this:

''A mirror on the spindle would determine when the transit (or autocollimator) were perpendicular to it.''

I have a K&E mirror with a magnetic back, i.e. it was designed by K&E to have the surface of the magnet coplanar with the surface of the mirror. If this mirror is attached to your horizontal spindle it will be accurately aligned with the spindle's axis in the direction that matters, but be tilted somewhat up or down. However, that tilt is irrelevant as long as the mirror is big enough to reflect some of the image of the crosshair back into your transit.

Think of your image as reflected by the mirror on a medicine cabinet door (in this example, things are 90-deg. from that you will have with your horizontal spindle). Because the hinge is aligned with the wall, i.e. vertically, and you are standing vertically, when you start to swing the door open your image will begin to move left (or right), but the height of your eyes stays the same. If you had a transit aimed at that mirror, in one direction (the direction that doesn't matter) the vertical bar on the reflected crosshairs would immediately move out of alignment when the door started to move, but in the other direction the horizontal bar of the reflected crosshair would slide horizontally along the horizontal bar of the actual crosshair. To the extent the hinge were not perfectly vertical with respect to the axes of the transit, the horizontal bars would become misaligned as the door swung open.

I'm thinking the trackhoe boom has a round, flat boss 8"~12" diameter at either end of the hole you are reboring.

I'd indicate the boss face in line with the X and Y axes by shimming, pushers, etc. on the boom.

You could clamp a known granite or cast iron straight edge across the boss face and indicate X & Y as above.

If the face is square to the HBM within .001 inch in say 12"~24"... that's probably far better than when new!

Mike

Heavey Metal --

It sounds to me like optical tooling methods are WAY overkill for what you're trying to do.

My first thought was to suggest a good-sized tram / sweep bar and indicator, along the lines of what Lucas Precision suggests for aligning their HBMs, roughly midway through their technical article "Construction and Use of a Cylindrical Square": Construction And Use Of A Cylindrical Square | Lucas Precision Machine Tool Group

My second thought is that a higher-power version of the "laser edge finder", used in conjunction with eyeballed-to-center crosswires -- improvised from kite string and duct tape -- would also do the trick. Rotational Alignment Technologies (RAT) of New Zealand sells a Laser Piano Wire tool that would be darn near perfect way to project your spindle centerline through the to-be-bored holes onto the string crosshair targets. RAT's tool is right pricey, but probably not too far out of line with the price of having one made at a commercial shop. RAT's website does a good job of showing the Laser Piano Wire tool, and how to adjust and use it: Rotational Alignment Technologies

John

I suspect my simple solution is asking for things you can't supply, but here goes:


Start with a smooth clean concrete floor, 3-4 walls, and a ceiling (if you don't have a ceiling, there is a work-around).

A method of accessing the ceiling.

A method of attachment to the ceiling.

Several (half-dozen) plumb bobs, with string for each. Get a chalk line, also. Yellow would be hi-visibility.

A tape measure capable of repeatable accuracy.

A laser boresighter of your choice, perhaps from Walmart laser bore sighter - Walmart.com

Determine a method to install that boresighter coaxial to the mill spindle. Some boresighters are 12 gauge shotgun, some are .50 caliber, some are .22 caliber. Take your pick.

Aim the axis of the spindle at a wall. I am thinking 20-30 feet away, perhaps more.

Bolt the mill to the floor.

Install the activated boresighter in the spindle, ensure the wall is being spotted, and rotate the spindle to check for runout.

If the spot doesn't wobble, that's great. Otherwise, a few more steps are in order (you know what they are).

Hang a plumb bob at the wall, with its point just above the floor, the string intersecting the laser beam.

Mark the spot on the floor.

Go back to the mill, and repeat what you did at the wall, hanging another plumb bob in the line of the laser light. Mark that spot on the floor, and snap a chalk line between the two points.

For you geometry fans, or experienced carpenters, you already know what I'm doing, right?

Carpenters know it as "6 - 8 - 10".

For everybody else, I am implementing the Pythagorean theorem.
Pythagorean theorem - Wikipedia, the free encyclopedia

I know, the OP said "Transit", but how would that work, unless the transit has a straight line to index from?

If the OP insists on using the transit, then park that transit over the line on the floor (using another plumb bob), and insure that 180 degrees exists between the plumb bob at the wall and the plumb bob at the mill.


Whether a transit or the theorem is used to derive a right angle really doesn't matter.

Create that right angle at the location of choice, hang a few more plumb bobs, and align the workpiece parallel to the right angle.


I considered mounting a laser to a rotary table, but the accuracy at 20 foot (from the axis) would have been messy.

If the customer drops by while the plumb bobs and the laser are set up, they should be impressed, but don't explain the process, and hide that boresighter!

That brunson site will tell you how to do this

thanks for the help

Let us know how it works out, perhaps post some photos of the process.

The Brunson documents have a sense of humor, I like this:


Good Luck,
Steve