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cheap vervsion of aligment help for mill drill

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  • cheap vervsion of aligment help for mill drill

    After reading nice article from Dave Sage HSM march April. Here is my cheap solution. I hot glue a dollar store lazer pointer on the side of the head. In front of the cabinet 8 ft apart from the mill I suspended a plumb bulb. I replace the string with a .185th strip of aluminum . Same width as the red dot. Assuming the machine is level. Standing at almost the same place on the side of the mill, it is repeatable to less than.001 Not bad for a dollar

  • #2
    Have you checked level then to be sure your assumptions are correct? The basic idea is sound and you can't beat the price.
    .
    "People will occasionally stumble over the truth, but most of the time they will pick themselves up and carry on" : Winston Churchill

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    • #3
      This is a good idea - covered previously.

      It should be noted that it is for realigning the milling head by swinging it around the round column - which it will do very well.

      It is not and should not be confused with "tramming" tools.

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      • #4
        >> Assuming the machine is level.

        Yes. Assuming the machine is level is a dangerous assumption. If the column in not vertical i.e the whole machine is tilted forward or back even slightly then the laser will not be moving vertically as you crank the head up and down the column and will therefore not follow the vertical line on the wall in any case. In that case if you rotate the head to re-align the laser with the line you would actually be mis-aligning the head even if it was travelling straight up and down the column. Getting the machine level to the point that you can trust extending the planes accurately far off the machine IMHO would be difficult. (I'm not sure if the vertical error would be amplified by distance as well).
        As pointed out here (and in the article) key number one is a properly trammed machine. A machine can be perfectly trammed but that doesn't make it level.
        There are all sorts of other possible problems with mill drills and the way they are constructed that I did not point out in the article due to space constraints.
        Simple put it's the old adage "you can't make a silk purse out of a sows ear".
        One of note is. What makes you think that the Chinese were capable of machining the hole through the head (that fits around the column) straight through in the first place. Next to nill I'd say. So it's quite likely the quill is not parallel to the column in some direction in the first place and there's nothing that you can do to correct it. It can't even be trammed. Even if it was bored properly the fact that you are tightening that hole around the column is possibly mis-aligning it.
        I continue to use my mill drill with my modification and it works well. But it will never be a proper knee mill.

        Dave Sage
        Last edited by Sage5902; 06-23-2015, 08:17 PM.

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        • #5
          Believe it or not,
          the Chinese can make wonderful precision things,
          It is just that the importers tell them to make low
          grade cheap tools, because that is what sells in
          the market and makes the most profit.
          Expensive and precision tools have a very small
          market compared to cheap, and poor quality tools.
          -Doozer
          DZER

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          • #6
            What you say about the Chinese products may be true. But all we see here - for the most part - is the junk so that's what we have to deal with.

            Sage

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            • #7
              Originally posted by Sage5902 View Post
              What you say about the Chinese products may be true. But all we see here - for the most part - is the junk so that's what we have to deal with.

              Sage
              Old adage: You get what you pay for.
              You want a Chinese lathe with Monarch quality? They will happily build it for the Monarch price.

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              • #8
                I always liked the laser idea. My take ... the mill should be trammed in a traditional way to get it as close
                to tram and you can.

                Then a laser should be "indexed" to the machine so that it's position can be accurately replicated.

                Then mark where the laser hits on a wall as far away as practical.

                So as long as the machine doesn't move, this has to be fairly accurate I would think.
                John Titor, when are you.

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                • #9
                  Just a minute. The OP is talking about a mill/drill. It has no provision for tramming in a "traditional way" since the head can not be rotated in either tilt or nod. The only movement is the rotation of the head around the vertical column. If it was square with the table on both X-Z and Y-Z planes it will still be square no matter where it's rotated. If one wants to check for correct geometry you can do the usual indicator in the spindle test against the table to keep it honest but if there's any discrepancy the only means of correction is to shim between the column and the base.

                  So, to get back to the laser alignment. This is a perfectly valid method in principle, PROVIDED that the fundamental geometric error possibilities are accounted for. So, you could mount a laser on the head throwing a vertical line on an adjacent wall. Mount your plumb bob on the wall, adjust the laser line to be perfectly parallel to the line and epoxy it there. Now, as you swing the head around the column the laser line will always be parallel to a plumb line. Can you now just crank the head up and down, rotate it again to have the laser line be coincident with the plumb line and be confident in your re-positioning? Imagine if the machine is tilted at 10 degrees on the workbench. (Yeah, I know you'd never see one like that but it's easier to visualize) With the head at the top of the column you turn on the laser, assure yourself that it's matched to the plumb line on the wall which will not move. Now lower the head six inches and rotate it to again be exactly coincident with the plumb. Is it now in the same position over the workpiece on the table?

                  Get out the trig. As the head is sliding down the hypotenuse of the triangle for six inches it is moving sideways by Sin(10)*6 or about 1.042 inches. If you now rotate the head to again align with the plumb line you'll be that far displaced from the work.

                  So what's the solution? One would be to align the laser exactly with the column, even it it's tilted. Then you draw a line on the wall exactly parallel to the column. Now, as you move the head up and down the laser line will always track the column and if you're realigned with the wall line after the move you'll still be exactly right. The two difficulties with this are 1) how you align the laser with the column to start with, and 2) if you've got a line on the wall you always have to have the head in the same position relative to the table. In other words, if you were to swing the head to one side or the other to access a long workpiece, your laser line will now be parallel to, but not coincident with the line on the wall. You'd have to scribe another parallel line on the wall to accommodate the new head position.

                  The other method is to level the machine up so you can use earth's gravity as a reference. If the machine is square the the world you can mount the laser to the head and align IT to a plumb line anywhere. Now fixed to the head, you can rotate the head anywhere you wish, hang the plumb line to the current head position, move it up and down as you like and when it's swiveled again to plumb it will also be aligned with the table.
                  .
                  "People will occasionally stumble over the truth, but most of the time they will pick themselves up and carry on" : Winston Churchill

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                  • #10
                    The round column, import mill/drills CAN be trammed. You must first remove all the putty that is filling in the junction of the base with the column. Then you need to find which way it needs to go and how much. You CAREFULLY loosen the bolts holding the column to the base and insert shims under the corners, by the bolts, one pair at a time: left, right, front, or back. Torque the bolts back down and recheck the tram. Repeat as needed until it is square to the table.

                    Of course, you probably want to insure that the table is parallel to the ways first.

                    As for using a laser to set the rotational position of the head on the column, I favor using a first surface, high quality mirror that is tall enough to cover the entire vertical range of head movement. This mirror can be fixed on a wall and the laser can be aimed at it, in an approximate horizontal path, from any position of the head around the column.

                    To avoid changing the figure of the mirror, I would make a frame for it and suspend it by one point at it's top center. And with this method, you do not have to have the laser beam dead horizontal. It would be adjusted to be reflected back to a target on the mill's head which could be an inch or so above or below the laser. The mirror doubles the length of the optical path so the method is twice as sensitive to errors. And the laser's spot is at the mill's head where it can be observed easily, instead of being across the room. This also increases the accuracy of the method.
                    Paul A.

                    Make it fit.
                    You can't win and there is a penalty for trying!

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                    • #11
                      Great food for thought, our museum drill mill would be easier to use and only needs to have the column vertical from side to side to work. I shall be examining the walls and seeing if obstructions can be circumvented. Also, a mirror on the wall might be the way to go. I use a laser alignment tool to check my car wheels alignment, it works very well.

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                      • #12
                        Paul,

                        I'm struggling with the geometry of the laser and mirror you're proposing. Doubling the length of the light path is a good plan, and it sounds like you're using a spot laser rather than a vertical line. Is that true? And in connection with the mirror and swinging the head, doesn't that mean that the reflected spot is now moving at a double angle if the head is rotated? If I've got that right it means that each time one swivels the head the mirror needs to be rotated and possibly repositioned to bring the spot back on target at the mill. And then if the mirror twitches at any point the reflection is no longer reliable for position.
                        .
                        "People will occasionally stumble over the truth, but most of the time they will pick themselves up and carry on" : Winston Churchill

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                        • #13
                          Could the laser be mounted int eh spindle projecting on a horizontal plane and spun to create a circular line around the entire shop which can be checked if level/trammed all the way around? Assuming the table is level? Could the table be checked with the same level sitting on a turntable spinning in the same fashion as the spindle? The have two lasers spinning, one on the table and one in the spindle, measure the distance the two lasers are projecting on the walls all around and make it equal = trammed?
                          Andy

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                          • #14
                            Yes, that's valid if the turntable can be verified to have its rotating spindle exactly perpendicular with the base and the base is flat to the table. Having the extended distances would exaggerate any discrepancy and make it easier to measure.

                            In real life it's probably easier to use an indicator in the spindle checking against the table top.
                            .
                            "People will occasionally stumble over the truth, but most of the time they will pick themselves up and carry on" : Winston Churchill

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                            • #15
                              Or. You can forget all the smoke and mirrors and do as the article suggests and install the bar on the machine. No worries about lasers, mirrors, plumb lines, machine being level, vertical lines, angled lines, wall distance trig etc. etc.

                              Works fine here for me to within a couple of thou top to bottom.

                              Sage

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