I have a mill/drill which satisfies my needs, but I have discovered at least one disadvantage to such a machine.. I sometimes perform hole based operations which require height adjustment of the quill headstock in process. An example would be drilling a series of holes followed by tapping them with a Tapmatic. Since the headstock can rotate on its support column during the height adjustment necessary between drilling and fitting in the Tapmatic, getting the quill centerline concentric with one of the original hole centerlines is not a simple task. I was wondering if ahybody out there had any clever ideas to facilitate such realignment? TIA Bob S.
There have been lots of articles in HSM and MEW over the years about various approaches to work around this problem. I haven't paid much attention since I bought a Bridgeport. Suggest you go to your local library and do some browsing.
Grant Erw> I have a mill/drill which satisfies my needs, but I have discovered at
This is one of those "I heard that you can........." answers.
Get a narrow mirror that is at least equal in length to amount of movement that the head can make. Fasten the mirror a wall or suitable other furthest point possible away from the machine. Mount a cheap laser pointer to the machine head, and align mirror and laser so the laser beam strikes the mirror and returns to a mark on the machine head. Loosen and lift/lower the machine head to desired height, and then turn head to locate the laser beam back on the same point on the machine head before tightening the head.
Cheap and easy. Give it a try. Take care.
Brian Laws>I have a mill/drill which satisfies my needs, but I have discovered at
There have been various attempts to keep the head in alignment. One of them is to pin the rack to the column and use the rack to guide the head up and down. This has been discussed here or in magazines such as HSM. Another technique I have seen discussed here is to put a laser pointed on the head and aim it at the wall. If you have a vertical line on the wall (and the column is vertical) you can get reasonable alignment. Never tried either one. Got two knee mills now. :)
The best idea I've come up with is a laser pointer fixed to the mill head that shoots a beam to a mirror on the opposite side of the shop which reflects it back to hit a mark on the mill head (adjust the mirror so that it does). In my case, the shop is 34 feet across, so that gives a total lever length of about 60 feet (mill sits out a bit from one wall). A *very* small angular alignment error will displace the laser dot a very noticeable amount, so getting the laser dot back on the mark gets you very close to back where you were before moving the head.
The bigger your shop, the better this works, of course. The big advantage of this method is that you only have to fabricate a laser pointer bracket and set up the mirror once. Then it is always ready to use without being in the way.
A much cruder alternative is to pin the rack to the mill/drill column. That'll keep you in the ballpark as you move the head, but it won't keep you dead on. You'd also have to unpin it to let you swing the head when you wanted to do that.
You could also set your height gauge on the table with a dial indicator fitted so it touches the spindle. Zero the dial indicator before you make the move. Crank up the head, Then crank up the height gauge and swing the head to rezero the dial indicator against the spindle at the new height. That's accurate, but it is a PITA to set up every time you want to move the head.
The easiest and fastest lineup for me is to use a dial indicator on a magnetic base indicator holder. I adjust it so that the indicator touches the spindle and will continue to touch the spindle after moving the head up/down. I suppose that the head can be moved up or down farther than the spindle is long, but that doesn't seem to be a problem for me.
Make yourself an adaptor that takes up same vertical space as the tapamatic head fitted for an indicator. Indicate hole, remove adaptor install tapping head, and go for it???
I've just used a rod with a cone tipped point to do that (called a "spud" I think). If you only have to get to thousandths, rather than tenths, it is a relatively quick and easy way of lining up on a hole.
Sweeping the hole with an indicator is better, though. I have an Enco clone of the Blake coaxial indicator that takes up about as much space as a tapping head, so that might be a good solution too.
I have a Jet JMD18 and I have used it a lot. The secret is to get tooling that allows you do the job without moving the head.
Drill chucks and particular keyless drill chucks consume a lot of Z travel. I find that erickson DA collet chucks are very useful. The straight shank ones can be held in collet and the amount they stick out can be adjusted to suit the job at hand. They will also run about as true as you can get.
So now, I can mill with an endmill and change to drilling with the collet chuck without moving the head up or down.
You mention drilling a sequence of holes and then installing a tapping head to tap them. Even with a knee mill, drilling all the holes and then changing to the taping head would require registering the spindle over each hole. Seem time consuming at best and unreliable without a DRO.
I think taping heads (tapmatic ??) have some play engineered into the tap drive so they do not have to be accurately centered over the hole. Just close and the tap will follow the hole. Then they can be drilled on a drill press. Maybe you don't need to be as close as you though??
Chuck a long rod that is the same diameter as the drill. Then just align the head so that the rod will go into the drilled hole. Should be close enough for tapping.
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