Relocating some holes

[Harrzack]

I have a piece with a number of related holes that have turned out to be off center.

I can mount the piece in the mill which has a DRO. Then I can locate the new center properly. They aren't off by much - maybe 3/8" or so...

Is it possible to use the DRO to relocate the new holes as an offset from the existing ones? This is a Sinpo DRO which I think has most common functions. Looking for ideas on how to do this if possible...

[Harold_V]

Is it possible to use the DRO to relocate the new holes as an offset from the existing ones?

Sure, but only if you know the precise amount of error in both directions.

Wouldn't you be better off to return to your original datum points for the proper locations? I'm assuming you had them when you started the project, which is really good shop practice. That way it doesn't matter the amount of error you generated with the original holes.

And---keep in mind---if the hole size is such that the new holes overlap the old (wrong) holes, you're not going to have much luck drilling. You might be better served to provide more information if you're seeking guidance.

Harold

[curtis cutter]

This is a case where simple minded guys like me need a picture.

[Harrzack]

Sorry for the vague question - I just thought it was an operation that might be built in or do-able with the DRO. There is a central post-hole with 4 related screw-holes. I think I can just re-drill the aligning post hole, and set joystick base back on it - and mark the new hole positions to re-drill.

[spro]

I agree with the above. If these holes are all related and correct, the center needs boring, not drilling. A single tool boring bar isn't guided by the wrong central hole the way a drill is. It can bore a larger dia and bushed or sleeved so that the other holes align. Since you mentioned drilling the center, Particular attention that the other holes don't overlap or get 1/3 the thread width to them.

[Harold_V]

Sorry for the vague question - I just thought it was an operation that might be built in or do-able with the DRO. There is a central post-hole with 4 related screw-holes. I think I can just re-drill the aligning post hole, and set joystick base back on it - and mark the new hole positions to re-drill.

Keeping in mind, I have never used a DRO, in spite of having worked in the trade for years----

As I understand it, the typical DRO has the capability to provide locations for bolt circles, which is what you described. Once you are on proper location for the center of the circle, it should provide the proper locations, depending on the number of holes, and how they are oriented. I expect that the four holes you mentioned enjoy a 90° spacing. So, yes, if you locate the center point, you should be able to drill the new holes on proper location, assuming they don't overlap, as I suggested previously. You likely have two choices of orientation. They would be holes located @ 0°, 90°, 180° and 270° or holes located @ 45°, 135°, 225° and 315°.

Harold

[WesHowe]

Actually, there are apps for phones/kindles that will compute the hole centers for a ring of holes just like a DRO would. Inputs are the diameter and the heading (0, 90, etc) of the first hole and the number of holes. The output are sets of XY coordinates relative to center to drill at.

[Harold_V]

Not owning one of those "trick" phones, I am duly impressed with the features they have. They, truly, are a huge step up from the simple TracFone I have, which doesn't even take pictures!

Thanks for the enlightenment.

Harold

[Patio]

Yes! Most DRO's have a ABS (absolute) and an INC (incremental) mode. Locate in the ABS mode, switch to INC, move the offset you want, reset 0,0. Now all locations will be off by the amount you moved from ABS to INC.

[BadDog]

I have a full featured phone, but would never consider taking it to the shop. Greasy hands and skin embedded with tiny chips and grit don't go well with touch screens. I have a 25+ year old TI "scientific" pocket calculator. Thin, lightweight, unbelievable battery life, all the trig (etc) functions you could ever need, and even the ability to "program" (more like mathematic macros) should you choose to do so. I always thought it would be worth the time to pre-program the simple SFPM calculations so I just enter relevant values, but it's too easy to just enter it all as I go. My DRO does stuff like that too, but it's an older model with no manual I could find online, and couldn't figure out how to program it just poking at it, so I just grab the calculator and a note pad. I've got a Newall on the lathe, and sure wish I had one on the mill too, but I don't see that I'm really missing out on much.

[Harrzack]

Yes! Most DRO's have a ABS (absolute) and an INC (incremental) mode. Locate in the ABS mode, switch to INC, move the offset you want, reset 0,0. Now all locations will be off by the amount you moved from ABS to INC.

Aha! That was the one I was looking for - Thanks!

As it turns out I had previously machined a reference piece that I was use to re-establish thing. I re-drilled it in the new center - just offset a bit. This project is mounting the guts of a Logitech Extreme 3D Pro joystick inside the mounting of an original joystick on target determination radar on the battleship New Jersey museum. The original ($8k!) mechanical marvel joystick mechanism was set aside as the Logitech provided easy USB access for software interface.

When I gutted the Logitech there was a couple nice metal plates in the base that provide good alignment holes to mount the stick center parts. Once I had the properly centered hole, I put my reference pin in the base, then dropped the plate over it and could pick up the 4 mounting holes.

When you are a noob it takes several iterations to 'get it right' - but in the end it all works out. At my current pay rate of $0.00 per hour this slow approach isn't too costly... LOL!

[WesHowe]

While I am not promoting any particular phone or anything, the Kindle can be had in a phone-less WiFi version that will run most of those apps, at least the ones that don't call anything. Latest look on Amazon showed a price of $49.95, which is way less that the $79.95 machining calculators (plus a much larger screen).