Repeating a drilling scheme

[atferrari]

I am looking for a practical solution:

Given two, three (or more) holes on a small plate, in order to repeat the drilling on another one, I would like:

1) Measure the diameter of each one.

2) Measure the distance between each pair of holes.

3) What if the holes are not drilled on a flat plate?

Just for you to have an idea, imagine I want to mount a stepper on a frame and that the mounting holes of the stepper are NOT symetrical to each other.

My need is by NO means limited to the stepper case, so please consider a generic situation where two, three or more holes drilled in a plate and that the plate is NOT available as a "template".

I have no access to any equipment.

Could you also add some idea of how much precision I could obtain with whatever method is suggested?

Gracias for any help on this.

 

[bryan1]

Allo Mate,
The easiest way to get repeated drilling results with very little equipment is make a jig plate with the hole centres you need, make the plate atleast 6mm thick and drill the hole so the final drill used will be a snug fit. Clamp the jig plate to the item you want drilled and just spot drill each hole so you get an accurate centre. By drilling right through there is a chance of the jig wearing and the next time it's used it will be out. This by far is the easiest way to get repeated results with little tooling.

Regards Bryan

 

[atferrari]

I need to measure

Hola bryan,

If you read my post you will see that my necessity is knowing how to measure those distances.

Thanks for replying.

 

[KMoffett]

atferrari,

What tool do you have to measure distances?...ruler?...caliper...????
Do you have a digital camera that can take sharp closeups?
Are the holes in the original threaded or clear?

Ken

 

[atferrari]

I am not trying to solve this, oriented to any specific case but thinking of building a small moving platform where I will be mounting different things of varied origin.

Asume that I have ruler, caliper and a common digital camera that could take sharp closeups.

Please consider both cases: threaded / clear holes.

 

[KMoffett]

Difficult without a specific case.
Frequently, to find hole layout dimensions for odd shapes, I will use a digital camera or scanner to take an image of the part next to a ruler. Plug the image into a graphics or CAD package (my preference), and use scaling and measuring tools to find the exact placements.
With threaded holes, I've sharpened screws, and screwed them into the object's holes so they slightly protrude. Then press the object onto graph paper, maintaining some sort of XY orientation. The points will leave marks so you can measure the hole positions with a ruler or caliper.
With un-threaded holes I would do the same, except just press a sharpened screw through the hole (s).

I suppose you could make an XY table with threaded rods to move it, and graduated knobs with markings for sub-rotation divisions. 20TPI threaded rods and knobs with 10 radial marks would read out 0.005" resolution. And a small magnifying lens with cross hairs for a reference position.

Ken

 

[shortbus=]

I am not trying to solve this, oriented to any specific case but thinking of building a small moving platform where I will be mounting different things of varied origin.

Asume that I have ruler, caliper and a common digital camera that could take sharp closeups.

Please consider both cases: threaded / clear holes.

To measure distance between holes with a caliper -
1. Put a screw if a threaded hole or a pin that fits the holes good, in two adjacent holes
2. Measure over the pins/screws, outside to outside
3a. If both pins/screws are the same diameter, subtract the diameter of one pin/screw, from the measurement in step2. That will give you the center to center of the holes
3b. If the pins/screws are different diameters, subtract 1/2 of each diameter from the measurement you got in step 2. That will be the center to center distance of the holes.

In this day and age you can find the hole patterns of most things by doing a Google search for that item. There is much more available today than when when I started out building things, then you had to get a catalog from a company to get the information.

 

[atferrari]

Practical, yes!

Hola shortbus,

Thanks for the suggestions. Short and to the point.

Happy New Year.

 

[260z]

If you need to find the centers between two holes with the same dia its easier just to measure edge to edge of the hole. Easier to measure with calipers this way. If the holes are different dia then the pionted screw would be best if they are only small holes. If the holes are big and you are using a centre reference then dont forget the old wooden dowell. Even a ground down broomstick could be useful.

To be accurate always use smaller drills first so that you can check that the drill hasnt 'run off' the centre. If it has moved you can always get the next drill to move a little off centre to compensate. Having said that it is easy to do that if the original hole is in the right place.

To acurately hold the piece to be drilled given certain references it is easy to make a jig out of a piece of old hardwood plank with nails in it marking the the references and bent nails around the outside to hold the piece still.

I hope that made some sence and that it is helpful.

Geof.