Drilling Cross Holes

[prasad]

Guys

I want to drill cross holes on this small brass part I am making. These holes need to be at 90 degree apart. I can get it by drilling two through holes or drill four holes half way. The diameter of the part is 1/2" and the holes are 1/4". The part has a through hole of 1/4" diameter. As you will see.


Here is a list of equipment I have.
1. Mini-mill with Kurt Style vise
2. Vee blocks of suitable size with appropriate clamps.
3. Edge finder if needed

I know I will not be able to through drill if I use the Vee block. I will have to drill four times.

My question is how to get the holes at 90 degree apart? (I.E., Without a dividing head or an indexer)
What is the easiest method?

Thanks
Prasad

 

[Wreck™Wreck]

Clamp the part in the vice on the flat ends that you have turned in a lathe, the diameters in the Y axis.

Set a stop on one side then drill through.

Place a gauge pin through the first hole and rest it on a gauge block and drill the second hole.
I realize that the part has a large shoulder so add this dimension to the gauge block.

 

[prasad]

Clamp the part in the vice on the flat ends that you have turned in a lathe, the diameters in the Y axis.

Set a stop on one side then drill through.

Place a gauge pin through the first hole and rest it on a gauge block and drill the second hole.
I realize that the part has a large shoulder so add this dimension to the gauge block.

Thanks. I get the general idea. I dont have gauge blocks or pins. I do have thin parallels. I will make a support of appropriate height in aluminum for supporting the thin end. I will try using a 1/4" drill bit when I have to turn the piece for the 90 degree rotation.

Thanks again,
Prasad

 

[Wreck™Wreck]

Thanks. I get the general idea. I dont have gauge blocks or pins. I do have thin parallels. I will make a support of appropriate height in aluminum for supporting the thin end. I will try using a 1/4" drill bit when I have to turn the piece for the 90 degree rotation.

Thanks again,
Prasad

Gauge pins and blocks are only used when as much accuracy as possible is required, they do not help much with drilled holes. If you would like shop accuracy gauges relatively cheaply buy hardened steel dowel pins in 1/16 sizes from 1/8" to 1/2" as these are normally within +- .0005/001 on diameter.

A single .5" X 1" long hardened steel dowel is $3.17 from McMaster, minimum package of 5 however.
I find them invaluable in the shop.

 

[Paul in OKC]

You could, using Wreck's suggestion basically by using a drill through the hole and resting it on a couple pieces of key stock on either side of the part.

 

[turnitupper]

If your vise jaw tops have no step in them when tightened together,use parallels or anything sacrificial (wood?). Put part in jaws with flange hard up to the end of the jaws with the part resting on whatever to keep it square with the drill. Use a 1/2" bolt or something in other end of vice to keep jaws parallel.
Tighten and drill hole right through piece. Release and insert a 1/16" or thereabouts drill or wire through hole. Rest drill/wire on top of vice jaws with the flange hard to the end of jaws again. Snug up and use straight edge on part to be parallel with top of jaws and tighten.
Remove drill/wire from hole and drill through. Rough but effective!.
John.

 

[Bill C.]

Thanks. I get the general idea. I dont have gauge blocks or pins. I do have thin parallels. I will make a support of appropriate height in aluminum for supporting the thin end. I will try using a 1/4" drill bit when I have to turn the piece for the 90 degree rotation.

Thanks again,
Prasad

Use parallels and a drill bit to get the part above surface of the V-block. The drill bit would act as gage pin to keep the part from turning. After drilling all the holes might want to use a hand reamer to remove any burrs. Good Luck with your project.

 

[fixit]

Get a piece of 1 inch square stock drill & ream a hole .001 under size in center & press your part into it. Drill your holes, then press finished part out.

fixit

 

[TOOLMASTER]

bolt it between 2 square block

 

[TOOLMASTER]

one thing to do when drilling a round surface in the mill is to hit it with a flat mill bit to give yourself a flat surface to drill so the bit won't wander...doesn't need to be a deep or wide cut just enough to give you a starting point for the drill tip