Drilling accurate depth holes

[Bob SillitoeParticipant @bobsillitoe83708]

The jig looks to be really useful, however devising a way of fitting something like that to my Southbend would require a bit of thought. Also to my mind what I want to drill is tiny, 1/8″ dia bar with 1/16″ cross hole. I am going to get creative on the miller, will post a picture if it works.

Thanks for everyones advice. Interesting how we have digressed from drilling holes using the tailstock to drilling little cross holes!

Bob

[JasonBModerator @jasonb]

It will depend on what you have and what accuracy but I regularly drill 2.5mm and 3mm dia short pins with 0.8mm holes to take a 1/32″ split pin.

Usually I will just grip the pin at one end of the vice as it invariably has a head on the end with the shank and the pin sitting a little above the top of the vice jaws. Put a 3mm spotting drill in the chuck and bring it down onto the work trapping a 6″ steel rule between. Adjust position of vice until the rule balances level while applying light pressure with the quill. remove rule and spot then drill your hole.

If a bit more accuracy than a thou or two is needed then use an edge finder to locate the vices fixed jaw and offset half your rod diameter from that eg 1/16″ which will put the drill over the ctr of the part.

Over 40 yers of making models and I don’t have a cross drilling jig but do seem to churn out completed models a lot faster than most here.

[bernard towersParticipant @bernardtowers37738]

Bob ,I posted a picture some time back of a 0.5mm hole thru 1/16 bar on a similar jig on a peatol, so yes its possible

[Dalboy]

On Dalboy Said:

If possible make a gauge up like this. Always handy for future projects I got the gauge from Machine DRO and some small pieces of Ali plate from my stockpile.

Here goes, third time lucky.

I made a similar device for my WM250 using a similar scale from Warco, and it works a treat.  Should have done it years ago.  If you look at Blondihack’s YouTube channel, she has also made one.

However Bob, if it’s to fit your Southbend Lathe, have a look at Linn Tools (not the HiFi guys), I believe he may have such a device to fit directly onto a Southbend.

[Bob SillitoeParticipant @bobsillitoe83708]

Cross hole successfully drilled. I decided to have a go using my lathe and holding the workpiece cross wise in the chuck. A technique I have used before but not with such a small diameter bar. Here are a few pictures, you can see that I had just enough room to get a centre drill down between  the jaws of the chuck, then drilled with a 1/16″ drill.

It is quite a good technique but you have no control over the axial position of the cross hole, so really only suitable if you need the hole near the end of the bar.

[Author]

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