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Drilling an accurate angled hole in a thin spindle

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u38cg

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The task: drill an accurate angled hole into a wooden spindle. The hole will be around 3-4mm diameter and the depth to the centre of the spindle. The hole will be at a 45 degree angle to the spindle. Accuracy of placement needs to be well under 0.5mm, say on the order of 0.1mm.

The equipment available: lathe, chuck, ER32 collets. A hand-held drill. The usual handtools. I'm thinking that endmills might be the best choice of cutter to minimise deflection.

I have half an idea that some kind of fixture attached to the tailstock would do it but I can't see a way of doing it safely. I don't mind buying equipment if I really have to but if I can do it on the cheap, so much the better!
 

marcros

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Any form.of a drill stand or pillar drill?

A fixture, the correct drill and my hand cranked pillar drill would do that I think. I haven't measured the runout but I would be hesitant to guarantee 0.1mm. I would buy a set of 1-6mm drills in 0.1mm increments and try slightly undersized to what you want. The set used to be available from UK drills, I bought the 6-10mm version. At least then you would have all of them to hand rather than needing to wait for a bit bigger or bit smaller one after testing.
 

u38cg

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marcros":1nxdt5dv said:
Any form.of a drill stand or pillar drill?
No, though that's probably the answer!

These are for tone holes on woodwinds, so hole size and position trade off each other a bit - so I don't need to have every possible hole size - I can select a 3mm hole then move it up or down a bit based on what comes out. The 0.1mm is really overkill - there will be fine tuning done anyway - I'm getting about 0.5mm by hand which is adequate, with care.
 

marcros

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You could experiment with a drill guide that would clamp on to the piece, then drill by hand. The guide prevents the drill being able to wander so the drilling machine is less important.
 

Dalboy

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Using an end mill in the drill press and slowly approaching the will allow for you to get it lined up all you will need to do is find a way of holding the piece at the desired angle and on the centre line of the turning. This is how I have done this type of thing when drilling an 5/16 dowel tp take a smaller dowel with a steeper angle than you need.
 

chaoticbob

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u38cg":1p6k9gtc said:
The task: drill an accurate angled hole into a wooden spindle.
...
I have half an idea that some kind of fixture attached to the tailstock would do it but I can't see a way of doing it safely. I don't mind buying equipment if I really have to but if I can do it on the cheap, so much the better!
A tailstock fixture was the first thing that sprang to my mind - something along these lines:

TailstockJig.JPG


I have something similar on my engineering lathe (albeit for 90 degree cross drilling) and it doesn't seem unsafe - the work is clamped into the V, not shown in my rough sketch, but easy enough to implement.
Bob
 

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MikeG.

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Is the spindle already a spindle? I mean, are you making the spindle, because it would seem easier to me to locate a hole accurately in square stock. Drill the hole first then turn the spindle.
 

u38cg

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MikeG.":1lie0fa8 said:
Is the spindle already a spindle? I mean, are you making the spindle, because it would seem easier to me to locate a hole accurately in square stock. Drill the hole first then turn the spindle.
Yes - the problem is that I'm also drilling a ~4mm hole up a (potentially) 16" spindle, and where that hole end up up defines the centre of the spindle! Some people do do it exactly the way you describe, but they also have metalworking lathes and gundrills, not a bit of silver steel butchered freehand on a bench grinder :D

Trevorturn":1lie0fa8 said:
I use A sorby precision hole boring jig they are made for the job
Actually this does look ideal - only issue is the limited bores offered - 6/9/12mm. But that's an excellent start, pretty sure I can come up with something sensible based on that.
 

Dalboy

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I Forgot about the Sorby jig for the odd hole I made a wooden insert for the drill size I needed if needed, for a lot of holes then find some one to make up a metal one or two because even these will wear over time unless hardened
 

Phil Pascoe

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I turned a wooden "peg" a bit like the Sorby jig, and put a hole through it. Fits in the banjo, and is adjustable for height and angle. The head could be square to get the exit hole closer to the workpiece and the hole could always be lined with something harder wearing.
 

MusicMan

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The ideal would be the system I helped to set up at Cambridge Woodwind Makers for Daniel Bangham. This had a Waco vertical milling head mounted on a rotary table (horizontal axis) to drill at any angle (45 deg only is limiting you to a particular instrument), aligned with a manually rotating pair of centres to hold the spindle. The angle of the spindle itself was measured with a Wixey encoder, quite cheap.

That is serious £, but the Sorby jig or a home built imitation would do a good job. You will need to be able to lock and preferably index the angle of the spindle in the lathe, and incorporate a protractor to set the angle of the drill guide. Then a means of fixing it in the banjo, but you must develop a way of setting the banjo to better than 0.5 mm along the axis. Yes you do need that accuracy for a woodwind. Though you can compensate for tuning by altering the hole size, you then lose control over your venting. I suggest you get pointed rods made up for your drill sizes, so that you can see accurately where the drill will locate by putting them in the drill guides first and seeing where the centre is. It is very hard to judge distance on an angled approach.

Drilling by hand is fast enough and far less scary ;). No need to use an end mill, spur drills work fine if the guide goes fairly close to the spindle.

MikeG is right for the occasional hole, it is easier to drill it on a flat. But this is not right for a woodwind for two reasons. First, you may want several holes at different angles around the axis. Second, even a gun drill doesn't drill as straight as the straightness of a turned spindle, and you won't know accurately enough where the centre of the tube is. If you put the hole in first you can turn the outside to be really concentric.

The best technique of drilling a long straight hole for a woodwind (without a gun drill) is to use the lathe. Hold the headstock end firmly (ie with a chuck, not with a Steb centre) and the other end in a fixed steady. The eighteenth-century makers just used a hole the right diameter in a fixed wooden block, Then start the hole with a gouge, and continue all the way with a shell auger. The straightness comes from the work rotating and the drill staying fixed (apart from translating) as this tends to centre the drill. You can then enlarge the hole to a precise diameter with a D-bit which you can grind yourself, and shape it if necessary (eg for a bagpipe chanter) with a reamer. Making the reamer is the trickiest part, but that is another topic.
 
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