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How do I drill a centered hole in the side of a turned piece?
- Thread starter Nelson
- Start date
depending on how big it is can you turn it side ways and install it in your chuck and use your tail stock with drill bit.:biggrin: Mac
T
Tom Griffin
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On a drill press, just put a 90 degree point in the chuck, ram it down against a V-block and clamp the block down. Then everything you drill in the V-block will be on center.
Tom
Tom
Nelson
All good methods allready mentioned above. If your drilling into the side of a turned piece that has just been done in your lathe, I most times use my side drilling attachment. Its just a home made rig the drops onto the QCTP. It has been setup on center and locked in position. The only thing I check is it 90 to the work.
I just run the carriage up to the chuck, loosen the tool post , and square it up.
Saves a bunch of time from re setting things up on the mill, or drill press. If I suspect my side driller is off centre, I have a 3/8 od round stock thats turned to a point. I run that up to the work, and pinch a 6 inch ruler the same way you check center on a cutting tool.
The side drilling attachment is a very usefull tool for drilling for a set screw, or even doing angled holes. A good addition to anyones tool collection, and a real time saver too. I made mine really cheap. I used a Boring bar holder they sell for the QCTP, and machined a shaft to fit, and mounted a drill chuck to the shaft. The outer end is milled with flats so it doesnt slip in the drill chuck of your hand drill.
Just a way to drill a hole in the side of your turned piece, without removing it from the chuck, and doing yet another setup.
Paul
All good methods allready mentioned above. If your drilling into the side of a turned piece that has just been done in your lathe, I most times use my side drilling attachment. Its just a home made rig the drops onto the QCTP. It has been setup on center and locked in position. The only thing I check is it 90 to the work.
I just run the carriage up to the chuck, loosen the tool post , and square it up.
Saves a bunch of time from re setting things up on the mill, or drill press. If I suspect my side driller is off centre, I have a 3/8 od round stock thats turned to a point. I run that up to the work, and pinch a 6 inch ruler the same way you check center on a cutting tool.
The side drilling attachment is a very usefull tool for drilling for a set screw, or even doing angled holes. A good addition to anyones tool collection, and a real time saver too. I made mine really cheap. I used a Boring bar holder they sell for the QCTP, and machined a shaft to fit, and mounted a drill chuck to the shaft. The outer end is milled with flats so it doesnt slip in the drill chuck of your hand drill.
Just a way to drill a hole in the side of your turned piece, without removing it from the chuck, and doing yet another setup.
Paul
B
British Steel
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In the lathe, a drill pad / crotch or V centre works well - it's a plate at 90 degrees to the lathe axis with a Morse taper shank - the plate has a V slot cut in it, so you can lay the round part in it and a centre drill in the lathe chuck, bring the two together and away you go!
Dave H. (the other one)
Dave H. (the other one)
I second the tool post side drilling attachment.
You know how i would do it 
But if it was in the drill press i would put in a center drill and lay a steel rule on your part. Then bring down the quill untill the bit touches the ruler and see whic way its leaning. Then scoot the part over until the rule is level...Bob
But if it was in the drill press i would put in a center drill and lay a steel rule on your part. Then bring down the quill untill the bit touches the ruler and see whic way its leaning. Then scoot the part over until the rule is level...Bob
Nelson,'
This was staught to me by a tool maker I work with and is the most precise way I know to get on center...
The first step is to locate the edge of the part with an edge finder, then move the mill 1/2 the diameter of the edge finder plus 1/2 the diameter of the part. That's the rough center point.
Now, chuck up a DTI. Lower the quill until you see a maximum on one side of the part. Lock the quill here. Now rotate the spindle back and forth by hand until you see the maximum reading. Zero the DTI on this reading.
Raise the quill and repeat this process on the other side of the part. The difference in readings is twice the amount (I think) you'll need to move the mill axis to get on center. You may have to go back and forth a few times until you get it perfect.
Now, spot your hole using a spotting drill or a center drill. Replace with the proper size bit and have at it!
I'm up to my eyeballs with honey-dos right now or I'd make a video. Anybody else want to step in?
John
That's pretty much how I do it, but for this part - not following what you mean here at all:
You've already put the spindle on center, so what is the DTI doing? I need another cup of coffee...
The edge finder is only good to a thou or two (more if it's a cheapo). Then when you consider another possible few thou of lost motion (lash) in the axis move, plus any uncertainty in the diameters, the tolerance stackup could be more than you'd like for precision work. If you have a DRO, lost motion isn't so much an issue, but even using the brand new Bridgeport's at work with DRO's, I find that centering can be improved upon by the method I described...
I'll try to reword it to be clearer...
1) Chuck up edge finder. Find an edge, then raise the quill.
2) Zero the mill dial.
3) Move the mill 1/2 the workpiece diameter plus 1/2 the edge finder diameter.
4) This will put you very close to on center. If you want better, then move onto step 5.
5) Chuck up your DTI.
6) Turn the DTI so the face is either directly towards you or directly away from you. The goal is to find the maximum point on the side of the workpiece.
7) Lower the quill until you get the most DTI deflection. This is a point tangent with the OD of the part on the Z axis.
8) What we don't yet know is if the DTI was really set with it's swing axis 90 degrees from the workpiece axis. So, by rotating the spindle back and forth, the DTI probe will move in an arc. By finding the minimum point, we know for sure the DTI probe axis is positioned perpendicular from the part centerline.
9) Now we have a reference point, so zero the indicator (or note the reading).
10) Raise the quill.
11) Repeat steps 6 through 9 with the DTI facing the other way. If the DTI no longer reads zero (or the same reading it did from step 9), you know you weren't exactly on center.
12) Make adjustments and repeat until you measure zero on both sides of the part.
13) Machine away...
Does that make sense? I wish I had time to make a video... It's hard to explain with diagrams or a video. This was explained to me a number of times but I couldn't figure it out until I was shown the technique in practice.
Remember, if a hole isn't spotted first using a spot drill or a center drill, the drill bit WILL start off center despite your best efforts to put your spindle over the exact center. Also, an incorrectly sharpened or an el cheapo drill bit can drift during the drilling yielding a cross hole that's right on top, but comes out off center on the bottom.
John
The way I would likely do it is to make a drill guide from a round piece turned in the lathe the same diameter as the round part to be drilled. Could be a small piece parted off when turning the original part. Drill a small hole through it say 1/8" in the lathe. The piece doesn't have to be long, about 1" will do. Set your part to be drilled in your vice supported so that it is horizontal to the jaws and set your guide on top of it where you want the hole drilled and tighten your vice. Now just align the piece under a 1/8" drill bit in the chuck and slide your vice around until the drill will slide up and down through the guide. You are now dead centered with no fuss. Once you have this pilot hole drilled just loosed the vice enough to remove your drill guide being careful not to move the piece being drilled, retighten the vice and finish to what ever size you want.
Nick
Nick