Drilling holes from tailstock

[Joe Stajduhar]

With a drill (1/4") in a drill chuck mounted in the tail stock, I am having a problem with the drill wobbling causing an oval hole in the work piece.
The drill bit is sharp. Before drilling, the tail stock is extended only 1" which is enough to lock the chuck. The length of drilling into the work piece is from 1" to 2".
Any help would be appreciated.

 

[Steve Worcester]

With a 1/4" drill, if you don't use a stub length (and possible even then) you will get the drill wobbling and bending. You may try a forstner bit, since they are a little more stout ad less likely to bend.

Why only a 1/4"?

 

[Charlie Knighton]

you might drill a pilot hole such as 1/8 or 1/16 , then drill the 1/4 hole

hope that helps

 

[robo hippy]

You need to clear the bit once for every diameter of the bit's depth you go, so 1/4 inch bit, drill 1/4 then clear, drill another 1/4 inch then clear. The shavings in the bit will push it off center. Going 2 inches deep also presents problems similar to reaching out too far off the tool rest with a small sized tool: chatter/flexing.

Slower lathe speeds as well.

robo hippy

 

[john lucas]

I lay a skew down flat and use the toe to make a small starter divot. Small twist drills don't want to start without wobbling and then it gets worse as you go. If you make a starter hole either with a centering bit in the chuck or with the toe of the skew the bit won't wobble and will usually drill an accurate hole.
Bradpoint bits and the starter hole are even more accurate.

 

[MichaelMouse]

This is one operation that wants the tailstock in line with the headstock! Those double morse taper alignment tools are almost mandatory. What type of bit? A metal-boring (point guided) type will be inclined to wander more than an edge-guided like the Forstner or a brad/bullet point.

That said, any slop or flop after the bit enters at center is most likely from the quill or the tailstock. Make sure the quill lock all but stops the quill advance to cut down on wobble, then clear often so the shavings don't clog and push the bit or piece itself around. I much prefer boring holes on the drillpress and using cones or mandrels for centering on the lathe.

 

[odie]

I lay a skew down flat and use the toe to make a small starter divot. Small twist drills don't want to start without wobbling and then it gets worse as you go. If you make a starter hole either with a centering bit in the chuck or with the toe of the skew the bit won't wobble and will usually drill an accurate hole.
Bradpoint bits and the starter hole are even more accurate.

This is some good advice from John, here...... Use of the skew to create a small divot in the piece to be drilled is what I do, as well. This method can be relied upon to perfectly center the divot....always, every time.

This doesn't mean the drill bit will be perfectly aligned, but the divot will be......which brings us to MM's post below:

This is one operation that wants the tailstock in line with the headstock! Those double morse taper alignment tools are almost mandatory. What type of bit? A metal-boring (point guided) type will be inclined to wander more than an edge-guided like the Forstner or a brad/bullet point.

That said, any slop or flop after the bit enters at center is most likely from the quill or the tailstock. Make sure the quill lock all but stops the quill advance to cut down on wobble, then clear often so the shavings don't clog and push the bit or piece itself around. I much prefer boring holes on the drillpress and using cones or mandrels for centering on the lathe.

Also, some good advice here........One way to quickly check the alignment of tailstock quill to spindle, is to use a very sharp pencil on the tool rest to scribe a tiny little circle on the workpiece. This circle, as with the skew divot, will be perfectly centered in relation to the spindle. Now use a pointed attachment in the tailstock: Brad point bit, prong centers, cone centers.......anything with a "pointy" center to it will work. Now, bring whatever you've mounted into your tailstock up to the penciled circle........You now have a good reference point that shows if the headstock/tailstock are in alignment.

ooc

 

[Bill Boehme]

It's what MM said! The centerline of the spindle and the tailstock rarely line up with any high degree of precision suitable for drilling on a woodturning lathe especially if done from the tailstock. This means that with a drill held stationary in the tailstock and the wood spinning in the headstock, the wood will be fed into the drill at an angle that applies a radial side-load as well as a bending moment to the drill. The bending moment is the result of the two centerlines not intersecting which is a high probability. There can be an advantage of drilling from the headstock if the piece of wood is held in place with the the point of the tailstock live center and the wood is then allowed to align with the drill axis by hand holding it. This can be tough to do with large diameter Forstner bits. Watch out for large diameter twist drills that can sometimes self-feed.

However, I would be afraid to use one of those diabolical double ended things because it seems like trouble looking for a place to happen. While it looks like a good idea for getting precision alignment horizontally, what do you do about vertical misalignment (both radial and angular)? Forcing things together is going to put these critical surfaces in a bind and possibly lead to some socket damage. Another concern is that this double ended thing is used at only one specific close position, but then the tailstock and/or headstock must be moved in order to remove this instrument of the Devil and the distance between the headstock and tailstock will not the same for the drilling set up as it is for using the "Devil's alignment tool".

 

[Joe Stajduhar]

Thanks to all for your input.

 

[MichaelMouse]

However, I would be afraid to use one of those diabolical double ended things because it seems like trouble looking for a place to happen. While it looks like a good idea for getting precision alignment horizontally, what do you do about vertical misalignment (both radial and angular)?

It does require some thought and preparation to use the biological impossiblity tool. First, your bed should be free of twist and properly aligned. That's the job of the tabletop and shims as required. Rather than give up on vertical alignment, use shims to make sure the tailstock center begins its trip down the ways properly aligned. It will be good all along if the work done to set up the bed is done properly.

I'm one who is blessed (cursed?) with the old style 3000 tailstock, (mal)adjustable independently of the headstock. Makes for some double fun without the proper tools and preparation. For those who have a fixed tab that rides between the rails, it can be important to make sure that you use a feeler gauge to check for center before tightening. If your casting is good, you might consider a shim or some dimples to touch when you tighten, as I do with the 3000. Only trick is to keep it there! I try to remember to snug the cap screws prior to total removal. Seems to do the job. There are benefits to proper alignment beyond a well-centered bore as well. I use bumper holds from the tail a lot, and good alignment and prep makes sure I don't load the piece asymmetrically. Same is true for the guys who do pens with tapered points to keep the mandrel centered.

 

[John Torchick]

Most interesting and iformative. I tried to make a winding check for a custom rod but had all kinds of problems. First, I turned a tenon on the piece I was using- so far, so good. I tried using a brad point bit (1/4 in.) in the tailstock- vibrated awful. I went to a regular drill bit- OK. I'm drilling at least 4 inches. But when I started to turn to a taper, the hole was off center in regard to the sidewalls of wood. I'll go back and look at my lathe, using some of the info here. Thanks.

 

[john lucas]

John to drill a hole accurately from one end to the other is quite difficult. I do it on my lamps using a lamp auger and it's almost impossible to get it perfect. Lamp augers cut with one side of the bit so they function more like a metal cutting bit to bore holes. Because they only cut with one side they have less tendency to follow the grain. However when you go deeper than about 4" the flex of the bit makes it start to wander.
The best solution for our project is to drill the hole as best you can and then mount the piece between centers using the holes as your centers. I make custom headstock and tailstock pieces out of wood to fit in the holes. this aligns everything from the holes so your turning are perfectly centered.

 

[Vernon Oberle]

Another option you can use with common size bits like 1/4 and 3/8 is to use either a end mill holder with the appropiate taper for your tail stock. It is solid and dosen't have the extra weight of the jacobs chuck. You can also use a collet chuck that fits your tail stock.

Vernon

 

[john lucas]

Why would the weight of the device to hold the drill make a difference. I have mill adaptors, chucks, and collets. The collets are lighter but there's not much difference in the drill chucks and my mill holders. I can't see that weight would make a difference. The collets would require a drawbar to work of course. However I certainly don't know it all and will probably learn something new from this.

 

[MichaelMouse]

Imagine he's really thinking about length of the taper/chuck/bit combination. One degree of angular error carries it more off center the farther you go.

A heavy chuck would make the quill droop if it were loose, too.

 

[Bill Boehme]

The main thing is to have good alignment of the centerlines of both headstock and tailstock. Trying to figure out how much angular misalignment exists is far more difficult than checking position alignment. As MM said, the quill can indeed droop regardless of the weight of the chuck -- it is really the free play that exists between the quill and tailstock bore as well as the fit between quill and lead screw. Drill press quills have keyways that allow a slight amount of preload on the quill to address this issue. Not too many lathe tailstocks have this feature.

Free play (slop) in the fit between the quill and tailstock bore is probably the main reason tht drills and bits chatter when drilling from the tailstock. Smoking and squealing are the result of misalignment between headstock and tailstock plus the slop already mentioned.

Drilling from the headstock is generally better since the drill won't chatter (unless something is really loose in the headstock). The wood can usually be kept from chattering by using hand pressure to stabilize it. Expcting a drill hole to be perfectly concentric with the exterior is expecting too much -- unless the method suggested by John Lucas is used.

 

[hockenbery]

To drill tool handles turned between centers with a spur drive at the butt end of the handle, I put the Jacobs chuck in the headstock and put the spur drive in the tailstock. Holding the handle I tighten the tailstock onto the drill bit. I use a brad point bit let it line up with the center hole left by the tail center.

This lets you drill a straight hole in a long handle parallel with the handle axis.

Generally for accurate holes I prefer drilling before turning.
Just about everyone drills pens before turning, most drill pepper mills before turning.

Al

 

[Vernon Oberle]

Michael is exactly right. If drilling with a jacobs chuck I pull the chuck back into the taper and this helps. A friend of mine had his chuck slip in the taper and the edge of the ring at the back of the chuck sliced his finger open. I just feel that the more compact the drilling rig the easier it is to get it straight. I also make a center spot before drilling. When drilling long pieces like pepper mills or kaleidoscopes it is better to drill from both ends.

Vernon

 

[Jim Keenan]

Google gun drill bit. These are also known as "D" drills. The shape of the point tends to continually force it to center. I found a few on ebay and if I need to drill a deep hole, I use a smaller size of the gun drill to bore a pilot hole ( i can get up to 5 or 6 inches deep) and then can follow up with a long twist drill for the finished size.

 

[John Torchick]

Good info from all! Thanks! I might make a jig to hold the wood and use the drill press. Put it on the mandrel and turn. I'll just remove any wood that doesn't look like an insert.

 

[Barbara Gill]

It has been a long time since I have read a thread with so much good information!

 

[Thomas Stegall]

Tailstock drilling

Having had a previous lathe that lacked alignment I have faced this challenge as well. I start as John Lucas suggested by turning a funnel shapped divit that is shallow but will encourage self-centering when drilling, I also use forstner bits. But recognize that with those types of bits one side will automatically grab before the other side does especiallywhen you advance the bit quickly, so advancing slowly to establish the entry point is important. I also will drill a "pilot whole" with smaller bits when intending on using a large diameter forstner bit it doesn't help with centering, but can reduce the heat etc of stock removal with large forstner bits.

 

[Syd Sellers]

Drill speed

A lot of your problems can be reduced by increasing the speed of your lathe. Get it up to around 4-500 rpm and use a good drill bit with a center point and you are set.