I was making a tool handle, turning it between centers using a spur drive and live center on a Nova DVR lathe. I needed to drill a hole in the handle at the live center end to accept a quick release coupling I was about to install. I used a forstner drill bit in the tail stock to drill the hole, using the live center indent as the reference point for the forstner bit center. Had to apply a little pressure with the tail stock to the whole assembly before turning the lathe on to keep it all together. The live center hole, however, was slightly larger than the center point of the Forstner bit. When I started the lathe, the bit went slightly off center, and as a result so is the hole - it is not concentric with the long axis of the tool handle. It is not a big deal, but I was wondering how I would go about this in the future to prevent this from happening again. One could always drill the hole first before even starting to turn the handle, I guess, but I thought there would be someway to do this on the lathe. Any ideas appreciated (I have to make another one soon).
I usually will drill the hole BEFORE turning the handle, then everything is centered. You can either drill the hole on a drill press or mount the drill bit into chuck on headstock and drill hole in piece first.
Just use a "Cone" on the tail center that will fit in the hole. I've made serveral different size cones that screw onto my tailcenter. 3/4 x 16 TPI I believe.
You've answered your own question. If you want the hole to be centered perfectly, drill the hole in the piece first, then use a cone center in the tailstock to keep it that way.
I also have a Teknatool NOVA lathe, mine is a DVR XP.
I have also struggled with drilling items on the DVR XP. Like you, my holes are normally larger than the diameter of the bit, due to the bit not being exactly on centre, or the tailstock not being exactly parallel to the lathe bed.
Last year I purchased a metal lathe, so now I have a good comparison. My metal lathe tailstock is parallel to the lathe bed and I can drill down the centre of the work.
In my opinion the NOVA design is flawed.
My first experience was rotating the headstock and then foolishly trusting the detent to have returned it back to 0. I now know better.
I have calibrated my headstock-tailstock alignment using a bar I machined on the metal lathe.
Next issue is that the tailstock design or manufacture on my DVR XP is not possible to be held aligned to the lathe bed. There are two blocks of steel under the tailstock. These blocks are screwed under the tailstock at right angles to the lathe bed. The blocks are about 1/16in narrower than the distance between the bed ways. Hence I can adjust the block to register on one side of the lathe bed, but not both. I end up having to pull the tailstock against the lathe bed rail closest to me to get the "best" registration.
To compound the bad design, the cast iron or cast steel pads which engage via the banjo or tailstock locking lever are not machined so they make intermittent and inconsistent contact with the machined underside of the lathe bed rails. I cannot believe Teknatool uses cast items without having the registration edges machined. I had a machinist friend fix my blocks. We had to take about 50 or 60 thou off to get the sides of the blocks to be consistent.
If I do drill on the DVR XP, I have to accept my holes will not be accurate, so either this is good enough or I have to correct on the metal lathe.
I hope you are able to correct your NOVA lathe to work better than mine does when drilling.
Thanks for all the feedback. Was hoping I could do this on the lathe, but looks like I'll have to drill before turning. Interesting information on the tailstock and associated registration design. I have never looked at this before, but you have raised some good points that I will have to investigate.
Some random thoughts about what I've learned about drilling on the lathe (in addition to drilling the blank before turning already mentioned)...
The tailstock and headstock should meet at exactly the same point when you slide them together with points in each. Some horizontal alignment can usually be fixed by raising one leg with a shim or adjustment which will twist most lathe beds a surprising amount.
A bit needs to get started right or it may never drill straight. I like to drill a starter hole with a Center Drill, used by machinists. They are cheap, short and sturdy, and will not flex: https://www.amazon.com/gp/product/B004MOJVKU
Be sure the morse taper holding the jacobs chuck is clean and no scratches or nicks. The jacobs chuck needs to be precise. Test the jacobs chuck by holding a piece of harded drill rod and turning in the headstock slowly and look for any wobble (better, use a dial or dial test indicator).
For a larger hole, I sometimes drill a short smaller hole first. This might not work so well for a forstner bit.
I also like to use taper drills which fit right into the tailstock morse taper (or with a sleeve adapter for smaller bits). This shortens the distance from the tailstock to the wood for less chance of play/misalignment.
For short precision small diameter holes, shorter and therefore stiffer bits are available: Screw Machine bits. These are especially good for small diameters since they are not as flexible.
Another thing I do when I need to make a deep hole that needs to be parallel to the turning, best done with larger twist bit sizes, say a 3/8" hole in a 1-1/4" blank:
1) drill the blank first as mentioned, then
2) use the drill bit as a mandrel in a jacobs chuck in the headstock,
3) bring up the tailstock and turn that end round, then
4) swap ends and mount the rounded end into a regular scroll chuck.
5) I hold the end with the open hole with the tailstock either with a cone center or turn a little wooden plug to fit if I'm making a bunch of similar pieces. Tighten the scroll chuck AFTER centering the hole with the tailstock.
A deep hole will sometimes follow the grain if it's at an angle. To fight this, I try to start the hole right then drill at a higher speed but in very short increments, backing out to clear the dust often. I'm not sure exactly what is going on but it seems to work better.
BTW, I also use the drill-bit-as-mandrel method for cleaning up the end of something like a handle after parting it off.
As for forstner bits, I did run into one poorly made with the point a little off center. I had to drill a small clearance hole in the center with something else so the point didn't throw things off. My favorite forstner bits are a set of carbide bits.
Interesting Dave. I also have the DVR XP. It is one of the first of the XP models and it is dead on when aligned. I also use a double-ended taper to make the alignment and have never had a problem. I will check to see if mine is different than what you describe - which it must be since it works.
Ditto what Jim and Bill said. Nova DVR XP and no problem with drilled holes. Like Jim, I use a double ended taper to align the headstock and tailstock.
Just because the points align on the headstock and tailstock doesnt mean the two are aligned and will drill a straight hole. They could be off horizonally or verticaly. Imagine if you had both headstock and tailstock swung so that the headstock pointed at 4 oclock and the tailstock pointed at 8 oclock. If you slidr them together the points would still meet but obviously you cant drill a straight hole.
I found this out by jury rigging my laser bore sight to a 2 morse taper. I put in the heastock and 30" away when rotated it forms a small circle around the tailstock live center. Its about a 3/16 ircle so its not off far but its not dead on. Put it in the tailstock and it traces about a 1/4 circle on he headstock drive center. So both of mine are off just a little. The points align perfectly when you push the 2 together. For 99% of what i do on the lathe it doesnt matter
I just put a dial indicator on the tip of my live centre.
With the tailstock tightened, the quill has 20 thou movement if not tightened.
With the quill tightened but the tailstock not tight, the tailstock has 20 thou movement.
With both not tight, I have 30 thou movement.
This may not sound like much, but it impacts my ability to get concentric holes when drilling on the lathe. The deeper the hole, the greater the issue.
I have a local friend with the same DVR XP purchased 1 year later than mine. This friend has the same tailstock and quill sloppy fit issues. A member of the local turning club has a DVR XP and commented he has the same issue of sloppy tailstock and quill.
I have to partially tighten the quill to reduce the quill slop but still allow me to move the tailstock.
I took this picture after I had the locking block. The bottom edge still shows some of the original casting. I did not want to remove any more metal.
It is good if others do not experience these issues.
The new NOVA Galaxi lathe uses thick round machined pieces of steel for the locking plate. I have seen these used on other lathes. I have not seen the underside of the tailstock to see the design of the registration with the lathe bed ways.
Thanks for all the additional info. Drilling first seems to be the best option. Any attempt to drill a hole on something mounted between a spur drive and the drill bit, I guess, will always introduce the risk of the drill bit "walking" until it bites. I used the forstner bit to minimize that, but didn't take enough care to see if the bit was properly seated so it wouldn't "walk" (however small). It really hasn't affected the performance of the handle and quick coupling I installed, but it is always nice when something goes the way one hopes or expects.
