Anybody ever do a "tune up" on a Morse taper?

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Russknan

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I've been trying to find a solution to runout on the Morse taper of the drive spindle on a used Nova DVR XP that I bought. Sending it to Teknatool would be too expensive (>$200 shipping alone), and their "standard" for runout inside the spindle is "<.005". Not good enough for pen turning. I've cleaned the taper with the "green thingy" and scrubby pad material. No help. I'm also looking at other work-arounds since the outside of the spindle is dead on. My plans are to: 1. Wrap self-adhesive sandpaper around one side of the double-ended taper ("Acculine"?) that Teknatool sells for aligning headstock and tailstock, chuck one end in the tailstock and bring the two together. Gently rotate the spindle by hand and see what happens. If that fails, 2. Buy a Morse taper reamer, chuck it into a Jacobs chuck in the tailstock, and gently rotate by hand again. 3. Try to find someone to make an insert for my Nova chuck, like the worm screw insert, but longer, and with a 60 degree taper to use as a dead drive. Experiences? Recommendations? Russ
 
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Why fight a taper that wasn't designed to meet your needs? Outside is dead on? Use that to your advantage by using a collect chuck. There is no need to use the morse taper on the head stock for pen turning.

Ed
 
We forget that we are using tools designed for wood working. General woodwork does not require the tolerances we like in pen making. If the taper itself is out, you will not be able to straighten it out without it being re-machined. There is not enough rigidity to try to re-ream it on the lathe itself.
 
Russ, how far off is it?
The reason I ask is because mine is out about .004"
What I have done is found the 'sweet spot' on the live center where the runout is only about .002". Yes, even a good live center can be off a little. For me, I can deal with that. Often I can turn blanks that show just that amount of difference one side from the other.
The process involves repeatedly rotating the center until the runout is at the least and then file a mark in the spindle and the center.
 
Dale Allen said:
Russ, how far off is it?
The reason I ask is because mine is out about .004"
What I have done is found the 'sweet spot' on the live center where the runout is only about .002". Yes, even a good live center can be off a little. For me, I can deal with that. Often I can turn blanks that show just that amount of difference one side from the other.
The process involves repeatedly rotating the center until the runout is at the least and then file a mark in the spindle and the center.
Click to expand...

Thanks, Dale. My good friend, John Goodin (Johnny CNC) introduced me to that concept. As a result, I've found that, oriented as you suggest, one of my two dead centers can get the runout down to about .006-.007. Still dreaming of being able to use regular Morse taper accessories. I'll fiddle, but am guessing that the collet chuck or insert for my regular chuck will be the best I can come up with. Russ

Thanks to all for your suggestions. I'm truly grateful. Russ
 
That's a bummer Russ.
Any chance of getting a replacement headstock spindle or is that thing all part of the motor armature?
Also, I know you said the outside of the spindle is dead on but I'd also check the bearings and make sure there is no side-to-side play.
 
DVR XP

Russ,
I have the same unit and normally work with the collets when doing pens.
I never noticed significant run out on the machine when doing pens.
How did you check the IR on the outside of the spindle, before checking the MT dead center?
.005 + sounds a bit high, but I have never checked my DVR XP for IR, but it may be this or more.

I will put the collet on the spindle and check the outside of it for IR, then put the MT dead center on and check it and will post results.

For TBC work have you checked your alignment for HS to TS using a razor blade?
With 2 good centers in TS and HS, move the TS near the HS and lock the TS down, get a razor blade put it in between the tips of the centers, screw the TS until it is snug and holds the razor blade, is the blade perpendicular in all planes, on a wood lathe most likely it will be askew hopefully only slightly. This indicates that the centers are not true.
There are few options for alignment between HS and TS on most wood lathes for TBC.

Regards,
RR
 
DVR XP

Russ,
I have the same unit and normally work with the collets when doing pens.
I never noticed significant run out on the machine when doing pens.
How did you check the IR on the outside of the spindle, before checking the MT dead center?
.005 + sounds a bit high, but I have never checked my DVR XP for IR, but it may be this or more.

I will put the collet on the spindle and check the outside of it for IR, then put the MT dead center on and check it and will post results.

For TBC work have you checked your alignment for HS to TS using a razor blade?
With 2 good centers in TS and HS, move the TS near the HS and lock the TS down, get a razor blade put it in between the tips of the centers, screw the TS until it is snug and holds the razor blade, is the blade perpendicular in all planes, on a wood lathe most likely it will be askew hopefully only slightly. This indicates that the centers are not true.
There are few options for alignment between HS and TS on most wood lathes for TBC.

Regards,
RR
 
Thanks for all the responses, Folks. Couple things. Paul, are you suggesting that, in general, one cannot expect a full size lathe to have the accuracy needed to turn pens, and that one should consider a mini lathe just for this purpose? I've only been turning for about a year and a half, so don't know these things.

Next, RR, thanks for taking on the measuring task. I'm very curious to see what you get. I measured mine by using a post made by Rick Herrell (rherrell here on IAP). It's great, and has a stop so you just drop it into the hole for your tool rest. I had an indicator dial already which attached to the post by a hex screw. Just poked the tip to the left of the threads to measure the outside runout (well <.001) and then inside the spindle where there was considerable variation in spots. At least .003. The drive center that I got with the lathe from the previous owner has a marked band of radial scratches, so I'm guessing that that has at least contributed to the problem.

So, yesterday, I attached a Beall 1/4" collet, and then took the almost-new mandrel that came with my recently-purchased PSI adjustable mandrel system (with the Tommy bars). Paired it with the "mandrel saver" for the tailstock. Measuring just in front of the collet, I got about .0035 runout.

Trying to think outside the box - something I'm not particularly good at, unfortunately - I'm wondering whether it would be worthwhile to buy an extra worm screw insert for my Nova chuck, then try to find a machinist who could modify it from screw to dead drive with a 60 degree tip. All suggestions/warnings/etc. are most welcome. Russ
 
Russ - It's not the size of the lathe that determines precision / accuracy. Making tools accurate / precise costs money and takes skilled workers. Woodworking tools do not need the same level of accuracy / precision as metal working tools and most manufacturers of wood lathes do not try to build to metal lathe specs. But a really well built wood lathe ($$$$$) can be much more accurate / precise than a poorly designed / built metal lathe. Just speaking to wood lathes, some brands are designed / built better than others. Most are perfectly adequate for making wooden objects that tend to change shape and size with changes in the weather. Some are not adequate for precision pen making, but adequacy won't be correlated to size.

Since you have a collet chuck, all you need is a steel rod with a 60 degree point ground / machined on it to mount in your chuck for turning between centers. One of your friends with a metal lathe could make one for you in a couple of minutes. It will last longer if you heat treat it, but it's not absolutely necessary.

Ed
 
Russknan said:
...Trying to think outside the box - something I'm not particularly good at, unfortunately - I'm wondering whether it would be worthwhile to buy an extra worm screw insert for my Nova chuck, then try to find a machinist who could modify it from screw to dead drive with a 60 degree tip. All suggestions/warnings/etc. are most welcome. Russ
Click to expand...
Hi Russ, I did something similar to this but I use it in my collet chuck using the 5/8" collet. I have a small metal lathe and turned a short piece of 5/8" cold-roll to a 60* point. When I need to drive TBC bushings I simply chuck it up into my collet chuck and go. When done I then remove it and install my 5/8" drive and tapered finishing bushings into the same collet.

Edit: Looks like Ed and I were on the same wave length, he just beat me to the punch. ;-)
 
Last edited:
Russ -- the value of turning between centers is that there some flex at the joints. Does not take much to make a few thousands work. The comparison to the universal joints on a drive shaft comes to mind.

Turing between centers is more sensitive to making sure the joints between the pen barrel and the bushings are an excellent match.

By the way -- be super sure that the MTs on the lathe are super clean and free of any debris. Small amounts of debris can result in missed fits and those kinds of numbers.
 
Russ,
IR on outside of spindle using a thread adapter for a smooth surface - .0015
IR using new MT2 dead center - .0007

If Turning Between Centers, the more critical issue would be the alignment of headstock and tailstock.
I pivot my headstock often to turn bowls and its easy to get off center with the tailstock when moving the headstock back to 0 degrees, try not to overtighten he headstock.

RR
 
Like Ed said, it's not the size that gives the accuracy. As we have gotten more precise in our pen turning we expect the same from the equipment we use and it was not designed for that close tolerance work in the way we use it.
 
Try a couple different centers to see if the runout is the same and make sure the runout is in the Morse taper bore.

Then use some Dykem or similar layout fluid on the center and check for any high spots inside the bore by pushing it in not quite tightly then rotating it very slightly while just tight enough to abrade the dykem off on any high spot.

The front end is subject to dings and these -if on the outer end- can be removed by a deburring tool. Any high spot further in can usually be worked out with a Morse taper reamer turned gently by hand or by lapping (which mates that center and the bore perfectly but leaves you in the position of using only that center in the future).

A Morse taper reamer can actually re cut and realign the taper bore, but you would need to use a very rigid and large machine to do it (either lathe or mill), I doubt it could be done by hand. A machine shop could probably easily correct it at a reasonable price if you want to use that spindle and not replace it with a new one - and that will probably be a more precise alignment than a new one as well.
 
Again, thanks to all the knowledgeable people who've tried to help me out. It looks like my future will be with using the collet chucks in various ways. I'll still play with the Morse taper and sandpaper to see what happens. And maybe I'll try to find a local machinist to consult. RR, thanks for taking the time to measure the tolerances on your lathe. Boy, am I jealous! The depth and breadth of knowledge here continues to astound me. Gratefully, Russ
 
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