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Thread: Advice needed with wonky lathe
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8th March 2016, 03:57 AM #16GOLD MEMBER
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Peter,
If the bearings sound good, you might want to use one of these:
1/2" Power Twist Plus Link V-Belt - Rockler Woodworking Tools
They are reputed to run smoother than a regular V belt and can be installed without removing the spindle.
You might first try rubbing your existing belt with a rag soaked with rubbing alcohol, giving the running surfaces a rub with 220 grit sand paper, and increasing the tension on the belt.
If a belt has gotten stiff and set from sitting for years, often a 10 minute run at medium speed will warm it enough to make it run smoothly.
It is best not to drive the spindle out. Banging on the shaft may damage the bearings by making dents in the running part with the balls or rollers. Better to pull or press out with a long bolt or timber and long clamps.
Be sure to check for one grub screw under the first one in each hole. When the area on the shaft appears where the grub screw has bitten, sand off the raised ridge. Use lots of penetrating oil on everything.So much timber, so little time.
Paul
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8th March 2016, 03:04 PM #17
Things turned out to be more wonky that I was aware of. I had a look at the shaft opposite the bed of the lathe,
and that runs true, no wobble in it at all. However ...
... up against the bearing there's a recess milled into the shaft that holds a split bush that presses against the bearing.
over the top of that sits yet another bush that holds the split bush in and comprises a register of sorts.
IMG_0810.jpgIMG_0811.jpgIMG_0814.jpg
But, as you can see, that register is nowhere near the faceplate. The faceplate sits up against nothing. That is, what my
friend had done was to put a grindstone in there with a couple of washers (and fat paper disks on the grindstone) so
of course it would be somewhat loony to expect that to be wobble free ... which apparently it was for him, but certainly
not for me.
Even the face of the outer bush is not wobble free as it were. I am at a loss as to how to actually get a register here that
the faceplate (or a chuck) can ride against. There's a huge gap between the bearing and the thread on the spindle.
This is how he had it set up when I got the lathe:
IMG_0815.jpg
Sadly, the register on the other side of the shaft, facing the bed, is no better. It's seriously scarred and looks like it's actually
been attacked with a cold chisel. The MT drive centre is fine, but I can't get a chuck on there either, I think, without taking the
whole thing to an engineer and getting it rebuilt. It does not look like that face can be undone from the shaft at all.
I was very much hoping to be able to mount a chuck on this thing. The lathes bed and housing is in very good nick, very solid,
very heavy, bearings are good, even though it does not have a variable speed motor.
I don't think I do enough turning to warrant replacing it with a midi lathe.
<sigh>
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8th March 2016, 09:14 PM #18
Hi PWH
Not sure of the relative ages of our two lathes or if something is missing from your one but mine has a slightly different arrangement on the outboard end. As you can see from the pic mine has an extended collar that fits over the split bush and goes all the way back to the threads to provide a surface to register against.
Not much help for your problem though I'm afraid.
cheers
WHI don't suffer from stress, but I have been told I'm a carrier
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9th March 2016, 07:09 AM #19
Well yes, actually, that gives me a clue. Presumably my mate has dropped a piece so he could do his thing
with the grindstone. I guess if I go and see an engineer with a metal lathe, something might be done about
this.
thanks -P.
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9th March 2016, 11:21 AM #20
Let me know if you need any more details pics to show the engineer.
cheers
WHI don't suffer from stress, but I have been told I'm a carrier
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9th March 2016, 08:38 PM #21
The insert / chuck design on Nova chucks uses the nose of the spindle thread to register the chuck, so you could true up the spindle nose & use Nova chucks.
Mobyturns
In An Instant Your Life CanChange Forever
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11th March 2016, 12:10 AM #22
That is excellent news, indeed. Thank you for the heads-up.
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11th March 2016, 08:16 PM #23
Peter my response was a little tongue in cheek as a lot of turners use their Nova chucks in that manner and then wonder why they get problems with vibration.
All chucks need to "register" the chuck (or insert) to the spindle to maintain accurate running, so it is important that we protect both the spindle thread and the "registration surface" which is generally a machined flat surface on a wood lathe spindle.
It is true that the inserts on Nova chucks register the nose of the insert thread to the inside face of chuck body at the bottom of the insert thread in the chuck body. Vicmarc inserts register the two flats on the rear face of the chuck body to the boss on the insert. However the rear of both Vicmarc and Nova inserts should reach and be nipped to the "register" on the lathe spindle.
Problems arise when the spindle nose thread is longer than the depth of thread in the insert which means the nose of the spindle binds to the bottom of the insert/chuck thread before the registration surfaces actually meet. Nova inserts and more so their direct threaded chucks have a relatively short thread which means they are quite often used incorrectly - which is what I was having a little dig about.
Nova / Teknatool actually advise turners to check this in their manuals and if necessary have an accurate spacer machined so that the chuck registers to the spindle register via the spacer.Mobyturns
In An Instant Your Life CanChange Forever
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14th March 2016, 09:47 AM #24
Right, and a good dig it was, too ) Thanks for taking the time
We'll just have to see. My wife made the pertinent comment "And what are you going to do with all those bowls?"
and she's not at all off the mark: there are a LOT of woodturners in these parts and I would be doing it casually at
best, I have more passion for designing and building furniture - my attempts at turning are more in the way of my
usual "I want to get a handle on how that works" diversions.
So I'll give this a little rest ... getting a sleeve machined that can be a good register for a chuck should not be too
much of a problem on the bed side of the lathe. The outboard side is a mite suspect.
-P.
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