Years ago I purchased an old Walker Turner wood lathe. The main shaft was damaged, so I had a machinist make a new one.
Somehow, either the Morse taper or the shaft itself got screwed up. The point of a drive spur describes a circle of about 1/8 inch as it goes around. It’s not a defect with the spur, as I tried several and they all do the same thing.
I sold the lathe but now have the opportunity to buy it back. I know the obvious answer would be get another shaft made. But how much will this discrepancy affect the work if I don’t? I haven’t turned in a long while and can’t think my way through this…
Zolton
Replies
I think it depends on whether you want oval turnings or not. Might be valuable if you make furniture reproductions--mount the wood right and you might make some people think it was old because the wood shrunk out of round.
Seriously, if the eccentricity was related in anyway to why you sold the lathe originally, then I would certainly buy it back. I'd also have a new shaft made. But, use a different machinist, a taper that far off suggests pretty shoddy work, I'd think.
A bit of a mind bender to think about.
In fact, an off center taper will still allow you to turn as though the center was concentric. The circular perimeter of the finished piece will just not be centered on the hole made by the drive spur.
I'm sure I'm going to get some arguments on this one.
John White, Shop Manager, Fine Woodworking Magazine
John,
Thank you for your reply. Your answer got into what I kind of didn't understand about the issue. I'm still trying to think it through.
There is a "center point" to the spur - it's just located in the center of the circle it is producing when it spins around. It's not at the "traditional" center point - the center of the spur.
At any rate, it's certainly not an ideal situation. And if I do buy the lathe back I'll look into getting a new shaft made, unless I find I can live with it the way it is.
Thanks again, Zolton
Yes the turning will still have a true center point, though not at the intersction of the spurs, and the turned piece will be round, not oval. Picture using screws to attach the wood to a face plate, the screws could be anywhere, with none of them at the true center, but the resulting turning would still be round.
John W.
Yup, I see it now. Round.
My first thought was exactly the same, the turnings would be oval, I even started to write up an answer to that effect. It is surprisingly difficult to envision.
John W.
Isn't there some sort of problem that comes with having such eccentricity? There ought to be some performance penalty for such sloppy machining.
There are a few minor problems with recentering a piece that was removed from the lathe, or turned on another lathe, and marking the "centers" on ends of new pieces so they run reasonably true when first installed, but woodturning lathes are surprisingly tolerant of all sorts of misalignments.
John W.
John,
The biggest problem will be in putting a Morse tapered chuck/drill bit in the offcenter hole and trying to drill a hole in the end of a piece of stock. It makes for a wobbly experience...
Ray
It's definitely not bad bearings. I checked that, hoping that what I wound up with wasn't what I feared...
When I last owned the lathe I could take the shaft in my hands and shake it all around and it never moved. Also, the bearings would have to be really, really bad to produce this much out-of-centeredness. The bearings are solid and tight. I replaced them at the same time I had the shaft made. It's definitely a bad machining job.
John raised a good point about removing a turning from the spur center and then remounting it. You'd have to mark it so it went back the same way or it wouldn't run true.
All in all, it gives me pause about whether or not I want to get involved with this lathe again. Sometimes it seems as though simply writing a check for something new makes things so easy. The only issues then (most of the time!) are removing cosmoline and setting it up.
Thanks for all your replies.. Zolton
I see a big time problems if you get into turning pens, especially with the 7mm series. There is only minimal material on the brass tube with them and the tube HAS to be dead center for kit to fit properly. I too have a Walker-Turner which I restored to like new and it serves me well, But it's not a monster Powermatic, Some day. ;-)
Are we sure it's not the bearings ? Have you put a dial indicator on the OD of the shaft and then on the ID of the morse taper, leaving no stone unturned !
Work Safe, Count to 10 when your done for the day !!
Bruce S.
Edited 5/24/2007 10:01 am ET by BruceS
That is a helluvalot for the taper to have been misturned, and difficult to understand how any machinist could be out by that amount. Sounds daft, but have you checked that the drive centre is fully home in the spindle? Or that there is no "foreign body" in the spindle, especially at the end, which is pushing/preventing the drive from going in fully and straight? (sometimes people put things into tapers and then can';t get them out).Check it out with a strong light.
Can't be the bearings , at that amount, or the balls would have fallen out long ago.....
Philip,
I tried several different spur centers and they all did the same thing. Wiped the taper out with a rag each time, though I didn't examine the inside with a light. But each seated properly.
Though it was a few years ago, I seem to recall that the guy said he machined it using a four jaw chuck and not between centers. I'm over my head in trying to explain it, as I'm certainly not a metalworker. But I think that's what he said.
At the time I didn't think anything of it, but since then, thinking about it, that seems as though that could have been the problem. The good thing is that he only charged me about $40. Of course it didn't fix the lathe though. I suspect a new shaft - machined properly - will run quite a bit more than that these days.
At the end of the day I'm not sure if I really want to get into this project again. As I said in an earlier post, buying a new lathe, or a used one that is already right to begin with, sounds more like the direction I want to head. Thanks for your comments.
Zolton
Walker Turner tools are popular with collectors, you can probably get a good price for the lathe even with the spindle problem, since there would still be a lot of good parts to salvage.
John W.
Buy a replacement spindle from any lathe manufacturerthat uses the same spindle .I built a lathe and bought the headstock and tailstock spindles from Grizzly .Cost under $40.00 for both of them if I recall, four years ago.
mike
Good idea, except the only mfgr that used that spindle was Walker Turner, and W-T's been gone a long time. It's not like nowadays where many different offshore machines have interchangeable parts.Pete
As John Said, there are collectors. If you decide to scrap it out for parts. I'am interested in the spindle pully ;-) I had to replace mine with a non-indexing sheave as the previous owner used the indexing holes for a spindle lock to remove face plates. He was a real Hammer mechanic. But personally, I would have a new spindle made if I were you.
Work Safe, Count to 10 when your done for the day !!
Bruce S.
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