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Forum topic by gljacobs posted 04-04-2011 04:00 AM 1067 views 1 time favorited 23 replies Add to Favorites Watch
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gljacobs

76 posts in 1439 days


04-04-2011 04:00 AM

Topic tags/keywords: turning lathe question

My apologies for another corny topic title…..I can’t help myself.
Anyway onto the meat and taters….

This is a cut and paste of a message about turning I haven’t gotten a reply to so I thought I’d start a topic on it..

I started a new stool project and I’ve got issues.
I’m turning the legs and they’re 20”.
The main issue is excessive chatter….or at least I think it’s chatter.
The chisel will start making a high pitched or a chattering noise and then I stop the lathe and there are these shallow spiral indentations where the high pitched noise happened. Again I don’t even know if this IS chatter, though if it is what are some good ways to avoid it.
As an added bit of info: I didn’t really have this problem before except when doing really thin stuff that was really long. The lathe bed is square steel bars, not cast iron and the housing is too.
I tend to crank down pretty tight on the wood to get the spur centers teeth into the wood, but this hasn’t giving me any issues until now.
Which was my initial guess that
I somehow bent or tweaked the machine to produce this excessive chatter.
I’m dying for some useful advice I can’t figure it out.
Thanks in advance


23 replies so far

View peteg's profile

peteg

3006 posts in 1574 days


#1 posted 04-04-2011 04:42 AM

Hi there, you havent said what thickness you are trying to turn down to ?
Have you “centered” your headstock to the tailstock? (could be out of alignment)
What are you using to cut with, skew? or…
what Speed? too fast can cause “bounce” on very hard/ heart timber
you may have it clamped too tight forcing it to try & buckle?
Are you rubbing the bevel?
Is there any vibration when the lathe is running? ie, before you try & cut
Hard to tell without seeing your set up, these things are all part of the fun of learning & enduce a lot of trial & error, good luck :)))

-- Pete G: If you always do what you always did you'll always get what you always got

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Grandpa

3208 posts in 1427 days


#2 posted 04-04-2011 04:49 AM

Thin turnings tend to chatter. A steady rest would or should help prevent this. It supports the turning in the center while you work on either side then you move it and work that area. They can be bought or made. Some have small wheels to push on the turning. It should be supported in 3 places 120 degrees apart.

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Barbara Gill

153 posts in 1412 days


#3 posted 04-04-2011 05:06 AM

Grandpa is right. Thin turnings tend to flex which will cause the tool to chatter. Do a Google search for steady rest. There are some you can buy and some you can make.

-- Barbara

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Barbara Gill

153 posts in 1412 days


#4 posted 04-04-2011 05:08 AM

Grandpa is right. Thin turnings tend to flex which will cause the tool to chatter. Do a Google search for steady rest. There are some you can buy and some you can make.
Also when the wood gets thin and there is excess pressure between the headstock and tailstock the same thing can happen.

-- Barbara

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bubinga

861 posts in 1419 days


#5 posted 04-04-2011 06:52 AM

You also need to be careful how much pressure you put on thin stock as ,to much will bow the piece

-- E J ------- Always Keep a Firm Grip on Your Tool

View William's profile

William

9287 posts in 1594 days


#6 posted 04-04-2011 12:38 PM

Can we see a photo or link to see the model of lathe you’re using? The reason I think this would be useful is to determine what you mean by square steel bars. Are they solid bars? Or hollow, thin bars?
I have a reason for bringing that point up. My first lathe was from Harbour Freight. I didn’t know at the time and thought it would be a good one for me to test the waters on turning. It had hollow, thin, square tubes. When turning short items, it worked great. When turning long things though, like 20” stool legs for example, you had to crank down hard on the tail stock to get the wood tight enough in there to keep it from flying from the machine (can you say DUCK?). Well when you cranked down on it like that, those thin square would flex, allowing the two centers to move out of line with each other. When this happened, I got the same problem as you’re having, especially towards the center of the project.
It took me a while to figure out what the problem was. I thought one day I noticed some flutter to a piece of stock. So I got it roughed out to a true round dowel. Then I got my sons to help me hold a straight edge across the length of it while I slowly, by hand, turned the dowel in the lathe. It was such a small movement that it was hard to see, but with the tubes flexing, it was allowing the wood to move out of line. If you stop and think about this, which I had to do for a while to figure out what difference this made, this scenerio was allowing my chisels to have varying degrees of pressure against the wood depending on what degree of rotation it was on. The thinner the object, the more I could feel this in my hands while turning. This also created not so smooth turnings, to say the least.
I never did find a way to completely fix the problem. The tailstock adjuster on that lathe broke off in my hands one day before I got that far with it. I have since moved on to a little bit better lathe. I also since turned that old lathe into a disk sander (another long story) and gave it away after acquiring the 12” disk sander on a ShopSmith (another even longer story). Before the break down though, the only thing that did seem to help some though, was to make sure that my cutting tools were kept razor sharp at all times.
Sorry I ramble on so. Back to my original point though. Could we see a photo of the lathe? Or a link to where we can see the lathe model?

-- http://wddsrfinewoodworks.blogspot.com/

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gljacobs

76 posts in 1439 days


#7 posted 04-04-2011 06:12 PM

Thanks for the replies guys.
I’m trying to turn down to 3/8” , but it chatters no matter what diameter, because it’s when I’m peel cutting or parting that the bigger diameters chatter
How do I recenter to align the two stocks?
I’m using a skew mainly and a parting tool sometimes; I don’t get as much or at all sometimes when using a gouge.
My lathe has three speeds: 980, 1430, 2060, 3010 and I usually leave it on 1430.
I always rub the bevel except when I catch.: )
I’m not sure about any vibration when it’s idling because I haven’t checked for any, though it seems that it wouldn’t pass the nickle test. But I’ll check it out.

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gljacobs

76 posts in 1439 days


#8 posted 04-04-2011 06:24 PM

I’ll try to get some pictures up today sometime.
In the mean time though what your describing William seems like the case, not sure though.
I crank it for all it’s worth to set the spurs, turn it on to hear the pitch of the whine and back it off until I don’t hear the whine anymore like demonstrated in Richard Raffin’s video.(the new turning wood).
And like you stated I don’t have any real issues turning short pieces.
Maybe I should try the same sort of deflection test.

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peteg

3006 posts in 1574 days


#9 posted 04-04-2011 09:43 PM

3/8 is very thin over 20” without some added support, have you tried holding your finger behing the cut area, an old leather gardening glove can help reduce the friction burn, Some timbers do not go well down this size, (you havent said what type of timber)

To align your lathe
put a live centre or similar in the tail stock, a spur or similar in the head stock and bring to two together, the two tips should be dead centred if not you are out of align & need to adjust.
you may also have a technique & machineery problem, try using a spindel gouge as opposed toth skew, if you are getting “dig ins” you are lifting the handel too high & the bevel is not in contact. The skew is a tricky tool to understand & master with confidence (lots of practice on old stock)

-- Pete G: If you always do what you always did you'll always get what you always got

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gljacobs

76 posts in 1439 days


#10 posted 04-04-2011 11:14 PM

I should have put in that the 3/8” section is only going to be 5” long.
I’m turning cherry, and I usually stick to turning cherry, walnut, and maple, sometimes oak or mahogany but only when I have the stock.
As for recentering, you mentioned pete how to figure out how to align. How do you adjust….I assume that(for mine) you would loosen the four mounting screws to the motor and realign the centers and then tighten the screws again until both are exactly centered. Let me know if this sounds right.

And as for posting pictures of my set up here they are I am in the basement of my apartment.
You can see in the first and second picture a bigger thicker prototype of my stool leg.
I had to set up the lights and run the wires that took forever just to get enough light down there.
I also have a delta variable speed grinder set up with a higher grit wheel and a buffing wheel with white rouge(thinking I could polish the grind further but it didn’t really work so I use it for other things, I’ill probably set myself up like alan lacer does with an mdf wheel for further honing later on)
In the fourth picture is the tail stock made of cast iron, it’s pretty solid so I don’t see that as a problem.
The other thing I thought of when I was down there is that I have yet to install the lag bolts that hold down the tail stock end of the lathe, though the has never been an issue before so I don’t know if it’s part of the issue now or compounding it some how.
Well there it is let me know what you think.
P.S. I know the piece set up looks rough it was a piece that snapped under duress as I was yelling at it with a skew. : ) just kidding it was the result of quick and unskilled parting, I could have been careful and taken more time, but the conditions under which this ugly result was produced didn’t permit it.
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William

9287 posts in 1594 days


#11 posted 04-05-2011 02:16 PM

The lathe you show in the pictures is a different brand name, but is the exact lathe I described before that I purchased at Harbour Freight. I’ll bet the bed tubes are bowing when you crank down on the stock. I wish I had an answer to the problem. Like I said before though, mine tore up before I found a solution.

-- http://wddsrfinewoodworks.blogspot.com/

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gljacobs

76 posts in 1439 days


#12 posted 04-05-2011 02:56 PM

Well if it does….I’ve always wanted a disc sander. : )

View William's profile

William

9287 posts in 1594 days


#13 posted 04-05-2011 03:11 PM

Mine came with plates for turning bowls and such, not that it had enough power to do so, but it came with them anyway. I screwed a disk of wood to each of them. It had one for the inboard and out board side of the machine. Then I used six inch (I think that was the size if my memory is correct) stick on sanding pads.
If that one is identical, and if it doesn’t have the plates, be sure to check the threads before buying any. Mine had some odd thread pitch that made it almost impossible to find accessories for.

-- http://wddsrfinewoodworks.blogspot.com/

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gljacobs

76 posts in 1439 days


#14 posted 04-05-2011 03:16 PM

Yeah I have a plate and I’ve try my hand at bowl turning, and ya know It’d probably get more use as a disc sander. I hope I don’t have to resort to that though my funds aren’t big enough right now to afford getting a new lathe.

View William's profile

William

9287 posts in 1594 days


#15 posted 04-05-2011 03:25 PM

Well I can tell you how I broke mine and maybe you won’t make the same mistake.
The tailstock mount is made of el-cheapo pot metal. Mine was having a tendancy to move for some reason while turning something that took a long time. The point that I cranked it down on the material tight as hell didn’t help any either, but anyway. Because it would move on me, I had a habit of cranking down hard on the handle that tightens the tail stock assembly to the bed tubes. This is where it broke at. A local machine shop quoted me a price to make a new piece for me, but the quote was about twice what I paid for the entire lathe.
If I had it to do over (and if I was forced at gunpoint to use that lathe again), here’s what I would do as a workaround to fix the problem I had. I would take a file and about every half inch or so, rough up the area on the tubes where the tailstock assembly rides. This would aid in keeping it from moving.
Another idea I had if the lathe had lasted to fix the bowing problem of the tubes involved channel iron or angle iron. I was planning on finding a piece of channel or angle that would ride along the outside of the tubes. It would have to measure to fit the tube but still allow movement of the tailstock assembly. I was going to weld it to the tube to give it extra rigidity.

-- http://wddsrfinewoodworks.blogspot.com/

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