Recently, I inherited a lathe from my father with the intent of using it to make
various parts for windsor chairs. It is approxmatley 30 years old and was made
by Delta/Rockwell (Model 46-111). The lathe sits on a seemingly sturdy
sheet metal stand and has four speeds ranging from 990 to 3250 which are manually
adjusted via belts/pulleys.
While I can’t complain about the price (free) I have considerable vibration when
turning chair legs or stretchers that exceed 16 inches or so in length.
Particularly in the middle section of the piece. This vibration causes spiral
gouges that can only be removed with considerable sanding. I have even had to
resort to using a file on occasion. Here is what I have done so far to reduce
the spiraling effect with little or no success.
1. Tried different woods, maple (hard and soft), cherry and pine
2. Mounted the motor to the wall (was previously on a hinged hanging bracket
attached to the stand)
3. New belt.
4. New drive center and live tail center.
5. Bolted stand to the concrete floor
6. Added 500 pounds of sand to stand
7. Checked and rechecked bearings (no apparent play at all)
8. Made sure all turning tools are SHARP and using proper technique. 9. Tried different rpms and usually turn on the slowest speed. Faster rpms result in a tightening of the pattern
What am I missing…
Replies
I'm wondering if the undesirable spiral that you are experiencing is the result of nasty harmonics that you haven't tamed yet. You might want to check your tailstock pressure first loosening it slightly to see if the relaxed tension on the spindle helps it to oscillate less. Too much tailstock pressure can cause the turning to do this. I experienced this on a jet mini lathe I was practicing on in an introductory wood turning class I was taking last year. The instructor recognized the spiral effect, made some adjustments for me, handed me a quality spindle gouge and when I went back to work things smoothed out considerably. You might want to make sure you are using a tool steel spindle gouge ground correctly. Don't skimp and use low carbon steel turning tools.
I'm a beginner myself. It sounds like you've done a lot to deaden vibration already so that's why I'm theorizing its tailstock pressure and tool quality and technique. Make sure to use the bevel rubbing technique ( not a scraping action)
Good Luck!
Sprocket,
Thanks for the prompt repsonse. I'm using good quality turning tools from Sorby and frequently play around with the tailstock pressure. My initial thought was tailstock pressure because the spiraling usually occurs in the middle of the piece. My thinking was perhaps the pressure was causing the piece to "bow" as material is removed. No luck. I'm certainly no expert on the lathe but believe I am making a pretty nice shearing cut. On shorter pieces using a skew I have very little sanding to do. I get pretty nice (almost glasslike) beads with a skew.
Termites,
Just curious....you said it happens when the stock exceeds 16"... does that mean everything is fine at 12" and 14" stock? If it is wouldn't that imply a bent base or perhaps something causing the tail stock to be out of alignment? Where did you leave your bubble gum when you were a kid???....lol
I just moved the tail stock up against the headstock and checked the alignment. Because there is no self-alignment mechanism built into the tailstock, the alignment can be off by as much as 1/16" or dead-on depending on what position the tail stock is in when it is locked down. Futhermore I took some measurements of the lathe bed a various locations, measuring width and thickness w/ a micrometer. Way off, as much as .052" in some places. Not sure how to determine the straightness of the bed but undoubtedly it is not what it should be. Hence the problem with longer pieces of work. Thanks for all your help guys. I guess I got a lathe worth what I paid... Nothing! Guess I'll start reading the discussion threads on buying a new lathe...
Have you checked that the head and tail pieces are aligned correctly? I have an older lathe where the tail piece can get twisted out of line with the head piece, which causes similar problems when turning long spindles.
Reducing lathe speed might help, but I'm no turning expert.
Good luck,
Paul
Paul,
Other than pushing the tailstock up against the headstock and lining things up by eye, is there a method or process to do this with accuracy? This is something I have not yet checked...
Try reducing the diameter starting at the tailstock end and work towards the headstock.Secondly support the wood with the left hand directly behind the action whilst cutting.Maybe this will help you
Sounds like you're getting some whipping action from centrifugal force and being slightly out of line.
You might look into getting a steady rest (basically a pair of wheels mounted on a C that is placed in the middle of your spindle).
Turning at a lower rpm may help somewhat, as may sharpening tools more often. A dull edge can cause harmonic chatter.
Good luck.
Q: How do you know when a politician is lying?
A: His lips are moving.
termites,
I don't think your problem is with head and tail stock alignment. You didn't mention the diameter of the stock you are turning, but it sounds to me like you're getting some whipping with the longer pieces. It's surprising how easily this will occur with stock less than 2" diameter, especially when you've got a really skinny element in the turning.
My experience has been to try to turn at the fastest rpm you can. Use only enough tailstock pressure to keep the stock snug. Lube the tailstock center, or use a ball bearing tail center. Sharp tools, and cut with the bevel of the tool rubbing, rather than scrape. Try to turn the larger diameter elements first, the smallest ones last.
A steady rest will do the most good. Couple of ball bearings mounted on a stout stand that can be mounted to the bed ways. Turn the stock round somewhere in the middle of its lenght, to its largest diameter. Take the lightest cuts you can, to minimise the whipping. Then push the steady rest up to the section you've turned, and lock it down. Then finish roughing out the square, and turn to shape.
Regards,
Ray
Termites,
As Joinerswork mentioned the bevel should rub but I will add one caveat to that, don't apply too much pressure with the bevel. This will push the spindle out of alignment and cause whip.
Good Luck,
Tom
Edited 11/18/2004 10:44 am ET by TCALISTO
If the bevel rubs, as is often mentioned in the turning literature, then where is the clearance angle. No tool of any kind can cut without a clearance angle. In fact one starts with the bevel rubbing, then gently raises the tool until it begins to cut. Now there is a clearance angle and the bevel is no longer rubbing.
another Tom
termites ,
I would agree with Leon and joinerswork, a steadyrest willprevent spiral and the whipping action and allow you to make much smoother and cleaner cuts. Sanding and clean up will still be needed . The steady rest itself can leave some marks on the turningalso , but the advantage will out weigh the cleanup. The day I turned my very first Windsor spindle is when I realized I needed a steady rest. I sent off for a picture and info for a steady rest and ended up fashioning one out of wood and some bearings , washers and a few nuts and bolts. I believe this will totally solve the problems you are encountering .
good luck dusty
Try turning the same thing on another lathe. If you have the same results, then it is you, or rather your technique, and not the lathe.
Without a steady-rest, if you have your gloved hand wrapped around the work and use your thumb to help guide the tool, you can sort off squeeze the blade into the work from an equal pressure from the back side. This is a good way to dampen vibration without taking the time needed to set up a SR.
Edited 11/18/2004 7:30 pm ET by rootburl
Are you just experiencing the normal flexing of the wood under the force of the cutting edge? Even a three inch diameter maple 3 feet long will flex a lot. There are several answers to that, if that is the problem: have you tried a steady rest? Take lighter cuts, rest your hand on the work-piece ( sounds scarey).
Using a steady rest made from wheels from in-line skates I was abale to turn rods or the back of a Windsor chair 30" x 3/8". It was slow.
The kind of "chatter" that I speak of is an inherent problem in spindle turning.
Tom
Termites -
My lathe head and tail stock spindles are as close to being perfectly aligned as my tired ol' eyes can detect but I will still get the kind of spiral 'chatter' problem you're getting. It's due mostly to the flexing of the work piece as many folks have pointed out.
The steady rest is an OK way to go and worth the effort to make one but I'll second the technique of using the fingers on the *back* side of the work to counter the thrust of the tool and thus minimize or even eliminate the deflection. It's important to note that you wrap your fingers *under* the tool rest and reach up from behind the work. The piece is thus turning in the same direction as your fingers are pointing so's to avoid having the piece turning 'into' your hand or fingers. If you find your fingers or hand get too hot from the friction then you're pushing too hard with both the tool and your back-up hand. I've turned crochet hooks to less than an 1/8" diameter (not 16" long of course! -hehe) using this approach and it works. In the long run, though if you have lots and lots of spindles to do then a steady rest is a good investment of time and $$. They're not that hard to make. I made mine using in-line skate wheels as another response mentioned. Don't use ordinary roller skate wheels - they're too wide. Bite the bullet and get some decent ones - they'll last longer at the higher revs.
From Beautiful Skagit Co. Wa.
Dennis
Your spindle is Whipping - Its looks like a Barber Pole
I have turned a few chair parts - some were 1 1/4 dia. X 42 in. post, what you need is to speed it up move the belt to the next pulley. Sharp tools light cuts - I use a home made steady rest on the long post. I use my left hand behind the turning and move along with the chisel.
Spinning it faster makes it more ridged - Don't over do it on the speed I learned the hard way turning some long 1 1/4 Hickory post, I took it up 3 steps on the pulley when my skew hit some wild grain it shot up out of the lathe . That's when I stopped and made the steady rest .
I use 3 skate wheels to trap the spindle so it can not come out - I have seen several plans on the net. like the one I made.
Ron
Thanks to all who have responded to this thread thus far. Today being Saturday I'll have the opportunity to try out some of the suggestions/techniques made thus far. I've seen videos of people putting their hands on the work to steady it but perhaps have been a little overly cautious and not tried that technique myself. I'll keep you posted. Thanks again
Termites -Obviously you want to have it turne down to a cylinder before you try the hand stablizing thing!...........
From Beautiful Skagit Co. Wa.
Dennis
Had the same problem on a chair leg (mahogany) recently and sought advice. Sharp tools and bevel angle helped, but the trick seemed to be posture and the resulting 'stiffness' of my hands. The bevel rides on the surface of the last pass, therefor and excess pressure is likely to duplicate the spiral or chatter on each pass. So, loosen up and relax the grip. This will aslo reduce the consequence of a catch with a skew. I removed most of the spiral with a very sharp scraper to get a start on the improved technique.
IMHO, alignment of head and tailstock in spindle turning of reasonable length is unlikely to be a cause - 2 points make a line. It is possible that lack on concentricity in the headstock will be a problem - check the drive spur is seated cleanly and the centrpoint is actually turning in the centre.
I experimented over the weekend with supporting the work with one hand and had limited success. I also sharpened my tools... It continues to amaze me that a sharp tool and a light touch can cause such vibration. The resulting spiral effect is really quite remarkable.
I have yet to try a steady rest and it sounds as though that might be the way to go. I also have investigated enrolling in a class on woodturning through our local Woodcraft Store. Hopefully that combination will identify the problem and minmize my difficulties. Thanks again
Not to make light of the issue, but have you considered practicing this technique and marketing as a 'unique spiral effects'.
Hope the course goes well - would love to have the time and access one day.
Termites -Just so you don't feel like you're in this situation all alone....!I've been turning some bread knife projects that involve a 20" long spindle piece made up of a 9/16" thick by 1 5/8" wide by 20" long core with 9/16" thick x 1 5/8 x 7" laminations on drive end that get turned down for the handle. The least diameter of the handle is 3/4" and occurs about 5" from the headstock end.After roughing down the handle to a cylinder 1 1/4" in diameter I begin tapering the handle down. When I get almost to the target diameter I begin to get harmonic vibration, which is, I'm pretty sure, what you're experiencing.I've been able to eliminate or pretty much minimize the vibration using the 'hand behind the tool' approach, sharpening the tool beyond scary, and taking such lite cuts the shavings are practically transparent. I also use the skew for the finishing cuts on the broadest more gradual inside curve as the handle sweeps forward. The skew will produce vibrations as well but seems easier to control them. I also get better results by sharpening my spindle gouges almost to a point. This results in taking an extremely light cut and not putting nearly as much pressure on the wood from the cutting edge.Your would benefit greatly from a steady rest.
...........
From Beautiful Skagit Co. Wa.
Dennis
I too am a chair maker ( hobby only) and I was out in my shop today putting the finishing touches to the components needed to make two fan back windsor childs chairs. The fan back has the long supporting spindles on the sides of the back. since these are long (22" overall), even in a childs chair and being scaled, diameter wise down for the size of the chair, the vibration problem is more pronounced. What I do in this situation is pay close attention to the "thicks and thins" I wait to the last to pare the thin parts down to dimension and use very small cuts to do it. When you have a lot of meat on the billet you can take a monster cut and not be bothered too much by the vibes. Hate to tell you ow many parts I break in making a chair! I use cherry a loy ( figures with the name huh) and it is less forgiving than maple or oak but it looks nice. Note the attached pic of a fan back side chair I recently finished and youll see what i mean by long support spindles. i hope this picture comes out the right size
Nice match of chair set nd cupboard door - did you do both?
actually no. the cupboard was a wedding gift. I tried to get the 2 colors to be close
John -Very nice spindle work!...........
From Beautiful Skagit Co. Wa.
Dennis
thanks Dennis. Been making chairs for 2 years now. Bought a Shopsmith as a lathe ( second hand) and it seems to work very well for chair work
Here's a very good illustration of using the hand in back of the tool to dampen vibration while turning long thin spindles:http://www.turnedtreasures.com/project.html/crochet_hook_pg2.html...........
From Beautiful Skagit Co. Wa.
Dennis
Very nice looking chairs Dennis. It is reassuring to know that others have been able to produce a good results while experiencing similar problems. Please give me more detail on your spindles (ie. kiln dried stock, air dried or green, sawn or riven)
The thin spindles are 5/8 on adult chairs and 1/2" on childs chairs. They are cut from air dried wood and cut into billets on my table saw. I then use a spoke shave to get them close to dimension. I mount them in a jam block and then turn them in my Shop Smith. One thing I like about the shop smith for this work is the tail stock has a cup, not a dead center. Mount the thin part in the cup and mount the jam block in the drive end. Be carefull when you start the machine to always have your hand supporting the spindle as it turns or it will whip right into your face. Then I sand the spindles to final shape using 2 steps of sanding grits and the final buff is with a nylon scouring pad. This sanding process is the same one I use for the all my turnings. I dont try to get the turning all that close to perfection, I leave that to the sanding part. My final step in all turnings is Watco oil and polish it as it turns. Comes out smoother as can be
TGermites -Wish I could take credit for John's chairs but that would be unethical (grin) ................
From Beautiful Skagit Co. Wa.
Dennis
When things get a little out of control with this problem I have been using the point of the skew from a scraped start point. this means that the should is now referencing from a smooth circle rather from the surface of the last pass. You still have to damp the harmonics for subsequent finish cuts but it seems to help correct the initial problem.
Dave
Hi,
in addition to all the techniques described I would like to add that you can use a steady-rest to support the workpiece. Look at this example from Lee Valley: http://www.leevalley.com/wood/page.asp?SID=&page=48722&category=1%2C330%2C49238&ccurrency=3
I made one from with ball bearings and used it for turning 35" ballusters. Without the support the vibration was terrible, see foto's.
Gert.
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