the other day i was ruffing a 80 lbs blob of wood on a newly purchased stubby 750. this piece is the largest i've turned. the wood was pretty unbalanced and so the max speed i felt comfortable with was ~ 150 rpm. at this speed lathe seemed to flex and the one way live center wobbled a bit. increasing the speed at all amplified the movement. the lathe is bolted to the floor. my question are, i am damaging the lathe bearings or the live center? what are the limiting factors to ruffing an unbalanced piece of wood?
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flexing live center
- Thread starter victortmina
- Start date
Victor, I can't answer your bearings question, but it sounds like either the live center isn't perfectly centered, or maybe the spindle is flexing under the weight. Does the tailstock line up perfectly with the headstock? Forgive me for asking; I know the Stubby is a serious step up from a powermatic, but do you have to re-align the tailstock when you extend/shorten the bed?
Victortmina, I don't own a stubby ( I wish) but I have noticed that their tailstock spindle is not large in dia., combine this with other factors, eg: was the tailstock wound out too far, the live centre (presumably no, 2 Morse ?) is long in design and not all that strong in its tang, and 'possibly' some flex in the lathe structure ( particularly if the tailstock is wound up with reasonable tension) could all result in the centres being off line and hence 'wobble'. (seperate to the piece being out of balance) Was the surface that the live cente 'bed' into straight? (also grain) If not this could also make the centre be off line.
It is difficult to answer your question in regard to damage, however if your live centre is not running 'on centre' and has too much end force it will heat up considerably (mine has over the years, particulalry with this type of work)
With heavy off centreparticularly work my 'go to' tool is an Arbortech unit. Rather than rough down with a gouge I use the angle grinder to remove the bulk (where possible) with the lathe stationary of course!!! Combining the Arbortech with a roughing tool (alternating between the 2) speeds things up and puts a lot less stress on me and the lathe. There is no such think as cheating when it comes to this sort of work, what ever tool works, provided it is safe to do so. IMO.
I hope this helps.
It is difficult to answer your question in regard to damage, however if your live centre is not running 'on centre' and has too much end force it will heat up considerably (mine has over the years, particulalry with this type of work)
With heavy off centreparticularly work my 'go to' tool is an Arbortech unit. Rather than rough down with a gouge I use the angle grinder to remove the bulk (where possible) with the lathe stationary of course!!! Combining the Arbortech with a roughing tool (alternating between the 2) speeds things up and puts a lot less stress on me and the lathe. There is no such think as cheating when it comes to this sort of work, what ever tool works, provided it is safe to do so. IMO.
I hope this helps.
You've got several issues operating, Victor. Let's take them in order.
1. Bolted Down Lathe. Your 750 is (I assume) on a component leg set (either Bill's or John's designs) which have some flex in the structure. That said, it is "popular learning" that bolting a wood lathe to the floor will cause early wear in the bearings because it channels most all of the work vibration to the bearings rather than allowing the energy to dissipate. This is somewhat opposed by more than a few machinists I've spoken to who site most industrial machines being floor mounted. They don't talk about doing so with a wood lathe, however. My S1000 is not bolted down (although my band saw is) and it's never been a problem. Being hyper-picky with leveling the bed in both directions is the key to a stable machine, and also functions as a safety feature for excessively out-of-balance workpieces. If your lathe starts to dance, it's time to slow down the music.
2. Remember as well that, while you own a beautifully made lathe with plenty of weight, it's not indestructible. The cast iron shell of your bed base is heavy and reinforced, but if you put so much stress on it that you force it to flex, you may crack that casting. Unbolting from the floor will prevent this scenario.
3. The tailstock and quill on your machine are easily heavy enough to handle much more weight than an 80 lb. piece. Part of your problem may (again) be due to the bolt-down (the stress has to go somewhere), but several other issues come to mind. First is that your center is not properly seated in the quill. This can be caused by not carefully cleaning the morse taper surfaces before insertion or by the presence of a bump or gall on either one. Careful inspection and cleaning of both will usually prevent this, but a gall must be removed. The male taper can be gently filed to remove a defect, but repair of the female taper will need a #2 morse taper reamer. ENCO sells them for about $30, and they should be basic equipment for any quality lathe. Second issue is over-extension of the quill. While that quill is plenty massive, it will flex if you're asking too much of it. For substantial wood in the beginning phase, keep it retracted as much as possible, and make sure that your bedlock is tight. Third, you should have your quill lock fully tightened as this eliminates any flex of the quill shaft inside the tailstock casting.
As an example, the attached pic is of a 25" rough of wet Sycamore just after being mounted on my lathe. The weight was well over 120 lbs., and had to be hoisted (power hoist above) onto the lathe. Note the short extension on the TS quill.
If this hasn't answered your problems, I suggest that you e-mail Bill or post the questions on the Stubby Group listserve.
1. Bolted Down Lathe. Your 750 is (I assume) on a component leg set (either Bill's or John's designs) which have some flex in the structure. That said, it is "popular learning" that bolting a wood lathe to the floor will cause early wear in the bearings because it channels most all of the work vibration to the bearings rather than allowing the energy to dissipate. This is somewhat opposed by more than a few machinists I've spoken to who site most industrial machines being floor mounted. They don't talk about doing so with a wood lathe, however. My S1000 is not bolted down (although my band saw is) and it's never been a problem. Being hyper-picky with leveling the bed in both directions is the key to a stable machine, and also functions as a safety feature for excessively out-of-balance workpieces. If your lathe starts to dance, it's time to slow down the music.
2. Remember as well that, while you own a beautifully made lathe with plenty of weight, it's not indestructible. The cast iron shell of your bed base is heavy and reinforced, but if you put so much stress on it that you force it to flex, you may crack that casting. Unbolting from the floor will prevent this scenario.
3. The tailstock and quill on your machine are easily heavy enough to handle much more weight than an 80 lb. piece. Part of your problem may (again) be due to the bolt-down (the stress has to go somewhere), but several other issues come to mind. First is that your center is not properly seated in the quill. This can be caused by not carefully cleaning the morse taper surfaces before insertion or by the presence of a bump or gall on either one. Careful inspection and cleaning of both will usually prevent this, but a gall must be removed. The male taper can be gently filed to remove a defect, but repair of the female taper will need a #2 morse taper reamer. ENCO sells them for about $30, and they should be basic equipment for any quality lathe. Second issue is over-extension of the quill. While that quill is plenty massive, it will flex if you're asking too much of it. For substantial wood in the beginning phase, keep it retracted as much as possible, and make sure that your bedlock is tight. Third, you should have your quill lock fully tightened as this eliminates any flex of the quill shaft inside the tailstock casting.
As an example, the attached pic is of a 25" rough of wet Sycamore just after being mounted on my lathe. The weight was well over 120 lbs., and had to be hoisted (power hoist above) onto the lathe. Note the short extension on the TS quill.
If this hasn't answered your problems, I suggest that you e-mail Bill or post the questions on the Stubby Group listserve.
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First things first. Makes not a bit of difference whether you bolt on a base with weight or bolt to the big weight - mother earth. If there's play in the bearings the energy is split in the collision over the gap. Newton's 3rd.
As to the flex in the tail. Two most likely candidates are misalignment or excessive extension. Misalignment can come from not matching points and making whatever correction might be required to get them in a straight line, or engaging off-center because the center slips on that rough piece. It's exacerbated by the extension of the quill, a loose banjo.base connection, and more.
As a matter of course I rotate the lathe by hand and see if the point on the tail center is making a circle or staying put. But that's because the Teknatool people saw fit to give me an adjustable tailstock, and adjustability means a chance for misalignment. Sometimes the answer is as simple as loosening the clamp that holds it to the bed and giving it a push opposite the tightening, and sometimes, like a couple in the last few years, it's a maladjustment caused by yours truly using carving tools and a mallet to gain clearance over the bed for a poorly chainsawed blank. No cure for dumb, I just have to try not to cut corners literally and figuratively.
Excessive extension increases any misalignment and decreases the amount of quill the tailstock can grasp to maintain alignment. Get it close.
As to the flex in the tail. Two most likely candidates are misalignment or excessive extension. Misalignment can come from not matching points and making whatever correction might be required to get them in a straight line, or engaging off-center because the center slips on that rough piece. It's exacerbated by the extension of the quill, a loose banjo.base connection, and more.
As a matter of course I rotate the lathe by hand and see if the point on the tail center is making a circle or staying put. But that's because the Teknatool people saw fit to give me an adjustable tailstock, and adjustability means a chance for misalignment. Sometimes the answer is as simple as loosening the clamp that holds it to the bed and giving it a push opposite the tightening, and sometimes, like a couple in the last few years, it's a maladjustment caused by yours truly using carving tools and a mallet to gain clearance over the bed for a poorly chainsawed blank. No cure for dumb, I just have to try not to cut corners literally and figuratively.
Excessive extension increases any misalignment and decreases the amount of quill the tailstock can grasp to maintain alignment. Get it close.
Think you might have misunderstood, Michael. A Stubby 750 like Victors is 740 lbs. of iron. Stubby owners don't need to "bolt on" more weight. But these lathes are uniquely designed for flexibility in how they are set up for a given task. If Victor doesn't have all his locks tight, he will get movement.
Your citation to Ike's #3 is apt however, because bolting the lathe to "Mums" serves to enhance the reciprocal force involved so that much more force is reflected back into the machine. By unbolting from the floor, large portions of the vibration can dissipate through lateral motion that is not reflected back. Allowing the machine to move as a unit, free of the floor restriction, maintains its structural integrity without focusing the forces on any one part, be it the base, the bearings, or the tailstock.
If anyone here is interested in or in need of dampening lathe vibration, I strongly recommend John Williams' cantilever system explained at the link that follows. I actually applied his method to my old JET 1236, and I can assure you it works very well and beats the snot out of sand bags.
http://www3.sympatico.ca/3jdw8/antivibration.htm
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There is something going on other than the eighty pounds of wood - I've roughed over 125 lbs on my 750 (not bolted nor extra weighted) with no problem at all. It was Oneway faceplate attached with about twenty sheet metal screws, but I ran the tail stock up to it with a Nova live center just to make certain something didn't go wrong. Nothing wobbled or moved and the piece wasn't all that balanced.
I'd check to see if the stand is secured and all bolts are tight. Then that the lathe bed is level (this will cause tail stock misallignment) and the tail stock is alligned. Then that your live center is seated and whatever your securing the wood to your headstock (faceplate I assume) is attached correctly.
I'd check to see if the stand is secured and all bolts are tight. Then that the lathe bed is level (this will cause tail stock misallignment) and the tail stock is alligned. Then that your live center is seated and whatever your securing the wood to your headstock (faceplate I assume) is attached correctly.
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The stubby or even the much lighter Jet 1642 will handle an 80 lbs blank between centers. You will get vibration with an out of balanced piece and the vibration gets more severe with higher speed.
Balance the blank for weight before roughing reduces the vibration. I do this by putting the blank between centers an spinning it by hand. If too much weight is on one side, it falls toward the ways instead of spinning, loosen the tail stock and move the tail center toward the heavy side that faced the ways.
repeat until the piece is fairly well balanced and will spin around without pulling to one side. the objective is to get 2 or 3 heavy sides that are about the same.
As you begin roughing the piece becomes more balanced. you can then move the tail center to adjust the grain pattern, align knots or whatever you wish.
Happy turning,
Al
Balance the blank for weight before roughing reduces the vibration. I do this by putting the blank between centers an spinning it by hand. If too much weight is on one side, it falls toward the ways instead of spinning, loosen the tail stock and move the tail center toward the heavy side that faced the ways.
repeat until the piece is fairly well balanced and will spin around without pulling to one side. the objective is to get 2 or 3 heavy sides that are about the same.
As you begin roughing the piece becomes more balanced. you can then move the tail center to adjust the grain pattern, align knots or whatever you wish.
Happy turning,
Al
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I file that right next to "alcohol drying." The old elevator theory. All you have to do is jump up just before it hits....
john lucas
AAW Forum Expert
MM The headstock dampening device works, sort of. I tried it years ago when I first read about it. I had a Nova 3000 that rocked even though I had it on a very heavy wooden stand filled with sand. I'm pretty sure it was flex in the wood where the lathe was attached. Anyway I took some all-thread attached it to the bed just in front of the headstock and put weights on it. You had to adjust the weights to stop the vibration and it worked extremely well. The only problem was you had to adjust the weights all the time until the piece got really well balanced. That was little too much work for me so I removed it.
Hey John,
It worked even better on my 1236 that was on their cheezy bolt-together frame. An out-of-balance piece would get the whole deal swingin' like a Saturday nite line dance. Didn't eliminate everything, but that 25lb. block of concrete did way more than the 200 lbs of sand I had in a box under the headstock. I didn't have any adjustments, however. Just an 18" piece of 4" lolli welded to a couple of 1/4" plates. Mounted to the outboard bed with a pair of 3/8" U-bolts. Of course, it didn't look near as sexy as the nice underbed boxes many guys make for sandbags and tool storage.
Bill Rubenstein
In Memorium
Offline request
I've asked Victor to take this issue off-line and work with me on it -- the best and fastest way for him to find a solution.
In the last week I've worked with two different customers having "lathe" problems. In both cases these were actually operator problems -- I'm reasonably certain that this is the situation here also. Hundreds of people are doing, successfully, and every day, what Victor is unable to do.
In one case a few weeks ago -- another "lathe" problem -- John Jordan was close, made a house call, and was instantly able to tell the new owner what he was doing wrong. That same customer had a "lathe" electrical problem which also turned out to be his error -- I was able to help him through that via a phone call.
Then there's the customer who told me that his lathe "wouldn't turn round" Now that was a really good "lathe" problem.
Sorry if this sounds a little short-tempered...
Bill
I've asked Victor to take this issue off-line and work with me on it -- the best and fastest way for him to find a solution.
In the last week I've worked with two different customers having "lathe" problems. In both cases these were actually operator problems -- I'm reasonably certain that this is the situation here also. Hundreds of people are doing, successfully, and every day, what Victor is unable to do.
In one case a few weeks ago -- another "lathe" problem -- John Jordan was close, made a house call, and was instantly able to tell the new owner what he was doing wrong. That same customer had a "lathe" electrical problem which also turned out to be his error -- I was able to help him through that via a phone call.
Then there's the customer who told me that his lathe "wouldn't turn round" Now that was a really good "lathe" problem.
Sorry if this sounds a little short-tempered...
Bill
Sorry if I offended you, clearly this is operator error which is why I went to the forum for input. Thanks for your assistance, however I believe others may also have information which I can learn from and appreciate all responses.
I've been a Stubby owner for over five years with no problems that couldn't be solved easily. Although I bought mine from JJ, Bill has been a great distributor and is more accessible and responds better than any customer service branch of anyone I've seen lately. Only drawback is that he's just as crotchety as me and I'm only selling small things.
+1 to Bill's support .... and I live an hour's drive from the Stubby factory 🙄