Pole lathe ad-on to carpenters workbench

discussion of the niceties of turning on a bow, bungee or pole lathe.

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Pole lathe ad-on to carpenters workbench

Postby Holzbob » Fri Dec 30, 2011 12:06 am

Hi all,

this is my first post so I would like to introduce me in advance: I'm 41 years old and I started in Kindergarten - age to play/work with tools and have only rarely paused since.
My hobbys are wide spread but often go along with manufacturing or repairing the needed stuff. Working dry wood and inventing little gadgets for my hobbies are things I do most frequently but I also work with concrete, cameras, electronics, blacksmithing and machining. About two years ago I built my first pole lathe (minus pole) and a shaving horse. My pole lathe is an attatchmet to my heavy carpenters workbench which provides the main support (foto included).

The main features are:
-adjustable height for adults down to my then 5 years old boy
-reduced storage space

Since I'm not turning frequently but need a tool - handle now and then I think about building a pole - lathe attatchment for the dog - holes of the bench. I hope to minimise setup time and space consumption. This construction has formerly been suggested by John/Jennie Alexander : http://www.greenwoodworking.com/EndVicePoleLatheArticle.

Has anybody had the opportunity to gain experience with an attatchment like this and can offer advice and a picture of this solution? The string would have to go through the opened vise and the position can't be varied much. The pedal can't be very long, otherwise the string would rub on the back of the vise or the pedal would touch the wall. The big advantage would be the fast setup and little space that is needed for operation and storage. My lathe now extends perpendicular to the workbench into the workshop an blocks it to an unfavourable degree. The height adjustability is only needed for my boys and they are growing fast. The foto is an superwideangle and doesn't show how tiny my workshop is - perfect lens for a real estate sales person.

Bob
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Re: Pole lathe ad-on to carpenters workbench

Postby jrccaim » Sat Dec 31, 2011 4:15 am

I see you have read greenwoodworking.com. I made a similar attachment. It being winter and my shop at -20C I tried clamping it in a workmate. Alas it does not work because the workmate is much too light. It wanted to walk all over the place. However if you have a workbench with a decent vise (or vice, in the UK) it would be fine. The workbench must be massive. The vise must be really big and heavy. This is a good idea anyway for any workbench. You don't want to walk your workbench, nor have your work move as you plane it. Mr Alexander's suggestion of a dog leash clip to hook up to the bungee works beautifully and is now my standard attachment method. Your ability to adjust the cord is limited. A bungee wants to center the clip right at the middle. If you are turning tool handles this does not matter, 30cm or less all right. Long turnings not so good. There is a great deal of material in this forum on bungee attachments, I'd suggest searching on "bungee" in this board. Short version: screw-ins not a good idea because they can pull out. Nuts and bolts much better.

As long as you realize its limitations -- short work capability -- the Alexander vise lathe will do the job. I'd advise making it, and learning from it. Nice thing about this kind of lathe: no high-tech stuff. Make one, try it; don't like it, make a different one!
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Re: Pole lathe ad-on to carpenters workbench

Postby Holzbob » Sun Jan 01, 2012 6:08 pm

thank you for your answer, jrccaim.
My workbench is a full size german cabinet makers workbench of estimated 90 kg + what is in the drawers + the mess on top and the vices are extremely strong. Stablity is no problem with my current lathe and apart from the vice it has only a single leg 38 x 58mm fir as a support.
My bungee cord has hooks on the ends which are placed into holes in the upright members. The string is attatched with a small carabine hook which worked fine so far on my mostly short workpieces.

Where I see problems with the end-vice lathe is the pedal and acheiving enough string movement per hit on the pedal. Maybe I will fit the lower end of the string to the underside of the workbench and let it run over a pulley that is fixed to the pedal. This way I would double the amount of string movement.
I plan to get going with this project but it might take some time. I will post the result here.

Bob
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Re: Pole lathe ad-on to carpenters workbench

Postby simon » Sun Jan 01, 2012 6:48 pm

Maybe I will fit the lower end of the string to the underside of the workbench and let it run over a pulley that is fixed to the pedal. This way I would double the amount of string movement.


You may get twice the movement but it will take twice the effort, plus added friction.
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Re: Pole lathe ad-on to carpenters workbench

Postby jrccaim » Wed Jan 04, 2012 5:17 am

simon wrote:
Maybe I will fit the lower end of the string to the underside of the workbench and let it run over a pulley that is fixed to the pedal. This way I would double the amount of string movement.


You may get twice the movement but it will take twice the effort, plus added friction.


Err, I think it's half the effort (with one pulley). Moving pulley halves force. Agree on friction. But travel is is cut by the same factor as effort is, so you will get only half the travel. When you have compound blocks and tackle you cut effort by the number of moving pulleys -- each one cuts effort in half. Three moving pulleys cut effort in by 6, but gives only 1/6 travel. Got to pull six meters of rope to raise the load up one meter. I use a sixfold purchase outfit all the time. Very useful for moving big logs. But you have to pull an awful lot of rope to get the log to go anywhere.

I found that room to move the treadle was a major nuisance with my work-mate rig. Never really solved that problem; workmate too light as I said. But a pulley arrangement is might be a way around it. Fixed pulleys do not change effort, the just re-direct it. Drawers get in the way of the pedal. Alexander has a narrow "cabinet maker's bench" with no drawers, so he can sneak a padal under the bench. I see lots of drawers in the picture supplied. Hmm. Lovely workbench, however. I would not worry too much about travel and effort if all you are going to turn is tool handles. I will think about this, since I have a direct interest.
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Re: Pole lathe ad-on to carpenters workbench

Postby Bob_Fleet » Wed Jan 04, 2012 4:58 pm

jrccaim wrote: Err, I think it's half the effort

We're arguing semantics here. It's double the force but half the distance so the work, or effort, is the same (ignoring friction).
Sounds like a good idea though.
If it fits and is simple, go for it and let us know how you get on.
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Re: Pole lathe ad-on to carpenters workbench

Postby Holzbob » Wed Jan 04, 2012 11:08 pm

I think about using the blocks backwards: I would get twice the way of movement and half the force of what I put into it. Since I may be forced to use a short pedal I will have enough force at it's end to spare, but only insufficient way of movement.
Problem with rollers is always to keep the string from falling off in the wrong moment.

Bob
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Re: Pole lathe ad-on to carpenters workbench

Postby jrccaim » Fri Jan 06, 2012 5:45 am

Bob_Fleet wrote:
jrccaim wrote: Err, I think it's half the effort

We're arguing semantics here. It's double the force but half the distance so the work, or effort, is the same (ignoring friction).
Sounds like a good idea though.
If it fits and is simple, go for it and let us know how you get on.


Sorry. We are discussing Physics, not semantics. If you hang a weight on a rope from a fixed block, or pulley, you change the direction of the force you have to apply to balance the load. But you must exert a force equal to that of the load, mg, where m is mass and g is good old gravity. If the block can move, that is, attach it to the weight rather than fix it, it cuts the force in half; the other half is absorbed by the fixed point of the rope. So it is no joke and it does matter. Otherwise pulleys would be largely useless. As it is they give you a mechanical advantage at the cost of a lot less travel. If you look at a sixfold purchase it has 3 blocks on top and 3 at the bottom. You attach the 3 bottom pulleys to your log and pull. Since the 3 bottom pulleys are moveable you cut effort by six. So a 300 Kg log can be pulled with 50 Kg effort. And I know Kg is not a unit of force, so multiply by g (9.98, about 10 m/sec.sec) if you want Newtons. And yes, energy (work) is conserved, so you pull 6 meters of rope at 50 kg, same work as pulling 300 Kg one meter. But most of us cannot pull 300 Kilo logs as much as one centimeter. I certainly can't . Not without my tractor, anyway :) and there are lots of places in the woods that I can't get the tractor into..
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Re: Pole lathe ad-on to carpenters workbench

Postby simon » Fri Jan 06, 2012 8:39 pm

Maybe I will fit the lower end of the string to the underside of the workbench and let it run over a pulley that is fixed to the pedal. This way I would double the amount of string movement


If the pulley is rigged so that one stroke of the treadle moves more string than the arc of the treadle then more work will be needed to move it, compared to the string being attatched direct to the treadle.

All you say about pulleys is right jrccaim. But Bob wants things the other way round, not to pull a lot of rope for a little movement of the object but a small movement, one stroke of the treadle, will shift a lot of string.

We are wondering off topic but what's new.
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Re: Pole lathe ad-on to carpenters workbench

Postby jrccaim » Sat Jan 07, 2012 6:11 am

simon wrote:
Maybe I will fit the lower end of the string to the underside of the workbench and let it run over a pulley that is fixed to the pedal. This way I would double the amount of string movement

...
All you say about pulleys is right jrccaim. But Bob wants things the other way round, not to pull a lot of rope for a little movement of the object but a small movement, one stroke of the treadle, will shift a lot of string.

We are wondering off topic but what's new.


What we are trying to do is solve holzbob's problem, I hope. At least, I am :). I have run into this problem myself. Thing is, holzbob has a beautiful German workbench (see pic in original post) but no room under it for a treadle, there being a lot of drawers in the way. Idea is to clamp a lathe framework in a front vise, erm, vice [in the UK the device is a vice. In the USA a vice is an unhealthy habit, such as excess alcohol consumption :)], a la Jennie Alexander, go see http://www.greenwodworking.com (as holzbob indeed did). So what to do? Alexander has a narrow cabinetmaker's bench with no drawers at all, as you will see if you go to that site. So do I, because I made my own bench. But I like a lot of room under my bench, and so I have no drawers. This is all a matter of taste, drawers or none, no discussion on matters of taste please. However, the problem with drawers is that the traditional long treadle won't go through drawers. Holzbob very ingeniously suggested pulleys, and I still think it's a good idea, but I'm still working out a possible arrangement where the hinge would be at your front and the cord would run through a couple of (fixed) pulleys to the workpiece. I do not want moving pulleys because they cut the travel of the cord. My experience with pole lathes is that you want all the travel you can get.

It occurs to me as I am writing this that there is a way around the problem. Most nice workbenches have a vice at the left side of the front of the bench. If yours is at the right it won't matter, just mirror-image the thing. Let's call it a front vice. It will clamp parallel to the long edge of the bench. So make the Alexander gadget. Make another piece and joint it to the Alexander gadget at 90 deg. Clamp that in the front vice. Your pole lathe is now rotated 90 deg. and you will turn at 90 deg to the bench. Can use as long a treadle as you wish, or have room for, but you will have to rotate the bungee to suit. That is one more hole in your ceiling, sorry. In effect you are working the treadle down the bench, rather than across it where all those lovely drawers are. You have an outrigger pole lathe. It will not do bowls I am afraid, but it should do tool handles.
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Re: Pole lathe ad-on to carpenters workbench

Postby mstibs » Sat Jan 07, 2012 7:48 pm

I'm unable to write my idea down in English in a way that you would understand it, so a picture:

benchmountedlatheidea.jpg
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You could even screw butt hinges to the wall side of the frame and the bench and flap it to the wall if unused.

Best!
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Saxons. Were good wood-turners, they had to be because they were poor potters...from "A Short History of Woodturning with the Pole-lathe" by Brian G. Howarth; My bilingual (de/en) Blog: http://mstibs.wordpress.com
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Re: Pole lathe ad-on to carpenters workbench

Postby jrccaim » Mon Jan 09, 2012 6:25 am

mstibs wrote:I'm unable to write my idea down in English in a way that you would understand it, ....
you could even screw butt hinges to the wall side of the frame and the bench and flap it to the wall if unused.
est!
STIBS


Lieber Herr mstibs, I admire your sketch a whole lot; double bravo; I marvel that you could get it onto a jpeg; but there is an omission and that is the treadle or pedal. Indeed that is what we are all trying to do. If you go to greewnwodworking.com you will find Jennie Alexander's version of this lathe and I suggest you do so. Problem is the treadle. or pedal, or whatever you want to call it. Since Holzbob's workbench is drawers all the way down, there is no room to put the pedal. This is why I suggested an outrigger or piece at 90 deg added to the whole thing. That way the treadle would operate parallel to the bench and not across it. I now must concoct a sketch like yours for my alternate suggestion. It may take some doing. Not the sketching, but getting it online.
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Re: Pole lathe ad-on to carpenters workbench

Postby mstibs » Mon Jan 09, 2012 12:15 pm

jrccaim wrote: Problem is the treadle. or pedal, or whatever you want to call it. Since Holzbob's workbench is drawers all the way down, there is no room to put the pedal. This is why I suggested an outrigger or piece at 90 deg added to the whole thing.


That's what I hoped, my sketch would show :wink: - the treadle isn't under the workbench but parallel to the workbenchs front. Holzbob would just not be able to open a drawer while turning at the same time.
Saxons. Were good wood-turners, they had to be because they were poor potters...from "A Short History of Woodturning with the Pole-lathe" by Brian G. Howarth; My bilingual (de/en) Blog: http://mstibs.wordpress.com
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Re: Pole lathe ad-on to carpenters workbench

Postby Ian S » Mon Jan 09, 2012 1:41 pm

Ah-ha!

I understand the sketch - very clever!

Rectangular frame with two front rails. Clamp on the bench (with end vice if one is fitted) with the front rails overhanging the bench. The poppets sit between the two front rails, and the treadle parallel to the front rails.

Cheers
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Re: Pole lathe ad-on to carpenters workbench

Postby mstibs » Mon Jan 09, 2012 3:35 pm

Ian S wrote:Rectangular frame with two front rails. Clamp on the bench (with end vice if one is fitted) with the front rails overhanging the bench. The poppets sit between the two front rails, and the treadle parallel to the front rails.


Straight to the point, I couldn't have said it better. :D
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