Spring Pole Lathe, completed.

After getting the majority of the lathe together in the first three days, the last couple were about finishing the tailstock/puppet, making the toolrest, treadle arm, axle, spring poles, and setting the dead centers. Most of this work was less strenuous but required a lot of precise work to get correct. Plus we got to pedal a metal lathe! That was fun.

Here I am turning the axle for the upper arm.

We started with some round stock, hack sawed it to length, then got on the Barnes 4 1/2 metal lathe that Roy has and pedaled away.  I watched most of the other students do this first and the biggest trouble most people had was pedaling backwards–it is a direct drive so the direction you pedal is the direction the piece turns.  As with wood turning, you want the piece turning towards the cutter.  There are two controls which determine where the cutter is in relation to the piece in two different axis.  Not being a machinist, excuse my terminology if I get it wrong.  One controls the feed rate along the axis of the bed, that is towards the headstock or away from it, and the other controls the feed rate at some angle to the bed.  In the photo above, you can see part of mechanism is angled at maybe 15deg, so that moves the cutter from the center of the round stock to the outside.  Basically this entire operation is to put a bit of a crown on the axle and make it more polished from the hacksaw. If you were doing this at home w/o a metal lathe, you could use some metal files to de-burr the stock and probably call it a day.  But Roy has one and it was fun to use.  And hey, a picture on my blog with me in it!  Ha, that is rare as I am always taking pictures of everyone else.  Thanks Chuck for doing the honors.

Here is the Barnes 4 1/2 sans operator.  If I ever get into metal work, I think having one of these would be a hoot, though an electric powered lathe might be cheaper (not sure what these go for).

The tailstock/puppet came from one big piece of pine, and after flattening and thicknessing, then cutting the long tenon that would ride between the bedways, I needed to mark out the mortise for the wedge which will hold the puppet tight to the ways.  But first I needed to cut the wedge to use that for marking out the slope on the mortise.  You want the wedge to be pretty long so that it is easy reach over the bed and whack it tighter and yet there is enough meat on the near side to be able to reach and whack it loose.  My wedge ended up being 10″ long, 1″ at the near portion and 1 3/8″ at the far end.  You want the flat end to face up so that it pulls the puppet tight evenly.  Using the wedge to mark out the mortise makes things easier.

I went a bit overboard in making the mortise extend up past the bed ways–the darker marks are where the puppet runs into the bedways.  It doesn’t matter though, just so long as there enough clearance to make the wedge good an tight.

And the wedge.  Exciting.  Yes, it does say ‘Joe’s Wedge’, just in case I dropped it in class.  I also have some directions on it–”Up” so I don’t get confused when using it.

The spring poles started as two pieces of ash, about 1″ square (sorry I forgot to measure the starting dimension).  The first step was to shape them to a rough octagon.  I used my new wooden jack plane from Ed’s toolshop for this.  Man, ash planes nice.  Roy gave us an easy way to lay out the octagon–using a 24″ square (a ruler would work just as well), place the end at one edge of the square side and the other edge at the 24″ mark, then at 7″ and 17″ make a few tick marks.  Those become your guidelines.  Grab a compass with a sharp pencil, and using the tick marks, set the compass.  Run it down the length and do the same on the other side of that face.  Repeat for all four faces.  Once we had the octogon, the drawknife came out to do some initial shaping.  Never having used a drawknife before, Roy gave me a quick lesson after seeing my rather herky-jerky technique.  As with many things in woodworking, describing it is tougher than seeing the actual motion in person (which is why taking classes for an amateur like me is so important), but basically the drawknife I was using is meant to be used bevel side down.  Then with a slight skew to the blade, you draw it towards you as simultaneously moving from left to right or right to left (which ever feels most comfortable).  This gives a skew cut and the shaving curls off the pole.  We didn’t have any shave horses, so this was all done with the piece in the face vise. Once basically round, the next operation involved making the ends fit the two holes for the lower spring pole and the one for the upper spring pole.  I used a metal spokeshave for this, as well as a piece of scrap with the same diameter hole bored in it for testing fitment.

The dead centers we used are 1MT (morse taper) centers, precision ground.  As Roy explained, any wood turner from the ‘old country’ would like have brought a few very important metal bits with him, and the dead centers are one of them.  Most modern lathes have their centers with sockets also precision sized for specific morse taper sizes (2MT being fairly common from what I’ve seen), and if I was making this lathe again, I might consider using that for the centers.  On our lathes, Cameron and Brandon helped figure out the precise auger bits we’d need for this operation.

First you find center between your bedways, then decide on the height for the turning.  Each lathe might be a little different in these dimensions, so there was no fixed measurement.  The fixed puppet/headstock got bored first, and if I recall correctly, it a #7 auger bit followed by a #6.  You drill the wider, outer portion first, then the narrower portion.  Then using a reaming bit, you connect the two until the center fits snug with no gap.  For the headstock you get to ride the bedway like a horse (yes, it easily held me and I am no small mammal), and with a spotter or two to be sure you are level, start boring away.  Once fitted, the center in the headstock is used to mark the tailstock–but, you want to be sure it is in ‘turning mode’ and so you get it right up the headstock, with the base of the tailstock just a smidge towards the headstock, then fit and tighten the wedge.  The wedge will bring the tailstock vertical and should leave a nice mark where the center needs to be.   Due to the thickness of the tailstock you have the option of not boring all the way through, but I figured I  might want to knock out the center at some point in the future.  My centers are just a wee bit off without the wedge in position as you see in the next photos, but almost dead on with the wedge fitted.

Once that is done, there is just a few more things to finish up before we were out on the sidewalk in front of Roy’s school, treadling away.  The arm that attaches to the spring pole and the work piece should be made from a light piece of wood, in our case just some white pine.  The bearing for the axle does have to be fitted precisely as well as the holes for the axle in the upright.  I think we used some stainless tubing for the bearing, which Roy had smoothed on the ends using the Barnes metal lathe, and which has a tight fit with the axle rod.  For boring the holes, we marked the centers on both parts of the split upright in both dimensions, then with a pair of spotters bored these holes.  In order to get the upright in the correct position, you need a few scraps under neath for support as you don’t want this shifting while boring.  Other than the dead center positioning, this is the most precise part of the woodworking.

The toolrest was a pretty easy affair, with a rabbet for a metal wear strip, a notch for the base, the base itself, and finally the holding mechanism for the toolrest.  I made the mistake of shaping the top of the tool rest before I cut the rabbet, but it didn’t seem to affect it much.  My biggest mistake was not making sure the toolrest was the same width end-for-end.  The right side is just a little lower than the left and when I measure the distance I needed for the notch to match the rest with the centers, I used the left side.  I need to go back and shim the notch a little to bring the right side level.  Overall I am not very happy with this tool rest as it is hard to tighten with the wingnut, and even when I get it as tight as I can, in operation, it will move some on me.  I think I need to make a new block between the tool rest and the base which rides under the bedways.  And find a better way to tighten it, either by making a wingnut extender or a completely different mechanism.  Maybe a cam clamp, which would be quick to move.

It might not be obvious in the next photo but you can probably see the toolrest on the right is below center.

The hole through the center block needs to be fairly straight, and the length of this block needs to be precise.  I think I got a few of these variables wrong and thus my dissatisfaction with the holding ability of this tool rest. That and the blasted wingnut which digs into your fingers.

We just used some woodscrews to attach the upright part of the toolrest to the middle portion.

The metal is just some flat stock, into which we bored holes for the wood screws.  We also took the time to countersink the heads so they fit fairly flush, that way they don’t accidentally mar any piece you are turning if the tool rest is quite close to the turned piece.  Of course, Roy had a hand cranked drill press for this.  A bit of 3-in-1 oil for lubrication, a sharp drill bit and some chicken-fried salad power is all you need.  Yes, they really do fry everything in the South.

For the foot treadle we just used a piece of pine cut.  The drive cord is leather, but we didn’t have enough for the entire class so the ends are parachute cord (which actually kind of sucks).  Future mod is to change to full leather drive cord and possibly change the foot treadle as well.  It takes some getting used to and I find I have to adjust my stance or the cord or the treadle more often than I am actually turning.  The spring pole and upper arm are connected with some galvanized wire.

Here is the drive cord if you are looking to make a lathe.

I’m not sure why one says 1/4 and the other says 5/16.  Roy had two rolls, so they must have been different diameters.  I’ll have to pull out my micrometer and check to see which one I ended up using.  This is important stuff, and it needs to be ultra-precise.  Well, ok, it really doesn’t need to be precise.

And back at home, ready to turn some wood.  Turning right in front of the front-door is not the best idea in the world though.  Wood chip tracks…but being able to turn on the porch in a nice, late summer day sure makes it worth the clean-up.  Plus I can just sweep the chips off into the flower bed for some instant mulch.

And my first practice piece, some sassafrass from the wood pile.  Yes, I need more practice.

I’ll have a couple follow-up posts on this lathe as I have already broken a few things.  :)

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3 Comments

  1. Jason Crawford

     /  September 25, 2012

    Hi Joe:

    Great pictures! I was at Roy’s school back in July and he said the Barnes lathe you were using goes for $3,000. The dirty ones up by the front window are worth even more! Please do another post on your spring pole lathe in a few months and let us know how you like it after you have some miles on it.

    Best,
    Jason

    Reply
  2. Joe, great post. Thanks for the detail on the belt. I’m still using a nylon cord and have been meaning to get a leather belt.

    Reply

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