Friday, January 11, 2019

Bench-top Bungee Lathe

FINALLY!  I have lathe capability!!

In October of 2017, I experimented with a bow lathe but had less-than-spectacular results.  (Read: it sucked!)  For a long time I've been thinking about how I might build a small, bench top, foot-powered lathe, since I don't have space for a free-standing one.  After scouring the 'net I found something on Lumberjocks that made sense for my bench and space.  It seems to be working well and is small enough that I can put it away easily.  And it's made mostly from recycled wood and scraps.
My bungee lathe
The lathe is powered by a rope that is attached to bungee cords that are stretched between the two end-frame steel perforated angle bars that support the garage door opener.
The end over the garage door.
The red bungee is routed over the cross member of the wood storage rack
to keep it away from the plastic parts of the garage door opener track.
At the other end, the white bungee is attached to the frame holding the opener motor
These two bungees give about the right amount of resistance for the lathe to work properly.  The other end of the rope is attached to a stick (the treadle) that I press with my foot.
The first treadle, hinged with a 1/4" dowel pin
This treadle kept inching forward as I turned so I tried different things to fix that.  The first was to step on a board that put pressure on the floor-contact part of the treadle.
The stick holding the treadle in place didn't work very well
Next I used a strap hinge, attaching the treadle to a piece of plywood that I could stand on and this worked much better.  However, this hinge was cheap and quickly got too flippy-floppy (that's a technical term).
Treadle hinged to plywood
I also found that with the treadle in that position I couldn't comfortably work at the left side of the lathe, and I got a far better idea.  Attaching the treadle to another scrap piece of plywood allowed me operate the treadle from anywhere along the length of the lathe.
The small piece of plywood is attached to the base plywood with two 3" door hinges
The head stock is a chunk of redwood clamped in the vise and the center is a 3/8" lag screw, filed somewhat conical at the tip.  The rope hangs just above that side, so the treadle works best just below that.  But the rope had a tendency to get caught on the vise, so I made a little guide to keep the rope away from the vise.
Top view of the rope guide
The bed rails are two pieces of red oak that are tenoned into mortises in the head stock.  The rails are supported at the tail end by a redwood 2x4.  That end of the lathe can wiggle back and forth a little, but it hasn't affected the turning.  The lathe is quite rigid.

The tail stock is made from glued-up redwood boards and its long bottom tenon is sized to fit snugly between the two bed rails.
Tail stock
Lower tenon of tail stock with mortise for wedge to lock in place
Tail stock with wedge in place
The tool rest is made from a piece of maple attached to an oak base in a shallow rabbet.  They are screwed together.  The base has a slot cut into it for adjustability.
The tool rest
... and from below
The rest is held to the bed rails with a long bolt and the "nut" that tightens it is a piece of oak that I tapped.
The head of the bolt is captured in a wider slot so it can't spin
The "nut" drilled and tapped to accept the bolt
This worked well, but the tool rest did move a little during use.  Adding two strips of self-adhesive sandpaper to the bottom of the base fixed that and now it's solid as a rock.
Stopped the tool rest from moving
I've been playing around a little before trying to make anything useful.  I've never turned before, so there is a learning curve.  But apparently I've picked up a thing or two from reading and watching because I was able to do something relatively quickly.
Some gentle shaping and some beads
One thing I did figure out quickly was not to try to turn soft woods.  My lag bolt centers wear away the soft wood quickly, loosening the work or worse, moving the center.
Tried turning this piece of 2x?, but the the end pilot hole enlarged and moved
This is exciting for me.  I've already made a few things that I'll post about later and it has been fun.  I don't think I'll be falling down the rabbit hole of turning, but it is exciting.

For anybody who is interested, next time I'll post some specifics about the construction of the lathe.

4 comments:

  1. Interesting set-up.
    Any reason to put the rope on the right side?
    Up to now I was considering Richard Maguire one's:
    https://www.theenglishwoodworker.com/bench-top-lathe/
    Sylvain

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    1. Hi Sylvain. The only reason for the rope being on the right is that was the easiest position for the bungee cords - almost directly above the right side.

      I saw Richard's benchtop lathe and I originally wanted to build something that would go on top of my workbench, but ultimately it made more sense for me this way. One thing to consider with Richard's is that the treadle needs to go backwards so as not to hit the bench. Clearly that didn't stop Richard, but I wanted my treadle to go forward. Seems like a more natural motion to me.

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  2. Replies
    1. Hi Antonio. Thanks - it's been fun to turn finally.

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