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Sebastian Metal Lathe

A Sebastian treadle lathe with the entire treadle mechanism replaced, except for the shaft bearing and bracket. The lathe is in good working order with good bearings and gears. The flywheel and treadle mechanism is working well, but the flywheel could be heavier. Any weight added to the flywheel should be near the periphery to provide a greater flywheel effect.

This is a 10" lathe with 28" between centers. The bed is 48" long. The spindle pulleys are 2 1/2", 4", and 5 1/2". Included are a 5" faceplate, an 8" 4 jaw chuck with key and reversible jaws, an assortment of centers and change gears.

catalog page from "Sebastian Lathe Co. Catalogue No. 6" showing the original flywheel and treadle

left end view

faceplate and 4 jaw chuck.

8 centers. These Sebastian centers are shorter than most other MT 2 centers. All my modern MT 2 centers fit this lathe, but the Sebastian centers don't fit my two other MT 2 lathes

Crank arm, shaft and sprocket from an old horse drawn corn planter were used to replace the original parts. The prototype pulley is made from an old softwood scaffold plank.

the single roller bearing and adjustable bracket are all that remain of the original treadle mechanism.

the 4 jaw chuck on the lathe

the wooden 3 step flywheel is secured to the shaft with a corn planter sprocket on either side.

the complete set of change gears including a 60 and 30 tooth set on a movable stud and a 60 and 26 tooth pair on a second movable stud. A 20 tooth and 40 tooth gear fit the stationary stud. All gears are present as listed on the thread chart. Also, two large gears allow a very slow power feed.

the threading chart

The flywheel steps do not match the spindle pulley so that one belt will fit all three speeds. Turning softwood pulley segments with changing grain was a foolish attempt and tearouts in the two smaller faces required turning down too much. Here I have shortened the new belt to fit the smaller pulley after it had stretched and begun slipping on the large pulley. It shouldn't stretch any more, but a longer belt would now be needed to use the larger pulleys. A more precisely sized pulley could be made by a more competent turner, using maple or other hardwood and using this flywheel as a guide to construction.

Where the pair of pulleys are of much different size and fairly close together, as in a treadle lathe, the angle of the belt must be taken into account in determining the belt length. This can usually be ignored in the case of overhead line shafting, where the countershaft and spindle pulleys are of similar size and the shafts are usually over 5' apart. In that case, I simply match the sum of the dimensions of each pulley pair. But, for treadle lathes, the following formula should be used.

L = 2C + pi(D2+D1)/2+(D2-D1)2/4C

L= length of belt required
C= distance between centers of the two shafts
D1= diameter of small pulley
D2= diameter of large pulley

10/21/2006 update I've fitted a hand rest to this lathe for wood turning. The slower pulley speed works very well for hand turning wood spindles. The rest bolts to the lathe's tool rest base so it's position is accurately controlled with the cross feed screw.

the hand rest in place

closeup showing the cast base salvaged from an 1890's Thomas horse drawn grain drill

the hand rest positioned for faceplate turning. I haven't tried this, but it would seem awkward to treadle while turning in this position.

Price: sold This item can be safely stored until your next trip to Maryland
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Contact: Richard Van Vleck - Email: richard@americanartifacts.com

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