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Thread: Lathe puzzle
04-24-2008, 04:47 PM #1
It’s four lathes in one. Note the canted headstocks and tailstocks to allow passage for the carriages.
I’ll quote from the 1870s(?) description, but with words in brackets substituted with something suited to today’s terminology. See if you can make sense of it:-
‘The carriages and beds are arranged for [machining] articles to forms determined by [templates], the carriages being made to hinge upon two centre ribs upon the beds, which are directly under the centre line of the headstock spindles. The carriages are provided with pointers at the back, which follow the outline of the [templates], and thereby actuate the carriages, raising the front of the carriages by the [templates], causing the tools to be canted inwards, and thus reducing the diameter of the articles being turned.’
The template would be bolted to the front of the bed, as represented by the rectangular plate, and the V-ended plate is the follower. I can see how the carriage would be lifted as it passed over the template, but it seems an odd way of altering the tool position. Any thoughts?
It was used for repetitive work like reducing the diameter of studs inboard of the threaded portion, making tapered plugs, etc.
I keep coming across these examples of simple machine tools made in the 1870s for repetition work, presumably using unskilled operators, probably boys, who would attend several machines at the same time. Operating this one must have been like musical chairs.
This was made by Shaw, Hossack & Co of Openshaw, Manchester. The demand for large batches of similar components must have been huge in Manchester at that time, with all the engine, boiler and machinery makers around.
04-24-2008, 05:59 PM #2
Based on the description and picture, I haven't come up with a way to get this design to work without altering the center height of the tool. My guess is the compound assembly slides (front to back) over the cylindrical carriage.
If the pointer rides up the template - the compound pivots forward moving the tool in. If the template allows the pointer to go down, the compound pivots back moving the tool away from the work.
It doesn't look like there are levers to engage automatic systems, so I would suspect this is a 4-station (person) lathe, and would not run unattended.
04-24-2008, 09:13 PM #3
Looks like it was designed by M. C. Escher.
04-24-2008, 10:10 PM #4
It think it's actually a simple design. The key is that the rear way is almost directly under the spindle, or even a little to this side of it. Because the rear way is also almost directly under the tool bit, most of the cutting load goes straight down into the way. The way looks like a shallow V, possibly with a radiused top. So the carriage rotates around that way, through a small angle, as the follower rises and falls on the template. I'm sure that the maximum range of travel on the template is small, like a 1/2" or less. And the templates and followers are probably subject to a lot of wear.
Yeah, it looks like 4 independent lathes, just sharing the drive for the spindles and feedscrews. Four poor blokes sweatin' away together, stopping as a team to change parts. Back when a laborer cost less than an electric motor.
04-24-2008, 10:15 PM #5
That is an amusing thought, to draw up M. C. Escher's home machine shop, done in the style of an old woodcut.....I can almost picture it now. I'm a long time fan of Escher's work, not just for the mind-bending geometry, but also for his pure technical skill as an illustrator.
04-26-2008, 11:51 PM #6
Boy that's a lot of iron to commit to a seemingly simple job! The carriage drives appear to be "tandem" for each side, leading me to believe two people would operate the machine but would it be one on each side or one on each end? It looks like it would be for turning on centers. I could see a greasy fingered operator slacking the tailstock and catching the finished part, grabbing another part w/lathe dog, slipping it against the live center and cranking in the "footstock" center then engaging the feed and moving to next "lathe". Remember, this machine would be turning at speeds commensurate with carbon steel tooling. I love it!