This might help, Robin

https://youtu.be/zC9BQcW9Uuw?feature=shared

If not … it’s very pleasing to watch anyway!

MichaelG.

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On 18 July 2024 at 20:46 robin coleman Said:

I have a small porch instrument makers lath.It has a single tool post which has a circular peice I presume it was made out or has steel a bit like the keys on pulley key ways does this sound right and Howe do I set the tool height on it it has one screw on top to adjust and lock it.

If you Google “lantern toolpost” all will be revealed. Very common on larger US lathes, eg SouthBend. You fit a large tool bit or tool holder in above the curved piece and clamp it down with the top screw. Tool height is set by angling the tool/holder to position before tightening the top screw.

The curved piece like a woodruff key on a pulley keyway should sit in a a disc that is dished to match the curve on the bottom of the “key”, thus allowing it to pivot in a smooth manner and be locked into position by the clamping bolt bearing down on the tool bit/holder and key.

Did anyone else notice that, on the video, the top slide and cross slide handwheels work the opposite way to what I think as usual. Anticlockwise rotation moves the cutting tool away from the handle and towards the chuck.

I only noticed because I have a Lorsch Schmidt & Co 8mm watchmakers lathe which has the same behaviour of the cross & topslide. It’s awkward, and it looks like the operator in the video has the same confusion.

Anyone know why some were made this way?

Yes, I was wondering about that too. Perhaps it’s had the feed screws and nuts replaced, and their maker carefully set up for left-hand threads, ‘because feed screws are backwards, aren’t they?’. When all fitted up, and the error discovered, it would take a strong will to start again… Also, brass dials don’t look ‘right’ to me, but I don’t know these machines.

See also the text describing this Junior:

https://pennyfarthingtools.co.uk/lorch-junior-8mm-watchmakers-lathe/2017/01/11/

MichaelG.

Regret to say, I have no idea

… my own little Lorch has no mechanical slides.

Almost certain that the direction of action, and the use of [perhaps bronze?] is standard for small Lorch lathes though.

Here’s another interesting one:

https://youtu.be/wNTUovr1Abk?feature=shared

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Note: I presume the clever motor-arrangement is a one-off, but the slides look very original.

MichaelG.

Anti intuitive?

I favour cw (clockwise) advance or cw retard feed screws.

dave8

Yes,  I’d take advance/retract.

dave8

I’d very much agree that with used machines, then anythings possible. But to use some logic and the visual clues, some of those videos show lathes that are in almost factory new condition including the paint condition. I think that alone rules out any feed screws or nuts were ever used enough to wear them out to require the previous owner to replace them with something incorrect. I’ve never owned or used any Lorch lathe, and it’s unlikely I ever will. But for lathes of this size, Lorch would also be towards the upper end of price, quality and accuracy. I think it’s much more likely that there were some definite design reasons for using opposite handed screws and nuts. I’m only guessing as to one possible reason, but since a telescoping power feed accessory could be used and shown in some of those videos. It’s not impossible that design choice, the available room and direction the change gears moved with the usual spindle rotation, they may have been forced into that decision. Lorch obviously wasn’t some tiny back alley lathe manufacturer, and they obviously had the resources to produce anything there designers came up with. There had to be a good mechanical reason to go against the almost universal direction lathes use for advancing or retracting the tool. In my opinion and whatever the real reason was, that’s still something that should have been redesigned until it was correct.

I’d also view owning any lathe that required a completely opposite rotational direction as having a major and built in design flaw if you also owned and use any lathe that has the more conventional direction of those same controls. It could even be detrimental to it or possibly the user just making a mistake in which direction those controls are used out of simple habit. Even George Thomas mentioned this briefly in his Workshop Manual book about the design of his geared top slide. He specified an opposite handed feed screw and nut compared to what Myford used on there Super 7’s just to maintain that same hand wheel direction. Those control directions and especially for anything produced in large numbers are almost always standardized even between dozens of manufacturers. With that, then it becomes simple to use without any conscience effort. In some cases it’s even required by law. Having to turn only some models and brands of vehicle steering wheels CCW to turn right would definitely create a bit of chaos on the roads. There are some controls that are purposely designed to be the opposite though. One I can immediately think of is the throttle on tracked bull dozers. Since there almost always operated at full engine rpm, that pedal works in the opposite direction everything else does, you press down to reduce the engine rpm. But that’s done simply for the operator, and it works well once you get used to it.

Just an idea. My Wabeco milling machine’s Y slide is configured so that the handwheel and it’s bearing are fixed to the machine base. The slide also has a right hand thread so that clockwise rotation of the handwheel results in the table moving towards the operator. This is a bit of a nuisance as I have another milling machine and a lathe which work in the normal way (clockwie rotation moves the gubbins away form the operator.

Looking at the Lorch lathe could it be that it has a right hand thread for the cross slide but the bearing extension for the handwheel passes through a clearance hole in the slide and is fixed to the saddle ? The only reason I can come up as why one would do this is to avoid the rotation loads on the handle moving the tool about (ever so slightly). But surely they were capable of making a left hand thread to make things ship shape.

On 4 August 2024 at 18:47 SillyOldDuffer Said:

On 2 August 2024 at 07:27 Kiwi Bloke Said:

Always glad to learn… So, likely to be original. Strange – I wonder why?

Ergonomics only got serious attention during WW2 when it was discovered that filling ships and aircraft with electronic equipment festooned with randomly placed controls operating in different ways overloaded the crew and got people killed.

Before WW2 equipment designers didn’t have much guidance and sometimes made poor choices, even on high-end tools.

 

 

They still make poor choices; just look at any electronic gadget that uses four buttons to control multiple functions. If you don’t have the instruction manual(assuming that it’s old enough to be printed and not some on-line thing) you’ll never remember that the emergency stop is used by pressing buttons 3&4 together for 4.7 seconds, then 1&2 consecutively for 2.9 seconds, while singing the Hallelujah Chorus backwards, at half speed, in a minor key whilst stroking your favourite rabbit’s foot. Similarly anything that uses a touch screen where more effort was spent on making the ‘buttons’ look pretty/fashionable instead of usable.