MYSTERY OBJECTS

[Stanley]

Exactly Bodge. This dates back to the days before modern circular dies. You had a selection of split dies and stocks and inserted the correct dies for the thread you were cutting and of course it was possible to cut under or over size. Remember the set of taps and dies for cycle threads dating back to about 1920/1930?


Now I'll have to think of another...... All right, it's an old carbon steel butcher's knife but what exactly was it used for?

[Nolic]

Boning or filleting? Nolic

[Stanley]

You're getting too good. It's a boning knife and from the size it would most likely be used on large carcasses.

[Big Kev]

Just an experiment to produce a "Big Kev" front page

[Whyperion]

Could you do a mystery objects explained thread as I cannot see how having square section die holding equipment can result in the ability to cut over or under size any more than using any appropriate die in a circular holder.

[Bodger]

Think of" stocks" as the thing that was put round your neck as punishment, the cutting die was a bit like that, the closer the stocks the smaller the thread, there was much more adjustment with stocks than with circular dies

[Whyperion]

So The tpi is constant , as is the pitch , but the depth of cut can be varied ? ( The square/rectangular parts have an amount of adjustment either loose laid in the holder or have a connections between halves they can move on ? )

[Stanley]

I don't even understand the question! There's only one way to really understand how an adjustable die works, get a bar of iron and a stock and die and start cutting. You'll soon work out how it can be adjusted. The dies are made so that if fully tightened they cut under size, the converse is that they can be slacked back to cut over size, a good thing if you're dealing with a worn thread in the hole. (That must be worth at least a small donation to the site!)


Closely related but different. How?

[Bodger]

Ive got the thread of this subject!!

[Whyperion]

I assume these could be for cutting external threads on pipes.

[Stanley]

Well done Bodge, I like your style....



Now then... Why did Johnny Pickles go to the trouble of machining a dovetail slide on the side of the saddle of his 1927 copy of the Birch lathe/ Don't bother going to look at other Birch lathes, you won't find this feature. It was a Johnny special!

[Bodger]

Take the tool post off, and replace with a flat T slotted table using the dove tails, you now have a lathe come boring machine ?

[Stanley]

I don't think so Bodge. There's a clue, what's the threaded hole in the side of the cross slide for?

[Bodger]

Stanley, not a mystery, but a link to the antique section of Practical Machinist, regarding a lovely bit of woodwork and metalwork, i wonder if anyone today would bother ?
http://www.practicalmachinist.com/vb/an ... et-112566/
also check this out, i have never seen this type of threading equipment
http://www.practicalmachinist.com/vb/an ... ke-111759/

[Stanley]

Interesting and I have come across Seller's threads before.
As for the last object, I'd better come clean.... The dovetail is to accommodate a rear tool-holder which is controlled by being fastened to the cross slide. It was used with an inverted tool for cutting, particularly parting-off, at the rear of the work-piece. The advantage of this method is that the forces transmitted to the workpiece are downwards on the front mandrel bearing. It is the tendency to lift the mandrel that causes a lot of the problems come across in parting-off as there is always a minute amount of play in the bearing and this allows chatter which is the start of a dig-in. I have often thought about making the tool-holder just for fun. If Johnny made it I haven't got it.

Same lathe. What's the bracket for that sits behind the headstock for?

[EileenDavid]

Too technical for me sounds like boys toys! Eileen

[Bodger]

I think ive got the angle of the bracket

[Stanley]

Bodge, if you are alluding to taper turning it could conceivably be used for that but there are easier ways of doing it. This was for a similar purpose. Try again......

[Stanley]

A deathly hush.... I'd better come clean. It's a bracket for holding a profile plate. Johnny used it for making small shaped items. You make a plate that is a reverse of the shape you want and fot a follower to the rear of the cross slide and this guides the depth of cut till you have the shape you want. I made the follower for it when I refurbished the lathe.



Try this one. Nothing to do with the shed.....

[EileenDavid]

A microphone for a giant Eileen

[Stanley]

It looks like it doesn't it. Clue. For some reason it's hanging on the front of the fridge with no visible means of support......

[Whyperion]

Velcroed or strong magnet pull tab enabling dog to open fridge to get best mince out when dog owner is out

[Stanley]

I'd better put you out of your misery. It's an orthopaedic wrist support that has five very strong magnets in it. I used it (under protest) when I broke my wrist and was surprised because I think it helped.

Try this one....

[StoneRoad]

Parking disc or other "timer".

Tide table calulator?

[Sunray10]

One of those disc lorry drivers use. Tachometer is that what its called?