Cast iron VS Cast steel lathe compound slide

Hi all,
In this heat today i have been inside with the aircon on, reading up on Leblond catalogs and service manuals whilst controlling the kids. I have found a spare parts diagram of the compound i need to make for Blondie, and can scale it off the cross slide dimensions and draw it up.
In the 1920 catalog though, it says "The top slide is made of steel casting giving the necessary strength to T slot and preventing breakage at this point".
I would presume that all smaller lathes would have cast iron slides, but would 4E cast iron really not be strong enough on a big machine, or do you think this may have been a good idea back then simply because the strength of the cast iron was not as good at the time?
The sides of the slots scale at 1/2" thick and protrude 3/8" into the slots.

Any thoughts would be greatly appreciated.

Edit, pics added, to give you an idea the slide is about 12 1/2" long O/A and 5 1/2" wide

Just found a pic of a slide i remembered i kept, from the notorious "leSmurf"

Can you upload a :photo2: of the diagram ?

Well, from the dimensions given, the T-slots would seem to be reasonably robust.

It could be the manufacturers had in mind workers on piece-work rates pushing the machines as hard as possible, and the topslide not surviving a crash. Did they typically use American style (lantern) toolosts at that time? In a crash those may be more prone to plucking the edge out of the T-slot, due to less contact area than with today's more typical block style toolpost and full length T-nut. Iron quality could be a factor, but I would expect they were pretty good at that by the 1920s.

Cheers,
Bill

Quote:

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Originally Posted by Ueee

"The top slide is made of steel casting giving the necessary strength to T slot and preventing breakage at this point".
I would presume that all smaller lathes would have cast iron slides, but would 4E cast iron really not be strong enough on a big machine, or do you think this may have been a good idea back then simply because the strength of the cast iron was not as good at the time?
The sides of the slots scale at 1/2" thick and protrude 3/8" into the slots.

Any thoughts would be greatly appreciated.

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In those slot dimensions cast iron would be OK for small lathe sized loadings. But when you step up to much bigger tooling ad overhang it may be a bit much and likely to fail.

Old cast iron was probably a bit more variable than new, but much survives to this day in pressure pipes, machinery etc, so it would have been up to the task at the time.

Cast steel was mentioned and probably for good reason. So I would go with that or plain steel.

Cheers

Rob

I believe that cast iron has 'self lubricating ' properties , there is graphite in cast iron , hence why it is great for engine blocks ..MIKE

Quote:

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Originally Posted by Ueee

Hi all,
In this heat today i have been inside with the aircon on, reading up on Leblond catalogs and service manuals whilst controlling the kids. I have found a spare parts diagram of the compound i need to make for Blondie, and can scale it off the cross slide dimensions and draw it up.
In the 1920 catalog though, it says "The top slide is made of steel casting giving the necessary strength to T slot and preventing breakage at this point".
I would presume that all smaller lathes would have cast iron slides, but would 4E cast iron really not be strong enough on a big machine, or do you think this may have been a good idea back then simply because the strength of the cast iron was not as good at the time?
The sides of the slots scale at 1/2" thick and protrude 3/8" into the slots.

Any thoughts would be greatly appreciated.

Edit, pics added, to give you an idea the slide is about 12 1/2" long O/A and 5 1/2" wide

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I would agree with comments from the others about GREY cast iron, but if $ are a concern, consider ductile Or SG cast iron, Automotive Crankshafts are made from it these days.Does any one remember the GMH 179 HP & 186S motors. Its very tough and can take shock whereas the GREY cast iron not so much. I don't think ductile cast iron was an option for the lathe makers in the 1920 s. Check it out as 3D iron.

Grahame

> I would presume that all smaller lathes would have cast iron slides, but would 4E cast iron really not be strong enough on a big machine, or do you think this may have been a good idea back then simply because the strength of the cast iron was not as good at the time?

On cast steel compound slides: the Emco Compact 8 is one of the most cloned lathes. These are generally known as Taiwanese 818 and Chinese 920 lathes. The Hare&Forbes AL50 is one of many such clones. The compound is of a very shallow design, there is not much "meat" in it. In the original lathe it was made from cast steel and works fine. The Chinese makers substituted cast iron for cast steel, and the consequence is that the compound slide has become the major target of modifications to increase its rigidity. It is also a common problem of this cast iron compound, that overtightening of the toolholder leads to a bulging of the compound surface around the toolholder stud. The lesson to be learned is that if a serious manufacturer decides it needs to be cast steel, one should not replace it by melted soup cans and still expect it to function as intended.

Now that is not to say that your topslide would not function perfectly well if you were to make it from good quality C.I. But if the maker decided to use a more expensive cast steel instead, there may well have been be a good reason. Chris

Thanks everyone,
I think it pretty well anonymous, it should at least be ductile cast or steel. My plan was to machine from stock rather than get the 2 pieces cast, so i guess i will machine the top half from steel and the bottom from CI, 4E or similar. Finding a piece of steel big enough could be an issue, at least locally. It will need to be roughly 12 1/2" long, 6 1/2" wide and 2 1/4" thick.

Hi Just a heads up.

The

Interlloy | Alloy Steels and Special Metals

metals site lists ductile as 3D and grey cast as 4E- just to clarify things.

The sizes were listed.

Grahame

Quote:

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Originally Posted by Grahame Collins

Hi Just a heads up.

The

Interlloy | Alloy Steels and Special Metals

metals site lists ductile as 3D and grey cast as 4E- just to clarify things.

The sizes were listed.

Grahame

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If you ring Interalloy and ask for a quote , they won't sell you small amounts of material, they want you to buy a whole billet or length which can run into many hundreds $$ , or thousands .

Thanks Grahame and Mike,
I'll have to get some from Sydney probably, Bohler have it, i started to think they didn't any more but found it under non-ferrous metals on their website:?
I'm pretty sure bohler will cut to any length, the worst bit is the 3D is only available in round bar and tube.