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KEJR
12-15-2010, 07:54 PM
Hello,

Anyone know if the semi steel chucks hold up to hobby use? I'm looking at maybe getting a Fuerda "adjust tru" chuck from Tools4Cheap and their semi steel chucks are significantly cheaper than the forged hardened chucks ($270 vs $440 ish US). From what I understand is the Fuerda is a very high quality chinese chuck.

From what I understand is that semi steel is basically cast iron with a little scrap steel thrown into the mix. Unfortunately this probably could be any hardness as it doesn't seem to be a tightly defined spec. I don't know what is typical.

I know many a chuck was made out of cast iron but does anyone know if this type of chuck is good for occassional use or would I be better off buying their forged and hardened steel version?

BTW, the RPM rating of the chuck is 3000RPM which is double that of my lathe capability.

Thanks,
KEJR

dalee100
12-15-2010, 09:12 PM
Hi,

You'll be fine with a semi-steel chuck. You won't be doing 10,000 part runs so it will out last you.

dalee

gwilson
12-15-2010, 09:19 PM
Forged steel chucks can stand higher speeds than cast iron or semi steel chucks. If you don't have a Monarch EE,doing 4000 RPM,I wouldn't worry about it. And,don't use a "cheater bar" to tighten your chuck.

J Tiers
12-15-2010, 09:26 PM
You'll probably wear out the scroll, the jaws and the jaw ways before any other problems occur......

DR
12-15-2010, 09:59 PM
The Buck Adjust-Tru chucks are/were semi-steel bodied. They will break if mishandled, like one of mine that cracked where the jaws slide in from having a chunk of steel extending too far out from the jaws unsupported by the tailstock.

Definitely operator error.

ulav8r
12-15-2010, 11:07 PM
What is semi steel? Maybe it is still the same thing that Henry Bessemer described.


A quote from Henry Bessemer"Before concluding these remarks, I beg to call your attention to an important fact connected with the new process, which affords peculiar facilities for the manufacture of cast steel. At that stage of the process immediately following the boil, the whole of the crude iron has passed into the condition of cast steel of ordinary quality; by the continuation of the process the steel so produced gradually loses its small remaining portion of carbon, and passes successively from hard to soft steel, and from soft steel to steely iron, and eventually to very soft iron; hence, at a certain period of the process, any quality of metal may be obtained. There is one in particular, which, by way of distinction, I call semi-steel, being in hardness about midway between ordinary cast steel and soft malleable iron. This metal possesses the advantage of much greater tensile strength than soft iron. It is also more elastic, and does not readily take a permanent set; while it is much harder, and is not worn or indented so easily as soft iron, at the same time it is not so brittle or hard to work as ordinary cast steel. These qualities render it eminently well adapted to purposes where lightness and strength are specially required, or where there is much wear, as in the case of railway bars, which, from their softness and lamellar texture, soon become destroyed. The cost of semi-steel will be a fraction less than iron, because the loss of metal that takes place by oxidation in the converting vessel is about 2 1/2 per cent. less than it is with iron; but, as it is a little more difficult to roll, its cost per ton may fairly be considered to be the same as iron. But, as its tensile strength is some 30 or 40 per cent. greater than bar iron, it follows that for most purposes a much less weight of metal may be used, so that, taken in that way, the semi-steel will form a much cheaper metal than any with which we are at present acquainted. "

KEJR
12-16-2010, 10:09 AM
Well, sounds like the semi steel chuck is a good deal then. I have a 3 jaw chuck now but it doesn't have outside jaws and it is not adjust tru. I figure getting a new chuck with adjust tru and 2 piece jaws will be a very good upgrade, especially since I can use soft jaws too.

I think the thing with the chuck is that even though the jaws take alot of force, at the point it is tightening up there is very little sliding motion. Really only the amount it flexes once the part is gripped, which is not much, probably less then a thousandth.

Were all the buck chucks cast? I find this hard to believe. We have some at my work that are all dinged up and they don't chip like cast iron seems to.

Thanks,
KEJR

dalee100
12-16-2010, 05:55 PM
Hi,

That's because they're probably semi-steel too. Last new Buck I ordered for work was probably 10 years ago now. It was a 14" Buck 4 jaw. That was semi-steel.

dalee

lazlo
12-16-2010, 06:38 PM
What is semi steel? Maybe it is still the same thing that Henry Bessemer described.

Interesting. Forrest posts a missive from time-to-time about semi-steel, and the lack of standardization of the term. From Forrest's post, it sounded like the remnants of the pig with a bunch of scrap steel thrown in to reduce the overall carbon content.

Edit: found Forrest's post on semi-steel:


http://www.practicalmachinist.com/vb/general-archive/mounting-plate-material-80372/#post94163

"For the record almost all steel contains a "lot" of scrap. Steel is being continually re-cycled into new products. Steel from smelted ore cannot furnish more than a fraction of the steel demand in the US. The greater share comes from the recycling yard.

It's possible your grocery getter contains scrap from 19th century railroad equipment, old Liberty ships, stainless flatware that had no takers from an estate auction, bicycle frames, obsolete typewriters, washing machines, rust belt machinery, etc; some on its umpteeths recycle generation. It's enough to send the imaginative off on a "if this truck (toaster, suspension bridge) could only talk" revery.

Scrap content has no effect on the quality of the alloy provided the analysis showed the proper proportion of constituent elements and the detremental elements (sulfur, lead, etc) were at their allowable maximums or less.

Malleable iron, semi-steel, etc are all steel mill products having metallurgical input as well as every effort by the bean counters to utilize every mill by-product and cut every corner. Steel mills have to make a profit. They also cannot afford to disappoint sophisticated and picky customers. Thus the balance between quality and economy is more finely drawn in commodity metals than it is say' for beer, Costco flannel shirts, or 6 HP shop vacs.

So scoff with care. This from: http://indmetals.com/glossary.asp?Start=30&Offset=10&ftype=alpha&letter=s "Semi-Steel: High quality cast iron (not steel) obtained by commissioning a large percentage of steel scrap with pig iron."

While a low cost product semi-steel is made to definite standards and has mechanical properties warranted by the manufacturer for certain applications including chuck bodies.

As for limiting RPM of faceplates they frequently have eccetric parts or large bending loads on them from set-up hardware. I've seen set-ups that were scarey looking at 30 RPM let alond 900.

Someplace Cushman published a technical paper on workholding when counter-centrifugal chucks were coming on the market. 8" units were being developed to reliably grip work up to 7000 RPM. In it, I dimly recall, is a table of safe operation for different classes of conventional lathe chucks and the RPM for "centrigugal grip relief" by size."

oldtiffie
12-16-2010, 07:49 PM
I have several "Fuerda" chucks and I am very satisfied with them.

oldtiffie
12-16-2010, 08:05 PM
Originally Posted by ulav8r
What is semi steel? Maybe it is still the same thing that Henry Bessemer described.


Interesting. Forrest posts a missive from time-to-time about semi-steel, and the lack of standardization of the term. From Forrest's post, it sounded like the remnants of the pig with a bunch of scrap steel thrown in to reduce the overall carbon content.

Edit: found Forrest's post on semi-steel:


http://www.practicalmachinist.com/vb/general-archive/mounting-plate-material-80372/#post94163

"For the record almost all steel contains a "lot" of scrap. Steel is being continually re-cycled into new products. Steel from smelted ore cannot furnish more than a fraction of the steel demand in the US. The greater share comes from the recycling yard.

It's possible your grocery getter contains scrap from 19th century railroad equipment, old Liberty ships, stainless flatware that had no takers from an estate auction, bicycle frames, obsolete typewriters, washing machines, rust belt machinery, etc; some on its umpteeths recycle generation. It's enough to send the imaginative off on a "if this truck (toaster, suspension bridge) could only talk" revery.

Scrap content has no effect on the quality of the alloy provided the analysis showed the proper proportion of constituent elements and the detremental elements (sulfur, lead, etc) were at their allowable maximums or less.

Malleable iron, semi-steel, etc are all steel mill products having metallurgical input as well as every effort by the bean counters to utilize every mill by-product and cut every corner. Steel mills have to make a profit. They also cannot afford to disappoint sophisticated and picky customers. Thus the balance between quality and economy is more finely drawn in commodity metals than it is say' for beer, Costco flannel shirts, or 6 HP shop vacs.

So scoff with care. This from: http://indmetals.com/glossary.asp?Start=30&Offset=10&ftype=alpha&letter=s "Semi-Steel: High quality cast iron (not steel) obtained by commissioning a large percentage of steel scrap with pig iron."

While a low cost product semi-steel is made to definite standards and has mechanical properties warranted by the manufacturer for certain applications including chuck bodies.

As for limiting RPM of faceplates they frequently have eccetric parts or large bending loads on them from set-up hardware. I've seen set-ups that were scarey looking at 30 RPM let alond 900.

Someplace Cushman published a technical paper on workholding when counter-centrifugal chucks were coming on the market. 8" units were being developed to reliably grip work up to 7000 RPM. In it, I dimly recall, is a table of safe operation for different classes of conventional lathe chucks and the RPM for "centrigugal grip relief" by size."

A very interesting post Lazlo.

Great article by Forrest Addie as well.

That inclusion of "scrap" as opposed to only new iron (ore) is a very timely item.

Some here have rejected that process as "poor" and only fit for or carried out by those in China and India etc. as justification for the poor products from those places.

Provided that the process is completed correctly and has the correct analysis and metallurgical qualities it will be OK when-ever and where-ever it was made.

I'd be the first to say that some cast and wrought stuff from China and India IS poor - but not all of it - as some very good product comes from there. Its just a matter of finding and paying for it.

I wonder how well those who cast cast-iron and aluminium from scrap as a hobby measure up as regards process and quality.

ulav8r
12-16-2010, 10:37 PM
I do not intend to argue the matter with anyone, but my uneducated thought is that Henry Bessemer was the man that originated the term semi-steel and is therefore the authority on the subject.

I am not willing to take the time to explore further, if someone else wants to do so that is fine with me.

lazlo
12-17-2010, 10:25 AM
I do not intend to argue the matter with anyone, but my uneducated thought is that Henry Bessemer was the man that originated the term semi-steel and is therefore the authority on the subject.

Robert, I wasn't arguing Henry Bessemer's definition, just repeating Forrest's explanation that in practice, semi-steel is scrap added to the remnants of the pig as an economical way to use the last bit of the melt.

As was stated, and re-iterated by Forrest's post, high-quality chucks are made from semi-steel. It's not a particularly demanding application, unless you're on a high-speed chuck (which are forged or alloy steel).