Thread: From Tractor Weight to Inspection Square

Originally Posted by Machtool

You two blokes better put a Talyrond on your Ebay / Grays watch list.

Regards Phil.

Thanks Phil, I had to google it to find out what it is.... they seem to come up on Gray's every so often... this one went for $387 with manuals and software..

Talyrond 32 Roundness Analyzer with some manuals and software Auction (0007-7002472) | GraysOnline Australia


A model 100 with some pictures...
Taylor Hobson Talyround 100 Roundness Tester - Asset #tst307826 - GoIndustry DoveBid

And of course ebay...
Taylor Hobson Talyrond 100 Rundheitsmessgerät Testgerät Prüfgerät Messgerät 4773 | eBay

Taylor Hobson Talyrond TR150 11 Surface Roundness Tester Controller Parts | eBay


Now to figure out how they work?

Regards
Ray

Originally Posted by RayG

I'm only aware of one, that is 1x10^-6 meters.. What's the other one?

Regards
Ray

Ray

I'm quoting from Wikipedia (not the best source of accurate information).

"In engineering it is common to use the micron as a replacement for the traditional thou or mil, each of which represent a thousandth of an inch. 1 thou = 1 mil = 25.4 microns. So a trash bag (in British English: a rubbish bag) may be originally specified as 0.35 mil thick, but stated as 8.89 microns".

Gene

Originally Posted by Brobdingnagian

Gene, The miron I'm referring to is micrometer not a microinch.

-Josh

Thank you, Josh. Very impressive to be able to work to that tolerance on such a large piece of iron.

Gene

Yeah I'd scrape that puck and see if it moved any after another cook. I'm personally very curious. I doubt they took much care when casting a tractor weight and it would be good to see whether that one cycle was enough to get it settled down. Likewise I agree, I wouldn't dick around with the square if it were me, at least not unless the puck did a pretzel in the oven.

Good to hear you also liked MH29. I just have to figure out how to get it to work when off-line so I can bring it up on my iPad when i don't have internet coverage. I think MH29 was a big step forward with metric, good to see the Americans finally coming, kicking and screaming, into the 19th century

I still do like my Black Book for workshop use however and I don't think MH29 will ever leave my office/computer, but it sure seems to be much better than it was.

Pete

I've been thinking about this one over the last day or so, and I'm not sure that the puck will move much. Stresses in castings come about from one part solidifying before another (especially rapid solidification - like the white iron on the surface). The chances are that the puck cooled relatively slowly and being in the middle of the casting was subject to relatively uniform stresses from the surrounding material.
If one side was skin and the other side the middle of the casting then there would be some movement but slap bang from the middle I think it won't move much.
Remember when aging castings, the aim is for them to settle to an equilibrium condition. These weights may have been 30+ years old and certainly would not have been moving. However, take off a skin or thin a section and it will move. That's why when machining castings it is recommended to do a rough cut, let it rest for a while (I've seen a week or two minimum) and then do the final cuts. Given that the square was done in one go, it might be interesting to measure it in say a month and see whether it has moved after that.
The best analogy that I can think of is an old fashioned canvas tent with zillions of guy ropes. It will stay the same shape until the tension in a guy rope changes. It will then move to a new equilibrium position in which it will stay until the next rope tension change.

Michael

Originally Posted by Michael G

I've been thinking about this one over the last day or so, and I'm not sure that the puck will move much. Stresses in castings come about from one part solidifying before another (especially rapid solidification - like the white iron on the surface). The chances are that the puck cooled relatively slowly and being in the middle of the casting was subject to relatively uniform stresses from the surrounding material.
If one side was skin and the other side the middle of the casting then there would be some movement but slap bang from the middle I think it won't move much.
Remember when aging castings, the aim is for them to settle to an equilibrium condition. These weights may have been 30+ years old and certainly would not have been moving. However, take off a skin or thin a section and it will move. That's why when machining castings it is recommended to do a rough cut, let it rest for a while (I've seen a week or two minimum) and then do the final cuts. Given that the square was done in one go, it might be interesting to measure it in say a month and see whether it has moved after that.
The best analogy that I can think of is an old fashioned canvas tent with zillions of guy ropes. It will stay the same shape until the tension in a guy rope changes. It will then move to a new equilibrium position in which it will stay until the next rope tension change.

Michael

Here is a graph of the temperature over the last 24hr or so..
Furnace Cooled.png


I think you probably are right the cooling rate is slow enough.. but it won't hurt to do the experiment.

-Josh

Just as an aside, with the ageing process, weren't the castings in Germany put into an ice cold river for a year or more??

Phil

Getting sick of saying "Great work Josh", but what else is there to say?
Great work Josh


<waffling on>
I'm not 100% sold on "myth" as yet. About 98.5% though
I don't think anyone would have said aging in the paddock would turn white cast iron into gray cast iron. I'm pretty sure the guys casting tractor weights wouldn't be surprised when told they weren't suitable for making master squares. Who knows how they were cooled? More likely in 3 minutes than 3 days. Though granted there have been all sort of stories over the years. RR was meant to age casting in the yard. Maybe its a story the foundry manager came up with when the accountant asked him why they had 3 years stock? BMW were supposed to have used old engine blocks for their 1.5l turbo F1 engines.
I'd agree that a trip through the furnaces will speed things along more than a little. I cant imagine how useful figures could be obtained one way or the other......unless someone has 30 years on their hands. Other than remeasuring your square in say 6 months and see if it has moved at all?
I wonder if in a perfect world there would be some steps in the cooling cycle. Like cool at max 100degs an hour, hold at XXX degrees for 1 hour per inch, then continue cooling? basically the reverse of preheating steps with tool steel, I've no idea. I don't think I have any graphs with for cast. Does cast even have transition phases?
Sorry for the waffle.

Stuart

Great Work the Square looks great.

Originally Posted by Michael G

Remember when aging castings, the aim is for them to settle to an equilibrium condition. These weights may have been 30+ years old and certainly would not have been moving. However, take off a skin or thin a section and it will move. That's why when machining castings it is recommended to do a rough cut, let it rest for a while (I've seen a week or two minimum) and then do the final cuts. Given that the square was done in one go, it might be interesting to measure it in say a month and see whether it has moved after that.

Michael

Originally Posted by Stuart

I wonder if in a perfect world there would be some steps in the cooling cycle. Like cool at max 100degs an hour, hold at XXX degrees for 1 hour per inch, then continue cooling? basically the reverse of preheating steps with tool steel, I've no idea. I don't think I have any graphs with for cast. Does cast even have transition phases?

Complicated business this heat treating cast iron.. The last cycle is supposed to have converted the carbides to graphite, not sure how much gets converted to spheroidal graphite or not? But to answer Stuart's question, yes cast iron goes through phases, and changes in structure can get complicated.. I'll get the book off Josh and re-read the chapter on Gray Cast, see if that helps or just deepens the confusion...

Stress relieving, and dimensional changes aside, changing the hard carbides to graphites should have a marked impact on machinability.

Regards
Ray

Those weights were most likely made out of the cheapest, crappiest cast iron you can get, or the dregs of the pot after all the molds were filled.. Probably one thing to keep in mind about them..

Originally Posted by Stustoys

Getting sick of saying "Great work Josh", but what else is there to say?
Great work Josh




<waffling on>
I'm not 100% sold on "myth" as yet. About 98.5% though
I don't think anyone would have said aging in the paddock would turn white cast iron into gray cast iron. I'm pretty sure the guys casting tractor weights wouldn't be surprised when told they weren't suitable for making master squares. Who knows how they were cooled? More likely in 3 minutes than 3 days. Though granted there have been all sort of stories over the years. RR was meant to age casting in the yard. Maybe its a story the foundry manager came up with when the accountant asked him why they had 3 years stock? BMW were supposed to have used old engine blocks for their 1.5l turbo F1 engines.
I'd agree that a trip through the furnaces will speed things along more than a little. I cant imagine how useful figures could be obtained one way or the other......unless someone has 30 years on their hands. Other than remeasuring your square in say 6 months and see if it has moved at all?
I wonder if in a perfect world there would be some steps in the cooling cycle. Like cool at max 100degs an hour, hold at XXX degrees for 1 hour per inch, then continue cooling? basically the reverse of preheating steps with tool steel, I've no idea. I don't think I have any graphs with for cast. Does cast even have transition phases?
Sorry for the waffle.


Stuart

Stuart,


Thanks, I'm trying hard on this one to push the boundaries, as it will be good to have the skills, techniques and understanding for the master squares.


In the regards to the waffle. The main reference I use for heat treatment and the book that Ray wants to get back is the "Heat Treater's Guide - Practices and Procedures For Irons and Steels by ASM International - The Materials Information Society". It is a tome that is as weighty as its title suggests and has recipes for treatment profiles and graphs for the various irons and just about every imaginable steel.
One of the problems with the scientific treatment of the iron is the composition varies quite a lot even the types. The US Navy research document (which I will find a link to) tested iron from the same batch to eliminate variability in the materiel. From memory they conducted a study on a set of standardised wheel stres sections over longish time intervals (6 month or so).
See Attached

-Josh

Originally Posted by .RC.

Those weights were most likely made out of the cheapest, crappiest cast iron you can get, or the dregs of the pot after all the molds were filled.. Probably one thing to keep in mind about them..

It does have some minor defects in the way of a few pin holes, but you have to go looking. In general it seems to be of a good quality casting at least 1000 times better than the iron in the Chinese mill castings. Also after being heat treated the iron texture is much finer with evenly distributed rosettes. All in all it was an improvement in constancy and i hope stability. It is has improved the iron enough that I would recommend it when recycling iron. I'll see if I can get a microscopic picture, I think Ray has one of those usb toy microscopes.

-Josh

Originally Posted by RayG

Complicated business this heat treating cast iron

Life was some much easier when I had the illusion that steel stayed where you put it, unlike that stuff the grows in trees.



Thanks for the reading Josh.

Originally Posted by Stustoys

they weren't suitable for making master squares.

Just to be clear for others, I meant as cast. Not after a trip through the oven.

Stuart

After two days cooling in the furnace the iron finally reached the 90C that I was waiting for. Here is a picture that you did not get to see when the inspection square went though the furnace. Also for the inspection square I warped it in some stainless foil to minimise (graphite?) scale from the high temperature cycle.

DSCN2854.jpg
( Notice that there is quite a lot of carbon in the surface (I presume in the form of graphite) giving that very grey colour)

Because the inspection square was wrapped in the stainless foil it only had a light even dusting of grey that could be rubbed off with a rag. I only use the foil on items that scale would effect the required dimensions as it is costly and make the items hard to handle. Where as these piece have a very pronounced bumpy coating of grey that will need to be attacked with a wire brush.

Before putting them into the furnace I striped them of the majority of the paint, but there are some flaky deposits that are remains of the paint that was suck on too well to bother with.

-Josh