Thread: The Journey for a Master Square

Originally Posted by Ueee

Why not look into a small granite square to scrape everything to? I'm not sure how Christian is going with the mob i put him onto, but i can get a 00 400x250x40 out of China and shipped to my door for $220.....and if the Xinxing surface plates are anything to go by they should be pretty good. Can't you test then with the Laser anyhow?
I was planning to be the guinea pig on buying a square from them and reporting back on what it is like.

I haven't chased this up further. I acquired a Wyler 0.02mm magnetic triangle square so the granite will have to wait.

Christian

Originally Posted by CGroves

I acquired a Wyler 0.02mm magnetic triangle square

Christian

Where are you blokes finding those levels? I have a search set up for those, Tesa & Wyler. I get Ebay spammed daily, but never see them.

R.C, Greg Q and now you have found them.

Regards Phil.

I found it on a UK site advertised as a "half box level".
USED METROLOGY EQUIPMENT SUPPLIERS USED ENGINEERING TOOLS TRIMOS TESA SUPPLIERS WESTERN TOOLING BRISTOL UK

I sent an email to ask if it was magnetic and triangular and luckily it was. It was from 2007 and I paid less than what "hotwheelinmum" was asking ).

I'll post a picture in the euro tool thread.

Christian

Neil,
I like your pattern, I would be interested to know where it ends up being cast.


Casting it myself seems the most appealing, second most appealing is getting someone else to do the fun part. Third is finding a crappy set of blocks and getting them up to spec, fourth is chopping up a machine beyond rescue.

I have sent off inquires to three different foundries, Grigsby, Wagga, and Billmans (Castlemain). I will see what comes back. If the price is too high it might be a trip down to the scrappy to find something I can make a cupola out of...

I did a quick FEA on the square and it will take a 100kg sideways force to push it out of square by 1.7µm, the box alone without the struts would move 0.04mm with the same loading.


PS Added a couple of handles.

Master Squares.JPG

-Josh

Grisbys got back to me, their prices are very reasonable, enough so to make it a feasible option, cheaper than buying an old worn out block and shipping it.

Now just to wait a few years for the cast to stop moving

Originally Posted by Pete F

Now just to wait a few years for the cast to stop moving

about 30-40 years should do it.. :P

Serious though, how long do you reckon they should be seasoned for in the heat treatment oven? a few days, a week, a month?

Hi Josh, try this:

http://www.dtic.mil/cgi-bin/GetTRDoc...c=GetTRDoc.pdf

Stress relief of grey cast iron.
An old US Navy document.
Neil

Originally Posted by Brobdingnagian

about 30-40 years should do it.. :P

Serious though, how long do you reckon they should be seasoned for in the heat treatment oven? a few days, a week, a month?

It depends on what temperature you take it to. Basically the hotter the temperature, the shorter the cycle and the more complete the stress relief. However (oh but so often there's so often a "however" ), IIRC there can be some be some metallurgical changes at the higher temperature that may not be desirable. I recall reading a paper on this some time ago, it's possibly on my machine, but I have no idea how to post a pdf. Around 600 C for 6 hours (at full material thickness) with a slow cool rings a bell, but don't for goodness sake quote me on that. I just remember the 600 for 6 rule.

I still have half a cuppa, and not much argon left, so I'll try to chase up the paper and then either see if I can either post it or find it on the net to post the link.

Pete

PS not trying to on any parade, nor doubt your casting ability, but if this is a master square you're building here, and based on some of the tolerances I've seen (admirably I might add) achieved and being called for, I wouldn't suggest casting your own. Anyone who has gone through the process of manufacturing or procuring precision cast references, such as the straight edges we bought a while back, knows that "iron ain't iron" when it comes to this field. My 2 cents for what it's worth, but hey, what would I know.

Edit: Oh Neil beat me to it, I'll need to type faster/drink slower. Yes I think that was the paper I had in mind.

I think you are right, a professional foundry has a better control of the quality of the casting than I do.

Cool thanks for info guys, I'm also having a re-read of the cast irons sections of the Heat Treater's Guide - Practices and Procedures for Irons and Steels by The Materials Information Society.

-Josh

Originally Posted by Brobdingnagian

'm also having a re-read of the cast irons sections of the Heat Treater's Guide - Practices and Procedures for Irons and Steels by The Materials Information Society.

Out of curiosity would you mind posting what is recommended there, as it's nice to file away. Although my oven is good for 1200 C I don't like the idea of taking it, or the material, and hotter or longer than I need to.

Pete

Originally Posted by Pete F

Out of curiosity would you mind posting what is recommended there, as it's nice to file away. Although my oven is good for 1200 C I don't like the idea of taking it, or the material, and hotter or longer than I need to.

Pete

For low alloy Grey Iron with 2.5% to 4% carbon and 1 to 3% silicon.

Summary:
Ferritizing 700-760C cool at 110C-290C/hr

Full annealing: 790-900C furnace cooled from 790 to 675C

Graphitizing: 900-955C hold for several hr/inch
For maximum strengh air cooled to 540C
For maximum machineability furnace cooled to 540C
For both cool from 540-290 at rate no more than 110C/hr

Stress reliving with minimum carbides:
540-565C for stress relief > 85% use 595C soak minimum 1hr/inch
furnace cooled to 315C or lower to as much as 95C for intricate parts

Normalizing:
885-925C soak at 1hr/inch furnace cool

Another Rendering.
MasterSquare HiRes.jpg

Originally Posted by Brobdingnagian

Another Rendering.
MasterSquare HiRes.jpg

#### that's good! Thne rendering even has a workshop background.... How the devil do you do it?
Can your CAD program tell you what it weighs?