What Bar Stock To Start 3self Referencing Scraping Project

[Playingwithmetal]

Hey,
I am looking to start the 3 plate scraping method to obtain a self referencing flat surface. Or 3 to be more precise. I am debating ordering some dura bar which is expensive. I am also considering buying a cheap used cast iron surface plate and cutting it in 3 eaquel pieces and starting from that point with the scraping. Any advise or suggestions would be grately appreciated. This will be a first for me so any tips will help. Also if anyone has a cast iron surface plate they'd be willing to sell for cheap (maybe a plate in less then perfect condition would be a good place to start. )
Thanks
Dylan

 

[Kernbigo]

I did machine repair for 25 years and my share of scraping, the way i scraped surface plates and straight edges in, i used a granite plate as a master. The granite surface plates are calibrated every year. If they are out of calibration they are lapped in with diamond dust.Good luck .

 

[dlane]

I have found table saws cheep on CL, useualy get them for the motors but the tables are CI
(old craftsman) was thinking of making somthing out of them. That may be a source for CI

 

[Mac1]

May not be exactly what you had in mind, but its cast iron and if you bought three, you would have six surfaces to learn on and when you got done you would still have a useful piece of hardware. Other sizes are available.

http://www.use-enco.com/CGI/INSRIT?PMAKA=418-4320&PMPXNO=947172&PARTPG=INLMK32

 

[Bob Korves]

Dylan, if you cut up cast iron it will move around more than you think, and it can take stress relieving and time to settle down. Ringing it also helps. The three plate method absolutely works if done correctly, which requires more match ups than anticipated at first glance. It is a very slow, fussy, time consuming job, and essentially no one uses it today due to the availability of extremely accurate granite surface plates at low cost to use as reference surfaces. If you want to do it as a fun project for the joy of accomplishment, go for it! If you just want to have references for scraping, buy granite references and get on with it.