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View Full Version : Continuous Cast Iron Dura-Bar



bpsbtoolman
01-03-2003, 02:34 PM
I recently purchased a 1-1/2" X 5" X 6" piece of Dura-Bar gray continuous cast iron to make a lathe tail stock base. It was flat and nearly square. Except for the dark larger flat surfaces it looked exactly like a piece of hot rolled steel. I made one .050" shaper cut to get below what I thought would be scale and it machined like hot butter with an excellent surface finish. Looks great for a scraped finish.
I occured to me this might be a great start on a precision scraped machine rebuilding tool. No pattern cost for many rectangular shapes, excellent machining,very little scale and no blow holes or hard spots.Check out www.dura-bar.com (http://www.dura-bar.com) . Lots of distributers.
This might be a neat group buy for a scraped tool or say a T slotted lathe crosslide or even gear blanks.
Walt

dpantazis
01-04-2003, 02:11 AM
dura bar IS great stuff. really economical.
great working. i have dealt with the dura bar folks personally on techinical matters as well. they are GREAT people. i wish that people knoew more about it. i may mention it to someone and they look at me funny...

the scraper straightedge thread has me thinking that it could actually make a great straight edge.

Forrest Addy
01-04-2003, 03:33 AM
Oh yes. A scraped reference made from continuous cast stuff can be a very fine tool but machining out excess weight could be a real chore.

Of course a small fitter's flat 15" or 18" long that weighs 20 lb would pose no probelm for the skeleto muscular system of the average plaid shirt wearer. Since the weight of comparable things goes up as the cube of their length, weight and deflection sooner or later becomes a problem in scraped tooling.

A fabricated bridgework properly stress relieved and carefully fitted and doweled to the reference prior to scraping may not comform to a purist's idea of a precision reference. If carefully done and used within a narrow band of temperature as the scraping temp there's no sensible reason why a composite technique wouldn't work.

Why a narrow band of temperature, you ask? Most cast irons have a slightly different coefficient rate of thermal expansion. 5 degrees one way or another may turn that laboriously made straightedge into a bimetal thermometer.

Before someone eagerly sets out to follow my suggestion let me emphasize that a composite steel fabrication/cast iron straightedge will require at least as much time and care -maybe more - in its manufacture as one made from a casting and it might be heavier.