1) What's the best way to cut this thing with least distortion/bulging at the cut line? I'm thinking angle grinder with a thin cutting disc?
Rich -- Unless the CI has been hardened you are better off making chips than abrading it. Abrasive cutting tends to get hot (that's what those bright flingy things represent). Uneven heat creates distortion. A bandsaw with lubricated coolant will almost certainly be better.
I have (in storage) an old 8 inch table saw for which I devised a multi-step, multi-pulley speed reducer. The lowest speed setting on it makes the blade turn at 60 sfm and the highest speed setting makes the blade turn at 1000 sfm. I also devised a weight & pulley system to pull material through the blade (crosscut & rip) so I don't have to stand there and push. I also added a "drip coolant" system to carry away chips and heat. I have used this for years to cut down steel bar and plate from the local steelyard's "drop" pile and it is
wonderful!If you can find an old CI table 8 inch saw, this would be a relatively simple solution -- and add new capabilities to your shop.
My problem is that my shop fits really nicely in 2500 sq ft of space and I am currently limited to 880 sq ft -- meaning that most of my tools are living in a storage unit until things change in this regard...
2) I understand how to scrape a surface flat, but I'm struggling to decide how to scrape one surface of a right-angle jig such that it's perpendicular to the other. Is there a way I can do this with some clever setup of indicators, or do I need a right angle reference to blue off? If I make two at once does that help somehow? I have a height gauge, precision ground square and the usual assortment of accessories but I don't have any decent quality right angle plate to reference off.
When you say,
precision ground square, does it have a knife-edge? If so, there's a way to simplify things. Scrape a small area on each end of your angle plate such that you get a
no light fit between your surface plate and the square's edge. Now you have
reference surfaces to which you can work as you scrape that surface flat. Your final
check is that your second surface is flat to the surface plate and that it is square to the first surface.
I used to do a lot of work for the (American) National Bureau of Standards (before it was dismembered into the National Institute of Standards Technology -- and made a
protector of intellectual property rather than a
promulgator and enforcer of standards). They had a set of (approximately) 6 inch diameter cylindrical squares used to check squareness by blowing air between them and the object to be tested. The air flow rate between the cylindrical square and the test object was measured in very small (vertical) increments. When the flow became constant over the mating distances, the item could be certified as square. (I have obviously glossed over a number of
issues in that summary. The
test specification was a seriously multi-hundred page document.) That set-up could measure squareness within .0000002 inches/inch of height.
This will hopefully give you some ideas. Good luck!
