Toolmakers block

March 2013

I got a small cast iron ingot as they are used in foundries to cool down certain parts of a casting during the casting process (Chill blocks).

I decided to make a toolmakers block out of it – That is basically a perfectly square and parallel block with a few threaded holes that can be used as a setup tool on machines. Especially usefull when you have to machine surfaces square to each other.
Mine is inspired by a sketch out of the book “Machinists Bedside Reader” by Guy Lautard

Once I had the basic dimensions sorted out I cut it to rough size on the bandsaw, which is in my mind still the fastest way of material removal – And the cheapest.

I ended up with a block that had a few millimeters of allowance for machining and scraping.

The machining was done on the shaper and I tried to get it as square as possible to keep scraping to a minimum.

The first side was scraped flat – That time around I did not have a powerscraper and no good way to resharpen the carbide blade of my handscraper, I had to use a diamond file which worked not very well.

Checking the block for parallelism. The numbers written on the block are 1/1000mm increments. The gage block is used to bridge the scraping valleys.

Checking for squareness – The block rests against the lower edge of the indicator stand and the indicator shows how much the block is out of square (Of course this setup has to be calibrated with an accurate angle standard).

What followed then was a lot of scraping and rechecking to get every surface square to its neighbor and parallel to their opposing surface.

After I got the block all square and parallel within 5/1000mm on all surfaces, I chamfered all the edges:

Slots where added so the block can be clamped on the machines table with strap clamps:

The finished block, with a grid of threaded holes and two fences:

Here some examples how the block can be used to align and hold workpieces. Once you clamp a part to the block and keep it clamped, it will stay square no matter in which direction you flip the block:

I made a wooden box with some green felt as a permanent storage and to protect it from the shop environment when not in use: