Carrier armour manufacturer?

[rob love]

Originally Posted by brengunman

W. A. M. Gregg in his Canadian Military Vehicles Profiles describes the manufacturing of the armour:

"Although a few hand built armoured cars had been built by Russell Motor Car Co. and others during the First World War, virtually no Canadian Manufacturer had any knowledge of bullet proof or armour plate production prior to 1940. The problem was further complicated by British advisors inferring that some mystical process was involved, which surely was beyond colonial comprehension. Metallurgists at Dominion Foundries and Steel (Dofasco) in Hamilton soon discovered, however, that good quality steel could take on all the desired properties through straight forward alloy and carbon adjustment. Dofasco established, through its tests in 1940, that a level of alloy well below that in allied use at the time, had optimum qualities for armour plate. The Dofasco formula was soon adopted by both American and British manufacturers. Dofasco was able to produce good plate but had difficulty with proper heat treating and straightening. Dietrich Saw Company of Galt had developed techniques for straightening large saw blades and were able to do the job with little delay. The plate was then sent to International Harvester Co. in Hamilton for punching and forwarded to Dominion Bridge Co. for hull fabrication which was done in an old plant south of Windsor which was reopened for the purpose."

George

George:
I was unsuccessfully looking for my copy of Blueprint for Victory so I could post that exact paragraph. Sounds like I was looking for the wrong book. Thanks for posting it.

[Lynn Eades]

Interesting that the steel was punched last. There must have been some good quality tooling for so many holes punched with a good level of accuracy.

[rob love]

That surprises me too. I have to wonder why they would not have punched them while still somewhat mild, then go through the hardening and straighteneing process. One would think the punching process woudl add stress to the plate.

As I mentioned earlier, on the hull I just sandblasted a couple weeks ago, it could be seen where the holes were cleaned up afterwards for things like the smoke discharger and the antenna mounts, but not for the rivet holes. Perhaps those were cleaned enough when they coutnersunk them.

[Lynn Eades]

Rob, maybe the hardening and straightening process changed the steel dimensionaly enough, so a to be sub standard?
The guys (and girls) involved from start to finish should have been proud of the quality end result.

[Bob Phillips]

I would like to throw a little information out about SDA - GALT.
I grew up in Galt about 3 blocks from the SDA plant. My neighbor was a traveling saw salesman and saw hammerer.In addition to a wide variety of handsaws SDA made the large ( 4 foot diameter) sawblades used in commercial sawmills. These type of blades are not flat but slightly dished so that at high speed they straighten out and run true. A saw hammerer was a skilled craftsman who traveled to service saw blades across Canada, and hammer them to run true again.
My mk2 carrier also was clearly labelled SDA GALT. The company closed 25 years ago ( maybe longer than that) and today the site is occupied by the new
Dunfield theater. Next to it is the large antique mall ( worth a walk through !!) that used to be the old Babcock - Wilcox- Goldie McCullough foundary where they made all manner of farm equipment, milling machinery, vault doors and safes etc. Back when we had industry close to home...B.P.

[rob love]

So Bob (and all), would the hammering marks on the armour be from a hand held hammer like a blacksmith's hammer, or was it more of a mechanised hammer forge type affair. I had assumed it was likely the latter, but when you talk about a travelling "saw hammerer" you almost make me think of a guy with a small chest of tools driving from mill to mill.

[Gordon Yeo]

The circular saw blades that Bob refers to had removable teeth that could be resharpened or removed when worn down or damaged. Keeping the saw running true in the kerf required it to have no distortion of the blade. If a spot on the blade over heated from excess rubbing and caused an expansion (bubble ) the saw would wobble beyond control and be unserviceable. This is where the saw hammerer services would be required. With proper training the hammer could hammer the steel back into its "flat" configuration and make the saw blade serviceable again. That is what must have been required to be done the armour plate for the carriers to flatten it.

Now, it's one thing to hammer a small area of a 3/16" thick saw blade back to flat by hand but it must have been a whole lot more complicated to hammer thousands of heavy carrier and Sexton plates.