Someone posted this earlier on the Practical Machinist forum: from the 3:25 mark you can see a short segment on sand moulds being assembled with sodium silicate cores to cast beds for the Colchester Chipmaster lathe. The rest of the film is quite interesting too:gang milling of the bed castings, induction hardening and then gang grinding bed ways, three castings at a time. The narrator mentions the painter (no mask) is using zinc chromate primer which is a hexavalent, known carcinogen and it's use correlates with cases of lung cancer in factories. The stuff should be bright yellow (colourized black and white film?.) so I'm not sure the grey paint contains much of it.
Zinc chromate.. Those were the good old days. Finest stuff ever made for aluminum. Today we are stuck using some half assed replacement phosphate stuff. It's utter CRAP, I can scratch it off with my finger nail. Cool video.
I'm learning fast that there's nothing even close to the sodium dichromate dip for zinc plating: it gives a self healing golden passivation layer with way more salt spray resistance than any replacement. According to some forums the trivalent chromate replacement eventually oxidizes back to hexavalent anyway.
lol... That sounds about right. One step forward, 2 steps back. I've had the pleasure of re-gluing my rear view mirror in my old car 3 times in the last month. The new stuff is useless. No doubt some twat screwed with the original glue formula to either save a dime or appease some group. The issue of zinc chromate is a serious one in the airplane world. Corrosion is a never ending battle for us and the new stuff just doesn't cut it. Now we get to waste expensive man hours every year revisiting previous areas that should have been fine for many years. These fckrs just don't get it. Wish I could boot them all right in the bread basket!
Wonderful video. I am seeking one of these lathes for my shop. I run a 13" colchester at work on occasion, delivered to my company in 1966. It is an absolute joy to run, one of the finest lathes I have ever had the pleasure of turning dials on. I was digging thru a file cabinet the other day in search of a wiring diagram for our Voest lathe and found the original manual & delivery paperwork for the colchester.
To me, they've always been a well built lathe, made in large quantities so they are available to the home user. I have a 1967 10" Bantam that was in a poor state but with a few repairs has been a really great lathe. I see in a Rolls Royce engine facility the apprentices are training on 1970's-80's vintage Colchester lathes.
I think the commentator of that film was an ex Colchester employee, hopefully more of these films will be unearthed and turn up on Youtube: I see a few channels with trades training course videotapes and films showing up now.
Also noteworthy to see the short duration of CO2 gassing of the silicate core—-maybe five seconds? Denis
I was surprised at the depth of hardening for such a setup, I wonder what the gas pressure was?. A friend I showed that video to, pointed out that almost all those English factories for woodworking or metalworking machinery did all their castings in-house. I guess that makes sense for a lot of reasons
Ya... The English had a way of building something that would last forever. The bace of my tablesaw casting weighs over 500 lbs.
