Thread: "L" pattern maker

Interesting that Bazza mentions patterns for precast concrete pipes. I have a reprint of A. A. Houghton's "Concrete from Sand Molds," originally published in 1910. For ramming sand molds for concrete or metals, wood is the material of choice for patterns.

In one of my previous lives, I was employed in architectural precast concrete manufacture. The company had got started making concrete practice bombs for WW2. They had an old patternmaker's lathe, which had been idle many years by the time I started there. They might have used sand molds at the time. One of the partners had experience in ornamental plaster, and they eventually used plaster of Paris, straight-run or rotary, for pattern construction. They still do, BTW. Instead of sand molds, they use concrete with suitable bond-breaker, to produce a production negative, and intermediate positives as needed for multiple negative molds. (The original positive is destroyed in the process of de-molding).

The proprietor of our woodturning club has a fine old Oliver. The tailstock is about the size of a lawn mower engine. I may have to use it when/if I get around to turning a large root ball.

Excellent find, GSRocket, and welcome aboard.

Cheers,
Joe

Hey Rocket, Our shop catered to all foundry customers large or small, whilst most of our customers were the large oil rig companies with all of their massive castings, ie:crank arms, gear boxes and counter weights weighing up to five tons we also did a lot of work for farm implement manufacturers like John Dear, International, McCormick Dearing , Alis Chalmers and Ford also we did a lot of work valve companies like Singer Valve with their massive Bell valves up to four ton casting weight for .
city water works applications.

We also did a fair amount of work for the shipyards down east building wildcats, props and anchors. The largest pattern that we made was for a bronze prop that was sixteen feet from hub to pitch which would cast a propeller thirty two foot across, I believe that it was for a tanker of some sort. It was a big job, the jigging and glue up took six weeks and then the real work started. A lot of mahogany went into that beast.

The pics that I have uploaded are from the last job that I did before going to University to become a Biologist. It was for a restoration project of a John Able steam powered tractor of which only one existed from twenty seven thousand made, they were all melted down for the war effort. The only things that I had to work from were the original castings sent from the steam museum in Ottawa Ontario. No plans and no drawings just old castings and some really grainy black and white photos. It was a bear, but it had a lot of gears in it and that had always been my job. If the job had gears it was sent to my bench. Damn I have cut a lot of teeth in my time. All manner of gears from cone gears to flat gears to screws, you name it and I made it. It's not as hard as people make it out to be but it's piddly work and one Really has to know how to make jigs.

I probably have more job pics laying around some where but it was along time ago and these were kept in an album as it was my LAST job as a Pattern Maker, now I just putter in my little shop in the basement Ya know just to keep the saw dust flowing in my veins.

Now the biggest problem I have is what to do with the several thousand board feet of Mahogany that was left in the shop when I shut it down, that and a massive storage shed full of pattern making equipment, tools that no normal wood worker could possibly have any use for due to their size and the fact that it's all three phase.

Of one thing I am sure and that is that these tools will not end up in the scrap yard, it's ALL Oliver and it's all in good shape and it won't be sold cheap.

Whoops they didn't all post.

Enjoyed your story Swallow. A massive change from patternmaker to biologist! But I went from train driver to photogragher then to roof tiling. Now I'm trying my hand at patternmaking, I'll see what I can make and then start casting it.
So what kind of work do you do in your work shop these days?
Thanks for posting the photos. I notice some of them are silver...Is this the resulting casting or a finish you use? And if you have the inclination I would like to see more photos.

Rocket: G'day, the silver paint on some patterns is part of a foundry code denoting what kind of metal is to be poured, in the case of silver it would mean that the castings were to be poured from Malleable iron which was a precuser to todays ductile iron which is of course much stronger than gray iron. I always did hate painting mahogany with colored paint, seemed such a waste.

As for what I do these days, well it's not much besides making the occasional tournament archery bow for a select few that are willing to wait till I gitaroundtoit . To me retirement means doing what I want when I want to do it so certain concessions have to be made.

I do still however make the occasional pattern for farmers in the area when they break a part on some implement and can't get a replacement part off of the shelf. I won't do any big stuff like front end transfer casings on four wheeled drive tractors, but small hubs, pulleys and gears is ok as it keeps the fingers nimble. As long as they can get the machining done. Once it was a job, now it's sorta fun.

If you run into any snags whilst making your patterns feel free to drop me a line and we'll see if we can't lend a hand.

Here we painted all of our patterns with shellac. We used three colours black was used for "off the mold" surfaces, Red used for all surfaces that were to be machined and yellow was used for where there was a core print.

We also used to make patterns for very large transfer gear boxes for Borg Warner. We also made patterns for the very first Ford Falcon gear boxes and diff housings. These were first cast in aluminium and then cleaned up and mounted onto aluminium plates. This was done to reduce the wear on the patterns from constant use.

I then later worked at the foundry that actually made the gearbox and diff housing castings in Malleable Iron called Malco Industries in Marrickville NSW.

Originally Posted by Barry_White

Here we painted all of our patterns with shellac. We used three colours black was used for "off the mold" surfaces, Red used for all surfaces that were to be machined and yellow was used for where there was a core print.

We also used to make patterns for very large transfer gear boxes for Borg Warner. We also made patterns for the very first Ford Falcon gear boxes and diff housings. These were first cast in aluminium and then cleaned up and mounted onto aluminium plates. This was done to reduce the wear on the patterns from constant use.

I then later worked at the foundry that actually made the gearbox and diff housing castings in Malleable Iron called Malco Industries in Marrickville NSW.

G'day Barry: Here the various colors would have been somewhat pointless as the moulder was not the coresetter, After the molds where made they were sent to the core room for core setts and then to pouring.

The only reason for various colors in these applications was to denote which type of metal was to be poured ie: gray 20,G30,G40,G80, Ductile,65,D80,D100, Malleable, White Iron or Black. The numbers above denote the strength of the metal in thousands of pounds per square inch.

Pardon my asking but what would have been the point of painting machined surfaces red as the Machinist probably never got to see the tooling and wouldn't have cared if he did as he is working from a blue print?

Also we never made any large patterns out of Aluminum, what we did for high run tooling was to make the master out of wood then send it to the foundry for sample casting. After it was ok-ed for production we then made a master mold using either Hydro Cal cement or plaster after which a permanent pattern would be cast using either Glass filled Urethane or glass filled epoxy. Either one would outlast aluminum ten to one and weigh one quarter as much as we used Balsa for the filler.

Oh and Rocket, do yourself a favor and don't use that crap called MDF or as it's known here "Termite Barf" With the Formaldehyde and various and sundry adhesives mixed in to keep this crap held together sooner or later it's gonna make ya sick. Oh sure you can wear a mask but sooner or later ya have to take it off and that crap dust don't just go away. Just because it's CHEAP don't make it good and when one considers the wear of the tools it ain't all that cheap either.

I am in awe of this body of knowledge, always heard stories of patternmakers shops who could create a timber master for mass production , thanks for sharing "the knowledge" Ross

Since it hasn't been expounded yet, a reason for different colors of the overall pattern for different metals relates to cooling shrinkage of the cast metal from molten to room temperature. To accommodate shrinkage, patterns are usually made oversize in different ratios for different metals. Different melt temperatures, and different rates of shrinkage, especially for iron, aluminum, and bronze. To make things even more jolly, peculiar parts of some castings may shrink not quite the same as their neighbors, so the needed pattern distortion must be found by trial and error. Worse yet, variations may exist from one foundry to another. Sand molds are soft enough to allow shrinkage to occur without imposing residual stress.

Hydrocal and plaster of Paris, OTOH, generally expand upon setting, although low-expansion formulations are available.

More than you ever wanted to know.

Cheers,
Joe

Originally Posted by joe greiner

Since it hasn't been expounded yet, a reason for different colors of the overall pattern for different metals relates to cooling shrinkage of the cast metal from molten to room temperature. To accommodate shrinkage, patterns are usually made oversize in different ratios for different metals. Different melt temperatures, and different rates of shrinkage, especially for iron, aluminum, and bronze. To make things even more jolly, peculiar parts of some castings may shrink not quite the same as their neighbors, so the needed pattern distortion must be found by trial and error.

Hydrocal and plaster of Paris, OTOH, generally expand upon setting, although low-expansion formulations are available.


Joe

And just what exactly would the color of the tooling have to do with the shrinkage of the metal Joe? I could paint any pattern designed for casting gray iron (paisley or Argyle ) and it would still shrink 1/8" per foot. Steel depending on the type would still shrink 1/4" per foot as would brass and bronze and Aluminum 3/16" per foot. Thats why pattern makers use a different shrink rule for each different type of metal to be poured (I still have 9) as it takes out all guesswork as shrinkage allowances are automatically factored in. Pattern makers DON"T as a rule use common rule ie: a tape measure except perhaps to rough measure out a piece before lopping it off a plank.

As to the isolated heavy sections there is very little trial and error as formula for this has existed for a very long time and this is in the realm of the engineer and the metallurgist not the pattern maker, besides shrinks or voids and distortions in isolated heavy sections are dealt with by the use of bosses, risers , pouring temperatures or chills not with paint. Sometimes distortions are built into patterns as in stove tops and panels but thats a completely different ball game, much too involved to get into here.

And BTW if memory serves, industrial molding plaster expands at 0.0018 inches/inch and Hydro-cal at 0.0005 inches/inch and this is on large molds and so is of virtually no concern to the pattern maker.

For identification. A pattern made for steel will produce an inaccurate casting if used for casting iron, or any of your other 8. More people are illiterate than color-blind. And lest you think it's limited to ancient history, I learned at a recent funeral for a very skilled mate that he couldn't read and write, according to accepted practice. He was smart enough, though, to develop his own "secret code."

The paint has nothing to do with distortions; should have been in a separate paragraph. And of course there have been great advances in technology in the past 40 years.

We used the same color-code trick to match-mark multiple concrete form components (otherwise identical) for repetitive assembly, and for the same reason as above.

Cheers,
Joe

Barry-White
1959 well at the end of it I was just a ich in my dads crouch, 1960 just born.
You know I do not know if you lot will think that I am mad but to think of a load of timber on the back of a truck brings shivers down my spine, your right you will never see that again.
I keep on thinking that we have seen the best of this world, that is why I love talking the to the older generation because once they are gone so will all the stores, keep them coming.
Not that I know any thing about pattern making but the not only did they have to make the pattern they had to think of the shrinkages in the material, well so I was told.
I believe that Swallow would be able to tell us more about.
Well nice talking to you guys, I love every minute of it.

Originally Posted by joe greiner

.......For identification.

I knew that's what you meant
Swallow I've got a few more questions, but i've got go so I'll ask later.
Thanks for the great discussion people