New Design 30 X 12" Featherweight Rectangular Cast Iron Square Design Available 55#
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  1. #1
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    Default New Design 30 X 12" Featherweight Rectangular Cast Iron Square Design Available 55#

    A while back a customer who owns a CNC tool manufacturing company asked if I could design a 30 X 12 x 4" rectangular cast iron square that would weigh under 60 pounds. He advised me there is no such square and never has been such an item available and wanted one for use in his shop and to take with him when traveling to his customers business's for calibration of their machines and for use in setting up their tooling.

    I felt it could be done but realized molding and casting a square of those dimensions from cast iron would be a challenge. I am happy to report that I got the job done and he is pleased. He feels there will be other manufacturers of CNC and related equipment manufacturers who will want to buy such a device. I am announcing availability of the square here too in case someone here is interested.

    As cast the square weighs 55 pounds and likely will end up weighing a shade under 50 pounds. It is cast in grey iron. It is quite rigid as I have subjected it to deflection testing and it has exceeded expectations and his specifications.

    Here are a few pics of the pattern from which it was cast. I made it from baltic birch. As you can see it is a split pattern.

    square-pattern.jpg


    Here is the first casting (which I rejected) of the square.
    img_6528-1-.jpg


    img_6530-4-.jpg
    img_6525-2-.jpg



    img_6529-1-.jpg


    My customer promises pictures of his machining and grinding of the square. I will check with him about using the pics when they are available. I am nearly certain he will have no objection.

    He will be using this square in place of his very heavy large granite squares which he presently uses and the 12K ceramic square which an employee dropped---entropy had its way with the ceramic---and the granite is very inconvenient to move around in his shop let alone travel with it.

    Here is a video of the pour. Note that the crucible is very full and I have just enough metal to fill the mold. I dare not spill any and that is especially challenging when pouring from a FULL crucible. Aiming the first few pounds of iron from a 3/4 full crucible is pretty easy. Not so much with a 90% full one.



    This was a very challenging design/build task and very gratifying to have a useful unique product.

    Denis

    PS I have in stock my other SE's---the 8", 18', 36" and 48"

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    Doing much with your social isolation time?

    ;-)

    Stan.

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    Well, like everybody else, I do miss friends and family together times. But I am looking for ways to find a silver lining, I doubt I am alone in getting some things done that have been pushed back a bit previously---like the square. So, now I have a couple or 3 more hours for shop time each day. In that time I have made some significant upgrades to the foundry (like the completely wireless foot-controlled variable-speed lift I designed and built---so incredibly handy for sand molding) and really enjoyed longer chunks of time for various casting and shop activities. That is how I have been able to catch up on casting the other 4 items in the growing Featherweight line of cast iron metrology equipment.

    Always good to hear from you, Stan. I trust all is good with you. I would guess you have not been sitting on your hands either.

    Denis
    Last edited by dgfoster; 05-07-2020 at 09:29 AM.

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    Yup, you are correct. Long delayed projects are done, projects that I thought might be started next year are well underway. Only minor frustration is inability to leave my own province. This is small potatoes though compared with bigger issues.

    Nice job Denis!

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    Denis-
    That is super! I want one. How much are they going to cost?
    Hahn Rossman

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    What is the as-cast price? I have a 36" cylindrical square and a 60" box parallel/square and they are two man and forklift move only.

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    That's a beautiful casting, the shape of the reinforcement webs is very satisfying. I'm also very interested in the pricing whenever you've figured that. This could be a good purchase for next winter's scraping project.

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    I am very pleased by the interest you guys are showing. I am working on pricing.. I’ll try To have an answer tomorrow. Your patience is appreciated.

    Denis

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    Very very cool to see your casting setup! I would love to build a setup like that one day, looks very well thought-out! The square looks beautiful as well!

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    I have thought some about the pricing question. I am going to sell these castings for 650 dollars each. Shipping will be around 100 dollars to the East Coast and packing done by a local shipper is about 65 dollars.

    I have sold two at that price which I think is a fair price.
    email me if interested as PM's are sketchy in reliability. denisgfoster at gmail dot com

    Denis

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    Any chance of doing one a tad smaller? Say 12 x 24 x 3" or 12 x 18 x 3? Ken

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    Not likely soon. Let me explain my wanting not to jump right in to a different size.The number of hours that goes into making a pattern is amazing. It takes a lot of time to not just make the pattern dimensionally. That is pretty easy. But every inside corner and corner junction has to be filleted very smoothly and then a near perfect lacquer coat has to be applied. There are 48 inside corner plane junctions and 24 intersections of junctions. Lettering has to spaced and glued. The pattern has to be split and flatness and squareness checked and corrected if needed. Then there are the 16 loose pieces to fit in the grooves of the pattern. All-in-all making a pattern of this type is a very large time commitment as you may know. After a while I may sort of forget the work involved in this pattern and then consider a different size. A group of at least 5 folks financially committed to buy a different size square might make me forget sooner I suppose... Well, I actually kinda enjoy pattern making. Someone pinch me. Stop, stop! ;-)

    Denis

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    Well, if a guy was being fully encouraging (translation: pain in the butt) I wonder what length of Featherweight Straight Edge is possible at 55 lbs cast?

    :-)

    Stan.

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    Quote Originally Posted by lucky7 View Post
    Well, if a guy was being fully encouraging (translation: pain in the butt) I wonder what length of Featherweight Straight Edge is possible at 55 lbs cast?

    :-)

    Stan.
    Stan,

    Ouch! ;-)

    I think a 60 would be possible. Possible and made are two very different things.

    Denis

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    I have thought a little more about the question as to whether a 60" featherweight with a 3 inch wide base could be made as-cast under 55 pounds. I reweighed one of my 48's as-cast and it weighs 40.5 pounds. I think it would machine down into the low 30's or so.

    I am sure a 60" could be made and probably could be made significantly less than 50 pounds with some additional pattern-making work. That would be done without compromising stiffness. If I just used the same basic strategy I have used for the 48 and scaled it up, I could get it cast at less than 55---just a little under. But, if did some FEA and started to vary the web thickness and similarly varying the cross-section of the vertical columns, a substantial weight savings could be achieved. I do not think it would, from a practical perspective, be worth doing that. But it could be done and that is how I would attempt to do it.

    Denis

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    im surprized there are no diagonal elements in the structure. how come?

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    Quote Originally Posted by dian View Post
    im surprized there are no diagonal elements in the structure. how come?

    I presume it's because it's a location reference, not a load bearing machine element, but Denis may have a better explanation.

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    Quote Originally Posted by dian View Post
    im surprized there are no diagonal elements in the structure. how come?
    Quote Originally Posted by TGTool View Post
    I presume it's because it's a location reference, not a load bearing machine element, but Denis may have a better explanation.
    TGT got it right. That is the short answer.

    The longer answer is the diagonals are there, they are just hidden. What I mean is the sweeping curves the web makes around each of the three openings provide substantial diagonal bracing. Obviously, if ultimate stiffness were the primary design goal and if cast iron liked to be cast to shapes approximating structural steel, the stiffest design would approximate a latticework bridge. But neither of those conditions are true. Cast iron does "like" smooth sweeping directional transitions and this is, indeed, a reference surface not likely to be subjected to side loading, span loading etc. So, the design created is a compromise (like all designs) with the primary (as articulated by the customer) consideration being provision of lightweight stable rectilinear surfaces in a shape that is feasible to cast and secondary considerations were resistance to deflection induced by external loads and comfort in use (those sweeping columns feel comfortable in the hand) and aesthetics. Yes, aesthetics. I have a strong aversion to ugly, clunky, needlessly heavy, and clumsily designed boxy castings whose features seem to be driven by ease of pattern making and tolerance for crude casting technique.

    I have done some careful load testing just to see how stiff these castings are. I tested them two ways. One was to load the casting diagonally from one corner to the other and the other test was to set the casting up on three points like a bridge and point load it at the center of the span.

    Here is a video of the span test using 30 pounds:I read the deflection as about .00025"


    And here is the diagonal 30 pound load video. I read this a about .0001"


    We could argue forever about how stiff these castings should be. But, for me, the final arbiter of the question is the customer. He's happy and very very pleased with the casting.

    Denis

    Added: Relative to the hand comfort and usability of these castings the columns are natural handholds. My suggestion for the end user of the casting is apply insulation in the form of cordage neatly wrapped in salty nautical tradition to the mid portion of both columns. There are other obvious solutions like wood or (uggggh) pipe insulation. I'm repo'ing any castings I see with pipe insulation on them! ;-)
    Last edited by dgfoster; 05-09-2020 at 01:58 PM.

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  24. #19
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    Ok, how about a pool floaty? Haha

    Nice work Denis.

    Joe

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    Quote Originally Posted by Liljoebrshooter1 View Post
    Ok, how about a pool floaty? Haha

    Nice work Denis.

    Joe
    Thank you.

    Actually I did cast some iron floaties and it worked! Except they all ended up at the north end of the pool. ;-)

    Denis


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