48 Featherweight Camelback Straightedge Pattern is Taking Shape. - Page 2
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  1. #21
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    Quote Originally Posted by Fal Grunt View Post
    If you are curious about using FEA, look at getting Fusion 360. Free for hobbyists and it does have a rudimentary FEA. Have not delved into it myself, but I have heard it is... good. Certainly not comparable to high end offerings.
    Thanks for the suggestion. I am sort of curious, but figure you’d have to invest 50 hours or more learning time to start to understand how to use it. Maybe that is not true. Then there is the question that if I were able to determine an optimal design, could I actually execute it both from a pattern making (I am aware of 3-D printing, of course, but on large patterns like this it is very time consuming to print patterns in pieces and glue them together. And they don’t come out of the printer as cast-ready either. I have done some custom casting from them and found they require a fair bit of hand-finishing work to make them suitable for green sand casting) and grey-iron casting point of view. Not every pattern will fill properly and remain reasonably true on cooling. I have spent the last 18 months learning some of the basic nuances of casting... It’s great sport but not for the easily discouraged or casually interested.

    Denis

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    Another basic FEA option is McNeel's Rhinoceros coupled with the Scan-and-Solve plugin from Intact Solutions. Higher price bracket than Fusion 360, but massively cheaper than Solidworks or one of the other "big five" CAD systems. I've used Scan-and-Solve on several projects for basic stress and deformation evaluation. It's got some functional limits I would like to see removed, but it's good within its limits.

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    Regarding FEA, it's not a *huge* amount of work to learn, but also easy to use it in a way that you get garbage results. If you have a CAD model already I'd be happy to run a few basic FEAs for you, as this is part of what I do for a living. Drop me a message and we can talk more if you like.

    Quote Originally Posted by dgfoster View Post
    I really had not considered a level.pad, but maybe I should. I do not think I could add such a pad to the bow since the bow sits off-center fore and aft. This location is intentional to allow the SE to reach under overhanging features like vee-ways. It seems like balancing on such a pad with the SE on a plate would be precarious (if I am understanding your suggestion) on such a pad. However, it would not be difficult to add a pad to the center of top portion of the sole that could be machined flat. A Geier and Bluhm 4-3064-20 high precision vial only requires a space1.25 by 3 for mounting, for example.

    https://www.geier-bluhm.com/gb-conte...20_drawing.pdf

    I could just build up the pattern 1/8 in the center in an aesthetically pleasing way to allow for mounting such a level vial. (On my 18 Featherweight prism/parallel/straight edge/ level I offer special machining to mount such a vial inside the prism on the sole.) Id be interested to know if folks think it might be worthwhile to add level-vial pad to the 48 and 36 Featherweights. Anyone reading along should please feel free to chime in pro or con.

    Halcohead, thanks for tossing out the idea for consideration! Do you think it would be useful to put a pad on the center, upper portion of the sole?

    Denis
    If it's just a small pad, I don't see the harm in adding a vial mount, but to be honest the ability to flip the straightedge on its back is more useful to me. It made quantifying error on my 24" straightedge super easy, and also allowed me to easily use it to check how straight my surface grinder was running. But understood it doesn't work with this design, so all good. Thanks for the thoughtful response though!

  4. #24
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    I very much appreciate the FEA offer. But, I have no CAD files for the pattern. The only files I have are graphite and paper sketches!

    I think my 18 SE is the one I have intended for use as a parallel and level and designed them from the beginning with that in mind.

    Today Ill be shaping and installing ribs in the 48 pattern but there will not be a lot of time for that with more babysitting grandkids duty and needing to ship out another SE. This one is an 18 going to Australia. Because of its lightweight design and the fact that it fits in a Flat Rate box, it ships for 100 bucks-which seems awful to me but is relatively cheap for international shipping. I think the cost would be similar to many countries though Im not certain about Eastern Europe or the Middle East.

    Sorry I cant post progress pics from my phone to PM. Maybe later today when Im home.

    Denis

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    FWIW, I machined and scraped the top edge of my 24" and 48" King SE's and occasionally put a level on them as I don't have a scraped parallel that long (or a KingWay setup). Pretty rare for me to do this and a bit of a bodge but it works.

    Just my opinion, but I think the beauty of Denis's 48" design is it's simple, and probably light weight and easy to handle (assuming similar to his 36" SE).

    L7

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    img_e5954.jpg


    I did get out into the shop for a couple hours to use the French curves and a little squinting to establish fair curves on the front side of the uprights. I think I am happy with the curves. But, it’s one of those situations where it is good to let it sit out for a while and just look at it every time you walk by and also to run your hand over the curves feeling for areas of “hardness” of the curve. Then out comes the sand paper for a few swipes here and there.

    You can see that only half of the ribs are contoured. Once those ribs are OK, I will transfer the curves to the corresponding rib on the other side. Then it will be time for cheeks to thicken the ribs and provide draft. The cheeks will be cut just a little oversized, glued and then faired to the pieces shown. Yup, slow, plodding work...


    Denis
    Attached Thumbnails Attached Thumbnails c02756dc-287f-42a0-8100-4d2662ffc0c2.jpg  

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    Having taken possession of one of Denis' 36" featherweights, this pattern work (not to mention his one-man iron foundry work!) really pays off. The casting has very crisp lines and a very elegant shape.

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    Some more progress as all front ri bs are contoured fitted an now have "cheeks" glued on to provide draft. I ended up using yellow cedar (a beatiful aromatic wood with extremely fine grain and medium hardness.) I had intended to use 1/16 baltic birch aircraft plywood but my local supplier was out and I did not want to wait on ordering. The cheeks add draft and strength to the ribs as they cover the joint between the triangular base piece of rib and the longer upper piece.

    Here are a few pics
    pattern-making-17-.jpg

    pattern-making-15-.jpg

    pattern-making-16-.jpg

    pattern-making-18-.jpg

    pattern-making-19-.jpg

    that is the 5 image limit for this post.

    Denis

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    Three more pics.

    the little tool-kmakers vise and cyano glue are handy for this job.

    pattern-making-20-.jpg

    pattern-making-14-.jpg
    By the way, Lucky&, I thought you had a good idea about leaving the end ribs extra thick. So, I did.
    img_0125.jpg

    Now it is time to add some back ribs and then to fillet all those inside corners...I have not counted them all, but it is close to 80 inside corners----they are not easy to get smoothed out as the fairing material wants to peak up almost no matter what you do.
    Denis
    Last edited by dgfoster; 08-25-2019 at 01:56 PM.

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  14. #30
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    Have you looked into using non-wood for your patterns?

    My patternmaker friend makes some mind blowing stuff and he generally uses more stable material for patterns he's going to re-use or store long term. Often times he casts the patterns in some kind of polymer or aluminum.

    I have an attic area filled with the patterns and construction bits for all my products and the final stuff is all aluminum with just the patterns to create the aluminum pattern made from plastic and wood.

  15. #31
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    Quote Originally Posted by Garwood View Post
    Have you looked into using non-wood for your patterns?

    My patternmaker friend makes some mind blowing stuff and he generally uses more stable material for patterns he's going to re-use or store long term. Often times he casts the patterns in some kind of polymer or aluminum.

    I have an attic area filled with the patterns and construction bits for all my products and the final stuff is all aluminum with just the patterns to create the aluminum pattern made from plastic and wood.

    Sure, it is pretty common to use aluminum for a working pattern. And if I were sending my work out, I would have to use a metal pattern as foundries are not known for their gentle handling of patterns. I have seen first hand the results of a guy gettin er done. My patterns were chipped, broken, threaded plugs pulled out etc.

    But, I handle my patterns pretty carefully and they have suffered no ill effects of use. So ,for now, I am ok with the Baltic birch and lacquer patterns. The lacquer is pretty hard and has been applied in multiple coats which makes them tougher. And the Baltic birch plywood itself is quite strong.

    I appreciate the suggestion and it is not an idea that is off the table.

    Actually, Ive been daydreaming about the next pattern. Seeing JSTs thread and people talking about a 30 with a prism base has me musing about a pattern for such made with a cored-out base. That would mean you could have such an SE with a prism base but it could weigh a lot less than one with a (far simpler to mold and cast) solid but back-breaking base. Just thinking...

    Denis

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    If anyone needs a 48" Camelback Straight Edge now I have them in stock. Model HK-48, 44 pounds, 47 3/4 L x 2 1/4 W x 9" H. Photo of my patterns straightedge-patterns.jpg

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    Quote Originally Posted by dgfoster View Post
    I appreciate the suggestion and it is not an idea that is off the table.

    Actually, I’ve been daydreaming about the next pattern. Seeing JST’s thread and people talking about a 30 with a prism base has me musing about a pattern for such made with a cored-out base. That would mean you could have such an SE with a prism base but it could weigh a lot less than one with a (far simpler to mold and cast) solid but back-breaking base. Just thinking...

    Denis
    Your multi-purpose dovetail as can also serve as a level is IMNSHO, just the ticket for he who doesn't REALLY want to dedicate all that much total investment in coin of the realm, storage space, protective cases, nor transport arrangements, for what might not even be a quarterly-use item, any given year.

    "2 Foster's worth, and I do NOT mean the alleged-beer"

    Also too much in the way of resources consumed by other clans and tribes of straight, not gay, Iron, despite the clever variety of azures, humped backs, dove'ed-tails, as might have hinted bent to the contrary. Hence my offer to JST.

    I need the space. The Foster's are the "keepers". Heirlooms, even. Thanks again!


  19. #34
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    Well, my Featherweight 48 is coming along very nicely. Today I had to take a step I had been anticipating and I realized could go well or could result in more or less disaster. After gluing up the back ribs, fairing them and getting them all dressed, I split the pattern right down the middle so it can be used as a split pattern rather than as a loose pattern and follow board. Having it split should make it easier to mold with fewer instances of imperfect (read that “start over”) draws of the pattern from the sand.

    Well it worked nicely. I used a “meat saw” blade on my band saw as such a blade takes minimal kerf but on the negative side, because of the minimal set in the teeth, has a tendency to wander. It stayed on course plus/minus 15 thou except for the last 8 inches where it did wander to one side 40 thou. In the casting world 40 thou is certainly acceptable variance. But, since I am making my castings to be as perfect as possible, I’ll spend the hour to add a shim on one side and sand down the other so the seam runs right down the middle.

    The other thing that could have gone wrong was that the pattern when split could have warped wildly if there were retained stresses. I think everyone that has split a 2X4 or similar has seen that occur with binding of the blade, smoke and possible kickback. That did not happen. Fixing a bad warp would have been much more difficult than fixing a little wander.

    So, right now, I am taking a break, having a glass of juice and thinking about next steps...

    Based on the weight of the pattern today the casting continues to calculate at a machined weight of about 26-28 pounds to 36 pounds. It’s base will be 3” wide with 45 degrees clearance intended to reach under vee-ways.

    Here are a couple pics.

    img_0128.jpg


    img_0127.jpg


    img_0129.jpg


    pattern-making-21-.jpg


    I think I can cast this in the next 7 to ten days. That is where the iron hits the sand! to corrupt a more common saying. Might as well have a little fun here.

    Any questions?

    Denis
    Last edited by dgfoster; 08-27-2019 at 12:11 AM.

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  21. #35
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    Quote Originally Posted by Richard King View Post
    If anyone needs a 48" Camelback Straight Edge now I have them in stock. Model HK-48, 44 pounds, 47 3/4 L x 2 1/4 W x 9" H. Photo of my patterns straightedge-patterns.jpg
    Seems weird to post that in this thread, maybe its me


    Sent from my iPhone using Tapatalk Pro

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  23. #36
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    Quote Originally Posted by ripperj View Post
    Seems weird to post that in this thread, maybe its me

    Sent from my iPhone using Tapatalk Pro
    Not just you. The self promotion is sometimes a little tiring. There are several threads for classes so no one could possibly forget or overlook.

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    Quote Originally Posted by ripperj View Post
    Seems weird to post that in this thread, maybe its me
    On the contrary, Itd be weird if 'that post' didnt surface in this thread at some point, unfortunately. Things dont usually go well from here so hoping this time will be different.

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    I wasnt looking to derail the thread. The pattern looks fantastic, very pretty lines


    Sent from my iPhone using Tapatalk Pro

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    I will post up a little more work done today by descriptiuon rather than pics which would be difficult to make for this work anyway.

    Here is an update of today's progress. I got the back ribs faired and smoothed the curves they make so that there is a smooth progression from one rib to the next. Even a 1/16th" deviation looks a bit like a sore thumb. I I end up squinting down the line of ribs from one end and then the other trying to see which one is a bit high which is a bit tricky since the curve of the bow varies the distance to the sole obviously and the top of each rib is different in height from its neighbors. then when you figure one is a bit high you have to use some sort of pointer to lay on the rib so that you can be sure which one you were looking at! then out come the half-round file, scrapers, sand paper and any other aids you cna think of. I find I have to be cautious not to overcorrect---it's sort of like cartoons of trimming the legs on a four-legged chair. This chair has 11 legs!

    Anyway, I have got the ribs standing respectfully in a line with them more or less in register with each other.

    Tomorrow involves filling in the inside corners of the pattern to produce fillets to ensure good pulling of the pattern from the green sand I use for molding.

    Denis

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    Your pattern is a thing of beauty Denis


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