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    Default How would you build this?

    Hi all!

    First post!
    I am trying to make this light fixture. The smaller tube seems 3/4 or 5/8 with the bigger one maybe 2 inches. I can't see how I would connect the two like in the picture. Any idea?

    fixture.jpg

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    Do you want a one piece seamless look or are you happy to have some kinda "adaptor piece" Theres no magic, but if you want one piece look you have to flare the end of the larger tube down, this is easy and cheap to do on a per piece basis with the correct tooling in qty, but the the tooling is costly!

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    Is there a weld-o-let reducer like that ?

    Or like Adama writes, get out the rosebud and a lathe, practice necking down the big tube.

    Me, I would simply plasma out a disc with a hole in it, to slip in the big tube, and hold
    the small tube, then a mound of Bondo to make the outside look "pretty".

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    You could make a cone transition piece to mate the small diameter to the large. Do you require smooth curves? Is it steel, aluminum, or what?

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    Explosion forming !!


    Or if you want to be boring, you could probably spin the expanded parts with a neck that just barely slid into the straight part. Then the joint would be invisible, especially from below.

    If you were doing a lot of them and wanted to miss out on the fun part, hydroforming maybe. You could probaly figure out a way to do that for not all that much money, it's a simple part.

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    this is a commercial light fixture- its a stamped or spun sheet metal part, made on a big, expensive machine, in quantities of several hundred an hour. Most likely, the smaller diameter tubing has a 1/8" pipe nipple brazed into the end- thats standard thread size for light fixture assemblies. Then, the spun can at the bottom has a hole in it to take 1/8" pipe, and a small jam nut is used inside to hold the two together. Thats how light fixtures have been built for 100 years.

    yes, it is possible to hand form cones- either from flat plate, then welding and grinding the seam, or forming from tube, hot or cold, depending on the thickness and size. You can actually forge a pipe down to this kind of a cone shaped end- I have done it a bunch with schedule 40- but it could be a half hour each, multiple heats, and its a hand process- how's your hammer control? Blacksmiths who have 3 to 5 years experience are pretty fast at this.
    Pipe is heavy, though, way over kill for these.
    But these are processes that take some learning curve to get right.
    Spinning parts like this is certainly possible, but again, would take some time to learn to make a correct form, require a low carbon steel sheet to get this amount of depth, and modifiying a lathe and building or buying spinning tools. Its pretty hard to find the right alloy of sheet for deep forming- I used to order it from a custom car building supplier in Indianapolis, but its been years since I did any of that work. Usually there are pretty steep minimums from local steel suppliers.

    industrial spinning shops will make these for you, but again will require minimums, and are not cheap.

    There are some wholesale lamp part suppliers who stock some of these shapes, but that is not a common one in your picture.
    Luminance, which used to be American Derosa Lamp parts, does carry a bunch of spun shapes, but most are more classic and historic than what you want.
    https://www.luminance.us.com/adl/sta...ings-spinnings

    there used to be a few other lamp parts suppliers in the Rhode Island/ Ct area, but most have been dropping out of business over the years.

    You could try direct from China, on Ali-Baba. There are a lot of spun metal lamp shades, but you would have to do some looking and emailing to find your profile-
    Metal Spun Lamp Shade-Metal Spun Lamp Shade Manufacturers, Suppliers and Exporters on Alibaba.comLamp Covers & Shades

    Whenever people dream they can reproduce, in their garage, with no tools or experience, something that requires a few million dollar factory, and a specialized supply chain of materials, tooling builders, and experienced workers, I laugh.
    Sure, its possible- there is the occasional mechanical genius, I know a few, who reverse engineer processes like this, and make amazing stuff.
    But unless you are a skilled fabricator, machinist, sheet metal worker, and die builder, I would just try to find a form that is close, and buy them, if I was you.

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    these guys dont sell your profile- only one spun aluminum shade- but they sell all the parts to make lights, and you can see how parts are assembled with nipples, nuts, spacers, and sockets that all thread together.

    Light ALUMINUM SHADE | Lamp ALUMINUM SHADE - MyLampParts.com


    most commerical lighting with spun shades use semi-custom shades- that is, they pay to have the tooling made by the spinner, and then order their unique shade design as needed. In quantity, its not expensive.
    But only a handful of shade shapes are available off the shelf.

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    watch this- it will give you an idea how this stuff is made.
    Manufacturing metal lamp parts - Juheko - YouTube

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    Why don't you just order a 2" to say 1/2" tube reducer. Tig weld and your done

    Sent from my 2PS64 using Tapatalk

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    Quote Originally Posted by Ries View Post
    industrial spinning shops will make these for you, but again will require minimums, and are not cheap.
    This is probably out of date too, but there was a guy in Redwood City (CA) who did spinning and it didn't cost very much. We did lots of short runs with him, he'd make one-off forms out of phenolic and do 25 pcs no problem.

    But this whole "Oh it's so expensive !" thing seems to have overtaken the US since I left (4 to 6 hours to draw a circle "in CAD !"), so who knows.

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    Investigate “swaging”

    And “necking down”

    And “metal spinning”

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    ALL the suggestions mentioned are right.

    Because time, cost, accuracy (cosmetics) are determinants easily affecting by 10-100x, or more, the final cost/unit.
    Qty is critical.

    Your skills, tools, capacities may/can affect it, usually.

    Many here may make 1, or 2, pieces for 10-20k each (or ((much)) more) in similar sizes for high-accuracy apps.
    But also many here, even those who can make the high-accuracy stuff, may sometimes use ghetto-forms to get stuff done, when it does not merit better engineering and or processes.

    Posts requesting advice should ideally indicate some range of quantity, time, cost range desired, finishing, materials.

    Example:
    I am "channeling" == 50 mm D soft brass/bronze/etc of low quality for examples.

    Any top artisan can make the part, cosmetically perfect, slowly, without any or few specs re: drawing/size/accuracy/tir etc. Say 2 hours/parts 2-3, 0.5 hours 5+.
    Many or most can make it with the specs to 0.05 mm, 0.05 mm tir for some more money.

    Some of the better artisans can make it to 0.04-0.02 - 0.01 mm TIR.
    Some can make it much better to about 1-2 microns or 0.001 mm in tir.

    E.
    You could make a male/female mold and hydroform the shape with grease.
    This is non-trivial and has costs in hours, skill, tests, but little materials cost.

    Hydroform // self is probably a good idea for an expensive widget of 1000 pieces or less total run lifetime.
    If YOU do not get 20$ / piece for the forming, you should not be in the industry. Q 999.

    MHO.
    If you expect to make the pieces well, and cheap, and charge 2$ or so per piece for the work in less than massive manufacturing quantities, forget it.
    Anything a skilled manufacturing professional makes themselves, costs 40$ / piece, or 150$ / hr, for the first 2 hours + 10 pieces.
    After paying 300$+pieces, the *rest* is machine time and efficiency.

    I hope this helps.

    Most of my advice to *hopefuls* was usually negative-as in not commercially viable.
    Most seemed to take it positively.
    I/we always explained why, cycle times, costs per machine and tooling, and operator, etc.

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    For a one-time project, get some cheap metal funnels and cut them to fit your tubes. You can either weld it all together, or (hate to say it) J.B. Weld that thing together, sand and paint.

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    Thanks so much for your reply! Amazing knowledge here, way beyond my expertise.

    A good point about putting the question in context.
    I am looking at building about 14 pieces (on the picture are 10 pieces) so I am willing to go the manual/artisan route.

    Looking at some of the post I think I will simply by a metal cone (didn't know I could buy this), or go to a nearby machine shop, or maybe change the design to something I should do in house.

    I'll keep you guys posted in the forum!

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    1. Get some " Foster " beer. (big cans)
    2. Drink beer and rinse/wash cans.
    3. Remove tops and bottoms.
    4. With tin snips cut aluminum can and bend in to suit your needs.
    5. Paint color of choice.

    I suppose an alternate source for the cans could be aluminum or copper roof flashing. Roll, pop rivet, form cone, however there would be no drinking involved...

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    Quote Originally Posted by Ries View Post
    watch this- it will give you an idea how this stuff is made.
    Manufacturing metal lamp parts - Juheko - YouTube
    Very cool. I have heard of people joking about being chained to a machine, but he actually is!

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    Quote Originally Posted by Anthony View Post
    1. Get some " Foster " beer. (big cans)
    2. Drink beer and rinse/wash cans.
    3. Remove tops and bottoms.
    4. With tin snips cut aluminum can and bend in to suit your needs.
    5. Paint color of choice.

    I suppose an alternate source for the cans could be aluminum or copper roof flashing. Roll, pop rivet, form cone, however there would be no drinking involved...
    ehehehe, just for the excuse of drinking in the shop I'd got with the can option

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  21. #18
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    IS that supposed to keep him from getting sucked into the machine, or stop it faster if he does?


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