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Lug Designs

Old 10-07-19, 05:33 PM
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Lug Designs

Are there any manufacturers who can custom 3D print the 'wax' lugs for investment cast processing of lugs? If so it seems the designs could be virtually limitless with regards to windows, tang shapes, pre-thinning and angles.
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Old 10-07-19, 09:27 PM
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And costly/time consuming compared to making your own lugs with tube stubs. But maybe you've found your calling, one that others haven't thought of yet

Actually such a service might be an interesting business model. How much would two sets of lugs cost? Since you asked I nominate you to find out. Andy
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Old 10-08-19, 05:29 AM
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I'm not sure there is a lost wax printer, but people do "lost pla" casting. I was experimenting with headbadges that way. I'm not sure a lug would pass the design tests.

ETA: it's expensive, but you can just direct print a lug. People are doing it with Ti, but it costs a ton. I don't think that steel would be much cheaper

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Old 10-08-19, 05:51 PM
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I did a little research. There is a 'wax' for printing for the investment cast process. It can be used on most any 3D printing machine with some basic modifications regarding 'feed', head temps and a few other things. Some machines are better than others for making waxes. I am not computer savvy and don't own any CAD software and machines or 3D printers. I am not a framebuilder (yet) but do make my own scale RC models. Some of them are sailplanes and are large with spans of 4.5 meter. I hand draw my plans after doing research, mold fiberglass, cast silicone rubber parts from my own patterns and molds, cut wood parts and machine metal parts some which require soft or hard silver soldering.

I don't know anything about costs and the question isn't about that, sorry! But... there are manufacturers who DO provide investment cast lugs so infrastructure exists for the process.

One business model: the customer could submit drawings for lugs then the fabricator could furnish the waxes, finished on the inside for tube fits, to the customer for final exterior finish sculpting. The printed wax items aren't the most smooth due to the thickness of the 'string' layers. When done the customer sends them back to the fabricator to be ceramic coated and then cast. I would think that framebuilders are artisans enough to deal with finishing wax parts.

Second model which would be on the opposite end of the 'custom' spectrum above: customer logs onto fabricator's site and chooses from a myriad of lug designs,windows and features and the fabricator would just print and finish the waxes for casting.

I'm sure there could be a whole host of scenarios but wonder if the framebuilder community is large enough to support it. I can only dream!
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Old 10-08-19, 05:55 PM
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Why not just 3D print out of metal?
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Old 10-08-19, 08:40 PM
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Boxkite- I would suggest a talk with Doug Fattic before you start up or spend much $. Between his teaching frame building and his willingness to have students "carve" lugs he also is a pretty savvy guy about what it takes to make it in the frame building world. What you propose has been done for decades buy by employing brazed/welded additions to lug blanks and/or sawing/filing (carving) said blanks. One can easily envision a CNC milling center used to carve blanks into whatever shapes are wanted. I'm not sure employing a 3D printing to then cast a lug is any real improvement. But there are smarter people in our community then I, Doug is one of them that also has the position and history to better discuss this with. Andy
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Old 10-09-19, 03:59 PM
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@Nessism- I'm no metallurgist but 'grain structure' would be better with cast lugs thus stronger. I do know crankshafts are stronger when cast than if cut from billet all else being equal. Think of wood grain structure.
@AndrewRStewart- I am not going to do any start-up business! I wish I had the means to do so. I was just wondering- ' Are there any manufacturers who can custom 3D print the 'wax' lugs for investment cast processing of lugs?'
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Old 10-09-19, 05:57 PM
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Originally Posted by Boxkite View Post
@Nessism- I'm no metallurgist but 'grain structure' would be better with cast lugs thus stronger. I do know crankshafts are stronger when cast than if cut from billet all else being equal. Think of wood grain structure.
Some research is in order. You can get 3D printed metal parts that are far stronger than the typical cast lug. Grain structure is a non issue for the most part as long as the strength is there, and lugs aren't strong anyway.
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Old 10-09-19, 08:36 PM
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If grain structure was really important then stamped/pierced/folded and welded lugs would be the choice. Perhaps the least expensive way to make lugs too. Yet other factors are considered to be more important so stamped lugs are not used much these days. Andy
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Old 10-10-19, 05:01 AM
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If you search through Richard Sachs albums on Flickr, he has numerous pictures of the 3d printed samples of his lugs and other cast frame parts. Those 3d printed models(which appear to be PLA) were sent for testing and approval before the final casting molds were made. I would assume, from some of his other posts that, the manufacturer was Samson. These were made for the purpose of producing large quantities of the lugs and other frame parts. I doubt that you will find any company that is willing to put forth the effort for a one set of lugs for a customer.
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Old 10-10-19, 08:01 AM
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It is worth while to take a fresh look at framebuilding material options because it is always possible something new can be learned. Just a bit of history to help put things into perspective. When I started to learn how to build frames in the 70’s investment casting had just started to be an option. Its disadvantage was that it was a lot more expensive than what was commonly available. Before that lugs were made out of sheet metal by stamping and welding (or sand casting). As frame production techniques changed to tig welding, lug companies that made a profit by volume found their market had disappeared. Custom framebuilders were supplied with investment casting products by Henry James and Richard Sachs and others. Now even those suppliers are disappearing as the number of builders using IC products has continued to decline. Hank has retired and the investment casting houses in Taiwan that were used by other suppliers have stopped production.

Several years ago I persuaded the Nikko company in Japan to make some blank lugs. Instead of stamping and welding they are bulge formed so there are no seams. Trek used Nikko lugs when they first started framebuilding in the mid 70’s because they required less clean up before and after brazing. These lugs are a little more malleable for changing angles than investment cast lugs. I had a graphic artist create a template of each lug socket twice its normal size. This large template makes it easier to draw a design. This big design can be reduced to life size on a copy machine that prints out the pattern onto a sheet used to make labels. This is sticky backed paper that can be bought in places like Office Depot. Once the template of a socket is cut out, the backing paper is removed and placed on the lug for cutting with a jeweler’s saw. Dremel cutting discs and jeweler’s files help complete the task.

Bilaminate construction is the most common way a builder makes a lug. This is where 2 sleeves are fillet brazed together to form a lug. Claude Butler frames in England used this method because lugs were not available right after the war.

I visited an investment casting company some years ago. Individual wax pieces are put on “trees” so that each pour can make 10 or so pieces. One of the challenges of doing an investment cast lug is that shrinkage has to be calculated into the mold. In other words the wax lug has to be a bit different size than the final product so that after the melted steel has cooled it is the right size. This is why engineers have to help design the lugs.
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Old 10-10-19, 11:33 AM
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it would be great if you could design your own lugs and get them cast. I don't think that anyone will start a business like that, but you never know. It does seem like it's something that can be done, but the bike industry probably wouldn't support it. So it would have to be a more general application. Like Doug implies, there probably would be a fairly extensive learning curve to get the lugs to come out right.

There are a lot of people working on 3d printing using welding. The stuff I have seen leads me to believe that a lug is not a great application for that, but it might be in the future.
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Old 10-10-19, 05:03 PM
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Thanks for the responses. I never said I would be purchasing one lug set at a time so apologies if it was implied. That would be absolutely outrageously expensive to fire the oven, etc. for just one set! Henry Ford got the assembly line part right! IF there was a business that offered the wax for the customer to 'fine tune' with regards to windows, tangs, etc. then it would sure open some possibilities. Just envision that all the customers would return waxes to the producer who, in turn, would ready them for casting once a certain batch number was accumulated.
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Old 10-10-19, 05:30 PM
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I'm no manufacturer (although if I did make frames as a business the courts would consider me one) but I don't think the model you describe would be economically viable. For a number of reasons, some already mentioned.

Nor far more likely might be an art casting business (like those that cast bronze sculptures) that is built on a small batch production and each design is a one off. Still I suspect the costs would be prohibitive. Andy
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Old 10-11-19, 07:42 AM
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There was/is an investment casting company just west of me that made frame components for a fairly well known American supplier. This supplier had used various casting houses so I donít know how long or far back they used this particular one. My knowledge of this connection came about 25 years ago from a framebuilding class student that wanted to explore making IC molds. He went to a casting house near the southern shore of Lake Michigan and their advertising brochure had pictures of some lugs on its cover. I just googled investment casting companies in Indiana and the ones closest to where I remember is Aero Metals in La Porte, Indiana although it might also be Bremen Casting in Bremen, Indiana. Or it could have gone out of business. What I recall is that their wax lug representative needed a little hand work to shape it some more before it went through the process of having various coating applied turning it into a mold for casting. You might consider giving Aero Metals a call to find out if they can provide any more information.

I went to a FABTEC show in Chicago in the late 80ís where a laser cutting company had demonstrated cutting a design on a tube and then laser welded 2 tubes together. I explored that option for a while but the problems of spreading the initial cost out with volume became impractical for me. The use of lugs had started to decline so the only buyers would be small volume builders and hobbyists. I liked the idea of laser cutting a tube better than investment casting because of the greater accuracy of both the design and constant ID of the tube.

Eventually the system I use of having a supply of blank lugs (they are for sale by the way) or making a bilam lug out of tubing was the most practical for me. By enlarging the design twice life size makes it easy to create and draw. Carving the lug is not that difficult with a jewelerís saw and files and perhaps a Dremel tool. If someone wants to buy a blank set of lugs it comes with the socket templates and complete set of instructions of how to do it. All the money goes towards our Ukraine Bicycle Project.
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Old 10-11-19, 11:57 AM
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I'm sure any casting house offering services like this would batch up until it was worthwhile to cast. But from the customer side, Shapeways casting service will do only one small part. The lead time is at least a couple of weeks. Since printable wax exists, someone must be doing the casting. I know I saw references to printable wax some time ago.

Overhang and support are a problem for most 3d printing processes, and I would guess that would preclude fancy lug designs from being printed directly. OTOH, the wax could be modified readily after printing.
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Old 10-11-19, 01:03 PM
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Originally Posted by Doug Fattic View Post
There was/is an investment casting company just west of me that made frame components for a fairly well known American supplier. This supplier had used various casting houses so I donít know how long or far back they used this particular one.
Trek used Signicast in Milwaukee for frame fittings in the 1980s. I don't know how amenable they are to small production runs.
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Old 10-11-19, 06:58 PM
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'OTOH, the wax could be modified readily after printing.' That's exactly the point I am trying to make. The customer can customize the waxes. The producer collects and readies them for batch casting (not one-off casting).

'Trek used Signicast in Milwaukee for frame fittings in the 1980s. I don't know how amenable they are to small production runs.' That's where the producer decides how large a 'batch size' will be run IF the producer offered 3D printed waxes for the customer to modify.

Oh well... it would be interesting if this concept materialized by using 'high tech' to speedily design 'low tech' components!

Thanks everyone!
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Old 10-12-19, 07:54 AM
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I think it would be interesting for us to learn more about possible investment cast lug making. The reason I looked up Aero Metals in La Porte, Indiana is because I believe they are the casting house that has already made lugs that required some wax modification before they were turned into molds. Their phone # is (219) 326-1976. The American company that sold these lugs and other frame parts to us is no longer having any IC parts made for sale. Certainly Aero Metals can give advice about volume requirements and possible wax modifications and whether anybody has done 3D wax printing. Or for that matter whether anyone has done any 3D printing of the wax molds themselves. It used to be that the best material for molds was aluminum because they lasted well under continuous use. However I know lesser materials for molds have been used in the past.

I visited this plant (at least I think it was this plant) maybe 30 years ago. My machinist friend used to work there and asked the owner if he would be willing to show me how investment casting was done. This connection was why I recommended my framebuilding class student try them out as a possibility for getting bicycle related things made. I’ve lost track of him over the years. Anyway it would benefit all of us if you give them a call and report back what you learned.
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Old 10-12-19, 08:54 AM
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My experience with Investment casting is primarily from the jewelry industry. Models the size and weight of bottom brackets would seem difficult to produce if the models were made from wax. There are plastic "waxes" that would probably be less likely to sag or deform in the investment process.
Lugs, on the other hand, seem more possible in wax. The tendency of Shrinkage in final product, however, seems to become more exaggerated as the wax model size increases ( at least in jewelry casting). Dental casters, have better investment powders where they can aparently "control " the amount of shrinkage. Their castings would be unusable if they shrank from the original wax models size- "in-office fittings" to people's teeth just doesn't seem tenable. This lack of shrinkage control has been a constant problem with jewelry casting. It seems to hinge on a few variables such as mold temperature at both burnout and metal introduction, as well as metal temperature at casting time. The different flow/ melting temperatures of different jewelry metals, i.e., platinum, Sterling or any of the various karat gold configurations seems to have an effect. These casting houses must have much better control of both their wax properties and shrinkage control than their jewelry counterparts.
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Old 10-12-19, 10:12 AM
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Originally Posted by Andrew R Stewart View Post
Boxkite- I would suggest a talk with Doug Fattic before you start up or spend much $. Between his teaching frame building and his willingness to have students "carve" lugs he also is a pretty savvy guy about what it takes to make it in the frame building world. What you propose has been done for decades buy by employing brazed/welded additions to lug blanks and/or sawing/filing (carving) said blanks. One can easily envision a CNC milling center used to carve blanks into whatever shapes are wanted. I'm not sure employing a 3D printing to then cast a lug is any real improvement. But there are smarter people in our community then I, Doug is one of them that also has the position and history to better discuss this with. Andy
I've thought about CNC milling a bit. One thing, even if one cast the blanks, there is a fair about of cleanup to do, and the mill could do most of that.

One thing about lugs is that most, at least commercial lugs are 2-dimensional patterns applied onto cylinders. Even with thinning, they are basically 2-D patterns.

Either casting or CNC Milling, or a combination of the two would allow applying 3-D patterns to the lugs.

Columbine Cycle Works: Our Bicycles



Are some of those "lugs" assembled in multiple pieces?
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Old 10-12-19, 09:20 PM
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I strongly suspect that the embellishments are add ons. Either by attaching prior to brazing the joints or after. This is how many of the fancy English stuff was done too.

As to CNC for lugs, sure I guess. But it seems to me a way to complicate what's been done by thousands of others long before we had such machines or methods. Like Doug said, making lug blanks from tube stubs and cutting/filing them to shape works really well and doesn't hardly cost anything. Andy
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