3D Printers

Frank Sergent

I changed the subject line here because this is shop talk and a little off topic but is in response to LJ’s question and something I am still passionate about.
I don’t believe a run of the mill (FDM) 3D printer that squirts molten plastic out of a heated nozzle can work for this. The features on the couplers are very small and they have to be produced accurately. Think about the diameter of the little hinge pin that the knuckle swings on. Its diameter is 0.0130 inches. My original 3D wax printer acquired in 2009 (for about $17k and probably never actually paid for itself) had a drop size of 0.0010” meaning it could squirt a single drop of wax 0.0010” in diameter. That was good enough to form an HO scale coupler than would work. My current printer acquired in 2013 (for about $24k that paid for itself in 3 years) has a “voxel size” of 0.0016”. That works too. My newest not yet in service printer acquired just this week (for less than $1000) has a voxel size of 0.0019” which I think will be fine as well. What’s the smallest drop of plastic a typical 3D printer can squirt out? About 0.01 inches in diameter which just doesn’t cut it. Its not the right tool for the job.
I put the pay off times in there for anybody that is thinking about jumping in. Those are based on profit from items sold that were 3D printed. They don’t take into account the fact that I sell many more diecast couplers just because I can offer the specialty couplers. You can see that my new printer will pay for itself in less than 2 months at the same rate.
For this work you need a printer targeted at the jewelry and dental markets. There have been some major advances that have occurred here recently that has allowed the price of these very high resolution printers to drop like a rock. Older designs use a UV laser or projector (like the one in a conference room) to selectively solidify liquid resin one layer at time to create a 3D object. The laser hardens one pixel at a time and is slower because the laser has to “draw” each layer. The projector projects the complete image for the layer at once, so its faster. Newer designs are actually much simpler. Rip the LCD display off your fancy new phone and put a few UV LED’s behind it. Now the pattern of UV light image that gets through the LCD can be directed at some UV sensitive resin. Add a computer to control the image on the LCD and some mechanics to advance the 3D object a little after each layer hardens and you have the world’s cheapest 3D printer. Fancy phones with fancy super high resolution screens have enabled this technology leap in 3D printers. As long as what you need to print is smaller than the display on typical phone, your all set. Imagine what happens if you have a 11” 4K LCD for a tablet computer. Hmmm. Most HO locomotives and rolling stock many structures are small enough to fit in that area. Trackwork components could fit in that area too if you don’t mind plastic track (Unprototypical shiny nickel silver railheads on passing tracks and sidings irk me anyway – why is that acceptable – dead rail is coming). See where this is all going. These are exciting times in the model railroading world and things are about to get crazy.
Also regarding 3D CAD. Check out Fusion 360. Free for a year for hobbyist and small businesses. I have historically used Solidworks, but Fusion 360 is about to eat its lunch. Fusion 360 plus a new ~$500 printer and a website can make you a model railroad entrepreneur. You still need to be able to turn those plastic parts into metal to make couplers, but maybe you have other ideas.
Finally in my opinion, the plastic parts created by any of these fancy new printers I’ve described is hard and too brittle for items that will take constant abuse like a coupler.

From: ljcasey1
Sent: Wednesday, July 11, 2018 2:33 PM
Subject: Re: [Sergent Engineering] Sergent Engineering Couplers
interesting question regarding the 3d printing.    what is the problem so far with people printing in 3d?   tolerance, or material strength.    I know there are some metal filaments available with different metal types in 'suspension' with the PLA or whatever.   Has that been tried?   perhaps that has no more inherent strength than straight PLA or whatever.   I also doubt it allows any finer tolerances.   Just wondering aloud.    I have a mostly put together home 3d printer, but haven't learned any CAD yet.   I would assume that a typical home 3d printer has insufficient precision to allow the tolerances needed amongst the parts, but would love to hear what you(Mr Sergent) has to say on the issue.
LJ Casey
Maryville, IL
who is still only a dabbler as the railroad is not running yet.
On Wed, Jul 11, 2018 at 1:21 PM, Frank Sergent <fsergent@...> wrote:
Hi All,
Let me restate what I have said before and give an update.
I did say I would eventually get out of the coupler making business. Wheels are slowing turning in that direction now. I have put all my designs in the public domain. Several folks have downloaded those designs and I know some have tried to 3D print these with varying levels of success. Printing the couplers is just the first step. No one has of yet demonstrated they can do this well, but there is interest. Casting them in metal is the real trick that requires an investment in equipment (not my equipment, its mine, mine, mine). That's probably about $10k worth of cool stuff (that can also be used to make things other than couplers) if purchased new. A dedicated workspace will also be needed (I do it in my basement) where you can vent fumes outside. There are a few skills you will need or need to develop as well such as 3D CAD, 3D Printing, urethane casting, basic metal (small lathe and mill probably necessary and included in the $10k), electrical (dedicated outlets, temperature control wiring), and plumbing (devest station) skills. Several folks believe a useful product might be created in raw 3D printed plastic. Maybe so. We'll see I guess. As I gain confidence that someone is on the right track and willing to make an investment, I will slowly discontinue 3D printed items, otherwise there will be little reason for anyone to make that initial investment in equipment. When I see success in making the 3D printed / investment cast couplers, then I'll offer to sell them the tooling for the die cast products at a price they can't refuse. Then that lucky person will get filthy rich. OK. Maybe not filthy rich, but the initial investment will easily be paid off within 12 months (probably 6)  assuming you're not paying somebody else to do the work.
Bottom line is that I don't want money for the product line. I want somebody to prove they have passion about it. Making these things is real work and takes real time. You're not going to be able to quit your day job. You will end up with a small pile of extra cash. If you think its a great deal because of the extra cash, you might find you would rather have extra time instead of extra cash.
I have promised a few folks that I will eventually add a section to my website that describes how I make the couplers in detail. I will do that.
Bottom, bottom line is that it is not my intent to let the product line die. If you would in anyway consider buying the business (which is not for sell), why not consider purchasing some equipment, dedicating some space, figuring out how to make the product, and creating your own business that sells the product? I'll help any way I can toward that effort.
--------- Original Message ---------
Subject: Re: [Sergent Engineering] Sergent Engineering Couplers
From: "Paul Dallard via Groups.Io" <shield1751=yahoo.com@groups.io>
Date: 7/11/18 12:00 pm
To: SergentEngineering@groups.io

How much would he want for his business?

An insincere and evil friend is more to be feared than a wild beast; a wild beast may wound your body, but an evil friend will wound your mind. - Buddha

On Jul 11, 2018, at 11:09, Alan Hummel via Groups.Io <ahummel72@...> wrote:

To all,
Early on when Frank made his couplers available to new marketers,1 person from oversees was interested but thought the cost for oversees shipping was too much.
I'm curious with seriousness:how much would it take to buy Frank out? I'm 60,not in the best of health can't find any work because of my health,love railroading,maybe this would be what I need.(?)
Al Hummel
On Tuesday, July 10, 2018, 8:32:00 PM EDT, Randall Vos via Groups.Io <r_vos1979@...> wrote:
I thought Frank said a while back that he had a few companies interested in his business?
Sent from my U.S. Cellular® Smartphone
-------- Original message --------
From: "Alan Hummel via Groups.Io" <ahummel72@...>
Date: 7/10/18 2:38 PM (GMT-06:00)
Subject: Re: [Sergent Engineering] Sergent Engineering Couplers
Frank is looking to have someone buy him out,or using his drawings,make couplers like his to my understanding. He's not pulling out,but is looking to leave the coupler business but wants to see his couplers fall into a new manufacturer's hands so his coupler line continues into the future.
I admit having thoughts of how long his coupler line will remain available,myself. What's REALLY concerning me,is noone has seemingly shown much interest in the project. These couplers are a milestone to HO Scale. The next thing that's on the way are Prototypical working ground throw switchstands with targets from ALL ABOARD TRAINS. These are a ways off as the 1st 'stands are being made in O Scale 1st,but the company's owner hopes to make an HO Model in the future.
Alan Hummel

Loren Casey

Loren Casey
Maryville, IL

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