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Re: Couplers

Josh Baakko
 

Kevin, I'd be interested in testing a few if you end up with some spare.  I'm in need of a few lower shelf only type F's.
Josh


Re: Couplers

Tim L
 

Frank did his own investment casting in-house.

- Tim

On 14/01/2020 02:59, Andrew via Groups.Io wrote:
Do we know if Frank did the investment casting in house or if he had a company do that part for him? I have asked several investment cast companies and so far haven't found one that is willing to do the size of parts/quantity of runs that I have inquired about.


Re: Couplers

Kevin Packard
 

Andrew, thanks for checking on that.  It would be interesting to see if PSC can/wants to do some smaller runs.  At least for type F's, double shelf, and long shank E's.

Dale - that is interesting regarding Formlabs.  I've never heard of creating a printed mold for die casting.  I'll have to look into that and see the cost associated with it.



On another note, my Siraya Tech Blu resin came in today and I ran a test batch to see what the results were.  First off, I did confirm like Frank said that these parts can and should be printed without supports.  I aligned the fret directly on the plate and they printed great.

Blu is very viscous and I had to keep a space heater going the whole 2.5 hours for it to flow properly.  It prints fine on the Elegoo Mars, which means it should be fine on any other LCD-type printer.  Detail capture was good, no obvious distortion noted.  It actually is more of a green color than blue, go figure.




It's hard to make out details with it being translucent.  I prefer the solid gray of the standard Elegoo resin.  I set up a real curing station this time with a proper curing light in the right wavelength (405 nm), and cured on a turntable for 30 minutes.  After curing I tested the pieces.  Blu definitely has some strength to it, and more flexibility than the Elegoo gray.  I'm not sure I like the flexibility part though.  

Despite a long cure though, the resin remained slightly tacky to feel.  Assembling a ball inside is going to be a real problem.  I honestly don't know if Blu is the right product for this application.  I'll keep messing with it and see if it improves.

I did, however, run my other coupler pieces from my previous gray print through the curing cycle and they feel great!  The Elegoo gray hardened right up and feels very solid.  No tackiness or stickiness anywhere.  They now assemble easier and are very strong without the large amount of flex that Blu is showing right now.  I'm leaning towards using Elegoo gray for most of my tests going forward.  I can say with some confidence that after a proper cure the Elegoo gray couplers feel very strong and stout.  The only way they will break is by dropping the model or dropping something on the coupler such that it snaps at the shaft.  Otherwise they feel sturdy.

-Kevin


Re: Couplers

George
 

Might be worth a call to PSC to see if they could cast them.

George Sebastian-Coleman
11 Taine Mountain Rd.
Unionville, CT 06085



On Jan 13, 2020, at 7:59 PM, Andrew via Groups.Io <a15andrew15@...> wrote:

[Edited Message Follows]
[Reason: Pricing still on Sergent Website!]

I reached out to Frank to see if he could provide more information. In the meantime, I have started searching around for other alternatives, as out of the 5 investment cast companies I talked to only one of them thought it might be possible to do it with their equipment. I will try and keep everyone updated on what I find.


Re: Couplers

Andrew DeKruif
 
Edited

I reached out to Frank to see if he could provide more information. In the meantime, I have started searching around for other alternatives, as out of the 5 investment cast companies I talked to only one of them thought it might be possible to do it with their equipment. I will try and keep everyone updated on what I find.


Re: Couplers

Dale Buxton <dbtuathaddana@...>
 

Frank has only shared that he did the printed parts in house. He has not shared if he investment cast them in house or his casting partners that he used in the process.

On another note. Formlabs keeps sending me information on how you can print a die casting mold using their machines for low levels of production runs. Clearly the printed molds are not as durable as steel dies. But I think this might be another option for coupler production.

Dale B.

On Mon, Jan 13, 2020 at 8:59 AM Andrew via Groups.Io <a15andrew15=yahoo.com@groups.io> wrote:
Do we know if Frank did the investment casting in house or if he had a company do that part for him? I have asked several investment cast companies and so far haven't found one that is willing to do the size of parts/quantity of runs that I have inquired about. 


Re: Couplers

Andrew DeKruif
 

Do we know if Frank did the investment casting in house or if he had a company do that part for him? I have asked several investment cast companies and so far haven't found one that is willing to do the size of parts/quantity of runs that I have inquired about. 


Re: Files

 

Found it, thanks.

Stephen


Re: Files

Andrew Porter
 

Its Instructions, etc then Instructions.


Re: Files

Andrew Porter
 

Stephen,

Click on Instructions, then Instructions, Etc.  Last item on the list.

Andrew


Files

 

I am trying to locate where Franks coupler drawing files are.  Can anyone point me in the right direction?  They used to be on his website, but I cannot find them anymore.

Stephen


Re: Couplers

Kevin Packard
 

Thanks Al.  Right now I'm just experimenting to see what will work and what won't.  Hopefully we can all pool our knowledge and experience in order to give us a way to enjoy these couplers that are no longer available.  I'm much more interested in sharing whatever I find with everyone else, so that hopefully all of us can benefit.

On that note, I've uploaded the STL files I've stitched to the file page.  These files should be able to be printed on any SLA printer.  Just download and put into whatever slicing program you use.  I use ChituBox and the files I made pull in as the correct size with no errors.  If anyone else has access to a SLA printer (or another type too) try the files out and see how they work for you.  I'd like to see what experiences other people have.

-Kevin


Re: Couplers

Alan Hummel
 

Kevin,

The couplers sure do look good all painted up!Emoji still think an ad in RMC or Model Railroader might attract interest. thought about emailing Exact Rail or Tangent or both.

Al Hummel


Re: Couplers

Kevin Packard
 

Type F prints!  They printed just fine, but I didn't get Frank's message about not using supports until they were already in the printer.  Next test batch will be with Blu and no supports.



I again slightly enlarged the hole using a hand drill) for the ball to allow it to move up and down easily.  To counteract the stickiness on the knuckle, I slightly widened the knuckle holes (also using a hand drill) to allow it to freely pivot on the studs.  I got much more reliable function this time around, but still nowhere near as reliable as the standard metal Sergents.

Installed on two Athearn Bethgons.  These cars are part of an empty unit train, so likely the plastic couplers will be more than adequate, especially once I print in Blu.  I have around 25 empty coal cars to outfit.




-Kevin


Re: Couplers

Tom Colasurdo
 

Kevin:

Thanks for confirming that your parts were HO scale ... detail and finish is amazing for such a small scale.

My friend printed the first test parts (S scale top and bottom ... no knuckles, since Frank indicated he has some in stock) directly from Frank's files.  The printed parts were amazing ... detail and finish with no flash ... fit together perfectly.  The ball didn't fit well into the holes, so operation wasn't possible.  The die-cast knuckle was very stiff ... don't know if printing one from Frank's file would have been better.

As for material ... I have to ask my friend (it's one of the questions, besides which printer, I would like to know myself).  I'll let you know what I find out ...

Have a great night.

V/r,
Tom C.



On Monday, January 6, 2020, 11:19:34 PM EST, Kevin Packard <kevinpackard@...> wrote:


Tom - Yes, these are HO scale.  I did not make any adjustments on the 3D file because I wanted to see if they would print first.  The two holes I described ended up printing slightly small, and I feel like the pin for the knuckle may have been a little tight.  That part may have been flash though.

I might try messing with those parts of the files if I continuously have issues with tightness.

What material are you printing yours in?

-Kevin


Re: Couplers

Mike Conder
 

I've heard that the Siraya Blue is better, but even better is a mix of Siraya Blue and a reason called "Tenacious" ... two suggestions were 80:20 Blue:Tenacious and 50:50 Blue:Tenacious.  I don't have a resin printer so don't know for sure, but might be worth a try ...

Mike Conder

On Mon, Jan 6, 2020, 9:36 PM Kevin Packard <kevinpackard@...> wrote:
Mike - Yes, resin printer.  Elegoo Mars SLA printer with plain Elegoo Gray resin.  Good detail from that resin, but definitely not the strongest out there.

-Kevin


Re: Couplers

Kevin Packard
 

Mike - Yes, resin printer.  Elegoo Mars SLA printer with plain Elegoo Gray resin.  Good detail from that resin, but definitely not the strongest out there.

-Kevin


Re: Couplers

Kevin Packard
 

Frank - Wow, those pictures are awesome.  It all makes more sense now how you designed them.  When you printed the initial models, what orientation did you have them in?  Vertical? Horizontal?

In testing the prints I've made the weak point is definitely the sides of the shank by the hole for the lower piece.  I think that some beefing up in that area would be great.  Or possibly also decrease the size of the hole and pin.  

I plan on trying out a different resin that is supposed to be better for working parts.  Siraya Tech Blu resin.  Apparently it has great strength and some slight flex to it as well.  I also have some stuff coming to set up a better curing station.  Now that the proof of concept works, I'm really curious to see what can be achieved with better resins and some minor tweaks.  Hopefully we can figure out something that works.  

-Kevin


Re: Couplers

Kevin Packard
 

Tom - Yes, these are HO scale.  I did not make any adjustments on the 3D file because I wanted to see if they would print first.  The two holes I described ended up printing slightly small, and I feel like the pin for the knuckle may have been a little tight.  That part may have been flash though.

I might try messing with those parts of the files if I continuously have issues with tightness.

What material are you printing yours in?

-Kevin


Re: Couplers

Mike Conder
 

Frank, are those couplers shown 3D printed in wax for lost wax casting?

And Kevin, great work, did you do that on a resin printer?  If so, which resin did you use?

Mike Conder

On Mon, Jan 6, 2020 at 8:56 PM Frank Sergent <fsergent@...> wrote:
Hey Kevin, looks like you are getting very close. Go look at the pictures in the sergent engineering groupsio page “Treeing 3D prints”. Look at the IMG_1095.jpg picture. All the 3D models are designed so they can be 3D printed with no support structure. I’m convinced that you don’t have to go to investment cast metal with the resins that are available today. You may have to modify the coupler designs slightly to beef up the cross section of the shanks where the hole that receives the “rivet” from the bottom part fits. Also, all my 3D model files have pre-distorted knuckle hinge pins that allowed the final product to come out correctly on my printer. You’ll have to modify the design in that area to give predictable geometry from your printer. Also, a good UV curing process is very important to get usable parts whether you are investment casting or not. Congratulations!
 
Frank
 
Sent: Monday, January 06, 2020 5:31 PM
Subject: Re: [Sergent Engineering] Couplers
 
Jeff - I did use dry graphite when I put the ball in, and it helped.  The knuckle could certainly use some of it.  I'll give that a shot on the next set I assemble.

-Kevin

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