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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


Re: Couplers

Frank Sergent
 

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


Re: Couplers

Tom Colasurdo
 

Kevin:

Very nice work !!!  Thank you for sharing your experiments / results ... really look forward to hearing results from operating.

I'm guessing these are HO scale couplers?  What size ball was installed in the coupler?

Frank Sergent mentioned to me in one of his e-mails that he utilizes a 2 mm ball in the S scale couplers ... as I've been playing with Frank's 3-D files for the S scale couplers I came to the same conclusion that the cup holding the ball needed to be sized a little larger (believe the dimension in the model was 1.6 mm) ... how much did you enlarge the dimension on your experimental coupler?

I also experienced sluggish knuckle operation on first printed samples ... I'm changing the cylinder dimension that holds the knuckle ... if that doesn't work, I may change the cylinder to a cone shape.

Since I had AutoDesk Inventor available to me, I'm currently assembling the modified parts in one file so I can add constraints ... I'm hoping this feature will let me animate and check for operational interference before I have the parts printed again.

These couplers are too good to give up on and revert to more readily available couplers ... staying the course, and your progress provides encouragement and optimism.

Thanks again ... have a great night.

V/r,
Tom C.




On Monday, January 6, 2020, 02:02:21 PM EST, Kevin Packard <kevinpackard@...> wrote:


I put together a couple couplers this morning and have tested them out.  They do work, though they are not nearly as smooth operating as all metal.  The resin tends to hold the ball, as well as the knuckle.  It takes more force to open the knuckle, and to close it.  It's far easier to couple to a car with all metal couplers because that one will have a knuckle that opens and closes easily.  

I did have to widen the ball space a bit, as well as the coupler box pin hole.  Besides that there were no fit issues.

Here's one of the frets after printing:


One of the couplers removed from the supports and cleaned up


Assembled with ball, metal knuckle, and metal lower shelf




Installed on a Walther's 50' boxcar


Coupled to a standard E


Coupled to a long shank lower shelf E


I'll keep testing.  Time will tell how it does in the long run.  There are other resins I might want to try.  The have "engineering" resins that are tough and designed to be used for moving parts.  We'll see.

-Kevin


Re: Couplers

Kevin Packard
 

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


Re: Couplers

Ryan Harris
 

Sounds great, Kevin. These couplers look fantastic!
--
Ryan Harris
Fort Worth, Texas


Re: Couplers

Rob Briney
 

Kevin
That’s pretty Amazing. 
Rob B


On Jan 6, 2020, at 11:01 AM, Kevin Packard <kevinpackard@...> wrote:

I put together a couple couplers this morning and have tested them out.  They do work, though they are not nearly as smooth operating as all metal.  The resin tends to hold the ball, as well as the knuckle.  It takes more force to open the knuckle, and to close it.  It's far easier to couple to a car with all metal couplers because that one will have a knuckle that opens and closes easily.  

I did have to widen the ball space a bit, as well as the coupler box pin hole.  Besides that there were no fit issues.

Here's one of the frets after printing:
<20200106_075921.jpg>


One of the couplers removed from the supports and cleaned up
<20200106_094417.jpg>


Assembled with ball, metal knuckle, and metal lower shelf
<20200106_095752.jpg>


<20200106_095803.jpg>


Installed on a Walther's 50' boxcar
<20200106_100612.jpg>


Coupled to a standard E
<20200106_103212.jpg>


Coupled to a long shank lower shelf E
<20200106_103331.jpg>


I'll keep testing.  Time will tell how it does in the long run.  There are other resins I might want to try.  The have "engineering" resins that are tough and designed to be used for moving parts.  We'll see.

-Kevin


Re: Couplers

Jeff Young
 

Hi Kevin,

Try lubricating the plastic with graphite and see if the knuckle moves more easily. (Just shade it with a pencil if you don’t have powdered graphite.)

Cheers,
Jeff.

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