Ideas for making an etched part

[ednadolski]

Problem Statement: how do you install a part where there is only empty space to attach it:





This is an IM rib side hopper and I am trying to think of ways to put a body-mount coupler pocket in the gap originally meant for a truck mounted pocket.  Initially I thought to make some kind of T-shaped adapter, but one other idea is to add two mounting pins at the end of the etched part which could be inserted into a pair of #80 holes drilled into the side of the bolster.   The top edge of the pocket would also have to be changed from straight to match the shape of the bolster/mounting pin  (a simple arc might be good enough).   It also seems that a special shim might be needed to fit between the top edge of the pocket and the underside of the end frame cage, in order to keep the pocket level and at the correct height.

Another possibility is to replace the entire end frame/cage with etched parts.  This could be a significant aesthetic improvement, since the plastic parts are quite chunky and oversized.  (Etched phosphor bronze or stainless steel would also probable be more durable than the thin plastic.)   I can think of two open questions off the bat:

 - Should the end cage be (a) one part that is folded to make the three sides, or (b) three separate parts that are assembled with glue or solder?   Option (a) seems tricky, since the parts will be *very* thin and hard to form;  yet option (b) also seems dicey plus not fun if you have a lot of cars.

- Should the ladder rungs and grabirons be etched as part of the whole cage, or separately etched parts, or separately added wire parts?   The latter would look better and more to scale, but would also of course be way more work.

Aside: whatever solutions work out for this might also be useful for tankers and other open-ended cars.


All comments and input gratefully appreciated!

Ed

[peteski]

I've body-mounted couplers on this type of a car (years ago) on some Atlas and con-Cor covered hoppers by adding a piece of styrene to simulate the car's frame and to create an attachment area for Micro Trains coupler.

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I don't recall the size but I think it was a 0.040" strip styrene. I shaped the piece to fit between the bolster and the end of the car, scraped the paint from the glue areas then glued the piece in.  I did paint it to match the car before gluing it in, then touched up the glue areas afterwards.  Then I simply drilled #61 hole and taped it for 00-90 screw to mount the coupler.  Of course before all that I made sure that the piece I added was at the correct coupler height.

[Scottl]

I would etch a longer piece into the coupler box to reach the bolster and perhaps just let the truck hold it in place.  If you don't want to change the coupler box, then Pete's idea would be a solution.

[Missaberoad]

The end "cages" are the weakness and strongest tell of those models. If you're willing to put the work in I think etching new parts would improve the look immensely.

Here's some good end detail shots.

B end -
http://freight.railfan.ca/cgi-bin/image.pl?i=atsf315938&o=atsf
http://freight.railfan.ca/cgi-bin/image.pl?i=atsf315797&o=atsf
http://freight.railfan.ca/cgi-bin/image.pl?i=aex16220detail8&o=aex
http://freight.railfan.ca/cgi-bin/image.pl?i=cnw174687_2&o=cnw
http://freight.railfan.ca/cgi-bin/image.pl?i=cnw173447&o=cnw
http://freight.railfan.ca/cgi-bin/image.pl?i=dlgx001001&o=dlgx
http://freight.railfan.ca/cgi-bin/image.pl?i=fshx476061&o=northamerican

A end -
http://freight.railfan.ca/cgi-bin/image.pl?i=cagx560&o=cagx 
http://freight.railfan.ca/cgi-bin/image.pl?i=crdx7234&o=crdx

Profile -
http://freight.railfan.ca/cgi-bin/image.pl?i=atsf315981&o=atsf
http://freight.railfan.ca/cgi-bin/image.pl?i=itc2013&o=itc

[James Costello]

I think I'd remove the diagonal braces and go for a 1) plastic 2) shapeways 3) etched replacement similar to the old N Scale of Nevada "Body Mount Coupler Adapter" products which is the same concept used by Trainworx

http://www.train-worx.com/details.coupler.htm

This has come up here before and @cjm413 hinted that there may be future products from Pat that might suit other models....it might be worth an email to Pat anyway.

[Lemosteam]

All,@cbroughton67  and I have been developing an RP solution for this- it is very close to a final design and anyone who wants to try the parts, I will open them for sale.

https://www.shapeways.com/product/ZSMECK8AP/30x-body-mount-adapter-tool-4750

The 30 pack comes with two little fixtures for hole placement into the bolster.

The plate fits to the bottom of the cage cross bar and runs toward the bolster, where the pin inserts into the drilled hole.  The pin will not protrude into the bolster pin hole.

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I must warn you that the assembly tolerances of this car are quite high, sometimes placing the plate at an angle in the side view (one of the reasons I have not released it for production)

Here are some pics with the coupler and bracket installed:

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[nscaler711]

Shocked nobody said to try and modify the Trainworx pieces...
http://www.train-worx.com/details.coupler.htm

[cjm413]

Shocked nobody said to try and modify the Trainworx pieces...
http://www.train-worx.com/details.coupler.htm

Trainworx should have new parts for the Precision Masters/Red Caboose covered hoppers (with brake detail) coming in the near future that I suspect would be a better starting point for the IMRC cars if they lack the side extensions that would need to be removed on a PS 4740 or 4750.

The Trainworx parts for the PM/RC Ortner RD do work on the PM/RC FMC 4700 since the bottom of the end cages is at the same height on both the sides and the ends.

[cjm413]

Trainworx should have new parts for the Precision Masters/Red Caboose covered hoppers (with brake detail) coming in the near future that I suspect would be a better starting point for the IMRC cars if they lack the side extensions that would need to be removed on a PS 4740 or 4750.

The Trainworx parts for the PM/RC Ortner RD do work on the PM/RC FMC 4700 since the bottom of the end cages is at the same height on both the sides and the ends.  I haven't tried them on either the PM/RC Greenville 2 bay car or the original PM 4750 that was based on the cars that were built by Richmond Tank Car.

[ednadolski]

Thanks dudes for all your comments.   It seems that the general consensus on the pocket mounting problem is on some sort of adapter (potentially with a drilling guide).  The trainworx parts capture the general idea, but (a) are specifically designed for the MT pocket; and (b) being some kind of plastic they seem rather beefy. (No surprise on either of those points.)

For an etched adapter it may be worthwhile to consider a T-shaped part, with the angle braces included.  The brass pocket could be soldered directly to the adapter and thus eliminate the need to drill/tap for an (unsightly) mounting screw.

On these IM cars, does the bottom of the end frame sit at the correct proto height (relative to the carbody), or has it been altered to allow for the truck-mounted couplers?   Also - how close to proto height is this car with BLMA trucks installed?  (or with FVM 36" wheels in the MT trucks?)

On the end cages, here is where I am at on these two points:

- Forming vs. soldering:  I tried bending some 0.005" stainless steel and it was basically impossible to get a good bend without a fair-sized radius.  A half-etch fold line should help but still this is inherently stiff stuff and very hard to get a grip on esp. for a thin strip.  (I used one of those photo-etch forming tools).  So forming may be untenable, which leaves soldering - but that would be no picnic either, esp. if the parts are etched in stainless steel.

- Etched-in vs. wire grabs:  Etched grabirons/rungs limit the amount of dimensionality that can be represented and may have a 'flat' look. While wire grabs would look better, it seems that separate wire parts would be an unrealistic amount of work to assemble.  OTOH, if the parts are close to scale size, then perhaps the 'flat' look would not be too objectionable...?   Doesn't seem to be many other options here (other than go to HO scale if you really must have fully detailed end cages  ).

I scanned in some images of the IM end cages, which I can import into the CAD program and use as a reference to develop some parts that fit:





Would anyone have any links to some square end-on pics of the proto that you could point me at?

Thanks again!

Ed

[Missaberoad]

Here's one (slightly mushed) A end, I'll keep digging and see what I can come up with...

http://freight.railfan.ca/cgi-bin/image.pl?i=gnbc753657detail4&o=gnbc

[Lemosteam]

@ednadolski , my adapter is 0.5mm thick under the IM cross beam, that's why a thin walled etch pocket may not work.  The screw mount in my design will be changed to a through tap drill size hole to assist in tapping the part.  I have had excellent success tapping FUD in a through hole (blind holes are a different matter altogether.  Also the flange in front of and behind the crossbeam help take the load of the pulling force.

I can see that an entire fold up etch for the end would be very desirable, and I would drop the mounting surface 0.5mm minus the etched material thickness to put the coupler at the correct height.
  Obviously not to scale...
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[cjm413]

One practical consideration to keep in mind is the availability (or lack thereof) of unassembled kits from Intermountain, and to a lesser extent, the availability (or lack thereof) of Intermountain 100T trucks.

Speaking for myself, if IMRC is going to insist on only selling assembled and decorated models with toy trucks on them, I'm not going to feel enough motivation to expend any more cost and effort than what it takes to replace the undersized MTL truck with the $@!&€💩 coupler box attached to it with a proper (and compatible) 100T truck and a fixed coupler box.

If I did find an unassembled kit that I may want to upgrade with new ends, it's my general understanding that IMRC's kits came with: 1) both the 100T trucks that are compatible with this car; and 2) an optional part that included a fixed coupler box (or at the very least, a fixed surface that could be used to attach a different coupler box)

If this is true, the most practical solution would be for Intermountain to get their $#!+ together, whether by selling kits that give us the option of building them the right way, or alternatively, selling them as RTR models instead of RTR toys.

[peteski]

Ed, judging by you last post you have already made up your mind what you'll do even before posting this question. If you are going for ultra-realism (which is not surprising) then etching the entire new end "cage" is the way to go.  My solution won't work.

 But as far as the mounting screw goes, the length can be trimmed to be flush either before or after installation. Then some touch-up paint pretty much hides it.  To me the screw (in a plastic beam) is not a big deal.

[ednadolski]

I can see that an entire fold up etch for the end would be very desirable, and I would drop the mounting surface 0.5mm minus the etched material thickness to put the coupler at the correct height.

I think your cardboard mockup closely captures what I would like to achieve.  I'm still unsure of the best approach for doing the folds.  Usually it would be done with a half-etch line on the back of the metal, but trying to model the corner angle irons of the proto which are around 3-4 scale inches means that the parts would be around 0.020" on either side of the etch line.  That's pretty small to get a grip for forming.

One possibility might be a mini bending brake like this one from Micro-Mark:

http://www.micromark.com/mini-bending-brake,6702.html

I don't have one on hand to try out, tho it does not seem to me that this tool is designed to work with metal parts of such small size as we are talking about here.  Even if the die were fine enough, there still seems to be the problem of accurately positioning the part for forming.

The other consideration is that a half-etch fold line on the back would preclude the possibility of etching raised details on the front side of the metal.  Aesthetically I am not sure that having finer parts devoid of visible detail would be much of an improvement over the factory parts (at least not enough to justify the work it would take). I guess the only way to find out is to etch up some test parts and see how it works out.

Ed, judging by you last post you have already made up your mind what you'll do even before posting this question.

Well, I have an idea what I would like to achieve, but it's how to get there that has me stumped.

If you are going for ultra-realism (which is not surprising) then etching the entire new end "cage" is the way to go.

I think I would be happy with improving the appearance to something finer, but I wouldn't say it has to be "ultra" realistic. The approach is seeming more impractical the more I think about it (and besides, if the cages are "ultra", then the rest of the model would also have to be upgraded to match....).  In the end I might just have to go with a basic adapter along the same lines as we have discussed.

Ed