Author Topic: Assembling pewter models  (Read 1746 times)

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160pennsy

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Re: Assembling pewter models
« Reply #30 on: May 08, 2017, 01:12:29 PM »
+1
CA doesn't have the shear strength. Has anyone found something better than epoxy for long term reliability?

I have successfully used JB Weld two-part epoxy to assemble cast metal cab sides, front pilots & detail parts on locomotive kits. You need to clean the parts well before using the JB Weld. I had the same problems with CA & the spray accelerator not working well on my first build attempt. For best results make sure to follow the manufacturers instructions on using the same amounts of each tube & fully mixing the two together until it's grey in color!

« Last Edit: May 08, 2017, 01:21:49 PM by 160pennsy »
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randgust

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Re: Assembling pewter models
« Reply #31 on: May 08, 2017, 01:35:21 PM »
+2
One thing I've done on a lot of ACC assembly jobs in general has been to basically 'bolt' pieces together by drilling .020 and putting pieces of brass wire in there at structural locations.   While ACC might have poor shear properties, it's darn near impossible to pull the stuff apart of a pin joint as the capillary action pulls it solid.   I've used that approach on Delrin with great success, and in major heavy assemblies like pewter cars I've done the same thing.    Last major N Scale Kits build I did was a Warren circus flat, and also the NYC Flexivan spine flat as modified - both got brass wire/pin reinforcements in hidden spots.   The 'deck' for the ATSF-converted Flexivan car was mostly metal shapes, soldered, but drilled and pinned into the pewter.



« Last Edit: May 08, 2017, 01:43:34 PM by randgust »

MK

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Re: Assembling pewter models
« Reply #32 on: May 08, 2017, 06:16:00 PM »
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JB Weld is just as good but a) you need to wait and b) it's visible unlike near invisible CA.

milw12

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Re: Assembling pewter models
« Reply #33 on: May 08, 2017, 07:27:36 PM »
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To echo randgust and 160pennsey, JB Weld and pinning parts are the way to go for strong joints. Pins are good practice for any joint that can reasonable handle it, and if set times are an issue, JB Kwik sets in something like 6 minutes iirc.
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peteski

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Re: Assembling pewter models
« Reply #34 on: May 08, 2017, 07:29:53 PM »
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To echo randgust and 160pennsey, JB Weld and pinning parts are the way to go for strong joints. Pins are good practice for any joint that can reasonable handle it, and if set times are an issue, JB Kwik sets in something like 6 minutes iirc.

Is JB Kwik really that different than any standard (decent quality) 5-minute epoxy? Or just a marketing ploy of using a known brand name to sell more adhesive?  :|
Also even 5-minute epoxies need several hours (or even days) to achieve full hardness.
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Missaberoad

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Re: Assembling pewter models
« Reply #35 on: May 08, 2017, 08:07:33 PM »
+1
Is JB Kwik really that different than any standard (decent quality) 5-minute epoxy? Or just a marketing ploy of using a known brand name to sell more adhesive?  :|
Also even 5-minute epoxies need several hours (or even days) to achieve full hardness.


Well... I'm sure its different but it isn't as strong as a good 5 minute epoxy...

Tensile strength (according to manufacturers specs)

JB Kwick                   - 2424psi (after 4-6 hours)

Loctite 5 min epoxy - 3211psi (after 24 hours cure time)

JB Weld                    - 3960psi (after 15-24 hours)

Traditional JB weld is about the strongest adhesive I know of marketed to the general public. I've seen automotive crankcases put back together with it, and while ugly and cringe worthy, they held...

I wish I could remember the name of the aluminum epoxy my dad had from when he worked in the areospace industry, similar to JB Weld but much stronger...

Of course you could always use Mighty putty or Track lock  :trollface:
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MK

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Re: Assembling pewter models
« Reply #36 on: May 08, 2017, 09:04:05 PM »
0

I wish I could remember the name of the aluminum epoxy my dad had from when he worked in the areospace industry, similar to JB Weld but much stronger...


Just guessing here, PC-7?

milw12

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Re: Assembling pewter models
« Reply #37 on: May 08, 2017, 09:26:50 PM »
0
Is JB Kwik really that different than any standard (decent quality) 5-minute epoxy? Or just a marketing ploy of using a known brand name to sell more adhesive?  :|
Also even 5-minute epoxies need several hours (or even days) to achieve full hardness.

I've been called out! You guys definitely did more research than I did :D
Good catch, I should have mentioned that after 5-6 minutes the epoxy is dry to the touch and can hold the parts together, but not fully cured.

I was looking for regular JB weld but Kwik was available locally and it seems to hold, but I'm not doing crankcases (whoa) or anything under intense stress. In my experience it's plenty for pewter modelling purposes, but your mileage may vary  8)
"'Model railroading is a continuing series of frustrations punctuated by moments of mild satisfaction.'" -C855B

mmagliaro

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Re: Assembling pewter models
« Reply #38 on: May 11, 2017, 12:25:59 PM »
0
The quotations from these companies on "tensile strength" don't amount to a hill of beans.  That isn't taking into account what material you are bonding.  Sure, JB Weld dries rock hard and if you fill a hole in a metal engine block with it, it can really hold.  But stick two pieces of plastic together with it, and you can peel them right apart without too much effort.

It's really good on steel and some other metals, and great under compression and as a filler.  But not so good on plastics or where there is a lot of peeling and wiggling.  It also doesn't do well when the surface area of the joint is very small.
That's why butt-gluing two pieces of a loco frame together with it works "okay".  But if you drill some holes and insert wire pins between the two halves, and THEN use JB Weld, it holds like iron.  You get rid of the wiggling and you have some epoxy inside holes with the wire pins where it can be forced against the insides of the holes.

nscaleSPF2

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Re: Assembling pewter models
« Reply #39 on: May 11, 2017, 04:07:23 PM »
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JB Weld, as well as all the other epoxies, form a mechanical bond with the surfaces being joined, as opposed to a chemical bond.  This means that the two surfaces being joined by epoxy (if they are non-porous) need to be "roughened" by sanding them with a relatively course sandpaper.  If the two materials being joined are porous, like wood for example, then the sanding is optional.
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strummer

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Re: Assembling pewter models
« Reply #40 on: May 11, 2017, 08:08:54 PM »
+1
This has turned into a classic thread; everyone has their own experiences and opinions, and it all makes for some great reading...

Mark in Oregon

mmagliaro

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Re: Assembling pewter models
« Reply #41 on: May 11, 2017, 08:18:22 PM »
0
This has turned into a classic thread; everyone has their own experiences and opinions, and it all makes for some great reading...

Mark in Oregon

Ha ha, yes!  And I should have mentioned in my contribution that I have used JB Weld on pewter models (like GHQ kits) and it does work very well.  But these days, since I discovered that it works easier than I thought, I'm more a fan of heating the joint from the inside and melting the two pieces together.  If you are quick, you can melt the pewter a little with some solder on the tip of the iron,  right along the joint and then pull off before you liquify and completely destroy the parts.
... but it only works on larger pieces you can fuse from the inside where the slightly messy melted area won't show.

peteski

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Re: Assembling pewter models
« Reply #42 on: May 11, 2017, 09:45:22 PM »
0
But these days, since I discovered that it works easier than I thought, I'm more a fan of heating the joint from the inside and melting the two pieces together.  If you are quick, you can melt the pewter a little with some solder on the tip of the iron,  right along the joint and then pull off before you liquify and completely destroy the parts.
... but it only works on larger pieces you can fuse from the inside where the slightly messy melted area won't show.

That is exactly what I recommend much earlier in this thread - weld the parts with soldering iron.   :D
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mmagliaro

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Re: Assembling pewter models
« Reply #43 on: May 11, 2017, 11:52:38 PM »
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That is exactly what I recommend much earlier in this thread - weld the parts with soldering iron.   :D

Yep... Peteski.  I did notice that.  But nobody seemed to take you up on the idea, so I figured I'd bring it up again.
I only started trying that in past few years, and it worked so well, I will always use that technique to assemble GHQ kits
(if I ever do another one, that is).

peteski

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Re: Assembling pewter models
« Reply #44 on: May 12, 2017, 01:24:43 AM »
0
Yep... Peteski.  I did notice that.  But nobody seemed to take you up on the idea, so I figured I'd bring it up again.
I only started trying that in past few years, and it worked so well, I will always use that technique to assemble GHQ kits
(if I ever do another one, that is).

Yeah, I know - thanks for chiming in.
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