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Affixing cast gypsum abutments to layout -- how?

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Affixing cast gypsum abutments to layout -- how?
Posted by crossthedog on Saturday, November 20, 2021 5:13 PM

I bought some Monroe Models bridge abutments. They are stunning. And brittle. Half of the set were broken when they arrived, and Bruce Monroe quickly sent out a whole new set and told me not to bother returning anything. I was favorably impressed by his customer service, but their brittleness leaves me unsure how to proceed.

The place where I put my bridge is a curved "corner" cantilevered out from the benchwork and hanging over empty space. Before I cut through the subroadbed to install the bridge, the subroadbed held everything up, and that stretch of subRB was in turn supported by the benchwork at each end. In other words, the subRB was itself already a bridge, a trestle of sorts. But now I've cut that subRB span in the middle, and the bridge spans the gap. I have a vertical plywood support at each end of the bridge that the abutment can...uh... abut, but... how do I affix the abutment to that plywood?

The abutments are cast in a plastery gypsum, so I cannot imagine you could drill through it without it turning to powder. I imagine they are designed to sit ON TOP of the layout's surface, and I suppose I could build something to reach out underneath it, but it's starting to get a little bit like a Dr. Seuess construct as I build stuff out over empty space. I'd prefer to glue their backs against the plywood if there's a glue that would hold gypsum/plaster to plywood.

Have any of you done this? What do you recommend? Have I described it enough so that you can picture this?

I will try to post a photo later. Any help, much appreciated.

-Matt

Returning to model railroading after 40 years and taking unconscionable liberties with the SP&S, Northern Pacific and Great Northern roads in the '40s and '50s.

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Posted by crossthedog on Saturday, November 20, 2021 5:21 PM

I hope you can see this. I affixed the two vertical pieces of plywood to the L-girder so they extend out to support the subroadbed at each end of the bridge, and then I chopped the track and subroadbed out between them. The bridge is actually being held up here by rail joiners. I want to put the abutments with their backs against these plywood pieces. Glue?

Thanks,

-Matt

Returning to model railroading after 40 years and taking unconscionable liberties with the SP&S, Northern Pacific and Great Northern roads in the '40s and '50s.

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Posted by saronaterry on Saturday, November 20, 2021 5:28 PM

Could you try hot glue on a broken piece? To experiment?

Terry

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Posted by gmpullman on Saturday, November 20, 2021 5:56 PM

Duplicate post Huh?

     See below —

 

 

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Posted by gmpullman on Saturday, November 20, 2021 5:59 PM

crossthedog
Glue?

DAP Alex latex caulk.

saronaterry
Could you try hot glue on a broken piece?

I believe hot glue would get too tacky and begin to harden as the plaster pulls the heat out of it before you can align the pieces.

I would slightly dampen the pieces so the moisture doesn't get pulled out of the glue too soon and use a PVA like Weldbond, perhaps even slightly thinned, then carefully align and join the pieces. Once set add a little more to the back side of the break.

Good Luck, Ed

 

 

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Posted by Mark B on Saturday, November 20, 2021 7:39 PM

Hi

My name is Mark Ballschmieder and am the previous owner of AIM Products having sold it to Bruce Monroe about 5 years ago. Bruce is first class all the way and will always make things right for the modeler. 

Having said that I did manage to break a few pieces when I was making them and tried a few different ways to attach them to bench work or just repair the piece itself. For attaching them to the bench work I used PLA 300 as it was the closest at hand and it worked well. Other adhesives may work as well or better but I never tried them. Also wipe off any plaster dust that might be on the surface you want to attach. I also tried drilling pieces and found that if you used a light touch with the drill you could get a hole in a casting. To repair a break it was important to wet the castings' broken surface. A quick rinse or dunk into a bowl of water. This added moisture to the casting so that the moisture in the adhesive would not be drawn out too quickly which made for a very weak joint. I used Elmer's White Carpenters Glue. Put a dab on each broken surface and and push them together and let dry over night. Be careful not to get glue on the surface that is going to be painted. The glue will seal the surface and make it impossible to paint. I hope this helps and others that have answered seem to be on the right track(no pun intended)

Mark B.

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Posted by reasearchhound on Saturday, November 20, 2021 7:40 PM

I would think applying one coat of latex paint to the exposed surfaces of to act as a sealant would suffice. Then just use white glue or an adhesive caulk to secure them. Any visible cracks could easily be spackled over and then sanded prior to coloring.

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Posted by selector on Saturday, November 20, 2021 7:58 PM

Mark B

Hi

My name is Mark Ballschmieder... bench work or just repair the piece itself. For attaching them to the bench work I used PLA 300 as it was the closest at hand and it worked well. ...

Mark B.

 

This is precisely the product I used, also because I had it on hand, for affixing W/S plaster portals to my plywood roadbed, now on two layouts.  PL300 is foam safe, so it makes some sense to have it handy if you're likely to want to stack some bits of foam to carve them and form hills or to use as filler here and there.  

The PL300 doesn't harden over night.  It takes several days, but it will stiffen up enough over about 24 hours to let upright things stand on their own while you work nearby, even if they lean by 2 deg or so...no more.

In the scene below, there's a portal standing on its own, but the roadbed is part of a helix, so it's sloped.  I would have buttressed this plaster portal with something for at least a full 24 hours, and then removed the blocks of whatever, maybe a heavy Fast Tracks point tool. Click on the image, it will enlarge, and if you squint you can see the gobs of tan coloured putty, really PL300 construction adhesive, under the legs of the plaster portals.

 

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Posted by NVSRR on Saturday, November 20, 2021 8:24 PM

Grab-it works  Just make sure all the dust is off both the abutment and wood.

A pessimist sees a dark tunnel

An optimist sees the light at the end of the tunnel

A realist sees a frieght train

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Posted by doctorwayne on Saturday, November 20, 2021 9:41 PM

The PL 300 would definitely work, but I'd be inclined to use WELDBOND...as it says on the label, it sticks just about anything to anything.

Wayne

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Posted by crossthedog on Saturday, November 20, 2021 11:41 PM

Once again, thanks all for the replies. It occurred to me, after I posted this and ran off for the evening to help a friend, that there must be at least as many suitable adhesives on the market as there are members of the forum, and that I might inadvertantly have ignited a flaming "bake-off" among proponents of different products, so it doesn't surprise me to find quite a broad array of ideas here. Thanks heaps (or should I say thanks gobs ha).

Returning to model railroading after 40 years and taking unconscionable liberties with the SP&S, Northern Pacific and Great Northern roads in the '40s and '50s.

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Posted by SeeYou190 on Sunday, November 21, 2021 12:33 AM

Mark B
For attaching them to the bench work I used PLA 300 as it was the closest at hand and it worked well.

Is this the same as Loctite PL300?

If so, yes, that stuff works great for all kinds of gluing needs.

-Kevin

Wink Happily modeling my STRATTON & GILLETTE RAILROAD. A Class A line located in a personal fantasy world of semi-plausible nonsense on Tuesday, August 3rd, 1954.

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Posted by Mark B on Sunday, November 21, 2021 8:41 AM

Kevin-

I meant the PL300. Sorry about the extra letter. I just got home from a 13 day road trip and this old brain was/is a bit punchy. 

Mark

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Posted by SeeYou190 on Sunday, November 21, 2021 10:01 AM

Mark B
I meant the PL300. Sorry about the extra letter.

I figured we were talking about the same stuff.

I had not used any of the Loctite PL adhesives until I started working on my house. Now I love them. I know I will be using these a lot when I finally get going on the layout.

-Kevin

Wink Happily modeling my STRATTON & GILLETTE RAILROAD. A Class A line located in a personal fantasy world of semi-plausible nonsense on Tuesday, August 3rd, 1954.

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Posted by selector on Sunday, November 21, 2021 1:59 PM

As a tip, you need to store the tip....properly.  Once you cut open the nib, and puncture the seal, you'll want to use as much of it as you can at one go, but not strictly necessary...IF you preserve what is left in the tube properly.  I drive a screw into the smallish hole I make, then wrap the screw with plastic, say a shopping bag remnant, and then tape over that to effect a decent seal with masking tape/painter's tape.  That should buy you about three months.  After that, all bets are off.

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Posted by MisterBeasley on Sunday, November 21, 2021 2:22 PM

I did a lot of attaching hydrocal castings to foam and styrene years ago as I was just learning how to do scenery.  I eventually used silicone sealant, and it did hold up.  Perhaps it would be a good idea to cover the back surface of the casting with a sealant, as glues aren't going to take to a smooth casting surface get well.

It takes an iron man to play with a toy iron horse. 

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Posted by rrebell on Monday, November 22, 2021 10:25 AM

I used a lot of AIM castings on last layout (a lot), I just cauked them in place, then plastered an seams, once stained you could not tell where the seams were.

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Posted by Overmod on Monday, November 22, 2021 1:52 PM

What I used a long time ago was a mix of dyed plaster with diluted Weldbond, on the principle of acrylic binder.  Dampened the back of the plaster castings first, and brushed on some of the diluted Weldbond as a sort of primer, then troweled the material where the portals or abutments were to go and then bedded the castings in with a bit of water misted on the contact area just before to assure adhesion.

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