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Engineer
1st Class Member
USA
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Engineer
1st Class Member
USA
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 Posted - 28 Sep 2002 : 23:03:09
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Scot,
I had the same problem with the epoxy. So I tried Plastruct Plastic Weld for the PVC to styrene joints and it worked like a charm. Test it on a scrap piece if your unsure. I also use Walters Goo (a contact type cement) to fasten the plastic to wood parts together. If you finish off with the screws you'll still have a very strong joint.
Kevin
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Railway Exec (Moderator)
1st Class Member
United Kingdom
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Posted - 29 Sep 2002 : 03:36:38
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Hi All, & Scotty,
I also put a disc on the inside to give a greater area for the glue to work with, and used normal polystyrene (the stuff form Revell in a pistol grip) to start with and then backed it up with 5 minute Epoxy afterwards.
ALL surfaces need to ne clean (wipe them with Isoprop. alcohol) and rough if possible to give the glue something to grab hold of. I also made mine circular right from the start (I used a circular cutter, with a bit larger setting0, and then sanded down to size. The reasoning behind this was to lessen any shock breaking of the bond when you are cutting down the square with a chisel/knife; the sanding was towards the cylinder as well for the same reasons!
When the right size just 'round off' the outer edge, and don't forget the bands that will hide the joins of fronts/backs to pipe.
Yours Peter Bunce
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Brakeman
Germany
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Posted - 29 Sep 2002 : 04:12:26
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Hallo,
I have in germany a special gluten for PVC. It is from the Company "greven", but i think gluten from Property market for PVC-Gutters is o.k. Sorry for my english 
cu
Hans-Jürgen Eicke
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Engineer
1st Class Member
USA
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Posted - 29 Sep 2002 : 06:37:53
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Hans,
You don't need to apologize for your English. We can understand you just fine. I can't imagine what would happen if I tried to talk to you in German.
 
Tom
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Engineer
1st Class Member
USA
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Posted - 29 Sep 2002 : 09:00:06
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Definitely roughen ALL surfaces to be glued w/ epoxy if possible. Rough sandpaper is great, but even just a few scrapes with a hobby knife will make a huge difference. I've stopped using epoxies myself and have switched to acrylic and vinyl adhesives. Nothing works as well as solvent adhesives, but there's no non-destructive solvent for PVC! If you can't find Araldite, look for an aluminum-filled epoxy. Normal 5-minute epoxy is pretty handy, but it's the weakest of all the epoxies, so be warned!
Chris
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Engineer
1st Class Member
USA
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Posted - 29 Sep 2002 : 11:35:49
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What about good old-fashioned modelers glue (Testors or Revell etc..)? That stuff welds styrene together!
Steve Stockham
Kansas Central
& Colorado R.R.
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Engineer
1st Class Member
USA
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Posted - 29 Sep 2002 : 14:43:21
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Guys,
The strongest stuff I've seen lately is a polypropolene glue by Borden. Looks like the old horsehide glue, but will bond plastic to aluminum. The downside is that it achieves full set/bond at 24 hours, but what a hold!! Got about a pint from home depot fora bout $3.50.
Barry
There are no dumb questions.... |
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Engineer
1st Class Member
USA
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Posted - 29 Sep 2002 : 19:38:23
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thanks everyone!
I will probably just go with the sanding/scraping then..
but Barry, your Borden glue sounds promising!
do you have the brand name of the glue?
and how is its sand-ability?
thanks,
Scot
Scot Lawrence
Rochester, NY USA
http://gold.mylargescale.com/Scottychaos |
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Engineer
1st Class Member
USA
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Posted - 02 Oct 2002 : 06:18:39
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update..
I decided to try to the "sanding/roughing up" technique, using the same epoxy.
I took an x-acto knife and made many scrapes/scores on the inside of the PVC cylinders, and on the stryene end caps..anywhere the epoxy was going to be in direct contact. I re-glued and waited 24 hours.
the next day I picked up the cylinders and gently wiggled the end cap to test its holdness..it easily peeled off again!
oh man..this sucks..
well I noticed the epoxy left in the cylinder had a nice smooth surface, formed by the styrene cap, but I didnt use enough epoxy to TOTALLY cover the bottom, there was still a hole in the center..so I got to thinking.."hmmm..if I just used a little MORE epoxy, slapped the styrene end caps on same as before, then peeled the end caps off ON PURPOSE, the epoxy itself will form a nice smooth end cap!"
so I tried that on the other side..(the epoxy held strongly to the inside of the cylinders with the scrapes this time, just not the styrene)
I mixed up a BIG batch of epoxy, and gooped tons of it to the inside of the cylinder, so I would be sure there was enough that it would slime down and totally fill the end of the cylinder.
(well..not TOO much epoxy..the epoxy plugs are probably about 1/8 inch thick..just enough to totally fill in he end of the cylinder.)
here are the cylinders drying:
after peeling of the styrene end caps, the epoxy itself forms the cylinder cap!
after trimming up the loose ends, sanding smooth, and painting, the cylinders look like this:
not bad!
I still have to add the bands, but I think this will work!
so now I have 2 solid ends, and 2 ends that have holes..but the holey ends are ok because im going to cover them with an additional cap or two anyway..
so thats the story of my cylinders.
the end.
Scot
Scot Lawrence
Rochester, NY USA
http://gold.mylargescale.com/Scottychaos
Edited by - scottychaos on 02 Oct 2002 06:22:06 |
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Railway Exec (Moderator)
1st Class Member
United Kingdom
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Posted - 02 Oct 2002 : 14:01:16
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Hi All & Scotty,
Hey, how do you manage such a clean, non-cluttered workspace!! Puts mine to shame; mind you I have a good idea where things are. I suppose I will have to clear a larger space for workin' on the boiler - next chapter.
That 'clear space' wasn't what you had been doing whilst 'waiting for the next chapter' was it?
Nice work re the cylinders they look good.
Yours Peter Bunce
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Conductor
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Posted - 02 Oct 2002 : 14:17:49
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Don't forget Scot, those cylinders are going to have a working piston rod pumping in and out of them.
Next thing, Are you using 5-min Epoxy or 24 hr Epoxy? 24 hr Epoxy is significantly stronger than 5 min epoxy. Expectially if you rough up the surface area. (Some brands sell an 8 hr Epoxy).
At one time when I was working on a product line, we've found that the Devcon brand to be the ONLY good 5 min epoxy. All the other 5 min epoxy brands were too soft and didn't stick very well.
In any case, I have both 5 min Epoxy and 24 hr Epoxy and I use the 24 hour epoxy for those really tough epoxy jobs.
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Engineer
1st Class Member
USA
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Posted - 02 Oct 2002 : 17:23:48
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Guys, I'm still curious about modeler's glue! Why aren't we working with it? It takes about 30 min. to set and about 8-12 hours to dry but has worked well on styrene in the past. Is there something that I'm missing?
Steve Stockham
Kansas Central
& Colorado R.R.
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Engineer
1st Class Member
USA
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Posted - 02 Oct 2002 : 19:22:27
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yes I have accounted for the pistons..
actually its just going to be a wire sliding in and out..
the solid ends of the cylinders (the ends I photographed) are going to be the "front"..
the ends facing the back, facing the valve gear, are the ends that still have the hole in the center, from where the epoxy didnt fully fill the end...im going to place a smaller styrene collet thingy on those ends, which will mostly cover the epoxy, and will then be the part the "piston" slides in and out of..
I havent tried 24hour epoxy..I should get some for the rest of my epoxy needs..this 5min stuff I have doesnt seem to be fitting the bill..
Scot
Scot Lawrence
Rochester, NY USA
http://gold.mylargescale.com/Scottychaos |
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Conductor
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Posted - 03 Oct 2002 : 08:28:44
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quote:
Guys, I'm still curious about modeler's glue! Why aren't we working with it? It takes about 30 min. to set and about 8-12 hours to dry but has worked well on styrene in the past. Is there something that I'm missing?
Steve Stockham
Kansas Central
& Colorado R.R.
Steve, Modeler's glue is same stuff as the styrene solvent we're using. In fact you can make your own modelers glue. Just add bits of styrene to your solvent till you get the consistency you want. The main reason not to use modeler's glue is so you don't get any glue blobs oozing out of your joints. Look at some of the pictures of the pilots that some of the others have done. Notice the nice clean joints of some of them. You get that with using solvent instead of modelers glue. Now I still use modelers glue in some places where I have a less than perfect joint, a gap or I need a fillet.
Scot's problem is that he's trying to glue a styrene cap to a PVC tube. Two different kinds of plastic that takes two different kinds of solvent. As he's finding out, nothing glues styrene to PVC. Some epoxies work ok. As I just had a styrene cap pop off last night, I'm going to stop by the hardware store and get some PVC glue and see if the PVC will glue styrene to PVC. If that doen't work, my next thought is to coat the styrene with styrene solvent and the PVC with PVC sol and stick them together.
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Engineer
1st Class Member
USA
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Posted - 03 Oct 2002 : 20:10:54
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If you are using the light cream colored Hot-n-Cold PVC please try Plastruct Plastic Weld. It will bond styrene to it. I tried to knock an end off and it held fast. Try it, you'll like it.
Kevin |
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didnt stick at all..