What's a Resin Kit?????

[JeremyB]

Can anybody tell me what makes a resin kit any different from a normal kit??

Jeremy

[Anonymous]

Resin kits are made using resin castings. These differ from normal plastic kits in the materials used - resin is mixed and poured rather than being melted and poured.

[nfmisso]

Jeremy;

Resin kits are made in low volumes, tens or hundreds typically. A model builder makes the masters, for a typical kit, there will be several parts, each one requiring a master. Rubber molds are created from the masters. A two part resin system is poured by hand into the molds, and allowed to set (5 to 30 minutes typically depending on the resin, temperature, etc)., then the parts are removed from the mold. Two sets per hour per mold is a pretty good rate. Equipment to get into resin kit making will set you back less than $1000 to start.

Presently, most "normal" kits are injection molded. A precision mold is made out of metal that fits in an injection molding machine. The injection molding machine take plastic pellets, melts them and injects the melt into the mold. A set of tools (molds) for a typical car kit will run over $100,000, and be good for more than a million pieces. Typical cycle time is on the order of 30 seconds, part to part. More than 100 can be made in an hour. To get into plastic kit manufacturing is going to run you over $200,000 to start.

[DSchmitt]

Because they are made in very limited quantities a resin kit is usually more expensive than a comparable injection molded kit (if one exists) despite the lower set up costs. The variance in the quality of resin kits is much greater than for injecttion molded kits. The worst are just solid lumps with very poor detail and often mishapped, others are solid limps with good to excellant detail and correct shapes, and still others (some terrible-some excellant) could be mistaken for injection kit parts until you try to assemble them (plastic cement will not work). The detail can be sharper than for injection parts. Because its brittle resin generally doesen't work well for very small parts. On larger parts air bubbles can be a problem runining a part as can be warping. Quality within a production run can also vary greatly If the manufacturer isn't careful one kit could be good and another worthless.

[detting]

Resin kits are usually made from some obscure, low production prototypes. For example the B&O wagon top caboose.

I just build an 8-rib 9-panel 2 bay hopper, which may not sound to strange at first hearing, but the majority of open two bay hoppers have an odd number of ribs so that the 2 hopper bays join on a rib. This car has a bunch of rivet detail on the center panel. I put this car in service and was very pleased with the way it handled. I was a little tentative at first, since there was a substancial time commitment involved and I feared that the care may be brittle. This was totally not the case.

Jeremy, you should give one a try. They take a little longer to build, but you will be rewarded for you efforts with a care that is truly different.

Some things to remember:
Most resins kits do not have trucks or coupler, so you will have to buy these items seperately.
Resin kits require the use of Super Glue -> Model Cement will not work.
Your file is your best friend. A good set of needle files are essential to achive good results.
Since these are limited runs and unique prototypes, you pay for the research the kit manufacturers have do to make these models accurate. In the case of Westerfield Kits, you actually see the depth of research with the epistle the Al Westerfield writes for you. If you figure that better than half the cost of the kit was for research, the price is not that bad.

Good Luck...

[Anonymous]

Here's a good description of how they are produced.

http://members.ozemail.com.au/%7Eandkeller/page9.htm

"Resin" usually means polyurethane resin, although ten years ago epoxy and other resins might also be used. The material comes in two parts, the resin itself and a catalyst, which must be mixed to start the whole process. It sets up in a very short time, usually a couple of minutes, and once cured it can be "worked" much like polystyrene. BUT!

Resin cannot be glued with conventional modelling adhesives. Cyanoacrylates are about the only thing that will work, apart from epoxy and raw resin. The catalyst used with polyurethane resins contains isocyanates which are carcinogenic. If you're ever tempted to pour resin (it's not hard!) avoid getting the liquid on your skin. When sanding or filing resin, avoid breathing the dust and clean up all traces as soon as you're done.

Resin kits make use of moulds made from RTV rubber, a material like latex. It is possible to get much better detail on parts and much deeper undercuts than is possible with steel moulds as used for injection plastic kits. The rubber is not cheap, and moulds have a limited life (about 100 to 150 "shots") so mould replacement is a significant part of the dollar and time expense of producing kits. Nor is the process foolproof. The rejects cost as much to produce as the gems do, again adding to the cost. Therefore resin kits tend to be more expensive than mass-produced injection-moulded kits are, but as pointed out, resin/rubber offers MUCH more flexibility in choosing a subject, since a moderately-sized injection-moulding tool costs upwards of $350,000 to produce, while a rubber mould will cost a small fraction of that.

HTH
Scott Fraser

[Anonymous]

Yes, resin kits do cost more. They also sit on the store shelf a long time and eventualy go on sale. However, for a $30.00 resin kit ( okay $45.00 with trucks and couplers) I would be modeling for about 30 hours. A $20.00 plastic kit would give me about 5 hours of modeling. For me I get more bang for my buck with a resin kit. Also I get to choose which trucks and couplers to put on, and not have it dictated by the manufacturer of the kit. (All my couplers are KD).That said, it would take me a long time (years) to populate a large layout.

So, if your objective is to build a lot of cars and run trains, go for the plastic. Personally, I get alot of enjoyment in the building of the car.

[Anonymous]

The biggest difference as far as an end user is concerned is glue. Resin will not bond with styrene glues. Most people use ca or epoxy to put them together. Resin structures are ususally weaker when done than styrene due to the glue joints being mechanical rather than chemical. Resin structure are ususally heavier too due to thick walls. Most of the time this is not a problem unless you want a boxcar or building with its doors open. Then the extra thickness is sometime objectionable. FRED

[Sperandeo]

Hi Jeremy,

You can look up the following article and learn a lot of what you want to know about resin car kits:

Building resin freight cars
Model Railroader, August 1999 page 62
Get those detailed models out of the box and onto the layout
( KIT, "MCGUIRK, MARTY", RESIN, CONSTRUCTION, FREIGHTCAR, MR )

And by the way, thanks for signing your name.

So long,

Andy