homyakchik wrote:I really can't afford Alumilite prices for the stuff (the Smooth-On stuff certainly seems a better bargain), but the only dealer for the SO is down in Norfolk, and I'm betting they're not open on Saturday. Dangnation and blastoderms, anyway. Another week to wait for a UPS delivery.
Reynolds Advanced Materials. I get my stuff in a couple of days, shipping is cheaper than direct from SO AND Reynolds doesn't charge me sales tax, SO does.
Modular
Models Build your fleet
YOUR way. http://www.modular-models.com
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"I know you think you understand what you thought I said, but I'm not sure you realize that what you heard is not what I meant." - Alan Greenspan
____________________________________ "The customer that spends the least complains the most."
Thanks, Ziz. I went there to look. Interestingly enough, although their website appears to be wholly different from Smooth-On, both have the same base setup for their buttons, and right now both are having exactly the same DB access errors in serving up information on the rubbers they sell! *bwah-hah-hah*
Still, I shall check them out as soon as they're back on-line. Thanks for the heads-up.
I have a question, is there any way to make a mold without pressure casting? That will turn out without bubbles or defect to the mold or to what your trying to make? That is affordable, and if so what kind of product is it? I'm sure this question has been asked before. But I've got a 1/1000 scale Jupiter Station Klingon D-7 variation kit I built that I need to redo the neck on because it warped after many years and when I used hot water and tried a blow dryer it snapped into. Any help is appreciated, thanks
What do the USS Enterprise and toilet paper have in common? They both circle Uranus looking for Klingons.
I think this might be where I could ask this question; thread owner, if it's not, feel free to dump it wherever it might be more appropriate.
I know about using the rubber to make a mold for casting resin parts; need to get back to doing that. But I had a thought the other day, while working on an older Zoid.
Zoids were in general held together by 'Gyro Caps,' little caps of what honestly feels like the rubber we make molds of; you push them onto the axles of the joints (in the main) and they keep the arms and legs (and necks and heads and tails) from rattling apart as the Zoid moves. Each Zoid came with a sprue or two (or three) of Gyro Caps sized for it; there were three or four different sizes, usually interchangeable to a small degree between some Zoids and others.
I have one project that I'd like to work on, a Zoid Centaur (combining a Gojulas and an Ultrasaur, possibly with other parts tacked on to make it even more fearsome), that are going to require an influx of Gyro Caps from somewhere as the leftover Gojulas I have hasn't any of his original Gyro Caps. Argh. And they aren't making those Zoids any more and my sources for trading classic Zoids have all dried up and I don't want to have to pay inflated 'collector' prices just for a handful of rubber pieces (assuming I can even find any on eBuy).
So the thought occurred to me: would it be possible to make a cast of a sprue of such rubber parts (my as-yet-unassembled Mad Thunder uses the right-size Gyro Caps) and then cast the parts out of more casting rubber? Slather everything in lots of Don't Stick To This Mold Release 'cause I can't afford to lose my last sprue of these things and do it?
Or is that a futile hope? IF so, is there any way to make a casting of such things, and/or to make a mold and cast such soft rubber? What might I cast the part in? If not the same rubber as the mold, then what could I cast the stuff in? Is making a cast of soft rubber even possible (at my level of hobbyisting)?
Sorry about the length. Wanted to be clear what I was after.
Looks like that's probably what I need to look into, 'cause knowing me, as soon as I start this, I'll have to officially notice that a lot of the other sizes of Gyro Caps--still on the sprues--are starting to rot from sheer age. *sigh* "Modeling is fun." I keep telling myself that.
Having seen a few of the caps so mentioned I would use 10:1 rubber as it is firmer than the usual 1:1 mix.
Garry AKA --Phoenix-- Rising above the Flames
The Mighty Ten-12 lives.
Star Trek mort. Viva la Star Trek admiraetur.
Olde Phoenix Inn http://www.oldephoenixinn.net
I bought some silicone spray to coat masters with before molding them as I've been having tearing issues even with baby powder. Being the cheap-skate that I am, I was trying to get away with something inexpensive so I picked up a can of this for $12: https://www.amazon.com/Sprayway-SW946-S ... 924&sr=8-6
But then I wondered if it would work on the master to help it release from the mold since the mold and the spray are both silicone-based. Is this going to have any sort of reaction if I use this spray on a part that is then being covered in uncured RTV, or am I going to have to get something else for a release agent?
If a redhead works at a bakery, does that make him a gingerbread man?
RTV rubbers are so susceptible to contamination that can affect curing time (including whether or not it cures at all), strength, flexibility, durability, etc. and each brand, type and sub-type seems to have a different sensitivity to different contaminants.
I would suggest experiment on a small scale to see how this particular mould release spray works with the particular rubber you have. You may also want to consider the reaction it will have with the resin you are going to use.
Most problems with casting are due to poor mixing ratios, compatibility of components (rubber, release, resin & filler), and contamination.
"I'd just like to say that building large smooth-skinned models should be avoided at all costs. I now see why people want to stick kit-parts all over their designs as it covers up a lot of problems." - David Sisson
RTV silicone for mold making is just "expensive" there's no way around that.You gotta bite the bullet if you are going to cast parts.Stick with the manufacturer(don't combine others) and do your homework.Know what you are casting in the mold,know if your silicone is tin or platinum based and if that will have issues with what resin you are using?Most times there shouldn't be,but urethane resin is a funny animal...different manufacturers etc...so you need to know some basics.Otherwise its not too terrible to wrap your head around.
This study by Nagoya University and the Zeon Corporation is the first to evaluate the impact resistance of the new elastomeric materials based on i-SIS
I don't know if anyone answered this, but in answer to the question can you cast an RTV mold without a vacuum chamber, "YES you can". Its a little bit longer of a process. The best way to go about it is to brush on a thin layer onto the part(s) being molded in silicone. The next thing is to (after thoroughly mixed, and there will be loads of bubbles in the mix) is to hold your silicone mix a good distance above the mold/mold box. At least a good foot or so. You want the silicone to pour it into a very thin strand. This will burst/break most all of the bubbles in the silicone mix. Pour it into the corner of the mold box, not directly on the part being molded. You don't want any surface bubbles on or near it if possible. It is not 100% full proof, but I have made good RTV molds this way with few(if any) bubbles that might show on the surface. You still might get some, but hopefully in spots where they are easily filled later on or in an area you wont see. casting the resin is the next headache, but you can get bubble free castings for the most part, but there are some things you have to contend with.
I'm giving this thread renewed attention due to a need for knowledge.
In this case, I bought an old-school Marantz stereo receiver, from their champagne-gold era. One of the faders is missing the little handle on the end. Bu the others can be (carefully) removed and reinstalled.
So this is a good chance for me to try my hand at casting a replacement in resin. I don't have a vacuum pot, and I am only casting one small part. Overall dimensions are 1cm x 1cm x 1cm.
In the year 2024, what is a good silicone or RTV for making the mold, that is newb-friendly?
As an old school Marantz lover( I had an old 2226b) I am going to tell you to please don't try this as your first ever experiment, please PM me a picture, and send me the part to do it. I won't even charge you.
So me, trying to be tolerant of everybody's situations, went to a feminist picnic. Things fell apart fairly quickly after nobody made any sandwiches.
Stu Pidasso wrote: ↑Sun Apr 14, 2024 2:33 pm
As an old school Marantz lover( I had an old 2226b) I am going to tell you to please don't try this as your first ever experiment, please PM me a picture, and send me the part to do it. I won't even charge you.
Would it be possible to scan some original 1/650 AMT Enterprise model tree parts to back-engineer a mold that could be virtually adjusted in a computer to rotate that neck back a tad to level it out.
Keep the secondary hull repop, the 1966 B/C deck but no grid.
Had I the funds—I’d do this and send the mold to Round2 as a gift for a “special edition” line.
Last edited by publiusr on Sat Apr 27, 2024 2:28 pm, edited 1 time in total.
It is possible to scan to get a 3D map, which I think can be compiled as an stl.
The Illinois State Museum sends animal skulls in for a CT scans, which allow them to replicate with a printer.
I think that also be amenable to laser shaping.
zaphod wrote: ↑Sun Apr 14, 2024 1:22 pm
...In the year 2024, what is a good silicone or RTV for making the mold, that is newb-friendly?
Thanks Hivemind,
Brian
I use the silicone rubber sold by TAP Plastics. After I pour the rubber, I poke in with a bit of wire, trying to dislodge any bubbles which may have adhered to the surface of the master. I have used urethane rubber, too, but it's not as flexible as the silicone and is prone to tearing.
Another way to reduce bubbles in silicone rubber (if you don't have a vacuum chamber) is to brush the first layer onto the part surface(the important part). After that, hold the container you are pouring from high(within reason) and slowly pour into a corner. As the silicone is poured and held at a distance above the mold box, the thin stream of of silicone will break and burst most all the bubbles. There were still be some. The goal is to reduce the bubbles/air pockets and to really keep the surface of your parts bubble free. This typically works pretty well. As mentioned, surface air bubbles can be broken, but it takes a really long time for most of them to surface. Silicone rubber has a pretty thick consistency unless you thin it. It pretty much is like a consistency between molasses and marshmellow whip. There are thinners and you can also thicken it depending on your needs.
Oh that is excellent, thanks folks. I think I'll use that to cast copies of the little engine inserts for my current build, a Fine Molds Millennium Falcon in 1/72. I will use that silicone and will make a go at water clear resin.
Stu Pidasso wrote: ↑Sun Apr 14, 2024 2:33 pm
As an old school Marantz lover( I had an old 2226b) I am going to tell you to please don't try this as your first ever experiment, please PM me a picture, and send me the part to do it. I won't even charge you.
Thank you Jimi !
They arrived yesterday, and are flawless inside an out.
For those who are curious, it's a Marantz SR640, and we are talking about the little handles on the ends of the levers for the sliding volume and tone controls.
