Tool time.

[Kazzer]

Yes, my motivational techniques are good. I learned when I was part of the American combat submarine culture. A culture that, long before Lucas used the line, personified the concept, there is no try. There is only do. Perform to expectations, or suffer. It's called, 'qualification' and the stick is hazing. In the old days of sail it was called 'learning the ropes'. Until recently, in the crafts, it was the apprentice-journeyman-master assignment of status. All successful forms of motivation and class establishment-advancement employ the carrot and stick.
M

Hazing eh? In the US Navy eh? I wasn't much impressed when I went to dinner with friends of mine and we discussed the lack of greens on his dinner plate. He was an Executive Officer i/c a minesweeper (Sounded like second in command). At Navy College they were made to eat a huge plate of Brussels Sprouts and suffer the inconveniences thereafter. Consequently he couldn't stand even the smell of them. Poor baby was traumatised for life.

I then explained how my dad went through his hazing on his first submarine. All the new men sat around the dining table/bench, intently waiting, and two seniors entered the cramped room.

"We're going to play 'Freckles'! Anyone ever played Freckles?" No one had, so the scene was set.
One senior man jumped onto the table, dropped his pants, and deposited a large pile of do-da right in the middle of the table. There were many astonished faces, staring at this warm, steamy pile! The seniors were contented with the effort, and so the other senior said, "Right men! Look closely! They all moved closer, and then suddenly, the senior's large hard flew down and whacked the pile, splattering 'freckles' everywhere.

"There! That's how you play Freckles! Now clean this bloody mess up."

After that, there were a lot less squeamish men on board that submarine.

Sprouts or Freckles? Depends which navy you were in! (Expecting a barrage of freckles coming my way!)

[Kazzer]

Hello again


Have you ever thought about a Tool/raw material how to video?

Thanks Again

George

George! NO! NO! and THRICE NO! I'm the one that has to edit his 'movies'! He's got an obsession with sanding, and will let the camera run for hours while he's sanding the most boring part of a boat. And he drones on, and on, and covers the same thing six times!

We're not doing it! No! NO-no-no!

Arghhhhh!

Have I got to come over the border to sort you out? It'll get ugly!

[He Who Shall Not Be Named]

Hello again

Yikes ! I will have to read and reread MORE and think hard before I ask again. I like your motivational technique.

Have you ever thought about a Tool/raw material how to video?

Thanks Again

George

I try to keep it humorous, but I do see way too much useless asking of questions by the same people, people who seem to do nothing with the information handed to them. I'm a results sort of guy, and when I see non-performance from someone who has stated a goal but refuses to make the real, tangible effort to achieve the goal, then I see a guy who has WASTED MY PRECIOUS TIME! And time is the one thing that when it's gone, you can't get it back.

I so cherish CLARITY. I speak plain; I convey meaning directly, and bluntly, so that those hearing me will KNOW what I mean. CHAOS is happy-talk and smiley emoticons. Clarity is achieved through plain speaking. Display of purpose is actions, not words.

Yes, my motivational techniques are good. I learned when I was part of the American combat submarine culture. A culture that, long before Lucas used the line, personified the concept, there is no try. There is only do. Perform to expectations, or suffer. It's called, 'qualification' and the stick is hazing. In the old days of sail it was called 'learning the ropes'. Until recently, in the crafts, it was the apprentice-journeyman-master assignment of status. All successful forms of motivation and class establishment-advancement employ the carrot and stick.

There is no equality in life. There are the elites and the non-elites. One should strive to be an elite. There is no 'fair'. There is only accomplishment or non-accomplishment.

My world is black and white. No grey. I'm productive as a result. Most are not.

I've done plenty of video, a lot of it on youtube, George. Go find it. And check out Culttvman, lots of my stuff there as well.

M

[george]

Hello again

Yikes ! I will have to read and reread MORE and think hard before I ask again. I like your motivational technique.

Have you ever thought about a Tool/raw material how to video?

Thanks Again

George

[He Who Shall Not Be Named]

Hello

Question to HWSNBN David

First Thank You for posting your tool making instructional lessons. I would like to ask you about your Alumilite slow-cure polyurethane casting resin that you use now. If I remember, a LONG TIME AGO you used the Alumilite yellow brand and had discovered over a few years that the product shrunk slightly, in WTC end caps that was an issue.

Does this version have better properties OR how do you work to avoid that?

Again Thanks for the Lessons of Tool building and your techniques.

George

My pleasure, George.

That was the BJB 610 casting resin, if memory serves. I stopped using that over ten years ago when I discovered the Alumilite product line.

I've found that after 30 days (the 'green' period) the Alumilite has shrunk all it's going to. The 610 just kept creeping away.

I have no problem giving pointers to the guys out there who actually do something with my little pearls of wisdom. Ask away.

But ... remember this! There are such things as stupid questions. Ask one and I'll hand you your still beating heart!

M

[george]

Hello

Question to HWSNBN David

First Thank You for posting your tool making instructional lessons. I would like to ask you about your Alumilite slow-cure polyurethane casting resin that you use now. If I remember, a LONG TIME AGO you used the Alumilite yellow brand and had discovered over a few years that the product shrunk slightly, in WTC end caps that was an issue.

Does this version have better properties OR how do you work to avoid that?

Again Thanks for the Lessons of Tool building and your techniques.

George

[He Who Shall Not Be Named]

O.k dave,

looking forward to it.

dave h

It's David. Not Dave ...

... ******!

M

[Davidh]

O.k dave,

looking forward to it.

dave h

[He Who Shall Not Be Named]

I'm delighted to help you, Dave.

You plowed ahead and got your RESOLUTION done. That tells me volumes about you (most of it good). It's a joy to help someone who clearly has the will and hands to see a project through to completion. I'm at your disposal, sir.

GRP hull tool making next. I've started in on the article, but need a few more days to complete it, so be patient.

M

[Davidh]

Hello Dave,

Thankyou for spending your time imparting this gold to us. I really appreciate it. I realised that tooling is a big part of what you do/ we do however it as a subject does'nt get a lot of air time and yet it is make or break for the end result.

I went into the unknown 2 weeks ago when I bought my first tin of silicon. I realised that to really do the kinda stuff you do at that level required it. There was not much in the store ( literally at my local supplier a good hours drive away) all they had was 3481 base. I guess they'd sell a general purpose silicon for the widest application.

My my first mould barely set after three days, not enough hardener, however as you can see from the pics I've learnt a lot in a fortnight. I love the White fluffy cheesecake like look. Makes me want to bite into it.....

ok enough of that disturbing.. Anyway I'm a convert and asked myself why I wasn't using this stuff years ago. I am going to build a couple of kits of the Resolution so we are only talking very low volume use of the moulds. Not 300!

i am really interested in how you do a whole hull RTV mould with grp backing. I would love some pics of how you construct this although I have already been guessing the process. I am tempted.

i don't know why this pic


regards,

david h

[He Who Shall Not Be Named]

Research was extensive and netted a lot of good dope. The result were finally detailed masters such as zinc anodes (three different types, no less!); crew figures; masts; deck fittings; ladders; anchor; propellers; antennas; and sail detail items. In fact, there were so many eventual white-metal parts that I was compelled to make two spin-casting tools -- I'll just cover one of them during this presentation.

The diameter of the tool is driven by the spin-casting machine -- in my case an old blood-separation centrafuge -- a rubber disc of about eight-inches diameter. I first mock-up the placement of the masters -- used to give form to the RTV tool cavities later -- onto three concentric penciled circles. The outer circle denotes the peremeter of the tool; the middle circle denotes the center of mass of the master; and the inner circle is the warning track, where there is not enough force generated by rotation to adiquatly fill the tool voids with metal. I also work to diametrically place like volume masters, so as to not get the tool too out of ballance as the metal is poured into the sprue.

The masters are transferred from the mock-up poster-board and pushed into a clay-faced mold-board. Note the inclusion of a central sprue, runners, and bolt cavity cores. A masking-tape damn will be wrapped around the perimeter of the mold-board and catalyzed RTV rubber poured over the imbedded masters and cores creating the first half of the two-part spin-casting tool.

I use the same relatively hard, high-temperature tolerant RTV silicon mold making rubber, BJB's TC-5050 for all my non-hull making rubber tooling. The stuff is measured, catalyzed (done with vigorous mixing that invariably introduces air-bubbles in the mix), de-aired (expanding and evacuating the air-bubbles by subjecting the mix to a near perfect vacuum), and the bubble-free mix poured over the prepared masters.

If any air-bubbles remained in the mix the air within would expand as the tool halves get hot, distorting the rubber, ruining the form of the cast metal part. An alternative to the vacuum de-airing is the practice of exposing the mix, as it transitions from liquid to solid state, to at least two-atmospheres absolute -- this crushes the air-bubbles and puts the gas into solution. Vacuum or pressure, you have to get the air-bubbles out or the tool is useless!
Oh, did I mention ... RTV rubber is expensive ****! So, get it right the first time.

Just a quick aside: To insure a perfect capture in metal of the detail and finish of the tool cavity you have to insure that there is no water within the tools cavity. At normal humidity there is water in there, so you use a hydroscopic powder such as Talk to absorb it. Just before using the tool for metal casting -- here you see an open faced RTV silicon lead weight making tool -- Talc is dusted into the cavities and the excess banged out and onto the floor, and the metal poured.

Same for the two part disc type metal casting tool: the halves are dusted, excess Talc banged out, the tool assembled, clamped down onto the centrifuge bed, spun up, and metal poured.

And make sure you've got Talc and not corn-starch!!!! Guess why I bring that up?....

The spin-casting tool bolted down onto the bed of the spin-casting machine. Note the use of a Dumas speed controller to set the ideal spin for metal casting -- each tool has an 'ideal' speed of rotation, found through experiment. This part of the game is more art than craft. To the right is the metal melting pot-pouring ladle. Behind it is some of the 'plumbers solder' I use for metal casting. For clarity I've omitted the splash-shield -- an item you must use or you'll burn your titties off!

And the FOXTROT metal pieces; the end game. Trees of metal parts ready to be snipped off their runners and bagged.
Metal casting is a very quick production method -- an important consideration in a business where time is money. Also, there are some model parts, owing to the stresses they will be subject to, that are better produced from metal than plastic.

Another use of spin-casting is to drive metal or resin into very thin sectioned cavities, such as the blades of this OTW 1/100 VANGUARD pump-jet, white-metal rotor. With this tool two forms of force are used to drive the molten metal into the tools cavities: gravity and centrifugal force. The tall sprue -- by virtue of its vertical height -- produces a pressure head forcing the metal into the bottom cavities; and centrifugal force which works to drive the metal outward from the center of rotation into the very thin blade cavities.
There are numerous ways to skin the cat at the disposal of the competent model-builder! The trick is ... talking the cat into cooperating.

Another example of employing the spin-casting technique to achieve a complete fill of a difficult tools cavities with resin is exemplified by this 1/48 SEAWOLF pump-jet I was commissioned to build for a customer. This monster required the use of five, large, disc-type tools for the pre-swirl stator-hub; post- swirl stator-fairing bullet; after duct; forward duct; and ringed rotor.

RTV SILICON RUBBER TOOLS THAT PRODUCE POLYURETHANE RESIN PARTS

RTV silicon rubber tools for gravity assisted polyurethane resin casting differ in that the tool design has to allow for the escape of air out of the tool cavities as its displaced by the filling resin.

(provision of vent channeling in disc-type tools subjected to centrifugal forces is not necessary as when the metal or resin is introduced the force applied to it and the mass of the liquid is enough to distort the flange-face of the two-part tool, causing the escaping air to burp out as the metal or resin rushes into the cavities -- the same mechanism at work as goes on within the metal tool of an industrial injection forming machine, the same ones that produce the traditional plastic model kits).

Since gravity is the agent of resin motion within the tool, we are compelled to make the sprue channel as tall as possible, and to provide vent channels from each cavity to permit the easy escape of displaced air. A failed tool design is one that produces incomplete fills of the cavities, resulting in 'short-shots', i.e. parts that are incomplete; partially cast. This problem usually fixed by simply enlarging the sprue and/or vent channeling.

Tool design is embedded in my DNA, I can do it in my sleep. Yes, I'm that good at it. Study the pictures and you'll get a lot of insight on proper tool design from one of the world's best.

The majority of the resin casting I do is the manufacture of machines. Items that do useful work. All of the bulkheads and some of the discrete parts that go into my Sub-drivers (SD's) are cast from polyurethane resin. The above, assembled 2.5" diameter SAS type SD is but one example of our use of polyurethane resin parts. And here is a shot of the different 3.5" motor bulkheads produced here.
Resin parts are robust, easily machined, are excellent insulators, chemically resistant to all but the most aggressive acids and alkyds, and do not suffer significant alteration of their physical properties over time.

All of our fittings kits -- after-market packages that contain parts to convert a static plastic model submarine kit into a practical r/c submarine -- employ cast resin pieces. At one time, as D&E Miniatures (before our association with the Caswell company) we produced resin kits for the SF and Space modeling communities as well as 1/192 resin kits of the LA and STURGEON class submarines. Examples of model parts produced using the resin casting technique are presented here.

Your typical RTV silicon rubber tool for gravity casting looks like this. The two halves of the tool, held together between two stout wooden strongbacks, clamped tightly with either rubber bands or pass-through bolts.

The resin of choice is Alumilite slow-cure polyurethane casting resin. As is it cures to a tan color. But, for proprietary reasons, Caswell-Merriman dopes the resin to a blue color. Other than that, it's the same stuff sold in the hobby-shops (at a ridiculous mark-up!).

Talc was used with metal casting as a hydroscopic water-catcher. In resin casting Talc is used to coat the tool cavities after the part-release spray is applied. In this application talk acts to wick in the resin to corners and small cross-section cavities that otherwise might not fill completely with resin during the pour. Here you see a bunch of SD bulkhead tools being prepared for casting. Note the talc, Mann-200 part-release (also the preferred mold-release agent during tool fabrication), powdered tool halves, rubber bands, and strong backs. Unlike metal casting, this is a situation where you can substitute corn-starch if you're too cheap to spring for Talc.

It's not enough to pour the catalyzed resin into the tool and leave it to sit as the resin changes state to a solid. No. You have to pressurize the mix as it changes state. This to crush any bubbles introduced during mixing and to crush any void bubbles in the cavities into the solution. Two atmospheres of pressure will do it (30 PSIG). That's two Bars for you European types. My pressure pots are nasty old paint spray pots modified for this type work. Today I get mine from Harbor Freight.

You prepare the tool, button it up and make up the strongbacks, pour catalyzed resin into the sprue holes, place the tools into the pressure pot and button it up, make up the air hose and pressurize the pot to 30 PSIG and wait for the mix to harden. De-mold the parts and repeat the cycle.
We're hav'n fun now!

In the interest of economy and time it's a good idea to gang as many cavities into a tool as you can -- why go through multiple preparation and other tooling tasks when you can go through the steps one time? Such is the case with this 2.5" SD set of parts tool. All the cast resin items to make up a complete SD in one easy to use tool.
Time is money!

I'll close the RTV silicon rubber tool for resin casting talk with a bit about inserts and cores -- used to encapsulate non-resin parts within the resin part and produce bores.

A good example are these SD internal ballast bulkheads which require a horizontal bore hole to pass the ballast tank conduit tube, and in the middle of that bore to partially encapsulate a sealing o-ring or quad-ring. The packing making watertight the union between bulkhead and conduit tube.

A brass core is machined to fit within the tool cavity, a slight groove in the middle of the core accepts the packing ring which will be partially encapsulated within the resin bulkhead. The packing equipped core is set into the tool during assembly, the resin pored, and the resulting cast resin bulkhead parts is popped out, and the core pulled free, leaving the partially embedded packing ring within the bore, The inboard face of the packing making the seal between bulkhead and conduit tube, which connects the forward and after dry spaces of the Sub-driver.

A similar insert-core process is employed to make our line of pushrod seals.


Don't panic Dave, I'll get to the hull tooling later this week ... for now I need a breather, pal.
David

[He Who Shall Not Be Named]

Hi Dave, and anyone else who wants to contribute,..

After building Resolution and doing a lot of looking into silicon RTV moulds I have finally dived in the deep end and use RTV as I have wanted to do castings of hydroplanes etc..

i have looked very carefully at all the pics you've put up of your green and Blue Rtv moulds as well as Youtube and have started doing similar for the Resolutions control surfaces. I haven't done the whole spruce and vent set up yet, want to get experience just with the basic castings.

I get the impression from your workshop that silicon moulds are probably the most common form of tooling that you develop for fabricating parts, is this right? Do you still use hard shell (grp) moulds for hulls? I would consider using silicon moulds for larger parts if they give better fidelity but just don't know enough about how wobbly a large mould like that would be and making sure it was supported enough.

what kind of lifecycle do you get out of your silicon moulds? Any particular hints in looking after them or specific things I should keep an eye on whilst making them and or using them?

i see that these moulds are really wobbly. You back them with what looks like a piece of chipboard. Is there the concern that you may have a little give in the silicon mould and it may slightly distort the piece coming out of it?

Out of curiosity you must have made hundreds of these moulds, would that be correct?

the skills you freely impart are fantastic, I just wonder whether more discussion about tooling design and use would complement the other skills that you teach. I would certainly find it beneficial.

thanks Dave,


David H

Hey, Dave! Good to hear from you again. So .... you want some pointers on tool making, huh?! Careful what you ask for, pal! I'll split the discussion into two parts. The first part (this one) is on: resin and metal RTV tool making -- the same rubber can handle both resin and low-temperature metal).

[Later, I'll give you the low-down on GRP hull tool making and use. But, here's a teaser: I prefer not to use hard-shell (GRP) tools to make hulls -- I use a highly detailed RTV rubber 'glove' mold to give the detailed form to the hull part, and a stiffening 'mother' mold element to hold the rubber element in proper registration during the lay-up process of the hull part].

You're observation that the most numerous type reproduction tools I have in this shop are RTV silicon rubber is most correct. I not only have tools in the shop you've seen in pictures, I also have a shed full of the tools that are least active these day. As a side-note: the 'garage sale' WTC's Mr. Caswell has been offering in the catalog are pieces formed from some of the old, no longer used tools I had kicking around here and was thinking of throwing out before Mike intervened.
But, first, let's clear the air ...

A word of caution (you know this already, Dave, so I'm shouting at those looking over our shoulders):

Don't make tools off of other peoples work without their permission. You don't have their permission? Then DON'T COPY THEIR WORK!!!!! You don't have the skill or time to do your own master work; or purchase the services of a pattern-maker or secure permission of the property owner? Then learn those skills! Don't steal someone else's work!

You need a duplicate of a kit part, then BUY another kit! Or, secure the permission of the property owner to cast duplicates. The kit you need additional parts from is out of production? That does not give you license to copy it -- that kit is still the property of someone or some corporate entity ... it's not YOURS!

Don't hit me with that 'fair-use' crap. If I knock you down, take your wallet and run off, am I making fair-use of your money? NO! It was your money, not mine!
Don't be a thief! I'm not teaching you this stuff so you can rip someone off.

There!

You ask how long the RTV silicon rubber tools last, Dave. The following is in regard to solid part casting in these tools:

Back in the 70's I was getting only 40-80 pulls from a tool before it started tearing up. Three things changed to vastly increase the cycle life. First was an improvement in the silicon chemistry itself. Second, the availability of the more benign polyurethane resins as the substrate of choice for 'resin' parts. And, finally, the introduction of a superior part-release spray (Mann 200) and the discovery that a Talc coating not only enhanced part fidelity, but also extended tool life -- these two part-release agents working to improve cavity fill and to act as a barrier between the resin and the silicon rubber. Today, if I don't get at least 80 pulls from a tool, something went terribly wrong. Now, all that was about resin casting tools. Metal tools are something else.

I've found that the tool-life of JBJ's, TC-5050 RTV silicon rubber, when used to produce cast white-metal parts, seems to be unlimited. My old 1/60 ALBACORE tool is still going strong, pooping out near perfect metal parts after nearly 300 cycles. And that tool is about twenty years old! So, Dave, there you have it .... tool life over time and usable cycles is much better than it used to be.

RTV SILICON TOOL MAKING AND DESIGN FOR PRODUCTION OF METAL AND 'SPECIAL' RESIN PARTS

There are two common means of injecting the molten metal (white-metal: a little Antimony and a lot of Tin) or catalyzed resin (polyurethane) into the tool cavities: gravity and centrifugal force.

Typically, gravity is employed for resin casting, and some metal casting (providing there is a significant height between sprue opening and cavity); centrifugal force for metal casting (and, on rare occasion, for resin casting).

These two methods dictate two different type tool construction: the tool takes the form of a two-part disc for metal casting. And typically two tall tool halves for resin casting -- the higher the sprue over the cavities, the more pressure applied (pressure head) to drive the resin into the cavities. The one thing the tools have in common is the type rubber their made of. I use the high-temperature (up to 500-degree continuous)tolerant, room temperature vulcanizing (RTV) silicon mold-making rubber, product code TC-5050, produced by the BJB company.

Dave: you speak to the 'wobbly' nature of the rubber tools. Yes, they are flexible. Elastic if you well. But the degree of flexibility is a function of what type RTV rubber you purchase -- it can range from the stiffness of tanned leather to mush. The TC-5050 rubber I use is somewhere between the two with a Shore hardness of 50.

I recommend you stick with the Platinum curing type as it will last longer over time than the cheaper Tin based silicon rubber. Here's the relevant pages for these products. Here's the entire list of mold making rubbers BJB produces. http://bjbenterprises.com/index.php/...latinum-based/
Find and study their on-line videos on how to use the stuff.

Typical metal casting rubber tools and various trees of metal parts. The tool is in the shape of a disc that splits into two halves -- a top and a bottom. The top half has a central sprue hole through which molten metal is poured after the disc has been brought up to speed. Centrifugal force pushes the molten metal outboard through connecting runners to the cavities that will give form to the metal as it changes state from liquid to solid; the white-metal freezes almost immediately.

White-metal is the alloy of choice here as it is non-lead bearing, melts at about five-hundred degrees, and is readily available as 'leadless solder'. In this series of pictures you see the metal as bought, the rubber tool, freshly cast trees of parts, and in foreground those parts removed from the tool. The metal parts are then snipped off and bagged for sale.

Note that inserts, placed into some of the tools cavities, are bonded to the cast metal parts. Like resin casting it's possible to combine pre-formed or non-substrate items with the casting medium so that they become one once the casting cycle is complete. Or, cores can be inserted such as greased brass rods, that when extracted from the cast parts form bores in the parts that can later accept control surface operating shafts, mechanical fasteners, or bores in propeller hubs to accept propeller shafts.

Metal casting produces parts quickly, parts of considerable strength, and even the smallest item can be produced.
(there is a practical limit to the cross-section of resin cast parts owing to the fact that catalyzed resin requires self-generated heat to make the state change -- not so with metal that freezes at room temperature).

Below I'll cover the manufacture of a spin-casting tool, one of two metal casting tools, used to produce the cast metal parts for the defunct 1/72 FOXTROT kit .
... I'm going to get some utility out of that failed project, if it kills me! So, why not this term-paper?

Above you see two cast white-metal propellers for the never-to-see-daylight 1/72 FOXTROT kit we started development on. You see a left-hand and a right-hand pitched model propellers atop a photo of a prototype FOXTROT. Just to give some insight in how close I was able to re-create this submarines propellers in model form. The tool making process is simple. Master making is hard. Master making IS model building. But ... that's a whole other story.

OK, some tool making 101:

[Davidh]

Hi Dave, and anyone else who wants to contribute,..

After building Resolution and doing a lot of looking into silicon RTV moulds I have finally dived in the deep end and use RTV as I have wanted to do castings of hydroplanes etc..

i have looked very carefully at all the pics you've put up of your green and Blue Rtv moulds as well as Youtube and have started doing similar for the Resolutions control surfaces. I haven't done the whole spruce and vent set up yet, want to get experience just with the basic castings.

I get the impression from your workshop that silicon moulds are probably the most common form of tooling that you develop for fabricating parts, is this right? Do you still use hard shell (grp) moulds for hulls? I would consider using silicon moulds for larger parts if they give better fidelity but just don't know enough about how wobbly a large mould like that would be and making sure it was supported enough.

what kind of lifecycle do you get out of your silicon moulds? Any particular hints in looking after them or specific things I should keep an eye on whilst making them and or using them?

i see that these moulds are really wobbly. You back them with what looks like a piece of chipboard. Is there the concern that you may have a little give in the silicon mould and it may slightly distort the piece coming out of it?

Out of curiosity you must have made hundreds of these moulds, would that be correct?

the skills you freely impart are fantastic, I just wonder whether more discussion about tooling design and use would complement the other skills that you teach. I would certainly find it beneficial.

thanks Dave,


David H