Tooling Dough How To

General Composites Discussions Products Talk
#1

Just was referred to this product on another forum:

http://www.freemansupply.com/video/pastelam/pastelam.htm

Don’t know how much they want for it yet, but it looks like it should cover 3 sq ft per gallon. I’m wondering if there isn’t a way to make the dough from scratch. Just like grandma used to make… =) What resin additives would you use? I saw a write-up some time back where a guy made a dough out of play sand, but for a larger mold, you obviously don’t want it to be too heavy yet as strong as possible… I’m thinking a mixture of either wood flour or talc mixed with some microbaloons? Maybe some milled fibers thrown in the mix too? Anybody ever try it? I’m just sick of spending hour after hour laying up a PER/CSM mold. Blah. There’s got to be a better way!

Cheers,

Ubermotos

#2

All of the molds i plan on making are just 3/16" to 1/4" thick. metric thats about 3mm to 5mm thick. How thick are the parts you are laminating?

If this guy says you can do 12 layers of fiberglass cloth per day using epoxy as the tooling resin… that would give you a mold that would probably end up being 3 to 4mm thick or so… I would think. To make the mold sturdy you could add some type of external reinforcement using wood or metal.

To make the first coat of epoxy surface coat that goes into the mold you just mix epoxy with cab-o-sil. You can also add aluminum powder to the mixture. Anyone can also buy tooling epoxy surface coat that is premixed ready to use once the hardener is added.

I think maybe if you explain how thick the part is your making others here can help come up with some molding ideas. If it helps you feel any better, I hate laying up PER and CSM molds also. It stinks and it’s messy.

#3

I have sampled epoxy tooling compunds before, but I didnt like them too much. I think they would be good for quick small molds, but one problem I found was splicing two pieces together. You should just do the traditional methods of mold making, much more reliable and durable. with the tooling compounds they have no fibers, so they can shatter if your not careful. I have heard of people doing traditional mold making then backing up the mold with the compund to bulk up the thickness. the stuff also sucks to mix.

#4

My parts will just be about 3/16" thick. Multiply that by 2 or 3 and all of a sudden you’ve got round about 1/2". How many layers of 1.5 oz/sf CSM is that???

12 layers would be a marathon for me!!! Ugh! My back hurts just thinking about it.

I’m seriously thinking about these, but I was thinking of using cardboard ‘core’ ribs and wrapping the ribs in fg/per. Maybe plywood would be a better option? Definitely stiffer to start off with but harder to cut to the desired shape.

At any rate, I think it helps that my mold has some three-dimensionality to it. I could definitely see a flat mold needing to be thicker than a 3D mold…

Cheers

Ubermotos

#5

FROM A bookmark:

http://www.rcuniverse.com/forum/Sand_%2F_epoxy_molds/m_2421428/tm.htm

#6

cardboard tube, split in half, makes awesome mold sturcture, can be mitered & knotched to go over curves. Don’t have to be anywhere perfect and backed with some reinforcement, they are damn cheap and effective. Most molds only require a perimeter around the back of the flange area to prevent gross bending or twisting of the mold as molds are generaly plenty strong to prevent localized bending.

A chopper gun is VERY hard to beat for mold making.

In reality, tooling dough is just easily formable core material. For what most are doing, it would be hard to justify the cost & extra work.

#7

If you intend to make just a few parts out of a mould then it doesnt need to be particularly thick, and 3-4mm would be just fine.

However if you need the mould for multiple parts, then unless it is pretty rigid you may well have problems with gel-coat surface chipping as the mould flexes when you release parts, particularly so if you have used tooling gel-coat, which is less flexible than the std variety.

Some moulds can be made a great deal more rigid though the addition of paper rope, or even resin resistant plastic tube that has been split down the middle , being laminated to the surface of the final layer of mould layup.

#8

Thanks everybody. I’m really liking the idea of the cardboard tubes as stiffening ribs. Think I’ll go that route for this mold. Better start using more paper towels! Or I s’pose I could just run by the craft store… I guess I’m just cheap…

Hey classicbike - I’ve never seen ‘paper’ rope stateside. Where do you find it in the UK? What is it normally used for?

FYI, I got a quote from Freeman Supply at $36/gallon for a small quantity of the tooling dough. By my calculations, a gallon should cover approx 3 sq ft at the recommended 1/2 inch thickness. Seems fairly reasonable to me. Time is $$$! =)

Cheers,

Ubermotos

#9

Paper rope is commonly used for adding strength to GRP moulds, and is basically just paper thats been wound into something that looks a bit like rope.

The good thing about this product is that its very flexible and conforms to complex mould shapes pretty easily, but something like plastic tube split down the middle, would probably work just as well, but more costly.

As for any sort of paste that needs to be applied 1/2 thick, I would suggest caution, as you may well have lots of problems with cracking etc, and any savings in time would be quickly lost through repair work that would probably be required.

#10

This is part of a three-piece motorcycle streamliner mould I made.
Each part 12 feet (4 meters) long took me one day each!
Surface coat, 1/2" (13mm) tooling dough, three layers of 10oz tooling fibreglass.
No ribs necessary on the back side, No cracks in mould. No vacuum was necessary to make the moulds.
Advantages; No nasty smell, One session laminating, extremely stiff , Relitively lightweight, No air entrapment, Inexpensive,
High temp system can be used if necessary.

#11

JJ: Nice work!

So you didnt use a fiberglass skin on top of the surface coat? And then back it up with tooling dough?

Glad to see someone is having success with it.

#12

I used to use 3 layers of fibreglass after the surface coat, but there is still a chance of bridging or other voids over complicated shapes,as it is not vacuumed down. Carefull cutting of the glass will minimise this but lately I’ve eliminated the first application of glass altogether. I’ve even used no glass at all for quickie moulds(one-offs and suchlike).


This is a 4 piece Nascar 40% model mould using tooling dough.

#13

For wind tunnel resting?

I would recommend anyone to at lest use a couple layers of surfacing veil (the 1/2 roll is still for sale on eBay at $30 now…) on the back of the surface coats, letting that dry and then the dough and with some back up 10 to 21 oz FG cloth (I’ll be listing those sometime this week…:rolleyes:) layers for a muchly used mold.

#14

How do you keep bubbles out of the epoxy surface coat? I was using a freeman product and every time I was left with visible pores in the mold surface.

What products did you use in those molds?

#15

Im kind of curious as to what resin you can use in those molds.

A long time boat builder I know said that styrene will eat away at the epoxy tool over a period of time unless it has been post cured.

#16

Quote “For wind tunnel testing?”
Yes.

Question, Can you use surfacing veil with epoxy?

#17

I’ve never used the freeman product, do you mix it by hand?

I used to use the Adtech tooling dough system, which works well. 3 layers of 10oz 7500 tooling cloth are recommended on each side of the dough. It comes in two parts, one blue and one yellow. You mix it until it turns green and then roll it into “softball” sized balls and then place it on the pattern and work it down into a flat 1/2" thick piece.

I now mostly use a Ren product(Huntsman owned) called DT081.
It looks like sand, but a fraction of the weight. I then mix a measured quantity of US Composites Thick resin (because it’s cheap!) with it and apply it as described above. Works great.

#18

This is the epoxy mixer I use.

#19

Quote “A long time boat builder I know said that styrene will eat away at the epoxy tool over a period of time unless it has been post cured.”

The only reason I think he’s right is because I noticed that Ren make a “Styrene resistant surface coat” but it is epoxy.
Also that is probably why the PTM&W system uses PE gel coat, several layers of CSM & PE then cure overnight before applying the tooling dough. I’m not sure about the post cure, though.

I don’t see why that method couldn’t be applied to my system aswell.

#20

I mixed freeman’s surface coat by hand viscosity was 30000. Then brushed and hit the back with a heat gun to get rid of as many bubbles as possible. Biggest pain ever. After that i just switched to per gel coat. What’s the price on that mixer?