Randy Etken

My Feedback: (10)

What do any of you use between the male plug and parting board to fill the gap?

seanreit

My Feedback: (60)

Bondo or modeling clay works great!

DMcQuinn

My Feedback: (13)

I use bondo since it sets up fast.

Scorpion Racing

Hi Randy, I also used a polyester glazing (evercoat) and then some of the modeling clay with fairly good results. I have also heard of using clear wax, which I think might leave a cleaner edge. That is what I am going to try on my next mold.

jirvin

I use bondo or epoxy and micro balloons.
I over fill the slot and then remove the plug after it has hardened and then sand the bondo flat

To ease removal of the plug the splitter boards are made in 2 halves - secured with screws onto a base. That way i can loosen of a splitter board to get the plug out. I stabilize the plug in the holding frame with the use of bondo also. A big blob of bondo either end with somethin plastic lunch film over it to protect the plug - plug nescelled in while bondo still wet.

Somewhere in the composite forum on rcgroups is a discussion on use of bondo as a gap filler.

To improve the bonding of the bondo I put a slight bevel on the parting board to give a wider flatter adhesion surface. Using bondo allows more freeplay in fitting the plug to the shadow board as the bondo is more stable and doesn't get messed up when waxing.

cheersd Jeff

diggs_74

I've used the bondo too Randy but I did have some areas where tooling gel still seeped between the plug and the parting board.. I think it was because I didn't let the bondo cure all the way before sanding it flush with the parting board. It will probably try the bondo again because I think messing with the modeling clay is a PIA..

KC36330

i have to disagree. if you get a clay that is hard (not the soft mushy stuff) and roll it out into a thin string form, you can then use a sharpened off dowel rod to pack it into the gap, and use the sharpened edge of the dowel to trim it flush, you can do an entire plug in less time then it takes to mix the bondo.

diggs_74

KC, I have done what you explain a number of times and in my opinion trying to squeeze clay down in a very small area while trying to keep the plug from moving in the parting board can be a bit of a pain.. I found it a little easier to coat the edges of the parting board with bondo and set in the waxed plug.. The next day I pop it out and carefully sand the bondo down to the level of the parting board.. The reason I say carefully is that I have had issues with the sanding distorting the bondo if it's not fully cured which can effect the 'seal'..

As a disclaimer I don't claim to be any kind of expert in the art of mold making.. Just stating what's worked best for me in my limited experience..

Randy Etken

My Feedback: (10)

Scott what is clear wax?

Scorpion Racing

I saw Kevin Matney use parafin wax for his latest mold build thread. After using a CNC to cut the plugs, it looks like he uses the melted parafin wax to fill the gap between the parting plate and the part to finish the parting seam. Kevin Matney's thread is in the Q500 section on RCU, and the title of the thread is "This the plugs for my new Q/500". I think one can adapt the wax method to fill any parting line gaps, and of course, the wax is easy to shape and will not stick to the resin or part.

I was always wondering how the molds were make with that big trench around the parts! Thanks Kevin!!

MTK

Have always used Plumbers Putty for any of my molds. Easy to work with and fills even large gaps easily. It doesn't need to be waxed either...it just peels off the mold.

Particularly handy when molding up propellers to form the parting line of the clamshell.

I like plexiglas as the board stock for similar ease of use. FWIW

MattK

Kevin Matney

My Feedback: (1)

I use paraffin wax and tape. Tape the plug in the PB and tape the top side. Then pore in paraffin wax just past melting point fron the back and let cool. Then take a 90 degree square and scrap off the extra wax.

stealth assassin

Where Is the parifin wax found?

Scorpion Racing

I have seen it at composite retailers on the shelves. I think it is the same stuffas is used for Mason Jars for canning vegetables.

Maybe someone who has tried it can chime in and tell us if the canning wax is the same stuff??

MTK

Yup, it is. Regular ordinary candle wax is paraffin as well just higher MW meaning stiffer stronger

MattK

ArneK

Hi,

We had this discusion a number of times on the German board.
I tried most of the solutions to this problem, including clay (R&G) and polyester Bondo.
The clay is NOT hard enough so you get brushmarks along the centreline of the mold.
The wax also get "damaged" later because of applying the release agent to the plug.
I noticed that polyester (Bondo) can react with the release agent, PVA and W70 (wax),
perhaps because of the heat it produces while curing. [X(]
If you are "lucky", you will only have marks on you plug because of this reaction. If you're not, you
are not able to get the plug out of the parting board anymore... [>:]

What works perfect for me, and I know it takes a little time, is making a mixture of epoxy and talcum powder.
Make it as thick as possible and fill the gapp with this mixture.
Let it cure, take out the plug and sand the epoxy. You will see sanding this is a piece of cake because
the talcum "lubricates". This is better then microbaloons because it leaves not pinholes.
To make this process as easy as possible, I always make an at least two piece parting board.
That's easier to get the plug out...

The result is a rezorsharp edge.
Just try it, you will see it works!

Hope it helps you,

Arne.

Randy Etken

My Feedback: (10)

Arne
What kind of Epoxy and just regular talcum?
Thanks
Randy

ArneK

Hi Randy,

I use a slow curing epoxy e.g. the same I use to laminate the parts. I let it stay overnight and sand it the next day.
The talcum is the standard kind of "slippery" or "greasy" white powder, the same that's in your nitril or latex protection gloves.

Hope this helps you out, if not just say so...

Kind regards,

Arne.

Kevin Matney

My Feedback: (1)

When using parafin wax, put it on mold and let coll for 4 or more hrs. this will help the shrinkage. And I have never had a pva react with it

TeamSeacats

Any grocery store has it. I've used it for quick temporary mold making...it works OK.

stealth assassin

ArneK or anyone,
Could you post a pic of the two part flange so, I can make sure I am seeing the same thing In my head?
The epoxy sounds like a winner to me as long as nothing can seap by while laying up the mold. I hate pva by the way and never use It anymore...
Thanks,
Derrick

av8djc

My Feedback: (4)

Another option is beeswax. But then I'm a bit confused as to what you guys are talking about. To me a plug is the master used to make a mold. I'll use plexiglss or formica to make a parting flange and install it on my plug in order to make the first half mold. I'll drip hot beeswax into the inevitable crack then trim the excess off with a chisel type exacto blade. It fills well and is strong. After laying up the first half mold and pulling off the "parting flange plug" you have the parting flange for the next half. I'm thinking of when making a fuselage mold for example. I'm not sure I understand the photos and what I'm seeing there. It looks like a vacum bag setup? It looks like it is a flanged mold and you're making something in it. Not setting up a plug to make a mold.

Someone please straighten me out.

Dave

SCALECRAFT

My Feedback: (13)

This is what we do.

Bondo in a "pastry tube funnel thing" made out of paper and applied like a bead of icing. A thin bead, razor trimmed before full cure. Easy and fast. You can remove your plug and sand it if you need to, but I don't.

Has always given perfect results.

Steve

stealth assassin

Does the razor not touch the plug If you do that?

Thanks,
D