g-live

Those with experience using mdf as your forms. Is anyone coating them in anything other than CA? Any other recommendations? My forms are fairly large so there are not a lot of narrow or thin pieces to be supported.

Thanks
Greg

HugoW

Sorry, no experience with MDF moulds yet, other then that my first is coming together slowly.



I will change the nose completely to the modern flat boxy look, as it supposedly generates a bit more downforce. I formed the in-body rear wing thing yesterday.

I have been given an old broken compressor, which I like to use as a vacuum pump. I first thought of a 2 stage system, using a vacuum cleaner to get the air out and the pump to really form. But my new table has no (or hardly) any internal volume, and I found the specs of the pump online; it can move 215 litres of air when not compressing, and it is 2,2kW. My guess is this could work without going two-stage. So that is what I am going to try.

Hugo

g-live

Anyone with a recommendation of brand of superglue / CA for this purpose?

Greg

g-live

The result of my first prototypes.

g-live

Water putty guys. When is the best time to "work" a poured form for sanding/ modifying etc. I am starting with an existing part and would like to pour the form and then modify.

Or is it better to try to make with plaster and get a couple pulls out of it and then use water putty and let harden?

Thanks
Greg

DrFish

Most of my molds are made out of 3/4" laminated mdf... Have just received some Replicator 400 From Alumilite.com, i'm using it as a heat resistant, sealing topcoat on couple smaller mdf molds... Should have spent an extra $20 for their VacMaster 50 5 lb. kit.. it contains 50% powered aluminum by weight for a filler...
The replicator 400 needs a couple coats, with sanding between coats..... Plan on pulling them in a couple days.... It seals well and leaves a finish that can be wet sanded smooth after being completely sealed.. It has the advantage of fast recoat time.. Can't link to my vacuum former builds.... Don't know how many posts i need to link to off site..

DrFish

g-live, check out Stanley Surform pocket planer... you can use the blade by its self for smaller areas... as soon as the wood putty sets up it's easy to shape.. A final sanding after its dryer..

g-live

Thanks for the tip. seems to be working.

Greg

HugoW

Does anyone have any data on the vacuum levels they draw / use forming 1mm real lexan? My vacuum cleaner does a nice job making PET bodies, but it's not doing the lexan properly.

Cheers,

Hugo

30Tooth

iTrader: (1)

Hugo, can you tell/show me how the PET looks against the lexan after being formed?

HugoW

Sorry for the late reply; PET sucks. Pardon my language. It looks decent, it's easier to pull but for any RC car application it does not hold up. With my driving style, at least.

Hugo

30Tooth

iTrader: (1)

Thanks Hugo, no problem I ended up buying lexan in 1mm thickness if not mistaken so I'm good if my machine can pull it!

OneLyfe82

Have you tried anything for trophy trucks? I have a Axial Yeti Score Trophy Truck and really want to make my own bodies for it bit have no idea how to go about it. Any suggestions

HugoW

Kinda quiet, here… Not much to show in respect to forming bodies, but I was asked to share the way I make moulds of existing bodies so I thought I’d post it here. Here we go. Oh, BTW, in this case I use a readily available ProtoForm body because I had it laying around. I rarely do that, I mostly receive old bodies that are out of production and someone would like some copies. With this current ProtoForm Mazda, just go out and buy one. That will save you a lot of hassle and is cheaper, too! Anyway, again, here we go…

I start by making a wooden frame and I tape the body to it with clear packing tape.



I then close the bottom of the body with packing tape, leaving a filler opening:



And as you can see in both pics, I mix a small quantity of plaster. In this case 1 lire of water with 1,45kg of plaster powder (sorry, I don’t do Fahrenheit). I stir and sieve with forks until all lumps are gone, then leave it for five minutes. Next I pour it into the body through the opening (and I spill, of course, it will all become one big mess before I am done). After another few minutes, I do seven, I start to ‘rotacast’ the plaster:

+ YouTube Video

Now I use the wrong plaster which stays liquid for a long time and takes a short time to ‘go off’. So the layers building up in the body aren’t marvellous. But it’s a start:





By the time the plaster does not move anymore despite my dancing efforts, I repeat this casting / dancing routine a second and third time. By that time you’re dancing around with 7,5kg, but once it has settled the walls be sufficiently strong you can pour more in without the need to spread the load. So I filled it up, in this case with three more fillings, so a total of six. Yes, the mould weighs 14,7kg by the time it’s cast.

Once the plaster has set, another 15 minutes later, I remove the tape from the bottom and release the wooden frame.



Then I leave it to go off a little more, you can see it does because it gets warm and moisture appears between the freshly cast plaster and the original body. When you see a lot of moisture, you know the plaster does no longer stick to the body (there’s water in between) and you can easily push out the body. I do this on a plastic covered pillow to avoid breakage of the fresh cast. It still needs a lot of time to breath out all moisture and set properly. But it already looks nice:



and all details are there:



So now it is sitting for a few days at least before I try to vacuum form over it. In this case it will take a lot longer as I am rebuilding my forming machine with a different vacuum system. But at least you get an idea how to cast. I do advise to buy a better plaster that builds up better and goes of less instantaneously.

Cheers,

Hugo

BTW, the original body survives without any problems, just needs a good wash afterwards.

30Tooth

iTrader: (1)

@HugoW thanks for sharing that way, as you mention the mould weights a ton. In order to avoid that I now add some wood blocks or wood shavings in the centre of the mould, where it doesn't cause much trouble.
I made one mould in plaster, I think it's the last and next ones will be wood.