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wozza
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Hanaldo (31/03/2014)
Well given the surface of the fitting flange is flat, and the pipe is curved, will that not give me two sides where the adhesive will have to do more gap filling? And hence not work so well with the masking tape? What if I bonded the fitting in from the inside using the epoxy adhesive as I was planning, and then put 2 carbon strips over the back of it to give it some more surface area and support, and vac bag it. As it's not threaded on its bore, I would then be able to drill out the hole from the carbon? If that makes sense? I shaped the bosses with a Dremmel to match the curve of the tank, that way it is effectively the same as two flat surfaces being bonded together. The lip on the fitting in your link may not be thick enough to do that, not sure. On the second version I modified the mould by bonding in flat discs of Ally where I wanted the fittings. Once infused the part has flat areas moulded in making attaching the fittings easier. Can't see why what you are suggesting won't work, just seems like quite a bit of extra work. If the part is for you then that's not really a problem but for me the extra time would have to be added on to the final cost of the tank. Warren
Carbon Copies Ltd
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Hanaldo
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Thanks Warren. Given me some good food for thought, I'll try to make a decision now haha. I've asked Speedflow whether 10mm flat bar is necessary or if I could get away with 6mm. Should make my life a bit easier if I can.
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wozza
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No problem  Let us know what you go with and how it turns out. Warren
Carbon Copies Ltd
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Hanaldo
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Well, bit of an update on this. Decided on a direction with the fitting, though it was a fair bit of extra work so not totally happy with the solution. I am also now discovering some oversights with the design of my mould and the whole process of making this part. I had planned on putting the two halves back into their moulds untrimmed to bond them together, as this would allow me to exactly align them, and the excess material would protect the mould from the adhesive. Given that my solution for the fitting meant the one half would no longer fit back into it's mould anyway, so that plan sort of went out the window; I also did not account for the extra thickness that the fabric on the flanges would give me, and when I put the two parts together they are now actually 3mm bigger than what they should be. Unfortunately this is critical, as the part needs to fit inside silicone joiners which have an ID of 3.957". If I were to bond them together like this, the part would end up not fitting into the joiners and would be totally useless. What I should have done was made the moulds 2-3mm SMALLER than the final part size that I wanted, to account for the fabric going onto the flange area. I have now trimmed the parts, unfortunately it's impossible to get a neat join line along the two halves, so the final product is going to look a bit messy. Not happy with how it is turning out. I also have another problem in that with no excess material, I now have no way of clamping the two halves together and applying pressure while they bond. I will need to attempt to vacuum bag it, though I am concerned that as soon as I put any pressure on the halves, they will fall out of alignment. So I need to work out a better way of doing things, though I'm not sure which way to go. This may be a start-again scenario where I need to go back to my 3D drawing and account for the size tolerances.
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wozza
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Hi, I am not saying this is the only way but this is the method I use for similar parts.
Once the two halves have cured I leave them in the moulds and remove the mesh and peel ply. I then cut strips of thin shim steel the same size/shape as the flanges. Slide the shim steel between the part and the mould. Then using the orbital sander, carefully sand through the excess material on the flange down to the shim steel. The shim steel is only there to protect the mould. You now have two perfectly matching halves. Because the shim steel is so thin the dimensions should be almost unchanged. (you could allow for this in your mould if it is critical)
I then use gaffer/tank tape along the split/join line to hold the two halves together and in line.
I then cut strips of cf 25mm wide, lay it on some bagging film and wet through with resin. Carefully lay the strips half and half over the inside join line and allow to cure. Remove the tape, clean off any excess resin on the seen side and polish.
I don't think bagging is necessary as the above method produces a strong join. But you can bag it by making a tube out of bagging film. Make the tube at least twice the length of the part. Push it up the inside of the tube, then pull it back over the outside of the tube like a sausage skin and seal the ends with gum tape to enclose the part. That way when you pull vac equal pressure will be applied to the inside and outside of the part keeping the join in line.
Hope that makes sense.
Warren
Carbon Copies Ltd
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Hanaldo
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Thanks Warren, I'll give that method a go for my next pipe. Have you got any pictures, by chance?
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wozza
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Hanaldo (10/04/2014)
Thanks Warren, I'll give that method a go for my next pipe. Have you got any pictures, by chance? Come on!!! I am not going to make it too easy for you.  Not sure what pictures I have but will have a look. Which part would help most, the bagging? Warren
Carbon Copies Ltd
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Hanaldo
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 I understand the bagging, I just wanted to see how you're doing the steel shims. Saves asking a million questions trying to picture it in my head Really all I'm unsure about is what you mean when you say shim steel, is that a type of steel or do you mean you're using a thin steel sheet as shims? Could I use 0.55mm galvabond sheet? And I presume you cut it to cover the entire flange, not ust the part underneath the carbon being sanded? The only downside I can see with this method is it's going to make a helluva lot of dust... My only method for extraction is my out-door table with a fan pointed at my neighbours fence
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wozza
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Group: Forum Members
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Hanaldo (10/04/2014)
I understand the bagging, I just wanted to see how you're doing the steel shims. Saves asking a million questions trying to picture it in my head Really all I'm unsure about is what you mean when you say shim steel, is that a type of steel or do you mean you're using a thin steel sheet as shims? Could I use 0.55mm galvabond sheet? And I presume you cut it to cover the entire flange, not ust the part underneath the carbon being sanded? The only downside I can see with this method is it's going to make a helluva lot of dust... My only method for extraction is my out-door table with a fan pointed at my neighbours fence Sorry will try and explain better. Always had this problem when I worked as a service engineer. Different countries have different technical terms. Yes shim steel is very thin steel sheet, you can get in various thicknesses, it is used for things like setting pre loads on bearings etc. If you allow for the extra thickness in your mould then any thin sheet steel will do. It is only there to protect the flange on the mould. I use shim steel because you can cut it with a pair of scissors, easier for shaped flanges and slides under the part easily. You can always remove the parts from the mould and trim off the bulk of the excess first before putting them back in the mould to reduce the amount of dust. But your extraction sounds fine as long as I am not your neighbour.  Warren
Carbon Copies Ltd
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Hanaldo
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Hmmm, might have to look around for something more suitable. The galvabond is only 0.55mm thick, but I wouldn't be able to cut it with scissors. Aly foil?
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