Mould allignment, or not!

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#1

I have a little problem that I have come accross today. Someone brought a mould to me for a motorbike fairing that someone else had been making. They had started to have a problem with the mould sections not lining up and it causing large ridges in the part (its a three part mould). The parts are only GRP, the problem is that the ridges are too big to flat out after release from the mould. I have tried this and it didnt work out great, would be fine if the parts were being painted but he wants to run them on his bikes in gelcoat.

Anyone have any ideas for how to bring the mould sections back into line? the mould is good and strong so I dont think that it has warped or twisted. Just seems to sit offset!

#2

Could you use the original part to line them up?

#3

I dont have the origional part! its a custom part… its about 1mm out of line at its worst. the only thing that lines the mould sections up is the bolts used to clamp the sections together. there are no dowls or interlocks on any of the faces

#4

Dang! And I bet the plug is gone too otherwise you wouldn’t be having this problem. Could you post pictures of the mold?

#5

Are you geting any resin build up between the mold sections?

#6

No there is no resin build up between sections. the mould is really clean and a really good mould that has produces a number of items out of it previously without these problems. The bolts are tight in the holes (not slack) so I doubt that has caused the allignment problem. Its got me baffled at the moment, all the sections fit up nice and snug aswell without any gaps.

Canyon, no I dont have the origional plug.

Im now laying up another item to try something to see if i can find another way around the problem. Im putting a stripe of gelcoat oven all the mould seams first then putting the regular two coats of gel that this part has on it, in the hope that I may be able to flat out the joggle that is being caused by the mould misalignment. Im not holding my breath tho!

#7

have you tried bolting one corner, then using a screw driver to pry the mold in to the correct location and tighten the next bolt?

#8

can you rework the mold to even the flash area? or clean ALL RELEASE off the mold, add more tooling gelcoat to fill in the flash area, and resmooth?

#9

I managed to find a way around the problem with extra gelcoat then flatting back after, just started laying up another one then if that works ill be ok as i have only been asked to do two for now but the mould is being left with me as he is likely to want more later in the season, its for a racing bike. SORRY i dont have a pics of this one as Ive been asked not to publish any photos of this by the customer…
…not sure why cos its not anything particually different to anything else I have ever seen, well except its a one off custom racing motorbike but nothing ground breaking!

Some people in racing can be stupid about this sort of thing.

#10

Managed to improve it a little by doing this, it helped but is deffinatly not the cure.

#11

Clamp the flanges sort of lightly, then tap with a nylon hammer untill everything is lined up. Now retrofit dowels.

#12

Don’t think it’s been mentioned, are these for wet layup open molding, or will they be bagged?

Sounds like it will need new locators/fasteners. Stopp using the old holes if they’re not lining up. Take some time to align it all, clamp it well, and drill new holes (precisely) one at a time installing bolts as you go.
It’s likely not worth it for this low volume part, but it’s best to use metal bushings for bolts to pass through, as the holes in the tooling will wear out and allow movement again.

#13

TET this was a wet lay GRP part. Open moulding. The odd thing that I found was that the tool does not seem to have any wear in any of the locating bolt holes, although it does not have any dowls/pegs to keep it alligned. Not my mould.

I came across some mould allignment bolt/cones a while back that I have used on a few things previously, On more expensive moulds that I have made and they worked out great :slight_smile:

http://www.henleycraft.co.uk/GRP%20Mould%20Clamp/The%20Method/The%20Method.htm