|
oekmont
|
|
|
Group: Forum Members
Posts: 550,
Visits: 27K
|
Two things:
1st: I really want to help you. If the parts you have done so far are like 20% skill level, this would be like 90%. It is even harder than you can imagine. At least in infusion. I just want to save you from using 400£ worth of material to get a part you are not satisfied with. Be live me, I went that path. Better make slow progress with your part complexity. Said so, prepreg is definitely the easier way for a part like this.
2nd: As you realised yourself, the double wishbone chassis is not nearly as smart as everybody says it is. When it comes to torsional stiffness, the elan has to rely on the additional resistance from the body. By converting it to a flip front, you pretty much cutting away all of its moment of inertia.
|
|
|
|
|
Steve Broad
|
|
|
Group: Forum Members
Posts: 408,
Visits: 4.1K
|
+xI would agree that by the time you have added flanges and stiffened the mould sufficiently then you would need a multi-part mould to get a release. You will struggle to make a dimensionally accurate or a part that easily lines up if you keep the mould or part too thin.. Cheers Warren.. Nice to put a face to a name :-)
|
|
|
|
|
Steve Broad
|
|
|
Group: Forum Members
Posts: 408,
Visits: 4.1K
|
+xI use infusion for the big parts, as the material get's quite expensive. I don't know how stiff you want your part to be, but 3mm sandwich is usually enough for body panels. I followed your project on lotuselan.net (I am a elan fan). you are planning a flip front? No offense, but I think that this might be a little beyond your current skill level. To get this looking nicely and working good, you will need to do some serious rework on the bonnet and the car (an inward edge around the back of the bonnet for example). I would recommend to redo the front in cf sandwich, cut of the original section out and glue both parts together. Personally, I would do it with resin infusion, with soric lrc 3mm as a core. But split mould infusion is a difficult task. Prepreg will be a lot easier for people with less experience. I would make a three or four piece mould (front, sides and maybe top, depending on the original bonnet cut off) No doubt it is beyond my current skill level but that hasn't stopped me before, as you have obviously noticed :-) However, even with my limited experience and skill level I realise that there is a little more work to do on the body :-) I have a stock of fabric and I bought all the gear to infuse some time ago so the additional cost compared to prepreg is minimal. If I make the mould to cope with prepreg heats I have options. How well does the fabric adhesive stick the cloth to the mould, as the trickiest part seems to be the nose section?
|
|
|
|
|
Warren (Staff)
|
|
|
Group: Administrators
Posts: 2.5K,
Visits: 8.5K
|
I would agree that by the time you have added flanges and stiffened the mould sufficiently then you would need a multi-part mould to get a release.
You will struggle to make a dimensionally accurate or a part that easily lines up if you keep the mould or part too thin..
Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant
|
|
|
|
|
oekmont
|
|
|
Group: Forum Members
Posts: 550,
Visits: 27K
|
I use infusion for the big parts, as the material get's quite expensive. I don't know how stiff you want your part to be, but 3mm sandwich is usually enough for body panels. I followed your project on lotuselan.net (I am a elan fan). you are planning a flip front? No offense, but I think that this might be a little beyond your current skill level. To get this looking nicely and working good, you will need to do some serious rework on the bonnet and the car (an inward edge around the back of the bonnet for example). I would recommend to redo the front in cf sandwich, cut of the original section out and glue both parts together. Personally, I would do it with resin infusion, with soric lrc 3mm as a core. But split mould infusion is a difficult task. Prepreg will be a lot easier for people with less experience. I would make a three or four piece mould (front, sides and maybe top, depending on the original bonnet cut off)
|
|
|
|
|
Steve Broad
|
|
|
Group: Forum Members
Posts: 408,
Visits: 4.1K
|
+xI have made quite a few carbon sandwich car bodys. You can believe me, when i tell you, that a mold, that can be flexed 2-3cm by hand will not stay in shape during the bagging process. This is a minor problem, if the part ýou are doing will be flexi too. But you will have a hard time, bending a 5mm part back in place. Thanks for that. Could I get away with a 3mm core? I am also considering making the part using infusion instead of prepreg as I have the equipment, resin and cloth. Which method did you use?
|
|
|
|
|
Steve Broad
|
|
|
Group: Forum Members
Posts: 408,
Visits: 4.1K
|
+x
If you're making a mould suitable for pre-preg, then I'm guessing that it'll need to be reasonably sturdy and able to withstand the required cure temperatures anyway, so a bit of flex in the finished part looks necessary to de-mould, but hopefully that'll be there around the side sections. I think I'd likely consider putting the parting line laterally along the forward-most tip of the nose. This way you'll be able to focus on releasing the more intricate bumper area in one section and it'll present a relatively straightforward angle of release. This will then, hopefully, allow you to flex the panel a bit more when getting out the top panel and side wheel arch sections. I don't think that splitting it down the centre will offer you much in terms of making things easier. Good point. Making the joint along the front of the bumper also makes tidying it up afterwards a lot easier.
|
|
|
|
|
MarkMK
|
|
|
Group: Forum Members
Posts: 338,
Visits: 2K
|
If you're making a mould suitable for pre-preg, then I'm guessing that it'll need to be reasonably sturdy and able to withstand the required cure temperatures anyway, so a bit of flex in the finished part looks necessary to de-mould, but hopefully that'll be there around the side sections. I think I'd likely consider putting the parting line laterally along the forward-most tip of the nose. This way you'll be able to focus on releasing the more intricate bumper area in one section and it'll present a relatively straightforward angle of release. This will then, hopefully, allow you to flex the panel a bit more when getting out the top panel and side wheel arch sections. I don't think that splitting it down the centre will offer you much in terms of making things easier.
|
|
|
|
|
oekmont
|
|
|
Group: Forum Members
Posts: 550,
Visits: 27K
|
I have made quite a few carbon sandwich car bodys. You can believe me, when i tell you, that a mold, that can be flexed 2-3cm by hand will not stay in shape during the bagging process. This is a minor problem, if the part ýou are doing will be flexi too. But you will have a hard time, bending a 5mm part back in place.
|
|
|
|
|
Steve Broad
|
|
|
Group: Forum Members
Posts: 408,
Visits: 4.1K
|
The mould would only need to flex slightly to get is past the arch lips. The plan would be to add a support bar between the wing bottoms once bagged.
Part to be made of 4 layers of 210gsm prepreg carbon with 5mm Nomex core.
Gettting the mould off without damage is a valid point. Also getting the finished clip out of the one piece mould could also prove tricky. OK, so I make a multi-part mould. Next, how many parts and where to put the joins? One joint straight down the middle would be simplest but would this be sufficient?
|
|
|
|