Is a one piece mould possible here?

Talk Composites - The Forum for Advanced Composites

Back

Is a one piece mould possible here?

Is a one piece mould possible here?

Author	Message
Steve Broad	Steve Broad posted 8 Years Ago HOT Topic Details
Group: Forum Members Posts: 408, Visits: 4.1K	I would like to make a one piece mould (less work) of the front of my Elan so I can make a one piece flip front. The bonnet will be fitted and blended in prior to making the mould. I can't see any locks. The mould should flex around the wheel arch lips. Can anyone see any problems? Attachments elan body mould thoughts.jpg (687 views, 124.00 KB)
	Reply Like 2
Reply
Steve Broad	Steve Broad posted 8 Years Ago HOT Post Details
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?
	Reply Like 3

GO

Merge into selected topic...

Merge into merge target...

Merge into a specific topic ID...

Threaded View

Threaded View

Is a one piece mould possible here?

Steve Broad - 8 Years Ago

Yes, the problem I see, is that the mould should flex around the lips of the wheel arches. A mould as flexible as that will result in inaccurate parts.

oekmont - 8 Years Ago

I thinkthat Stevemeant to say that the pattern/plug will flex around the wheel arch area in order to allow it to come out of the resultant mould. It's hard to judge from the picture, but it looks lik...

MarkMK - 8 Years Ago

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...

Steve Broad - 8 Years Ago

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 mino...

oekmont - 8 Years Ago

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...

MarkMK - 8 Years Ago

Good point. Making the joint along the front of the bumper also makes tidying it up afterwards a lot easier.

Steve Broad - 8 Years Ago

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 - 8 Years Ago

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 o...

oekmont - 8 Years Ago

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...

Steve Broad - 8 Years Ago

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...

Warren (Staff) - 8 Years Ago

Cheers Warren.. Nice to put a face to a name :-)

Steve Broad - 8 Years Ago

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.....

oekmont - 8 Years Ago

I am always happy to listen to others, so thanks for the advice.. If the infusion attempt goes wrong it is a few hundred pounds, with the prepreg it is over a grand! However, the jury is still out on...

Steve Broad - 8 Years Ago

Yeah, the more I look at it, especially the nose area, prepreg seems the less hard (rather than easier) option. And, yes, I still plan to hide the carbon :-)

Steve Broad - 8 Years Ago

Have you the facilities to cure the pre-preg...either a temperature controlled oven or access to an autoclave? If so and you are planning to paint the panels afterwards, then this feels like the...

MarkMK - 8 Years Ago

Cheers, Mark. I have just built an oven big enough to take the bonnet -1.8m x 1.8m x 0.9m, with thermostacially controlled temperature so cooking isn't a problem :-) The car is away being wired so ...

Steve Broad - 8 Years Ago

I rewatched the photos. My point about the moment if inertia might not be that important, as the front will be entirely ahead of the front axle.

oekmont - 8 Years Ago

If prepreg goes wrong, you could likely fix it with a fair amount of 2k filler (If you are still planning to paint it). At least if you get the bagging right, for wich you have several tries for a fe...

oekmont - 8 Years Ago

The problems with difficult infusions are: It is much harder to get a frayless finish in places where you need to cut the cloth. With painting, this isn't a problem for you. The flow media is much....

oekmont - 8 Years Ago

You have convinced me that prepreg is the way to go, cheers.

Steve Broad - 8 Years Ago

If your experience with infusion is limited Steve, I'd concur with Oekmont that pre-preg offers, in theory, a more straightforward process in many ways for a first-time user. Key with it is to...

MarkMK - 8 Years Ago

I have made many items using wet lay vacuum bagging and a fair number of small parts with prepreg but no infusion, although I bought all the stuff many months ago. But, despite the huge extra cost of...

Steve Broad - 8 Years Ago

I drew a few lines into your pic, where I would add flanges. I did not consider any changes, that have to be done, to convert it to a flip front (filling of the bonnet recess, maybe adding a backward...

oekmont - 8 Years Ago

Thanks for that. Looking at the photo I reckon that I don't need to take the bonnet all the way down the back of the arch, stop around half way thereby removing the section that curves inwards and...

Steve Broad - 8 Years Ago

But to get to the point, where you can cut the mold to get the carbon piece out, you have to get your pattern out of the mold. This is usually much harder, because of higher thicknesses and the amoun...

oekmont - 8 Years Ago

Good points, well made as usual. I'm just thinking aloud really. As you say, an extra joint or two is better than hours of struggling.

Steve Broad - 8 Years Ago

Don't be offended by my percentage comparison. You achived more than 80 % of the people who tried making some cf parts. But your current idea leaves out a few steps in the difficulty ladder. You made...

oekmont - 8 Years Ago

I don't get offended :-) You have convinced me that my best shot will be with prepreg as I have NO infusion experience. Note to self, don't scrimp on the number of mould parts :-) Very nice work, by...

Steve Broad - 8 Years Ago

This is a project I realised for Westfield Deutschland. The bonnet is quite the same "project level" and type than the one you are planning. Half a car, cf sandwich, 4 piece mold, a few difficult...

oekmont - 8 Years Ago

That's why I am talking to you! I don't recognise the word problem however, I call them challenges :-) If this stuff wasn't difficult and challenging, what would be the point in doing it? Practice....

Steve Broad - 8 Years Ago

Lucky for you, the Westfield grp quality is way beyond what lotus did those days. So your weight saving will be greater than mine. I managed to get the body down to 20kg. Original is about 40-45kg......

oekmont - 8 Years Ago

Yeah, the fibreglass is over 1/2" thick in places! Too many Elan owners are purists so the thought of doing what I am doing is almost a hanging offence to them. The only fibreglass left on the Elan.....

Steve Broad - 8 Years Ago

Titan is quite a nasty stuff. You need to drill with mid-low rpm, with coolant, low pressure and take back every few seconds. For bigger diameters drilling out with a carbide drill works best.

oekmont - 8 Years Ago

And you should use uncoatet drills, as the usual coating contains titan, wich causes problems working with titan.

oekmont - 8 Years Ago

For colbalt read carbide. Well, they start with the same letter :-)

Steve Broad - 8 Years Ago

Where did you get small carbide drills? Those are quite expensive. Maybe try cobalt ones next time, they are not as brittle as carbide ones.

oekmont - 8 Years Ago

I'm confused now as to what they are. I asked the guy I know in my local specialist tool shop for the best drills to cut titanium but it was a year or so ago. However, whatever they are they worked.

Steve Broad - 8 Years Ago

Die you Pay like 10£ each? If so, they could be carbide.

oekmont - 8 Years Ago

Nah, £3-4 I think.

Steve Broad - 8 Years Ago

Here's my oven, more or less finished.

Steve Broad - 8 Years Ago

I seem to keep hearing these stories of how hard Ti is to machine or cut -- Ti is NOT hard -- it is Though -- Highest obtainable hRc hardness in Ti Alloys is found with full Beta-Titanium (used by...

Dravis - 8 Years Ago

I never said titanium is hard. I said is hard (difficult) to work with. At least compared to regular steel or aluminium. Hardness and tensile strength are all most proportional. Both characterise the...

oekmont - 8 Years Ago

Similar Topics

Post Quoted Reply

Reading This Topic

Login
Remember Me Reset Password Resend Validation Email Login	Facebook Google

Explore

Messages

Mentions

Search