New FG teardrop design

[Mark Mckeeman]

Hi All,

I'm rather new at this but I did manage to upload a couple of my ideas in my personal gallery. Any and all comments welcome.

Thanks, Mark

[mikeschn]

Hey Mark,

Glad you figured out the album. Will you be able to upload the front and rear views as well?

Mike...

[Mark Mckeeman]

Yes Mike,

I will upload the front and rear views as time permits. This was a bit of an experiment for me. As we discussed the fore and aft views do not comply with my goal of producing the tear in a one-piece mold. The sides have too much curvature in the lower third. My fabricator told me you need 5 degrees of break angle from vertical to allow the part to release from the mold. Another consideration is the depth of the mold or height of the tear as there is a limit to how far you can shoot chopped glass from the rim of the mold to the bottom. This is for thickness control and gassing off during cure. I’m learning a lot and having fun as I work through this process. I'll post the originals for conversation and redraw some sketches with the 5 degree break angle.

[mikeschn]

Okay, sounds good.

Can you do a 1 piece mold, or do you need a parting line due to the depth restriction of shooting fiberglass?

Mike...

[Mark Mckeeman]

Mike,

I've uploaded the front and rear views. I believe that the limit on depth is around the four-foot mark. I'll have to confirm that with my fabricator. I think that the trailer should be in the 5X9 range for a foot print and the height may have to exceed 4 feet to get the proportions right. With the general design being a big bowl I'm hoping the height won't be a problem.
The mold would be filled while inverted so access to the top could be gained through the cut out for the rear hatch. These details will get sorted out when I meet with the fabricator.

Bye for now, Mark

[CheshyreKatt]

Sweet design. Of course, I love rounded.

Hmm....I wonder. Any boat makers out there that might be able to make this shape in wood? You know, wood strips that are bendable.

[Shrug53]

That curved shape is not too hard to do in wood. Check out the Runlite plans on my site.

[angib]

Sorry to be the one to rain on your parade, but you need those draft angles on all sides.

Your profile looks just fine to me - pull the back out and the front will pop out after. But those front and rear views you've drawn won't work - you can't pull the widest part of the body (at mid-height) through the narrower section at the bottom. So your front and rear views need to be like your side profile - always getting wider fron the top to the bottom.

My rule of thumb is a minimum 2 degree draft angle (that's a draft of 3.5% of depth) on both sides of a body, or 4 degrees on one side.

Andrew

[Mark Mckeeman]

Sorry to be the one to rain on your parade, but you need those draft angles on all sides.

I know I drew those views incorrectly. See earlier posts. I will correct and post later. I just threw them up to get a discussion going.

The biggest cost savings will be to produce my own plug to pull the production mold off of. I have definitly thought of using cedar strip construction for this part of the project. The plug needs to be glass smooth with a show car finish for a good quality mold. That means covering all that beautiful cedar with primer filler and wet sanding it out. I also want to cast the fenders in the one-piece mold for a seamless transition to the body. Of course the floor pan and rear hatch would be separate molds as well as a rear bulkhead.

Mark

[Mark Mckeeman]

OK,

I’ve redrawn the fore and aft views with a more representative draft angle with regards to mold release. As I look at these drawings I can see that the unit appears a bit too tall for it's width. Remember that these drawings are freehand with no scale. I suspect a final draft will be a more low profile design, which should appeal to the hot rodders out there.

Mark

[mikeschn]

Well, you're not die locked any more, but just wondering if that looked a little bit like a toaster to you? Maybe it's just the height. Perhaps once you lower it a bit like you said, it'll be better!?

Mike...

[Mark Mckeeman]

A toaster eh!

Well according to a RV dealer up hear the Boler trailers of the ‘70’s were nick named the boiler for its lack of insulation. For warmer climates A/C may be required, or at least good insulation and a vent fan. I wonder how Scamp and Casita are making their trailers now. Have they concurred the insulation problem since they are nothing more than revised Bolers. I have seen Casitas with roof mount A/C.

I don’t want burnt toast customers!

[mikeschn]

I looked at rear view of a pt cruiser on the way home, and it looks the same way... so it it's the vintage look you're after, you're probably on the right track.

As far as toasting your customers... well I'd recommend that you have a good design for a built in a/c. Not a roof mounted one!!!

Mike...

[angib]

Sorry for misplaced comments about front/rear views.

Cedar strip is used for building plugs in boatbuilding, but it is a fairly expensive way to go. If you're making a plug then you are only interested in the shape and surface finish - everything else is overkill. I am making some plugs for motorcycle bodywork and have used quite a few materials.

If you are good at design, I'd recommend solid "bread and butter" MDF - lovely to work with (if heavy) and reasonably cheap - it would work well on those tricky radiused corners you've got between the sides and top. There's some photos of doing this for the head fairing of my bike here.



But look on the positive side - the high-build catalysed polyester sanding primers are probably the most lovely product to work with that exists - I swear people would pay money to try sanding it, it's so nice to do!

Andrew

[Mark Mckeeman]

Mike,

Yes it’s the vintage look I’m after. I think that’s the look that appeals to widest cross section of potential customers. I wouldn’t even consider roof mounted A/C. It messes up the lines too much. I was just thinking that Casita may have used the addition of A/C to solve over heating problems instead of improving insulation quality. You probably would need the A/C even with improved insulation anyway.

Andrew

That’s a great site you have there. Anyone thinking of doing a fiberglass project should give it a read. How far along is the project now?