Originally Posted by
chojn1
CFB,
I drew up my wheel mount yesterday:
It is designed for a roller skate wheel and will be recessed into the case. I'll print it up on my 3D printer later today.
Vroom,
Do you think fiberglass over the foam core would be sufficient? I either have to remove the core to add the internal support structures, or leave it and and skip the additional support. I could add external support, but I am trying to keep the design clean.
Great idea on the saran wrap. That is what I'll use on the frame for the pour-able foam.
No worries about the resin. It is the only one I got.
PK,
I think the piano hinge along the entire back side of the lid would give better support than two latch points. You are right about the need for a reinforced band around the case though. I was going to use rubber weather stripping at that site, but I think I need to come up with a better support and seal.
The latches from the old cases are similar to the one you showed but with out the spring load. It will be reused to save money and reduce waste.
What do you think about rivets, versus screws, versus epoxy for mounting hinges and hardware?
CJ
Expansion fasteners in composites can always compromise the hole and work loose compared to a tension or tension / expansion fastener. Closely sized holes and wide area washers may prove best for this application with threaded fasteners. Id you are installing this in the core areas, you wil need to densify those areas. Easiest way is to drill your holes. Then use a tool such as an allen wrench and work through the hole to remove the foam. You are doing this to prevent crushing when the fastener is tightened. Fill the area with a milled fiber / epoxy mix and cure. Use tape to keep the mix from running out. Once cured, redrill through the location, using the now visible filled hole as a guide. Wide area washers or full size doubler plates will minimize any disbonds or tear out.
As for the latches and piano hinge, the hinge is easy, but will require a true surface to fold without binding. The slip fit top, may or may not be best, but is easily molded from the first half.
As for internal support with no increase in size, you can add ribs to the foam. In simple terms, envision the letter W. If this is the side panel of the case, you can remove foam from the valleys. Apply fabric to follow the valley contours. Next fill the remaining valley, now covered in cured fabric / epoxy, with foam, then add a fabric poxy to cover this new foam. Done this way you will have internal ribbing with angled support.
The above can be tied into wheel locations of add reinforcement to open panels.
I do have a question, in regards to the foam, are you using low density styrofoam from Home Depot or Lowes?
FWIW, whenever possible, bevel all the foam edges 45 to allow the fabric to lay easier and provide a better load path. If you need to bond, foam to foam, always splice it with a Microballon / epoxy slurry, cure, shape them add fabric. Epoxy without Microballons to foam is not always best, it can give an inconstant bondline.
Curious if you have started making panels yet.
Let me know.
PK