I will be making something that will have a shape almost identical to the plastic lid on a 5 gal bucket. It has to be several times stronger and rigid. Any suggestions. Right now I am thinking fiberglass But there might be better materials to work with now I am not aware of. I will be using it in a mold. For reference If I put a 3/8 bolt through the center of it with a 1" washer i should be able to pull up on the bolt with 200# force without damaging the part. Right bow I am using 1/2" plywood but need a better look and a built in 2" flange around the edge for a clamp.
How rigid is “… stronger and rigid”? IMO/IME A fiberglass part won’t be very rigid unless it’s got stiff reinforcements of some other material embedded in it. And if you haven’t worked much with fiberglass it’s a right bitch. And you need to make a mold to mold your fiberglass part in. So now it’s molds all the way down.
When you say lift 200# through the center bolt, how much deformation is acceptable? A sheet of 1" thick Lexan could probably sustain that load with minimal flexure.
Or is your real challenge attaching the rim / flange onto the plate-like portion of your part? Knowing where there’s tension and where there’s compression would be useful.
Without meaning to be mean or hostile, you have a habit of asking part of a question where you’ve assumed most of the solution and ask us to supply some small missing tidbit in the middle. Often asking a larger more general question invites a more integrated end-to-end solution.
This habit is very common with people. it even has a wiki article:
That wiki is not great, but it at least proves the issue is noteworthy enough to rate wiki. Here’s a collection of a bunch of folks’ stabs at it over the decades: XY Problem.
For strength, nothing beats metal.
For rigidity, carbon composite is the winner.
How do you plan on making this object? A machine shop? or in your garage?
Could you use 3D printing to make this? They use different materials, some of which are fairly strong.
I certainly do have that problem I have fought it all my life. I think it comes from a nervousness that if I talk to long the listener will get bored and I will lose them. I will start over. The reason I am thinking a mold is because it needs to have a finished look for doing demo’s. The object I am talking about will be used as an end cap for a bellow system. It will be pushed and pulled with force. The 200# per bolt is overkill. It will be spread out over 4 bolts and a mounting plate. One version I am currently using that is not quite strong enough is actually an adapter lif for a 5 gallon bucket. It is a screw on version with a removable flange. It would actually work perfectly if it were a bit stiffer. As it is I can use it at about 1/2 the load I would like to use it. I believe the lid is made from abs and is far too flexible. I will add some photos in a bit.
I would like at fiberglass-reinforced epoxy resin.
I think 3 d printing would work. I just don’t know what kind of plastic to specify. I have been trying to upgrade my knowledge on plastic, both material and fabrication methods and and finding a really need an expert here. But yes I believe that would work fine
What about a disc of thicker plywood? - maybe 18mm marine ply or something - easy to cut into shape, easy to fix things to, or through…
This is what I am using now, It works fine but doesn’t have the look I am after
Paint?
laminating fibreglass fabric (or carbon fibre fabric) over a plywood shape is probably easier than trying to fabricate a part composed wholly of glass or carbon - plywood+resin+cloth+more resin then cover with a sheet of polythene and clamp it flat with another scrap of ply - the composite will form a flat surface on the ply, strengthening it and altering the appearance.
Trim the edges with a flush cutter bit in a router (wear breathing protection)
Attaching the flange looks kind of mickey mouse
This might be my most practical solution based on what I have to work with. Weight is also a consideration but not a major consideration in a prototype.
Can’t you just bolt a plywood circle to the underside of an ordinary plastic lid? Paint it to look better. Some containers are stronger than others. A Home Depot utility bucket is pretty flimsy compare to the ones used for paint and other heavy materials. I think all you need to do is reinforce the underside of the lid with plywood.
Also, you can add pigments to the resin to make it any colour you like
Not to go against the DIY aspect, but CNC-ing it out of aluminum would be a cinch. Alternately, you could laminate hardwoods (home-made plywood) for a much nicer look. (2) 1/4" plies at 90 degrees out of maple or beech should do it. Actually, the aluminum doesn’t even need to be CNC-ed if you’re willing to ruin a few router bits.
Have you looked at commercial products like Leaktite Screw Bucket Lids? There are a lot of products made for 5 gallon plastic buckets.
Also, have you ruled out using metal buckets? Those are sturdier and have heavy duty lids.
This is exactly what I am using now for my less robust model, It works perfectly I just cut off the outside flange on the ring. I would like to be able to buy a heavier version of this.
“C:\Users\14244\Downloads\bellow lid.jpg”
I haven’t ruled them out but I haven’t seen any with a big enough flange… I just looked them up and found one with a built in clamp around the flange that would work perfectly, I am going to order it now and try it. 11.00 each, A large flat washer at the 4 mounting points would probably work fine.
That link is to a file on your computer. Not on the internet.