Long term flexibility and durability of curved versus straight line

[GramInvents51]

TL;DR Summary

Is a curved line or straight line more flexible and/or durable in a circular material used as a way into an object?

Visualize a lid to a toddler snack cup. Making an entry into an object which is to be placed in nature which can be used by humans but not easily by animals, would the curves used in some toddler snack cups be more durable and flexible without being floppy, or would straight line radii from the edge to the center be preferable?

 

[berkeman]

Welcome to PF.

Summary:: Is a curved line or straight line more flexible and/or durable in a circular material used as a way into an object?

Making an entry into an object which is to be placed in nature which can be used by humans but not easily by animals

Woo-wee. I don't suppose you'd be willing to share your application, would you?

 

[GramInvents51]

Welcome to PF.
Woo-wee. I don't suppose you'd be willing to share your application, would you?

Rather mundane, I'm afraid. I want to make a bag dispenser system for beaches and trailheads that will dispense previously used plastic bags (like shopping bags, and everyone has at least a bag full of bags) one at a time and will allow for a human hand to easily enter and get out one bag without dozens coming out. Also, it needs to discourage animal entry and any weather that comes along. The products I've been able to find are woefully inadequate in more ways than just this one. This is the one I'm trying to optimize the useful life for.

 

[berkeman]

Interesting. Can you just use one of the standard plastic bag dispenser designs like you see at grocery stores in the Produce section?

 

[GramInvents51]

I can (and intend to) use that as part of the dispensing system. However, unless your bag dispensers are different from the ones at my grocery store, they have little protection from the elements. Being open also means that the bags tend to come out in random bunches if we are using formerly used plastic grocery bags or loose bags of any description. It also allows squirrels and birds ready access to the bags and/or use of the dispenser as a nest, an undesirable outcome.

 

[berkeman]

I want to make a bag dispenser system for beaches and trailheads that will dispense previously used plastic bags (like shopping bags, and everyone has at least a bag full of bags)

You mention in your New Member Introduction thread that this is for dog owners to use to get plastic bags for picking up their dog waste (which is great, thank you). What do you mean by "previously used" bags? Does that preclude using the rolls of plastic bags like from the supermarket and existing dog waste plastic bag dispensers?

https://propetdistributors.com/wp-content/uploads/2016/02/1010.jpg

 

[anorlunda]

I think he wants to stuff used grocery store bags into the dispenser, then have people pull them out one at a time.

This simple device below does part of the job. But it is not protected from the elements or from animals. But you could maybe use it as a starting point.

Edit: here's another variant.

Obviously, the KISS principle rules. Simpler is better. I think the problem is that the chance of having even one of those bags carry odors from spilled food is too high. The smell will drive squirrels crazy.

 

[berkeman]

This simple device below does part of the job. But it is not protected from the elements or from animals.

Maybe she could enlist the help of some bears to guard the dispensers against other pesky animals. Bears are pretty fond of their close relatives the dogs (and hate smelling dog poop in the woods), and bears work for peanuts...

https://www.nationalgeographic.com/animals/article/karelian-bear-dogs-keep-bears-away

 

[Tom.G]

Maybe she could enlist the help of some bears to guard the dispensers against other pesky animals. Bears are pretty fond of their close relatives the dogs (and hate smelling dog poop in the woods), and bears work for peanuts...

Training though could be uhmm... problematic?

 

[GramInvents51]

LOL! I don't think the bears would be good partners.

Seriously, though, anorlunda is right. As a cost control measure, and to increase the invested feeling of the frequent users, used plastic grocery bags, bags used to wrap or enclose shipped materials, or even small garbage bags or ziplock bags can be used in this container. While it may not be always sanitary, if you don't immediately discard your grocery shopping bags, you start to accumulate quite a lot of them. I have about 3 bags of bags currently. Obviously, you won't be keeping any such bags if they smell, which is the primary problem with pre-used bags.

We have an "Adopt a Road" program here, where people commit to picking up trash in a given area of roadside. It is moderately popular. We are currently considering doing an "Adopt a Trail" program which would include walking the trail you adopt regularly and reporting problems (downed trees, poison ivy encroaching on the trail or chocking saplings, etc) plus putting bags in the dispenser at the trailhead and picking up trash or reporting its presence.

Since putting out supplies of commercially available doggy waste bags could be expensive, we would like to present a dispenser which would ALLOW that, but also allow for the community to responsibly get rid of disposable plastic grocery bags instead of having them in the town dump. While the ProPet dispenser comes close to the ideal, the opening does not seem to have a way to keep the wildlife to a minimum or shield the contents from wind-blown rain and snow. Also, this design (experience speaking here) won't keep loose bags very well. They come out in clumps and wind up making a horrible problem. I've included a small bottom enclosure that allows the traditional rolls of doggy waste bags to be inserted and a door closed so that you can take one at a time through that small space.

The real question I've got is about the opening. I've decided to make it about 4 1/2" (about 9cm) wide to accommodate an adult male hand, but the barrier (rubber or equivalent) needs to be sectioned (see, for instance, the Munchkin Snack Catcher) but I don't know whether the best model would be curved or straight slices in the material. I don't want it to tear off, wear off, or be easily removed.

 

[GramInvents51]

By the way, KISS is at the center of this. The overly complex, overly secure boxes you see can be difficult to use and who needs to have a lock on their doggy bags?

 

[anorlunda]

Instead of an opening big enough for a human hand, how about providing some tongs to pull the bag out?

If bears are the problem, they'll smash whatever you do. However, I suspect that squirrels are a bigger problem than bears. You need an opening too small for a squirrel's skull; 1.5 inch PVC. For example:

 

[GramInvents51]

Bears are unlikely to be a problem where I am but might be a problem elsewhere. However, yes, squirrels would be a bigger problem. That's why the flexible barrier exists. I don't like the idea of tongs, as they might disappear. It also seems needlessly complex.