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8

As your construction is 3D printed, increasing the strength at the point of current breaking will more likely transfer the damage to a new location. The obvious and possibly impractical solution is to solve the jamming problem, rather than to try to power through it. If it's not practical to prevent the jamming, consider to convert the jamming related ...


5

You might consider dealing with it in software. Sense the stepper motor current, and when it exceeds a certain threshold that indicates jamming, perform a high speed reverse rotation for one or more revolutions. Then proceed in the forward direction.


5

Build the auger around a stronger shaft which has a better connection to the motor shaft. Perhaps a carbon fibre or even a steel centre. But then consider what will be the next breaking point. Or make a joint between the auger and the motor that fails if the mechanism gets jammed - just make it easy to replace.


4

For me a good (compromise of a) solution would be to redesign the shaft with an rectangular slot (although I am still unclear as to the fracture type, so I suspect is torsional). Like so Then you can use a rectangularly shaped metallic shaft along the length, which will be able to transmit more gradually the torque. *Figure 2: rectangular shaft image ...


3

In machine tools where an auger is used to remove scrap metal chips, the current in the auger motor is sensed. If it exceeds a certain level due to jamming, the electronics temporarily reverses the auger direction which can clear the jam. Lubrication of the material-auger interface is very important with augers, which have a huge swept surface area.


3

Anelastic is a material that exhibits a delay in the deformation with respect to the loading. figure 1: Anelastic material bevahiour (left: wrt to time, right: stress vs. strain) (source Princeton) Visco-elastic are materials that the load to obtain the deformation also depends on the strain rate. I.e. How fast the deformation is applied. It might depend on ...


3

I have had good luck with plastic specific consumer grade epoxies. Both JB Weld Plastic Bonder and Loctite Plastics have worked well. I have not performed any structural tests with them, but in my experience they are ~25% stronger than just standard 5 minute epoxy for plastic. Perhaps they addressed some of the surface chemistry Jim Clark mentioned. ...


3

"... while minimizing the thickness of the end plate. I don't care about how much material I use." Those statements are in conflict with each other. If the end plate must be flat on the inside, you have constraints on the design. To reinforce the end plate without increasing thickness, consider a web of plates perpendicular to the end plate. If ...


2

Buy a pressure cooker, drill holes as needed for tube and electric connections .It will have an approved safety valve and a second vent that usually allows for a couple different pressures . This should protect you from yourself. Steam - boiler explosions prompted creation of ASME over 130 years ago . I believe a government agency let manufacturers know if ...


2

TLDR: look at Viton / FKM PTFE has poor mechanical stability, would be careful whether to use it in most sealing apps (unless it has mechanical backup). Look at other fluoroelastomers, in particular Viton (FKM) or Kalrez/Chemrez (FFKM). The other common elastomer substitutes for NBR are EPDM and silicone (PDMS). Those are the most common ones you can usually ...


2

If you know the torque, or a close approximation of it, you can size the auger shaft more appropriately. From Machinery's Handbook the max torque T a shaft can handle is T= S_S* Z_P S_S = allowable torsional shear stress of material Z_P = polar section modulus (0.196 * diameter^3) Make sure your units are consistent. So you can either use a stronger ...


2

Many times manufacturers make bottles from coextrusions of plastics (see... coextrusion blowmolding). Think of blowing a bubble with two or more thin layers of virgin material (without mixing the materials) so the materials lie against each other without air between them. The bubble is the region that will contain the product (when they inflate the bubble ...


2

Two pieces HDPE can be welded together with heat. You can use filler rod for this but it is also possible to do this with just heat. Additionally you can ultrasonic weld HDPE but this itself is a bit tricky in my experience. Any one of these should be sufficient for your application. You can obviously try to glue HDPE, its possible. But the glue itself ...


2

Source 1 - Polysulfone (PSU) Plastic has one of the highest service temperatures among all melt-processable thermoplastics, combined with high-temperature resistance and inherent flame retardance. PSU is tough and stable at high temperatures, and actually shares a lot of the same traits as polycarbonate plastic. These fundamental traits make PSU used for ...


2

If you have the ability to cut glass in the manner required, thereby saving those costs, you can find rear projection televisions that are being tossed out. I have ceased looking for them, as I have three collections of parts. Typically, I discovered them while driving to and from various clients in my area, but also via the now-extinct freecycle and non-...


2

Anelastic materials have an element of time delay between stress and strain, and a time-dependent relaxation of strain. Wikipeidia link But the viscoelastic materials have both properties of elastic and viscous materials when undergoing deformation. Viscous materials resist shear flow. And have defusion of atoms under stress as compared to bond stretching ...


1

Use an expanding mandrel, but you probably can't make one). What you could make is what you would describe as conical shaft collars. It grips, is self-centering, and handles variation in bobbin hole diameter. You can can use plastic, wood or metal, but wood cones seem easiest to just buy off the shelf. The ideal setup is to have an interrupted shaft with ...


1

This is a minor addition to Fred_dot_u's answer. Regarding the radial stiffeners the best shape for the stiffeners (minimizing the deflection for a given weight would be a stiffener with the following shape (in green). This optimization only makes sense if you have large production numbers, otherwise you can use plain rectangular profile for the stiffeners ...


1

This is a suggested procedure to achieve your goal. I'll simplify your model to a cantilever beam with a constant cross-section as shown below, and assume the critical section is located at the root of the fillet. The first step is to determine the maximum deflection $\delta_v$. The second step is to find out the equation for the deflection. For this ...


1

What tools do you have available? 3D printed and layered PLA is your best choice if you only have a 3D printer. For gears you usually want precision within .005" or less. You could CNC route material but I would not recommend wood (ply or lumber) as it would split easily when stressed along the grain. Fiberglass coating would help but then again you ...


1

A google query “hdpe book binder screw sets” revealed a product made of hdpe which consists of a screw and matching sleeve. This item shows that hdpe can be used as a screw or bolt, with tapped threads in hdpe as well. Finding a product which has appropriate dimensions for my project will take additional work, but it’s good to see that hdpe can be used for ...


1

You should research things yourself instead of "hearing" that things don't work. Bonding Low & High Density Polyethylene with Industrial Adhesives. Superglue (CA glue) Cyanoacrylates Cyanoacrylate adhesives can be used along with primer Permabond POP. Cyanacrylates set almost instantly and provide good adhesion to HDPE provided the surface is ...


1

Does it have to be vinyl? Model airplanes use this process to apply skins to wood framed wings. It's called "covering film", like Monokote. Just any sheet of shrink wrap with a pre-applied adhesive really.


1

If I understand correctly you need the part to be able to rotate around point B, so that the AB section remains vertical, while the BCD rotates. In that case, the following is not really an answer, just a heads up, that there are other properties that will have a detrimental effect on the properties: The horizontal distance between the fulcrum and the ...


1

My experience is that salt is not necessarily corrosive if kept dry. Moisture will interact with the salt if there is sufficient humidity. For your grinder objective, consider a coffee grinder using a burr mill. I've recently purchased a Mr. Coffee bean grinder that specifically notes that it's a burr mill design. I can grind with this burr mill ordinary ...


1

Stainless tube with end caps that clamp on using threaded bar - no welding and easy to seal. Easy enough to find in 2" or 3" or 4" diameter, plate for the end caps as well. Drill holes and get some threaded rod.


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