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Mechanical Engineering


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  1. Hi Naresh, I'm interested to find out if you used a different mechanism?
  2. Maybe have a look at IKO linear motion rolling guides. They have a lot of linear bearing solutions such as The Crossed Roller Way & Stroke Ball Spline.
  3. I think the article said something about moulded plastic bearings lasting longer because they are more corrosion resistant and maintain a constant and reduced coefficient of friction compared to metal versions. I can't find the article anymore, but igus have published something similar about their machined plastic bearings being long lasting too : https://www.machinedesign.com/materials/article/21835812/five-reasons-to-use-plastic-bearings
  4. Rigidity (or stiffness) is a material's resistance to bending. A hollow tube would bend more, so it is stiffer in bending than a solid rod with the same mass. However, if a hollow tube had an extremely thin wall thickness, it can buckle faster due to the buckling of its wall. If you are using the same amount of material, a hollow tube would have a better ultimate tensile strength than a solid bar because it would have a larger diameter.
  5. I was reading an article about rotary bearings and I was surprised to find out that injection moulded plastic bearings (made from POM) often last longer than metal equivalents. (Except in high load or high temperature applications). Is this because solely because of their corrosion resistance and chemical resistance? Does anyone have any experience in with plastic bearings?
  6. Hi Hamdi, I found your old post and was just talking to someone on another forum about a very similar question. So I thought I would post my answer on here too, just in case anyone looks for the information in this forum in the future. Residual stress is the remaining stress in the material after the original cause of the stress has been removed. It can be desirable or non-desirable. It can be done or purpose or as a consequence of the application that caused fatigue in the material. Work hardening is a general term that is used when the material is being manipulated to make it stronger. The first few deformations might weaken it, but then it starts to strengthen as the crystalline structures rearrange. Although it hardens the metal, it also makes it less ductile, therefore some metals can become brittle. So again, it can be desirable or non desirable. It can be done on purpose or as a consequence of the manufacturing method such as machining at high speed, not enough coolant etc.
  7. Wipnel, There are 5 general types of linear actuators which turn rotational motion into linear motion. (Hydraulic, Mechanical, Magnetic, Pneumatic, Electric). I think the best way to find out how his prototype works is to comment on the video or email him to ask if its a motor or pressure gauge at the side of it. Would high precision lead screws and a stepper motor work for your project? Its the most common type of electric actuator, but we will need more details about what you are building. For example, lead screws aren't recommended for high speed applications. Zane
  8. Interesting tutorial video, thanks for sharing it. I love making things, so this will come in useful.
  9. Hi, So I've now got hold of some new stainless steel screws and they seem to be much more durable. How is it that the other stainless steel screws seemed softer? Is there a test I can do to see if they were aluminium?
  10. Sorry I wrote M6 x 4mm, I meant M4 x 6mm long. The length of the thread is 6mm. Sorry for the confusion. Zane
  11. I've lost a small screw from my bike for my OBE cartridges. It seems to be a common problem on road bike braking systems and so does stripping the screw heads. Its a very small screw ( almost a grub screw). The supplier confirmed that its a M6 x 4mm long screw. They either come loose or I end up rounding their heads, which is even worse because it makes changing the brake pads a nightmare. (I am using the right size Allen key) I'm looking for a different fastener, perhaps a bigger head or recess so that I don't round them. The screws are 4mm long, so not many stainless steel options. Can someone recommend a solution please?
  12. Hi, I was wondering which is stronger : phosphor bronze or grade 5 titanium? Zane,
  13. Hi, Welcome to the forum. There are different grades (and prices) of clear polycarbonate sheets. You can get a hard coating on them to improve scratch resistance.
  14. Hi Chris, I've filled it in for you. Good luck with your masters.
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