Design and build a derrick crane

In summary, the conversation was about designing and building a derrick crane for a university assignment. The speaker realized they had not included tolerances for the holes in their design, but since the crane was built without tolerances and everything was fine, they were unsure of what tolerances to use. The other person advised that since the holes were just for clearance and not for withstanding forces, the tolerances would depend on the available machining tools and the criticality of the dimension. They also suggested using nominal dimensions for all the holes.
  • #1
Tolale
5
0
Hi
As an assignment for uni, we had to design and build a derrick crane.
After having designed it on catia, I've realized i haven't made any tolerances for any of the holes.
All the holes are 8mm and 6mm diameter, but i don't know what tolerance limits I should put, as we built the crane without using any tolerances and everything was ok.
What tolerances should I put for each one of these holes?

Thanks
 
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  • #2


They are just clearance holes which do not have to withstand any forces, the only thing that goes through those holes are dowels.
 
  • #3


If you have to put tolerances, then it depends on the machining tools available and how critical the dimension is and whether you need a symmetrical tolerance.

Put it this way: say your dowel was 5mm nominal. The dowel peices have a tolarance of .2mm and you knew you have to have a clearance between the peices. You knew you had .1mm tolerance on the drillbit. You knwo that you have to make the nominal hole at leat 5.3mm

As you are unlikely to know any of this information, you can't realistically put tolerances on to your drawings. Just say that all dimensions are nominal. Also you should always do 3D models at nominal dimension.
 

1. What is a derrick crane?

A derrick crane is a type of lifting equipment that consists of a vertical mast and an inclined boom. It is commonly used in construction sites and oil fields to lift and move heavy objects.

2. How is a derrick crane designed?

A derrick crane is designed using computer-aided design (CAD) software, which allows engineers to create detailed 3D models and simulations. The design process also involves considering factors such as the crane's load capacity, stability, and safety features.

3. What materials are used to build a derrick crane?

The main materials used to build a derrick crane are steel and aluminum. These materials are chosen for their strength, durability, and ability to withstand heavy loads. Other components such as cables, pulleys, and hydraulic systems are also used in the construction of a derrick crane.

4. How is a derrick crane built?

A derrick crane is built in a factory or workshop using the design specifications and materials. The components are fabricated and assembled together to form the mast, boom, and other parts of the crane. Once completed, the crane is then transported to the desired location and assembled on-site.

5. What safety considerations are important in the design and construction of a derrick crane?

Safety is a crucial aspect in the design and construction of a derrick crane. Engineers must ensure that the crane is stable, the load capacity is accurately calculated, and all safety features such as emergency stop buttons and warning systems are in place. Regular maintenance and inspections are also essential to ensure the safe operation of the crane.

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