Making seat mounts from aluminium

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    Aluminium
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Discussion Overview

The discussion revolves around the suitability of using aluminium flat bars as seat mounts for a gap of 630mm, focusing on the structural integrity and safety of the proposed design. Participants explore various materials and configurations for mounting a seat, considering both static and dynamic loads.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant inquires whether two 670mm lengths of 5mm thick, 60mm wide 6060 grade aluminium flat bar would support their weight of 80kg when mounted across a gap.
  • Another participant suggests that flat aluminium may not adequately support the span and recommends using tubing for better structural integrity.
  • A later reply mentions that while box section may be better, it questions whether it would be sufficient for the application.
  • Concerns are raised about the flexing of the aluminium and the need for a vertical structural element to enhance strength.
  • One participant advises considering safety regulations and inspections if the mounts are intended for use in a vehicle, highlighting the importance of addressing potential shock loads when jumping on the seat.

Areas of Agreement / Disagreement

Participants express differing views on the adequacy of flat aluminium for the seat mounts, with some advocating for alternative materials or designs. The discussion remains unresolved regarding the best approach to ensure safety and structural integrity.

Contextual Notes

Participants note limitations related to the material properties of different aluminium grades and the implications of dynamic loads on the proposed design. There is also mention of safety regulations that may affect the design choices.

Noj_1991
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Hi all,

I'm hoping one of you clever people can help me with whether my seat mounts will be suitable or not.

I've done loads of googling and forum searches, but I just can't get my head around it.

I have a 630mm gap that I need to bridge and mount a seat too, so the seat will be directly above the gap.

If I got 2 x 670mm lengths of 5mm thick, 60mm wide 6060 grade aluminium flat bar, and bolted them across the gap (with a 20mm overlap on either side) and then subsequently bolted the seat to these bars, would it take my weight (80kg)

What about if I jumped on it?
 
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Noj_1991 said:
Hi all,

I'm hoping one of you clever people can help me with whether my seat mounts will be suitable or not.

I've done loads of googling and forum searches, but I just can't get my head around it.

I have a 630mm gap that I need to bridge and mount a seat too, so the seat will be directly above the gap.

If I got 2 x 670mm lengths of 5mm thick, 60mm wide 6060 grade aluminium flat bar, and bolted them across the gap (with a 20mm overlap on either side) and then subsequently bolted the seat to these bars, would it take my weight (80kg)

What about if I jumped on it?
Welcome to the PF. :smile:

Can you post a picture or sketch of the situation? What is the seat mounted to?
 
berkeman said:
Welcome to the PF. :smile:

Can you post a picture or sketch of the situation? What is the seat mounted to?

Cheers for the welcome.

After getting my hands on some aluminium, I can see it's not going to work, it flexes too easily.

I appreciate box section would be better- but would it be enough?

FB_IMG_1550175503953.jpg
 

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Typically, in a car, you will support off of tubing. There are a few that make formed aluminum as a base, and it uses the seat for additional rigidity. Kirkey has a variety of brackets that you may get ideas from. There will typically be one of these on each side of the seat, but I don't know that it will span the distance you have in the OP. Flat aluminum will not do a good job making this span. For aluminum, you will need a bend to give you a vertical structural element for strength. 6063/6061 are not considered formable without annealing. 3003/5052 are better aluminum selections for formability, if you make them yourself.

Typical Kirkey bracket
kir-99214_xl.jpg


Other seat mounts that may give you ideas:
https://www.swracecars.com/store/Seats--Seat-Mounts-OSCAR_248.aspx
https://www.cachassisworks.com/p-358-tube-style-seat-frame-for-full-chassis.aspx
https://www.cachassisworks.com/p-357-stock-floor-seat-mount.aspx
https://www.appliedracing.com/search?query=seat+mount&submit=Go

If this post is not for a race car or the like, I apologize for sending it down a rabbit hole.
 

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Slightly off-topic but, if I did such to a car I owned, I'd have to declare it to the insurance who may require a formal inspection. Similarly, formal and semi-formal competitions have rigorous safety inspections. May I suggest you ask those authorities sooner rather than later ? BEFORE you 'cut metal' ?
Based on their findings, you may be able to eg nest box-sections, add spreaders, double brackets etc etc to satisfy safety concerns.

Be aware that you, at rest, may be 80 kg. Your butt arriving rapidly will provide a bigger shock-load. Washboard surface will double it etc etc...
 
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