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Topic Date User

How thick could a bolt plate be? 24-Oct-2016 At 12:03:52 PM TimP

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On 24/10/2016 mikllaw wrote:

>They are if clipped between 2 biners. They smear off a bolt head at about
>10kN, depending on how bendy the bolt is.

Hi Mike, saw your post about this on RopeLab Facebook which made me lower my target load for the new bolt plate. Very useful real-world data thank you. 20KN stamped on that plate! I can see the angle of the load in relation to the bolt axis would effect the failure mode.

So I'm going up from 3.2mm to 4mm in thickness, that should help make it stronger and fit onto any carrot 5mm off and over.

I was talking to an engineer who suggested casting in precipitation-hardened stainless steel to make it over 1000mpa tensile strength. With the design in sheet metal it's a play between tensile strength and bendability. I had found a good sheet stainless (7C) at 1600mpa but you can't bend it (will use this for the next version of LittleHammer though!).

It is surprisingly difficult to shift my design mindset for bolt plates from the traditional punched / laser cut & bent sheet, to casting. It may be more cost effective to go the sheet method but small production volume might make it close, I'll work up both designs to get the prices.

I'm pretty sure carrots are no longer installed and being only in Australia the market is small and closing. But if it doesn't cost too much I'd like to release the new plates just because they solve the jiggling-off problem. Yes, yes, designers and jiggling-off... and do we need more new gear... but I enjoy this process!

One more question. With an angled bolt plate do you prefer it angling from high on the right to low on the left or the other way?