Source of Seat pin bolt washers ?

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Farrina
Posts: 55
Joined: 26 Nov 2012, 8:15pm

Source of Seat pin bolt washers ?

Postby Farrina » 17 Feb 2019, 3:51pm

I have a Reynolds 853 steel frame.

Utilising my existing seat pin bolt to secure it, I am looking to fashion a bracket made from 1mm thick stainless steel to mount my rear facing camera onto my bike.

As will be apparent from the photographs the existing bolt (19mm wide) fits into a recessed hole in the frame (same both sides) and obviously were I to just bolt my proposed new bracket to the frame this would not be ideal! Note that I have already sourced a replacement 27mm wide seat pin bolt to allow for the additional bracket width etc.

https://www.ebay.co.uk/itm/123551912045

I think the solution to this is to mount additional washers under the bracket so that they can be compressed into the recessed hole and the forces transferred to the frame as originally designed.

As best I can tell these washers are 12mm outside and 8.5mm inner diameters.

However this is where I run into problems as this size of washer seems to be non standard. See here https://www.engineersedge.com/iso_flat_washer.htm

Does anyone know of a source of 12 x 8.5mm washers ?

Cheers
Image Attachments
Bolt Side.JPG
Bolt Back.JPG

Brucey
Posts: 32710
Joined: 4 Jan 2012, 6:25pm

Re: Source of Seat pin bolt washers ?

Postby Brucey » 17 Feb 2019, 4:14pm

binder bolts of this type

Image

are easily modified/adapted e.g. by shortening the female part of the bolt. You can also mix and match parts from different bolts because the threading is almost invariably M6x1.0. They also come with a washer; if you have several bolts you will also have several washers; maybe you don't need extra washers provided you can use a hacksaw and a file. You can also replace the male part of the bolt with a standard M6 caphead and use standard M6 washers as packing if you like.

FWIW mounting things on brackets that might turn the bolt they are fitted to is not always going to work very well. I'd suggest that your bracket is mounted elsewhere or has a brace that bears against something that will stop the bracket from turning.

FWIW if there is any significant weight to it, I'd probably mount the thing on the brake centrebolt or via two large P clips to the seat pin or something.

cheers
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colin54
Posts: 993
Joined: 24 Sep 2013, 4:34pm

Re: Source of Seat pin bolt washers ?

Postby colin54 » 17 Feb 2019, 7:32pm

Triple chain ring spacers are 12mm o/d x 8mm i/d, I've used them on seat pin bolts, they are made from aluminium, easily filed to suit your purpose if need be.

https://www.spacycles.co.uk/m2b0s173p2297/STRONGLIGHT-

....or I've got a couple of unused 6.2mm deep ones it they're any use to you.

JohnW
Posts: 5973
Joined: 6 Jan 2007, 9:12pm
Location: Yorkshire

Re: Source of Seat pin bolt washers ?

Postby JohnW » 18 Feb 2019, 3:22pm

Brucey wrote:.....................FWIW mounting things on brackets that might turn the bolt they are fitted to is not always going to work very well. I'd suggest that your bracket is mounted elsewhere or has a brace that bears against something that will stop the bracket from turning.

FWIW if there is any significant weight to it, I'd probably mount the thing on the brake centrebolt or via two large P clips to the seat pin or something.

cheers


Yup - +1 to all that.