safest way to hold

[mick70Participant @mick70]

got some rear bike hubs that very sturdy i want to modify to use on tadpole builds.

one is threaded internally to hold freehub.

i want to bore that out and remove spoke flange from it.

then make piece that fits in place with disc brake holder and larger soke flange on it.

reason for doing it is not easy or cheap to get hub i can fit bearings and 14mm axle to.

[mick70Participant @mick70]

[Bob StevensonParticipant @bobstevenson13909]

About 30 years ago when mountain bikes were still quite rare I was seriously into making custom hubs and also made several sets for patent applications and evaluations….I still have some somewhere. There are several pifalls for the unwary designer……. The brake coupling method really need to be integral with the hub so you may well be much better off going straight to machining original hubs and NOT trying to make a hybrid brake fitting for your existing hub. Both discs and drum brakes are extremely dificult to design and engineer because of the unique operating 'envelope' of off (or 'on' come to that) road biking….it's tiresome to experience catastrophic wheel failure withng feet of the door time and time again after many hours of wheel building and adjustment…….

……..Another major challenge is the design, profile and placement of teh spoke holes on the 'large' side of the wheel.

[JohnFParticipant @johnf59703]

Holding fixture needed here Mick, is the main bore [last photo] machined and concentric to the other machined parts? If so i would make an expanding mandrel thats reasonably close to the threaded part you intend to remove, you can then bore these out and remove the spoke flange, add what you want and machine that as well if need be.

John

PS heed Bob's warning life and limb at stake !

Edited By JohnF on 05/07/2018 17:28:06

[mick70Participant @mick70]

Point taken Bob will start from scratch.
John will look out for expanding mandrel as if starting from scratch will hold OD and bore center out to size then do outside.

[JohnFParticipant @johnf59703]

Expanding mandrels are easy to make, turn to the size you need, drill and tap for the largest countersunk allen screw that will fit – bigger the head the better. Then saw 4 or better 6 slits down the mandrel so that when you tighten the screw it expands – job done! Obviously de-burr the saw cuts and a slight counterbore at the end of the thread helps the screw to seat properly.

John

[Bodger BrianParticipant @bodgerbrian]

Posted by mick70 on 05/07/2018 15:31:13:

got some rear bike hubs that very sturdy i want to modify to use on tadpole builds.

Just curious – in this context, what is a tadpole?

Brian

[Mike PooleParticipant @mikepoole82104]

I think a Tadpole is a recumbent trike.

Mike

[Michael GilliganParticipant @michaelgilligan61133]

Brian,

A look at this recent thread will probably help: **LINK**

https://www.model-engineer.co.uk/forums/postings.asp?th=136343

MichaelG.

[Author]

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