An octagonal spanner.

[alexnharvey]

Where can I find a 32/36mm octagonal spanner for headsets and Shimano hub dynamos? Is it cannot be bought and must be made, what thickness would it be made from, 3 or 4 mm?

[Brucey]

TL-DH10



eg
https://www.bike-discount.de/en/buy/shimano-tool-for-hub-dynamo-tl-dh10-31271

Tool above is bi-octagonal.

Other options are

a) 'G' shaped headset spanners which drive six points of the octagon (these spanners are no longer widely available) or
b) DIY type.

I went with the DIY option and made full-octagon spanners using 1/8" thickness steel. Given that the driven piece is aluminium the steel doesn't need to be hardened to be good enough for this job. A full octagon is a lot more secure than a bi-octagon.

cheers

[alexnharvey]

I recall your posts about your DIY spanner. An old park hw2 spanner just sold for 44 pounds on eBay. Since my primary need is headsets I would prefer a 6 of 8 point spanner and hope that it might also serve for the dynamo as a bonus.

I suppose it is most sensible just to cut one out and be done with it but I keep on thinking that a water jet could make a very neat job of it.

[JakobW]

I always thought this (now discontinued) rinko headset tool was rather neat, though I did wonder about how much torque the aluminium could take: https://www.renehersecycles.com/shop/co ... dset-tool/

I've also seen a system where the locknut has a short length of 8mm ID tubing brazed horizontally to the locknut, so you can use an Allen key as a tommy bar to tighten it up.

[yostumpy]

I have one of those strong light headset spanners going spare.

Oops! No I don't

[Brucey]

Park Tool HW2 spanner



it was never a cheap tool, being thick investment cast steel. I think this tool is now NLA; £45 is about the same as the new price was.

I've made more than one DIY octagonal/headset spanner. A small titanium one, in 32mm size for emergency use (aluminium isn't really strong enough IMHO), and larger ones in 32mm and 36mm sizes, cut from 1/8" steel.

cheers

[alexnharvey]

A water jet cut mild steel one works out at 17 quid if I supply them with a DXF.

[Brucey]

A water jet cut mild steel one works out at 17 quid if I supply them with a DXF.

that sounds OK to me. I wonder if a group buy might further lower the cost?

It occurs to me that an asymmetric cut through a full octagon would give a 'G' shaped spanner that would be significantly better in one direction only.

cheers

[Manc33]

Brucey you make stuff from titanium?

If this was me... I'd just be rounding off the nuts with a pair of Vise grips.

Actually why can't a decent adjustable be used like a Bahco? Those aren't cheap but, it's not going to be £45. It will just round it off?

[alexnharvey]

Unfortunately not, at least not with this first company i contacted in Cambridge. They say there's not much break until 50+. There are quite a few water jet companies around though and it doesn't particularly have to be local I suppose.

I guess a 32-32mm spanner could have opposite asymmetric ends

[Brucey]

Brucey you make stuff from titanium?

yes a few things, odd travelling/emergency spanners, a few axles etc. Mostly I'd say it is 'not worth it' but the emergency headset spanner has been a 'comfort blanket' that has travelled far with me;



I've never had cause to use it 'in anger' on my own bike.

cheers

[Brucey]

I guess a 32-32mm spanner could have opposite asymmetric ends

it could, but it would be just as easy to flip the spanner over between loosening and tightening?

BTW with the correct asymmetric cut I think you will still get it over the quill, yet end up with seven point drive.

cheers

[Samuel D]

Actually why can't a decent adjustable be used like a Bahco? Those aren't cheap but, it's not going to be £45. It will just round it off?

Enormously heavy for the required size, for starters. If damage is a concern, a Knipex Plier Wrench in the required size would weigh about 0.25 kg and do a better job than an adjustable spanner, since the fit would be better. Still acting on only a couple of flats, though.

[Brucey]

if you are going to try on two flats only with a hub generator internal then it is (IMHO) best to use a bench vice with textured jaws and a moderate clamping force, rather than a wrench with smooth jaws and a low clamping force. This is because the corners of the octagon are most easily damaged if the tool can slide over the surface. Using a bench vice with textured jaws the octagon will be marked up slightly at least, but sliding is less likely and damage to the corners of the octagon is less likely as a result.

Most generator internals come out fairly easily, but if the thing has done a high mileage and/or has seen some corrosion too, the internal can be extremely tight, almost comparable with getting a freewheel off.

The full octagon spanners I have made can either be clamped in a bench vice or slogged as is deemed necessary.

cheers

[alexnharvey]

I can't quite picture the asymmetric cut The shortest distance between any two corners is 22.627mm isn't it so we can just clear the stem if we take off two sides but are you saying you would shift it over to complete the seventh corner and robbing a little from the other side?