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View Full Version : Mounting the drum hubs - Take-One!



DannyC
10-11-2014, 08:56 AM
Well,

I plucked up the courage to have a bash at the axle-tab mounting and a trial-fit of one of the drum hubs.

http://s5.postimg.org/ikouoxwir/P1030281.jpg (http://postimg.org/image/ikouoxwir/) http://s5.postimg.org/bvib8xb6r/P1030282.jpg (http://postimg.org/image/bvib8xb6r/)

I tried both hub/wheel pairs on this one steerer-tube (to see if there was any real difference, there isn't).
The inclinometer says the cross-boom is horizontal (so does a spirit-level).
Don't ask me why, but the picture angle makes the whole thing look canted.
I shall have a few more "measures" before I decide to finalise the welding and call it done.

I really love the way the wheels "pop-off" with just a button-press.

DannyC
10-11-2014, 09:34 AM
Update......

Following the "Measure twice, before you cut" maxim I decided it was indeed "out" so I have torn it down to have another go.
But, as it has decided to pour with rain this will have to be postponed to another day.

darnthedog
10-11-2014, 11:13 AM
Danny
If you did not tear it off already- Remember to get a long threaded rod so both tabs Can be attached at the same time. The threaded rod will ensure the tabs are 90 degrees if you use a couple nuts on each side of the tab,

As to the angle. Until both wheels are attached I don't know how you can tell if it is off. As the bench or the welder could be sitting crooked and the measuring device really has no reference. Also the angle of the camera can fool you 3 times. But I would have booth tabs atttached in a tack welded before removing the one. Or doing a final weld at all.

DannyC
10-11-2014, 12:42 PM
I hear you Bruce,

Today's attempt was founded in the belief that maths can be a fairly accurate science; and to be honest it was very, very close to OK.
I was heartened (and just a tiny bit surprised) that it came so close and I am considering a minor cheat for the next attempt (doing it upside-down on a bench) - the tab-mounting that is.

I will try to get some threaded rod and nuts & washers etc. (Imamedik already advised this approach, and I was trying to cheat with a short-cut) to ensure parallelism of the tabs , but it has to be 16mm which isn't carried by everyone everywhere.
It is pretty close to getting there though and I reckon the next pass will sort it out for good.

Thanks for all the encouragement.

imamedik
10-11-2014, 06:01 PM
DannyC, if the 12mm threaded rod is more common, you can use it, just make a couple of 16mm spacer

sandman
10-12-2014, 06:36 AM
I hear you Bruce,

Today's attempt was founded in the belief that maths can be a fairly accurate science; and to be honest it was very, very close to OK.
I was heartened (and just a tiny bit surprised) that it came so close and I am considering a minor cheat for the next attempt (doing it upside-down on a bench) - the tab-mounting that is.

I will try to get some threaded rod and nuts & washers etc. (Imamedik already advised this approach, and I was trying to cheat with a short-cut) to ensure parallelism of the tabs , but it has to be 16mm which isn't carried by everyone everywhere.
It is pretty close to getting there though and I reckon the next pass will sort it out for good.

Thanks for all the encouragement.
Hi Dan
would you believe I just bought into the new marina internet access and its now out of action so have to use a dongle:taz:
but in reply ,maths is an exact science what B****** it up when welding is the heat moves the metal and that can be controlled BUT its a black art of knowing where the metal will move and how much weld to apply to the opposite face to pull it back, I believe I have suggested before just welding two bits together and watch how they move, the studding method works quite well but over the length you are using its possible that the studding can flex, a getround is to slip a bit of 1" tube at the length you need over the studding and lock off the nuts against the tabs, dont get to disheartened, the tabs are the hardest part and adding weld to pull the tab to the correct angle is fine, you can grind the excess off if needed because its the heat of the weld that has contracted the parent metal not the added metal itself, this is very normal practise.
Wow that was more than I meant to say not meant to be a lecture HAHA
regards
john

DannyC
10-12-2014, 09:41 AM
Thanks John,

Sorry to hear of your network woes.

I now have some 16mm rod & nuts & washers on their way (courtesy of e-bay).
I will nip it up really tight and clamp it in place as best I can while welding it up so that it has minimal opportunity to move and misalign.
I would hope that a 16mm rod will be beefy enough to resist distortion due to welding heat (but you never know).

On my last attempt I tacked it up with the steerer in a vice and the tab held with a magnetic clamp.

I will get there.

Ticktock
10-12-2014, 10:06 AM
Hi Dan,
This where you start to learn the (quote)" black art " of distorsion control! There is no other way--its going to distort, and you can't stop it in a home workshop. So you have to outsmart the electrons! Short welds -- big tacks--on alternate sides is the best way--takes longer but it does work. Piling on an extra run of weld will move it, and you can grind off the weld when its cooled.
magnectic clamps won't beat distorsion, and neither will a 16 mm rod. But if the rod is locked tighr on the clamps, you may be able to see any slight bend in the rod caused by the tabs distorting--a straight edge is the only way. If its the frame that distorts there is no way to know. if there is a slight error after "final" welding, then the exra run of weld and grind idea can be done again.
Even better, if you can get some scraps the same size, and do a couple of test runs, just to see what really happens, and how to control it.
Its a black art that comes with practice!
Steve G

I forgot to mention the good old oxy torch if all else fails, but with care as the tabs are stronger than the crown !
Now I did not write that last line-- written under some strange outside influence!

DannyC
10-12-2014, 10:51 AM
Hi Steve,

Yeah, yesterday I used the magnetic clamp just to hold it for the initial "tacks".
Then after that I put some heavier "TACKS" to try it for size (knowing that I could always knock it about a bit to re-align).
I'm sure I will be able to win through eventually.


Cheers!

swizz69
10-12-2014, 12:08 PM
Great stuff - did you manage to get some used Drum hubs eventually or did you end up buying all the bits & building your own?

DannyC
10-12-2014, 02:16 PM
Hi Swizz69,

I paid the full amount :-(

> 240 all in (including rims, spokes & tubes).

They'd better be worth it!! :-)

They do look smashing TBH.

swizz69
10-13-2014, 08:02 AM
Nice feel, plenty of power, look brill, almost fit & forget - am sure they'll be worth it ( or "Eeeet" as the shampoo advert goes lol )

All in that doesn't sound too bad at all really.

stormbird
10-17-2014, 08:48 AM
Danny

Did your new hubs come with any mounting instructions ?

I got mine NOS off Ebay with no instructions on how to mount them , also no flash like yours so the axle is not QR

DannyC
10-17-2014, 09:17 AM
Hi Paul,

Instructions? Who needs instructions? Real men never read manuals, maps or other instructive texts (ask my wife).


No, they don't come with any manuals (which is really odd), but then you can only buy them as discrete components and not as a whole unit.

But, I think I have figured it out for myself.

The awkward bit will be fitting an anti-turn pin/stud onto the kingpin to ensure against the backplates moving when braking hard.

Quite looking forward to it really.

Ticktock
10-17-2014, 08:45 PM
Since being in China I have stopped reading instructions. We are used to getting multi language manuals for almost anything we buy, even the made in China stuff floods the world. But here in China, even for the same stuff, its either no manual, or only in Chinese!
You quickly learn to look at pics or just plain guess.
Steve G

DannyC
10-18-2014, 07:06 AM
Well,
The 16mm threaded-bar and the washers & nuts arrived by parcel-carrier post this morning.
No backing out now, the tabs will have to get welded on this weekend (unless the weather gets too blowy for Gas-Mig operations).

They are forecasting that the tail-end of Hurricane Gonzalo will come across the Atlantic to dampen our spirits, although it will no longer be anything like a hurricane by then as it will be in cooler northern waters.

Ticktock
10-18-2014, 08:49 AM
Hi Dan,
I think you are well out of range of Gonzalo--if he's still in a bad mood by the time he gets to you, the rest of the country has a real problem!
The threaded rod will almost certainly make things a lot easier.
But I am now going to break an oath of strict secrecy, and reveal a little known, and less admitted, way to fine tune the wheel alignment as regards to the tab fixing!!!
These words did come from me. That's my way of getting away from the flack from more serious types!!!!
The "hole " for the axle will almost certainly be a bit oversize, or you would not be able to get the axle in easily! This means it will "wobble" in the hole until tightened.
If you need to, just grind a SMALL amount of the correct place on the sides of the tabs to make the wheel line up as it should!! Do this each side of the tab to keep them parallel, and the axle will still tighten properly.
Any more than 1mm is probably a bit too much, but no problems under that amount.
1mm on the side of the tab represents a significant movement at the rim, so it quite a powerful adjustment, even if it is , or was, a closely guarded secret.
Now on the run,
location not disclosed,
Steve G

DannyC
10-18-2014, 10:06 AM
So, my courage was cornered in the garage where it had nowhere to run to or to hide and I took it by the scruff of the neck and gave it a blooming-good shake.

Then I attached the tabs to the 16mm rod with the washers & nuts and proceeded to tack the 4 corners of each tab where they intersected the steerer-tube end.

Note: The tip regarding exposing the contact tip while valid and really helpful to me does have a drawback.......
..........in that it is possible to put the contact tip into the weld-pool and weld your contact tip shut. Oops!

So, it cost me a tip (two in fact), but they are cheap and I think I shall re-work another shroud to reduce the "stick-out" by a mm or two so that instead of it being recessed by c.6mm it is flush with the end of the shroud.

But! The job got jobbed and I am pleased with the initial results where the vertical set of the wheels and the "contact-patch" are looking pretty good (see pics below).

http://s5.postimg.org/d8nwa9per/P1030283.jpg (http://postimg.org/image/d8nwa9per/) http://s5.postimg.org/fttgxsesj/P1030284.jpg (http://postimg.org/image/fttgxsesj/) http://s5.postimg.org/t9ghn8nab/P1030285.jpg (http://postimg.org/image/t9ghn8nab/) http://s5.postimg.org/425lmzk6b/P1030286.jpg (http://postimg.org/image/425lmzk6b/)

The hubs are removed once more and the steerer tubes and bearing sets dis-assembled so that the full welding of the tabs to the tube-ends can take place now the basic positioning is fixed.
I actually sat on the main beam and had a little "test-bounce" and nothing went awry.

I also noticed that it was relatively easy to pick the entire bike up one-handed by grasping the main-beam, so the weight compared to the cannonball express looks good too.

Twinkle
10-18-2014, 10:51 AM
Hi Dan,
I think you are well out of range of Gonzalo--if he's still in a bad mood by the time he gets to you, the rest of the country has a real problem!
The threaded rod will almost certainly make things a lot easier.
But I am now going to break an oath of strict secrecy, and reveal a little known, and less admitted, way to fine tune the wheel alignment as regards to the tab fixing!!!
These words did come from me. That's my way of getting away from the flack from more serious types!!!!
The "hole " for the axle will almost certainly be a bit oversize, or you would not be able to get the axle in easily! This means it will "wobble" in the hole until tightened.
If you need to, just grind a SMALL amount of the correct place on the sides of the tabs to make the wheel line up as it should!! Do this each side of the tab to keep them parallel, and the axle will still tighten properly.
Any more than 1mm is probably a bit too much, but no problems under that amount.
1mm on the side of the tab represents a significant movement at the rim, so it quite a powerful adjustment, even if it is , or was, a closely guarded secret.
Now on the run,
location not disclosed,
Steve G

Whats wrong with flashing the side of a 12mm lug with a grinder:jester:

darnthedog
10-18-2014, 11:43 AM
Looking great Danny- glad the welding is working better for you.

DannyC
10-18-2014, 11:43 AM
Thanks Steve, I shall keep this secret just between us girls. Who'd a thunk it? File/grind the tabs eh?

Thanks Bruce, it is certainly feeling better and less of a concern to me now. I am sure I could do with a lot more practice though :-)

DannyC
10-19-2014, 10:20 AM
Tabs now fully welded to the tubes and tidied up.
http://s5.postimg.org/a871tqe3n/P1030289.jpg (http://postimg.org/image/a871tqe3n/)
Relieved to have this job completed successfully.