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Discussion Starter · #1 ·
Hey guys I need an axle made, maybe 2 or 3 of these actually...

Im reading onine some guys just use DOM tubing. Some say 4140/4130. Im pretty lenient on material being that im not the most knowledgable guy on this sort of thing.


I have the major dimensions i need below, what Id like now is some consultation on how we can make fastening it easy.




On the left side here, I am open to having the tube go slightly longer than the clamping surface on the front forks and eventually grind 2 sides of it flat so i can put a wrench on it?

On the right, would it be easier to do the same idea i had for the left? Can a square hole be machined to fit a 1/2 ratchet?

Would I have better luck welding sockets in on both sides? lol
 
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That looks close to a stock Kawasaki front spindle setup but that's only from memory of the sizes etc, it could be worth a look to see if one is close enough to have machined down to size

I use en24 for spindles & not had a problem yet

Hope it helps
 
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Mine are usually just machined from solid bar with flats milled on the ends like you suggested, I have gone as far as having a full nut milled & having them drilled out for weight reduction in the past but to be honest its not really worth the extra time & expense even at mates rates
 

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lɐʇuǝɯᴉɹǝdx&#4
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Is this clamped at the ends, around the larger sections? I not loving the idea of having the fork leg effectively clamp to a nut the axle threads into, especially if its an upside down fork. For a USD, the axle is all that keeps the two legs from moving independently, and that threaded connection gives up a lot of stiffness. If its a USD, might be better to just have a plane shaft with a split collar on one end, instead of the threaded bit. Also easier to machine, as the person cutting it wouldn't need to do any real precision on the shaft mid-section length.

My lathe work has gotten better lately, but I think something like that is a bit much for our mini-lathe. If I got trained on the full size model, could give it a shot.
 

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Discussion Starter · #9 ·
hey seb, you are correct in the sense that both of the larger ends are clamped, this is how srad, tl and busa axles were designed, material is aluminum im pretty sure

Oh and it has the lip up top in the first picture, kinda forgot that for the 2nd dimensioned pic)

im having a hard time picturing what you meant by that

like this?

something like this for the ends?

 

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lɐʇuǝɯᴉɹǝdx&#4
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Pretty much as in the picture you drew there, not the photo. The bit the axle passes through would have a (single) slit in it along the length, so that the clamping pressure from the fork was transmitted to the axle. Make it from Aluminum so its nice and flexy, transmits all the clamping force. Not sure what the rest of the axle should be. My guess would be chromoly steel, but a solid 22mm steel axle seems a bit heavy; hollow would be much lighter and near as stiff. If you could find 7/8" chromoly DOM tubing with ~.1" wall, that seems a great start.

7/8" x .083 chromo 4130 seems fairly common (racing chassis places have it), you'd effectively be shaving .005 off the outside of the wall, might not be a bad option at all. Put one of those slit aluminum tube ends I was describing on each end, and you have something very simple and light. Is it strong / stiff enough? Does it have all the fitments you need? I don't know.
 

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Discussion Starter · #12 ·
Pretty much as in the picture you drew there, not the photo. The bit the axle passes through would have a (single) slit in it along the length, so that the clamping pressure from the fork was transmitted to the axle. Make it from Aluminum so its nice and flexy, transmits all the clamping force. Not sure what the rest of the axle should be. My guess would be chromoly steel, but a solid 22mm steel axle seems a bit heavy; hollow would be much lighter and near as stiff. If you could find 7/8" chromoly DOM tubing with ~.1" wall, that seems a great start.

7/8" x .083 chromo 4130 seems fairly common (racing chassis places have it), you'd effectively be shaving .005 off the outside of the wall, might not be a bad option at all. Put one of those slit aluminum tube ends I was describing on each end, and you have something very simple and light. Is it strong / stiff enough? Does it have all the fitments you need? I don't know.
the tubing sizes i can get to 31.75mm OD and 22.22mm ID as closest sizes to what i need for the outer sides in 513 DOM

as for the collar at the ened im having trouble finding aluminum tube that doesnt have to have a large amount drilled or machined out


THIRD IDEA
Ive also had the thought before to use the original r6 axle but weld a sleeve onto the end (its clamping surface on one side is clamped by USD and is 28mm OD. Can find 31.75 OD 28mm ID steel)

and creating a collar like you said with a closed wall for a nut to clamp against




This utilizing of original axle could mean no machining...or much less for the axle part



What forks is this for ?
For hayabusa forks

this is the front axle design
 
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For hayabusa forks

this is the front axle design
Easy job then :D just have an spindle machined from en16 or en24 use an original busa threaded end, clamp it up as normal & you are good to go, note how much thread is on the end of an original spindle & make the same amount on your new spindle, you will find that the threaded end is either solid for strength or bored out for weight reduction but its usually a smaller hole than the other end

Seriously do not mess with tube its really not worth the risk
 
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For a USD, the axle is all that keeps the two legs from moving independently,.
Sorry fella but it needs pointing out that the above statement makes no sense whatsoever, it makes no difference if the forks are USD or not the spindle (axle) performs the same function, IE with no spindle present either type of fork will move independently :)
 

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lɐʇuǝɯᴉɹǝdx&#4
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Sorry fella but it needs pointing out that the above statement makes no sense whatsoever, it makes no difference if the forks are USD or not the spindle (axle) performs the same function, IE with no spindle present either type of fork will move independently :)
That assumes the absence of a fork brace of some sort on the conventional fork. They usually have one, even if it is only a fender designed to pull double duty as a brace. Its possible some USD's use a similar item (though its harder to build such, for obvious reasons) but typically they just use a really fat axle, often hollow. Obviously the smaller spindle on a conventional fork still contributes a lot to keeping the two legs moving in unison, but the demands on that part in the absence of a brace would seem self evidently greater.

Does it make a big difference? I dunno, but from the howls of cafe racer traditionalists when they see a conventional fork without said brace, you'd think so. Is it possible to design & machine an axle such that one of the clamped ends threads onto the axle and won't flex / wiggle under high loads? Maybe, might depend on how it is retained in the fork, but its not design I'd attempt myself, so I tossed out what I saw as some alternative. YMMV.
 
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sebweirs

Read & understood, although I don't totally agree

The spindle is the main thing that stops the forks moving independently on either type of fork, braces in steel guards were used on older bikes more as a quick cheap fix because of the poor quality of a lot the other components, & hence the 80's preference for aftermarket braces such as Teleflex, comparison to modern usd forks which are much more rigid is pointless they simply wont move independently with a wheel & spindle in unless you hit something .......hard

The above is also part of why I would not use tube for a spindle but prefer to have a new spindle properly machined from quality materials
 

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lɐʇuǝɯᴉɹǝdx&#4
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... comparison to modern usd forks which are much more rigid is pointless they simply wont move independently with a wheel & spindle in unless you hit something .......hard

The above is also part of why I would not use tube for a spindle but prefer to have a new spindle properly machined from quality materials
I'd agree with the first, as the new designs with larger spindles really do the job they are meant to.

But what's the problem with tubing? A hollow steel tube of the same mass & outside diameter as a solid aluminum rod is gonna be stiffer vs flex than the solid rod, and equally stiff vs some other stresses (end compression).
And that's almost exactly what you end up with if you have a 22mm solid aluminum axle vs 22mm hollow / 2mm (.08 inch) wall- they weigh very close to the same (by my math, the cross sectional area of the tube is almost exactly 1/3 the solid ally). Could be there are entirely other concerns though... crush strength? Ultimate tensile strength?

Obviously, if there's a conservative, proven, conventionally accepted way to make the part he needs, that's probably the way to go.... no point dicking around on an axle, for sure.
 

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Discussion Starter · #18 ·
Easy job then :D just have an spindle machined from en16 or en24 use an original busa threaded end, clamp it up as normal & you are good to go, note how much thread is on the end of an original spindle & make the same amount on your new spindle, you will find that the threaded end is either solid for strength or bored out for weight reduction but its usually a smaller hole than the other end

Seriously do not mess with tube its really not worth the risk


I cant use the original end clamps, the threaded area is larger than the r6 axle size i need it down to so i can slip it through the wheels (no bearing swap available)
 
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I cant use the original end clamps, the threaded area is larger than the r6 axle size i need it down to so i can slip it through the wheels (no bearing swap available)
yes I only just spotted that, that will teach me to look at drawings properly :) the same still applies though apart from you will need to make a new end, sorry for the confusion.

just to clear up the conversation with sebweirs ....
I just use the quoted steel materials as they are proven to be safe & will remain so for years to come, I wont use aluminium as getting the right grade for this application is a nightmare & some will need heat treating to retain their strength after machining, tube you can buy off the shelf is generally of poor quality & any with a wall thickness as low as 2mm will not resist bending to any degree, you would be relying on the wheel spacers & wheel bearings to keep that straight, the risk of shearing in use is also high

I always think that my work now could go through 10 users in the next 10 years & I don't want to be responsible one of those users getting injured so am happy to stick to the tried & trusted methods until some of the newer ideas have stood the test of time :)
 
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