Q-Factor as narrow as practical with and without a lathe :-)

undertoad said:
Yes :confused:
Click to expand...
Ahhh... but they are very wild, inaccurate and preposterous guesses which is a specialty on here. ;)
Actions taken today:
Trim the centre sections minimally to ensure a consistent diameter across both and chamfer the ends.
Make a new joiner sleeve/tube that is a snug (tap it on with a light hammer) fit.

I was fixing my Mini this morning and I have injured myself a little bit so I have had to stop working.
Next step will be to repeat the failed "plug-welding" but in addition weld around the ends of the sleeve to attempt to join it to the bearing seats of the two halves (like Paul did in post #1 above).

Then the "breaker-bar+gorilla" test can be done to see if it breaks.
 
DannyC said:
I was fixing my Mini this morning and I have injured myself a little bit
Click to expand...
Have you ever seen the movie "Christine" ?
On another note:
I'd suggest grooving around the axle pieces, right against the sleeve ends, to give a little more area and depth for the weld bead.
Also - Turn up the amperage.
 
undertoad said:
Have you ever seen the movie "Christine" ?
On another note:
I'd suggest grooving around the axle pieces, right against the sleeve ends, to give a little more area and depth for the weld bead.
Also - Turn up the amperage.
Click to expand...
I had thought to push the amps to 90+ for the plug welds. Not sure I can do that for the thin 1.5mm wide bearing seats though because they will just disappear. Another thought was to do all this and then.......... [pause for dramatic effect] at 90° to the initial plug welds put 2 more holes (with an end-mill cutter) into the sleeve AND some way into the now "fixed position" axle halves and fill those up with weld so it acts like 2 studs from the outer sleeve into the axle itself.

The question then will be, how "HAM" should one go on load testing?
 
90A seems like a minimum to get a good penetration in that thick axle - But I'm for sure no expert :rolleyes:
If you have a junk axle, maybe weld on it and see.
If you burn away some of the sleeve, turn the heat down, and weld another fill pass, or 2
 
OK, so, well, err, ummmm......
I made another sleeve, whacked the amps up to 100 and plug-welded both holes.
Did my best to run a complete weld all around the ends of the sleeve tying the sleeve to the bearing seat webs.
I put the end result back in the lathe to square up the bearing seats etc. and assembled it all together.
Here it is before the stress test.
image.png


And here it is after the test.....
Need to put more of my weight on it maybe but it didn't yield like last time.
image.png
 
Radical Brad said:
The heat effected zone will become brittle unless allowed to cool extremely slowly. Even then... kinda iffy.
I tried a pre and post heat on steel like this with some success, but decided it just wasn't worth the risk.

Here is what I did (ultra high tech) to test the bb axles I tried welding after they cooled...

Put them firmly in a large vice with boards between to protect the races, then hit the extended end as hard as I could with a 4 3 foot long bit of 4x4 lumber.

Of 4 of them which I pre and post cooled as well as chanfered for proper 100% weld, all but one shatered at the weld.

I figured I may be subject to a leg injury if I was really pushing hard on the cranks and one sis that, so I chickened out and started using the lower carbon "drill rod" to make my own. Did a narrow one like yours and two mega wides for choppers, all good.

Maybe my basic buzz bix was just too crude for such technical welding!

Brad
Click to expand...
Thanks for warning us

Buzzbox put aside knowing the kind of steel being welded seems crucial

I wish i knew more and feel i am taking chances homebuilding

Off old bike frames, I could identify
low quality steel like mild steel,
Some is labelled " hi ten" for high tensile,
And there is the cromoly / 25cd4s..

For tig welding these i was told er70-80s2 would work, even on cromoly,
but that 309L or 312 are ok too on cromo.
But that the most important was slow cooling on thin tubes to avoid cracks...
( which happened to my despair )

I see that Brad with a lot of practice makes strong frames with a mma welder,
I assume not with the thinnest tubes,
and 6013 or 7018 rods ?

Others seem to have success with mig too...

I know this is not a welding class but would it help maybe if we summarized each other's experience about steel type / thickness / type of joint / welding process / filler / precautions that work or that would cause risks, maybe in a dedicated topic ?

I am grateful for all i have learnt on this forum already, hope my trial and error can benefit to others too?
 
As I said above (and sorry for the thread hi-jack Paul) I have milled 2 holes through the sleeve and down into the core material of the axle.
There is an awful lot of case-hardening on that axle that you have to chew through.
Here is a picture of one of the holes. The simple idea is to puddle weld it back full-up again and these "pegs" will further strengthen the whole shebang. Pretty it ain't! But the whole thing is inside an outer shell and you won't have to show the scabby welding of a blind bibulous welder with essential tremor to anyone. :D
image.png
 
Trickytrike said:
I know this is not a welding class but would it help maybe if we summarized each other's experience about steel type / thickness / type of joint / welding process / filler / precautions that work or that would cause risks, maybe in a dedicated topic ?
Click to expand...
Given most recumbent frames are beams I've not tried to use very thin steel as it's just a non starter. Diamond frame bikes can use sub 1mm steel tubes as they are in perfect compression or tension but even they tend to have thicker metal at the ends where they are welded or brazed. Beams tend to need 1.5mm or 16swg as a minimum from my experience and this welds quite easily with a mig and std mild wire. The only time I've not used that is when using stainless but keeping the thickness the same. Std stainless wire works fine in a mig.

One thing I have noticed is that my old Cebora 160 mig that I've owned since Noah sold me it is just not at the level of the modern synergic stuff. I recently bought a Telwin Treo 223 Synergic mig and it's way better. Massively less spatter and a doddle to set perfectly for whatever you are welding.
 
The only one cut and shut I have seen was one of the hollow axles [ they have splined ends so different cranks etc]

What they did was :-

Chainset
The 140mm cranks are machined from aluminium and are similar in design to what was used on the K-drive a few years ago. They lock together with two 30⁰ wedges and an M8 bolt and they transmit the torque to the chainrings via two 6mm pins.

image-73.png


Then it all got very complicated very quickly ;)

image-74.png


Picture from here Quattro

Paul
 
Hello Sportsfans.... :)
Today I fired up the electric-glue pot and filled those two holes in the outer sleeve and axle core.
My goodness the whole centre inche of the axle was shining orange after each puddle had been stirred. :)
As before it doesn't look at all pretty, but I am hoping it will be strong enough to allow it out into the wild to breed.
In order to draw this agony out for the maximum comedic effect publicity, the load test will take place tomorrow.
image.png


Just for S's & G's I took the original that I had made for Paul and tried the stress test and it too failed with a breaker-bar on it, in much the same way as this one did. So if this one passes the 600lb/ft load test then I can rework the original to match this'n. :)
Then I would indeed have a "breeding pair". ;)
 
It will more likely be that repeated stressing will be the potential killer than brute force in real use given the high tensile nature of the shaft. Very difficult to replicate that in any test though.

I too expect this to pass.
 
Ok I leant on it to the point where I was concerned that "If" it failed I would faceplant myself onto the floor, but it did not fail.
As I have enough "broken-bits" already I decided that I need a better testing method.
The only other way I can test I think is to have a sling over the bar and a timber through the other end of the sling with me walking up the plank/timber just a few inches off the ground. I would be in no real danger then I think. A <6" fall is not likely to result in any real injury.
 
DannyC said:
A <6" fall is not likely to result in any real injury.
Click to expand...
This sounds like famous last words :eek:
Seriously, if it passed your cheater bar test (which failed your earlier edition), it's probably good to go.
I mean, if you try hard enough, you can probably manage to break it, but how much is really needed to prove it?
Also, heating it as much as you described has likely annealed it, so I'm thinking that it may just bend, instead of breaking.
 
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