Running something up the flagpole to get opinions please.

Well we put it all together and we had a bit of a disaster. The cassette carrier got welded in slightly askew.
Now, while it doesn't look too dramatic it just will not do I am afraid as it implies the out end of the RH axle would be whirling around in an exaggerated circle. :(
So, I chucked it back in the lathe and cut all of the welds as precisely as I could and then put a large tube over the cassette carrier to act as a breaker bar and snapped the remaining weld material.
image.png

Solution:
A jig will be made out of 12mm Brass hex-bar and some M10 all thread and M10 nuts and washers and this will be used to perfectly align the two Hex keyways in the Left & Right sides of the unit and clamp them together while it is being welded up.
 
Yesterday was "Lathe-Boy's" 70th Birthday.
As a special treat we let him have a go at making hexagonal keyways in 35mm 680x bar after he had threaded it for use with freewheels.
Disaster.... The expensive tooling just did not work and it was very depressing.
Today we consulted many online sources for a possible reason why we had met with such an abject failure.
It turns out that the £36 "rotary broach" holder wasn't fit for purpose and should have been called "tool holder in a live centre".
So the best suggestion was to scrap it and buy a proper "wobble broach" holder for £187 + shipping from the USA.
We can't afford that so we looked at other alternatives and one approach looked really suitable to adapt what we already have.
file-file...Tig-Tig...Zap-Zap....... and we have a tool-post mounted live centre that accepts 1/2" wobble broaches.
We still need to get it to "wobble" though. But, the 'spensive units have the live-centre bits just at 1° off-true and we can do that with the lathe easily. So then lining things up by eye while inserting our hard little tool into the orifice that would not cut yesterday we are ready for the off.
Lathe "ON" and away we go.... It is an odd feeling as the wobble-broach nibbles each of the 6 corners of the hole individually as it rotates and the feedback is transmitted through the carriage wheel of the lathe.
Success!.... My hard little tool nibbled its way 1" deep into the Aluminium. The lathe was powered down and the tool was withdrawn. A sample of 12mm AF brass bar was inserted and was found to be a nice snug fit. :)
So now we know we can broach the keyways, all I need to do is develop a method of always getting the holes bang-on dead-centre.

EDIT: I am corrected because it is NOT a "keyway" it is a "Hole" (there is no key involved). However, the axle is required to be shaped to fit in this "hole" just like fitting a key into a Keyhole. ;)
 
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No comment on the broaching operation, as I've never used a rotary broach, just straight ones for keyways, etc., but watching with much interest.
But - Happy Birthday, Danny ! :)
 
Dany, welcome to the Generation of Eighties Gang!
(well, that is at the same of the next year, but I want to be first to invite you in our nice company)
Ciao,
 
Savarin, ​
All the best for your birthday and for the good start in your new year of life! Lucky you, I still have to wait almost two years on such date, but I know that it would come too quickly when/if it come!
Ciao,​
 
Oh, and here's the current state of play.
2 made, 3 more part-made.
I have settled on 4 bolts between the 2 flanges, welding the fixed flange on first before boring out for the mini freewheel.
The hex-bar alignment jig works well and the hidden component in the end of the cassette carrier is my only unknown quantity.
It is a hard nylon spacer that sits on the incoming 13.8mm axle shaft and helps prevent pedalling forces pulling the cassette carrier out of its welded in alignment. As discussed with Paul, I may need to trial this by converting my Tadpole to a Quad.
image.png
 
Here we have 4 more 2WD units (pictures from both ends). Not actually found homes for them yet, but that can wait.
The two Mk1 Units are reserved for me and Paul. This second iteration is no less functional but uses thinner flange plates that were more off-the-shelf and with 4 bolts instead of 6.
I am going to make some nylon/Delrin inserts for the top-end (where the second set of bearings would normally be on a bike) to make sure the cassette carriers are properly supported when the driver is pedalling hard. It may not do too much, but every little helps I think.

IMG-20250212-141307-568.jpg

IMG-20250212-141325-173.jpg



Update 13-2-25 - Put the images back in again. Postimage had discarded them it seems.
 
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DannyC said:
Here we have 4 more 2WD units (pictures from both ends). Not actually found homes for them yet, but that can wait.
The two Mk1 Units are reserved for me and Paul. This second iteration is no less functional but uses thinner flange plates that were more off-the-shelf and with 4 bolts instead of 6.
I am going to make some nylon/Delrin inserts for the top-end (where the second set of bearings would normally be on a bike) to make sure the cassette carriers are properly supported when the driver is pedalling hard. It may not do too much, but every little helps I think.

IMG-20250212-141307-568.jpg

IMG-20250212-141325-173.jpg
Click to expand...
"Image not found" ?
 
Now almost finished with the 2WD unit project.
Here are the last 4 all painted and re-assembled.
It has been ok as a "bit of fun" and I learned some things along the way.
Longstaff units (now out of production) were c.£400. These cost me about £35 to make. :cool:
 
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