Nothing to lose really.

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Hi Danny. Sublime to ridiculous example of 'precision lathework' I thought you'd like to see.

I bought a massive Southbend lathe on ebay a few years ago because it was cheap and the seller offered to deliver. I didn't really know what I was buying except it had a long bed (think it is 5ft) which I thought would be handy for the sort of stuff I was playing with at the time. Good as his word he arrived with a trailer and a kit-form lathe on the agreed day and three of us dragged the bits into my workshop where we assembled it again. I was a bit taken aback when I realised just how enormous it was but also pretty pleased.

Well this old thing had been worked to death pretty much and bodged mercilessly to keep it going. The tool post is a homemade thing with half a dozen tool holders made from heavy angle iron but which actually do work pretty well. The motor is a single phase unit which is way underpowered for the machine and it needs a shove to get the chuck turning but it does the job just about. The flat belt has stretched (worn out) to the point that it slips badly on the slowest speed step and the motor lacks the power to drive at the third step onwards so really only one speed is useable. The plain bush bearing on the chuck shaft has a fair bit of slop in it but if I try to shim it out the motor won't turn!

If you add to all this that my only machining experience was at school with one period a week for six weeks 55 years ago you can understand that the deficiencies of the lathe pale into insignificance compared to the deficiencies of the user.

Anyway over the last few days I've been doing battle with some steel to make half-shafts for the cast ally mobike wheels I bought off ebay. I cut and ground some 1/4 flat to jagged oversized disks then drilled a suitable hole in the centres and welded these to the axles. I then mounted in the lathe and slowly turned the OD till they were a good fit in the cast centre of the wheels. I then took a skim off the faces to true them and marked and drilled the five holes for mounting bolts. Nobody could have been more surprised than me but they mounted and spin as true as I could have dared hope. Joan didn't seem to be quite as excited as I was but then she's a woman?

Sadly the shafts were too big for the plummer bearings and it took most of today to mount them and skim down to fit but even these seem pretty damned good considering the combined lack of precision of the lathe and me.

Anyway I enclose pics of the shafts first trial fitted to the wheels. Clearly our methodology and expectations are very different but I'm as pleased as you are at the results I've managed to achieve. These will be the rear wheels of my next delta which will be started in earnest once Joan runs out of good ideas for me to do for her.

All the best

John



Nicely done John. I bet your Southbend is more rigid than my nasty little Chinese lump. :)
Its an addictive pastime turning stuff from raw stock to usable part and I quite enjoy it.
I keep looking at larger, better lathes but I don't have the £2k+ in spare change down the back of the sofa.
 
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Nothing to report except "thread galling" on the SS bolts/nuts on the 2WD unit.
I was trying to take it apart to clean it up and paint the parts.
Really awful binding issues as the bolts did not want to come undone.
I might just junk these 2 freewheels and get 2 more and do it with smaller bolts (M5) because I already suspect there will be chain interference issues with this M6 bolt-cage.
A 1/8th x 1/2" chain is expected to arrive soon so I can check if the bolts will be interfering and I will go from there.
It is all good fun anyway.
 
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Nothing to report except "thread galling" on the SS bolts/nuts on the 2WD unit.
I was trying to take it apart to clean it up and paint the parts.
Really awful binding issues as the bolts did not want to come undone.
Google claims that is most common on SS nuts/bolts ? so just throw them and go for steel [ like everyone else ! ] you know it makes sense ?

I might just junk these 2 freewheels and get 2 more and do it with smaller bolts (M5) because I already suspect there will be chain interference issues with this M6 bolt-cage.
A 1/8th x 1/2" chain is expected to arrive soon so I can check if the bolts will be interfering and I will go from there.
It is all good fun anyway.
You mean the FW's that cost an arm and a leg ?
Paul
 
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I've used a lot of stainless bolts and had galling on only a couple. It's a very infrequent issue but a bugger when it happens. I had to forcibly snap the two bolts it happened to. Fortunately they were small enough to force to break.
 
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Google claims that is most common on SS nuts/bolts ? so just throw them and go for steel [ like everyone else ! ] you know it makes sense ?


You mean the FW's that cost an arm and a leg ?
Paul
They are about £15 ea. And I already have one spare. Or, I can put my penny-pinching hat on and just re-drill the 2 I have in different places to save myself £15. :)
 
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I've used a lot of stainless bolts and had galling on only a couple. It's a very infrequent issue but a bugger when it happens. I had to forcibly snap the two bolts it happened to. Fortunately they were small enough to force to break.
I think the mistake that I made was not oiling/greasing the threads first. Galling is a known issue on Stainless threads and I should/could have avoided it. My fault.
 
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I think the mistake that I made was not oiling/greasing the threads first. Galling is a known issue on Stainless threads and I should/could have avoided it. My fault.
Not important in this case however does the oil/grease not alter any torque values when the bolts are bigger ?
Paul
 
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Not important in this case however does the oil/grease not alter any torque values when the bolts are bigger ?
I don't think so, the slightest amount of lubricant prevents the galling which is where the frictional forces of the mating SS surfaces effectively "weld" them to one-another.

Anyway........
As luck would have it the Super BIG old fashioned 1/2" x 1/8" chain arrived and "wonder of wonders" the chain can fully embed on the sprocket without fouling on the bolt-heads or nuts. :)


Now that's lucky. Perhaps I can start taking orders for 2WD units once I have proven it works as designed. Ha! Ha!

Next question/decision is whether to mill some "flats" onto the axle shafts and use M6 bolts and a locknut to effectively lock the shaft to the 2WD unit screw-in adapter rather than using grub-screws?

This is what it looks like with a 12mm round bar shoved through it ("They don't like it up them Captain Mainwaring" )


The overall width of the entire 2WD unit has come out at 100mm (4"), the distance between the input & output sprockets of the 8Spd is 90mm so the 2WD unit will only need to be minimally offset on the rear axle assembly to place the sprockets in line with one another, which is better than I had expected. Progress? Maybe. :)
 
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Next question/decision is whether to mill some "flats" onto the axle shafts and use M6 bolts and a locknut to effectively lock the shaft to the 2WD unit screw-in adapter rather than using grub-screws?
yes I wonder what was the best engineering solution ?
I assume 2 grub screws/bolts ?
90' apart ? or a different angle ?
small drilled hole for grub screw ?
grub screw end flat ?

Above allows some freedom in placement on shaft

M6 all the way through ?
Roll pin
You have to know what you are doing [ or intend to do ] to drill all the way through [ especially when some one ' cough ' ' cough ' [ not me ! ] ] has spent a small fortune on the shaft/rod :)

or A N other ?

Paul
 
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Grubscrews for schaft "clamping". Industrial standard is 2 at 120° (of 90°)

And for torque applications, a keyway please.
Not fancying cutting a Keyway TBH, I can do it on the shafts with my mill, but inside the adapters in the 2WD unit would be a real challenge.
I will have a think on it. :)
 
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Lucky me, I have a 6mm broach for "keyway-ing" 20mm bushings.
Well, I can sharpen up a bit of tool steel, find a way to lock the lathe spindle and use the carriage & cross slide to cut a key way I suppose. But 6mm is a bit large for a key isn't it? :)
A shaft 10 - 12mm is probably a 4mm key size.
 
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Messed about with some tubes today to see what the back-end tube arrangement will look like.
I am not too-sure the pieces at 45° will clear the chain that runs between the output from the IGH and the input to the 2WD unit.
I think I will stick with this arrangement and then mount the IGH on a frame under the diagonal tubes.
I think it will be OK and this triangular shape will provide a good platform for mounting things.

I had to stop because I am having a "painful" day today, and I don't know why. :(

 
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Dan

Certainly looks substantial and the picture has caused a pang of ' magnet envy ' ;)

Paul
 
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Today was a day of frustration and harsh-language. :mad:

I need to attach the axle-unit to the frame of the trike before I can cut out the central section of the to outer axle-tube(s) in order to insert the 2WD unit.
Heavy, unwieldy and awkward (and that's just me!). Tack welded the two diagonal pieces that will attach to the main keel/spine.
I did get them on but it was a struggle holding everything in alignment for the tacks. I hope to get the keel inserted and tacked tomorrow. :)







 
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