Cold Bluing Parts

To continue on from the earlier discussion about making the parts in Stainless Steel......

A 1-Metre length of 304 (Work Hardening) Stainless arrived today so I cut a short slug off it to see how well/badly I could machine it.
It wasn't too bad. Facing up was easy with carbide tooling (clue).
What you see below is the slug of 304SS with a 12mm "rifle-bore" hole drilled through it and a 12mm piece of Silver steel inserted through the hole.

What did I learn?
My chuck key for the big-boys lathe is AWOL so I had to use the M2 taper chuck and key from the Chinesium lathe in the Boxford.

Even when starting with a centre drill to create a pilot starting point a 4mm HSS drill-bit doesn't like it. It just did not want to know, it was shrieking and un-twisting the flutes.
I swapped to a 5mm solid carbide bit and it went through the 304 stainless like it was just butter. So "Carbide FTW".
I then went back to quality HSS bits and stepped up in successive sizes 6, 8, 10, 12mm using lots of lube (she likes it like that) lots of smelly smoke but no snags and no problems.
Without too much hassle we have a snug 12mm hole. :cool:

Perhaps I should invest in a few solid carbide, carbide tipped or cobalt bits for the longer versions for the SA hubs.

IMG-20240530-155301-620.jpg



IMG-20240530-155324-186.jpg
 
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As above, flushed with the success of machining the stainless steel I bought some more carbide tipped drill-bits for metal.
3mm, 6mm & 8mm all for <£20. They should make the boring operation a lot easier.
The parts are only 68mm long end to end it doesn't need exceptionally long drill-bits so they are affordable.
 
Any excuse to get the lathe powered up ;)

Does not take away from how excellent a job you have made of the bits.

...and as they say every day is a school day ?

however for me it just means sitting in the corner wearing the dunces hat :)

Paul
 
stormbird said:
Any excuse to get the lathe powered up ;)

Does not take away from how excellent a job you have made of the bits.

...and as they say every day is a school day ?

however for me it just means sitting in the corner wearing the dunces hat :)

Paul
Click to expand...
There is more truth to "any excuse" than I really care to admit to. :)
Thanks for the compliment on how the previous mild-steel bits turned out.
Let's hope I can do the same in Stainless.
I might depart from the standard length (as per Sturmey Archer) because I typically bolt these things up through 10mm tabs, so 68mm is overkill.
The only reason to do them at 68mm is if you intend to use the official £45 ea. SA QR axles.
If you are only going to use 12.9 hardness M12 bolts then you have to bear in mind the lengths those bolts come in.
I think you would make these axle-tubes of a specific length to ensure they accommodate the total end-to end span of the axle-tube, back-plate, hub-internals and that the threaded portion starts only just before the bolt exits the outer bearing.

These bolts are available from 55mm to 200mm in 10mm steps.
Note*
M12

Thread size: M12 x 1.75mm pitch.

Thread diameter: 12mm.

Spanner size: 19mm.

Head height: 7.5mm.

Bolts up to 125mm long have 30mm of thread*.

Bolts over 125mm long have 36mm of thread*.
 
I had a bash at the stainless steel for the SA hub parts yesterday. Not good. :(

The 3 new “Carbide tipped” drills (<£20) didn’t last 5 minutes (clue must be in the price somewhere). :(

The 5mm one just snapped immediately below the “tip” leaving the tip deeply embedded in the workpiece about an inch in and so that piece became scrap.

The existing solid carbide 5mm bit of mine still cut through the steel of the next piece like butter, but isn’t long enough to go right through end to end.

So I did a hole from either end with that and then tried to bully the new 8mm “Carbide tipped” through, but it just failed and the “tips” shattered. I reverted to HSS bits and tried the 6mm HSS drill through the middle. But the HSS went blunt so I stepped it up to 6.5mm and managed to get through it with that.
Then, I stepped up to 8mm HSS, but that went blunt part-way. Stepped up to 8.5 HSS and that went all the way through. Then 10mm HSS, then 12mm HSS. Success and a silver steel rod slips through there no problem. 😊

All this effort for one axle tube. 😊 But these are parts you cannot just buy without buying a whole new backplate too!
So do I invest in longer solid carbide drill-bits 5, 6,8, 10 for this? (Goodness, the real McCoy ain't cheap).

Today I took my piece of Stainless Steel and machined it down from 20mm Dia to "Smaller than the diameter I actually wanted" :mad:

Dagnabbit, I wanted 16mm OD and I have 15.72mm. "Curse you Imperial lathe scales!" Ha-Ha!

However, the missing <0.3mm is a whopping 14 thousandths of an inch so I doubt that it will really spoil things. :)

I had a play with the auto feed rate on the lathe and it appears that "the slower you go the finer the finish".
At 0.0015" longitudinal feed per revolution of the workpiece the finish is pretty fine to the touch.

Maybe some thread cutting tomorrow? I will need to put the perversion/conversion gears in the drivetrain for that. :)

Happy Days.

IMG-20240604-144809-685.jpg
 
Ok sports fans, a part in Stainless Steel has been produced.

"About ruddy time too!" they all shouted.

I have to admit that it has been a very, very trying process.

3 SS blanks got ruined/destroyed/borked, tools got broken, tears were shed and the workshop swear-jar is full to overflowing.

But, at long last we have a single part (they usually go around in 2's so at least one more must be made).
Here it is, the part at the top is the SA original, below is the "Clarke Industries" copy.
Mine is longer only because I could and it can be trimmed to length to match either the £43 SA QR axles or your own prefered bolt-length as required.

I will make its partner because that is the right thing to do, but I shall probably take @savarin 's advice and make them in mild steel and nickel plate them from now on.

Why? Well because Stainless I have found to be a lot harder to work with by comparison.

But YES, we can do it if required. :)

image.png


Update:
Just made the next blank ready for threading. :)
 
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Well done that man , search Ebay for you ...

had intended buy you some more perseverance as I assumed you had used all yours ? however there was non listed.

Paul
 
savarin said:
what lathe do you have?
Those parts I nickel plated still show no signs of deterioration.
Click to expand...
I have 2 lathes. A little Chinesium 8 x 14 benchtop thing that lacks rigidity and a nice 62 YO Boxford AUD Imperial lathe with quick change gearbox that is on a cabinet and weighs >600 Lbs.

I made these parts successfully in mild steel on the Chinese lathe last year but as they are prone to rust I thought I would try stainless on the newly acquired Boxford I bought myself last Xmas. :)
 
stormbird said:
Well done that man , search Ebay for you ...

had intended buy you some more perseverance as I assumed you had used all yours ? however there was non listed.

Paul
Click to expand...
I managed to scrape some out of the bottom of the barrel and I have made the blank I will thread it tomorrow and then drill it through.
That's enough. All the other bits are much easier to make from standard metric nuts. :)
 
I do a lot of stainless on my flexi 9x20.
When I was parting off you could visibly watch the top slide flex, parting stainless was virtually impossible and mild steel was very difficult..
I removed the top slide / compound and replaced it with a solid plinth.
Now parting any metal is a breeze.
This is 16mm stainless parted off just look at those long ribbons of swarf from a HSS "T" section parting blade.
448025637_979927670501918_574311359070728983_n.jpg

When turning a 0.5mm depth of cut is no problem.
When threading I have to go in at 90' but thats also never been a problem even M4x39 threads for a chuck backplate.
I've put this in here just in case anyone else has problems with cheap lathes.
I envy you your Boxford.
Another tip in case youve never seen it.
This gives an awesome finish on stainless, mild steel and even brass, its well worth it
Grinding the bit is simplicity itself with plenty of leeway regarding angles.
The swarf from it comes off like ultra fine steel wool.
 
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OK sports fans, here's how we roll today.

First part took 4 attempts and many days to get a successful part.
The second one has taken < 1 day because of errr.... Learnings.
image.png

That's all I am going to make for now. :)
A second carbide bit "died" in the process. :( Luckily it was the cheaper 5mm one that is ages old.
The worst part about making these is the 12mm through-bore, it is real "squeaky-bum" time.

But there we go, all finished.
 
savarin said:
I do a lot of stainless on my flexi 9x20.
When I was parting off you could visibly watch the top slide flex, parting stainless was virtually impossible and mild steel was very difficult..
I removed the top slide / compound and replaced it with a solid plinth.
Now parting any metal is a breeze.
This is 16mm stainless parted off just look at those long ribbons of swarf from a HSS "T" section parting blade.
448025637_979927670501918_574311359070728983_n.jpg

When turning a 0.5mm depth of cut is no problem.
When threading I have to go in at 90' but thats also never been a problem even M4x39 threads for a chuck backplate.
I've put this in here just in case anyone else has problems with cheap lathes.
I envy you your Boxford.
Another tip in case youve never seen it.
This gives an awesome finish on stainless, mild steel and even brass, its well worth it
Grinding the bit is simplicity itself with plenty of leeway regarding angles.
The swarf from it comes off like ultra fine steel wool.
Click to expand...
Hi Savarin, Rigidity is certainly a big problem on the Chinese 8x14 mini-lathe, not so much on the Boxford because of its sturdier construction.
Finish on the Boxford can be pretty good too as the Norton Gearbox provides a feed down at 0.0015" along the bed and 1/3rd of that across a face. Yes, I had seen that gadgetbuilder article and people rate the finish really highly. :)
 
Slight update on those parts (as above).
I looked at my stock of SA drum hubs and decided that the best use of these parts will be on the 70mm "Trailer Hubs" that I bought on e-bay.
They came without any internal elements (the spacers) so I bought SA originals to allow the "standard deployment".
These are the only non-standard SA style hubs I have and all the others are already equipped for QR axles.
So I went to make the parts that would convert these to QR axle capable. What I discovered was that the internal spacing is different from all the other hubs and the QR axle tubes. I have made a slight modification to these parts which will make them only suitable for these hubs.
C'est-la-vie!
We can always make more should the need arise.
 
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Dan

Sounds like just the sort of luck I have been having lately.

I think the problem lies in how long things have been going swimmingly in our lives makes us unprepared for when stuff is just a BITCH :((n)

Paul
 
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