An Interesting discovery

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Bufferstop
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An Interesting discovery

Postby Bufferstop » Tue Nov 05, 2019 11:06 am

Well interesting to anyone who shares my mental processes.
I've been working away replacing the steel axles on my goods stock with brass ones. To prevent them snatching when passing over the uncoupling magnets. I have a few lengths of 2mm nominal brass rod from Eillen's. It checks out as 1.98 with my calipers which is exactly the same as the steel in Hornby and Bachmann wheelsets. The curious thing is the wheels are a tight fit on the blackened steel axles, but quite an easy fit on the brass. My first reaction was pulling them off the steel axles and pushing them onto the Brass had opened up the holes in the plastic bushes.
Not the case, as putting them back on the steel ones they were as tight as before, at least as judged by my fingers. Repeated checking with the calipers gave the same range of readings on both steel and brass. The only conclusion I can draw is that the friction between the blackened steel and the plastic bush is much greater than it is with the brass. Happy to report however that the old standby superglue locks them in place, but not that solidly that they can't be pulled off again. What set out as a problem has turned to an advantage, I now leave the setting of back to back until the wheelset is in place, and passed a few trial runs around the layout, then a tiny spot behind each wheel locks them in place.
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Bufferstop
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Re: An Interesting discovery

Postby Bufferstop » Tue Nov 05, 2019 11:20 am

Perhaps I should describe the process of producing the brass axles, to encourage those who have the means but not the confidence to try.
First measure the length of the steel axle over its pinpoints.
Cut a length of brass rod 1.5-2.0mm longer. Scratch a fine line around the centre of the cut piece.
Make a test gauge, just a piece of brass, steel or plastic, half the point to point dimension wide.
If you have a miniature drill and stand turn it so that its horizontal. Other wise clamp a power drill in a vise.
Put your rod in the chuck until your scratch mark is flush with the face of the chuck. set it turning at a medium speed.
Using a slitting disk in a minidrill grind the end of the rod at around 45%, keep grinding and checking until the point of the rod matches the check gauge when held against the chuck.
Reverse the rod and repeat.
Growing old, can't avoid it. Growing up, forget it!
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Mountain
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Re: An Interesting discovery

Postby Mountain » Tue Nov 05, 2019 12:48 pm

Bufferstop wrote:Well interesting to anyone who shares my mental processes.
I've been working away replacing the steel axles on my goods stock with brass ones. To prevent them snatching when passing over the uncoupling magnets. I have a few lengths of 2mm nominal brass rod from Eillen's. It checks out as 1.98 with my calipers which is exactly the same as the steel in Hornby and Bachmann wheelsets. The curious thing is the wheels are a tight fit on the blackened steel axles, but quite an easy fit on the brass. My first reaction was pulling them off the steel axles and pushing them onto the Brass had opened up the holes in the plastic bushes.
Not the case, as putting them back on the steel ones they were as tight as before, at least as judged by my fingers. Repeated checking with the calipers gave the same range of readings on both steel and brass. The only conclusion I can draw is that the friction between the blackened steel and the plastic bush is much greater than it is with the brass. Happy to report however that the old standby superglue locks them in place, but not that solidly that they can't be pulled off again. What set out as a problem has turned to an advantage, I now leave the setting of back to back until the wheelset is in place, and passed a few trial runs around the layout, then a tiny spot behind each wheel locks them in place.



Interesting. Don't count your axles until they're brass?

Dad-1
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Re: An Interesting discovery

Postby Dad-1 » Wed Nov 06, 2019 1:42 pm

Perhaps a good micrometer will show a slightly different reading ?
Certainly surface texture will add a grab factor, but I would have
expected less that you seem to have found.

Can I be bothered to replace my magnetic axles (& wheels) ? I shall
just continue to have brass wire axle brakes on my Kadee stock. They
did well at the two days at Weymouth last weekend.

Geoff T.
Remember ... I know nothing about railways.
viewtopic.php?f=22&t=32187 and Another on viewtopic.php?f=22&t=28436&start=60&st=0&sk=t&sd=a

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Bufferstop
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Re: An Interesting discovery

Postby Bufferstop » Wed Nov 06, 2019 3:30 pm

The problem with good micrometers is that they tend not to be £10 digital ones, that means reading from some fine engravings on the barrel. which even my "arm and a leg retina mapped super lenses" struggle to resolve. That's the trouble with digital anything, there has to be an arbitrary cut off to the accuracy.
Growing old, can't avoid it. Growing up, forget it!
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Mountain
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Re: An Interesting discovery

Postby Mountain » Wed Nov 06, 2019 3:43 pm

I gave my micrometer away... But these days I would have to go for a didgital one because I could not see the markings on the other types.

I have been waiting patiently for a few years to find a didgital one at a reasonable price at the time when I have the cash to spend. Getting all three together... Hasn't happened yet! Haha! Should do soon rhough.... Hopefully! :)

Byegad
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Re: An Interesting discovery

Postby Byegad » Thu Nov 07, 2019 10:33 am

Brass was used in bearings for a good reason.

mahoganydog
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Re: An Interesting discovery

Postby mahoganydog » Thu Nov 07, 2019 4:15 pm

My advice is get yourself a digital Vernier and not a micrometer which can have reliability issues.

When I was making parts for a project I was chasing 5 microns accuracy; that's 0.05mm for interference fit parts or close. Anything more than this was too tight. I suspect your measuring device is rounding up meaning the brass is fractionally undersize.

Jim
In a world of fences and doors who needs windows and gates?

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Bufferstop
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Re: An Interesting discovery

Postby Bufferstop » Thu Nov 07, 2019 5:18 pm

Could well be, I knew from the outset that by calipers would get abused, so £10 from Aldi was a sensible price. If my dad was still here he'd be amazed by a digital caliper, especially for a tenner and he would probably have insisted that they were as good as the blokes on the line deserved, "what's the point of giving them any better the way they are going to get treated." I walked the line with him one evening shift and this guy was muttering that the journals on a crankshaft were all over the place, Dad took a sheet of paper towel and wiped the journals carefully, lowered the clock gauges into place three main journals dead centre on the range, "what's the matter with that then?" The gauges were able to measure the thickness of the traces of oil on the surface. the solution, cheaper gauges that apply more pressure.
Growing old, can't avoid it. Growing up, forget it!
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Dad-1
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Location: Dorset - A mile from West Bay.

Re: An Interesting discovery

Postby Dad-1 » Fri Nov 08, 2019 11:18 am

I gave my micrometer away to my middle son who is an engineer and works for Land Rover.
I use a good quality Digital Vernier, a freeby from when I was made redundant and although
it meets my usual plastic modelling standards I am aware that measuring at the tip of jaws
will not give the ultimate in accuracy.

Geoff T.
Remember ... I know nothing about railways.
viewtopic.php?f=22&t=32187 and Another on viewtopic.php?f=22&t=28436&start=60&st=0&sk=t&sd=a


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