NDT of thin wall tubing

[Neil WyattModerator @neilwyatt]

Ah well – I have only ever seen diagrams like the one I posted.

I wonder how they made it?

[David Standing 1Participant @davidstanding1]

Here y'go Neil, from the gee gee's gob

**LINK**

[Henry BuckeldeeParticipant @henrybuckeldee88769]

I will post a few photos. Yes the sticker is listed on the Lloyd website. Will find ref no.

Just to clarify Reynolds 531 tubing is available in plain gauge as well as butted. But these both tend to be a thinner gauge than plain gauge HM or A grade.

The seat tube would have been been single butted at the bottom bracket end, if it was butted tube, so thicker there.

I can see I am going to have to make up some sort of long caliper, as described (thank you), to reach down to the bottom bracket from inside the tube!

[David Standing 1Participant @davidstanding1]

I'm still not understanding how proving it is double butted proves it is Reynolds 531, as per the first post?

[Henry BuckeldeeParticipant @henrybuckeldee88769]

The Lloyd's ref no for the transfer is 531G38-53.

Not sure if I saw a post saying the seat post should be double butted, or was it deleted. Anyway according to the Reynolds catalogues the seat post is single butted in a butted frame. I am no expert, just what I read.

I have a few photos of the bicycle with incorrect wheels. Will post but not sure where or how. So if someone can help be pleased.

Getting too late now, so perhaps tomorrow.

Thank you all for your response. Not sure if got a answer to my question yet, other than make up a long caliper.

It's good to know there are cyclists on this website. Especially the Grubb collector. Does anyone have a Russ?

[Henry BuckeldeeParticipant @henrybuckeldee88769]

You are correct David. I was just trying to see if it was Reynolds 531 which can be plain or butted. The transfer says butted. But that may not be correct. I thought an ultrasonic test may show butting but that is inconclusive. Reynolds 531 plain gauge should be thinner than HM or A quality, but cannot prove that either.

[David Standing 1Participant @davidstanding1]

In a double butted frame, the seat tube would be butted at the BB joint, parallel at the top end to allow a seat post to be fitted.

The top and down tubes would be double butted (i.e. at both ends).

I've lost track of what frames or bikes are lurking in my garage and sheds – apart from the four Grubbs, there are two Mercians (one is 1949, my oldest), an Ephgrave, a curly Hetchins, a Parkes, a Pat Rohan, a Bianchi, a Ribble, and an F H Scott.

And that's just the steel framed ones!

[Henry BuckeldeeParticipant @henrybuckeldee88769]

Referring to old Grubb catalogues of the period, I have only ever seen reference to Reynolds HM & 531, and A&P. If you say A&P did butted tube, then need to double check Grubbs catalogues.

[David Standing 1Participant @davidstanding1]

Posted by Henry Buckeldee on 11/07/2017 21:38:42:

You are correct David. I was just trying to see if it was Reynolds 531 which can be plain or butted. The transfer says butted. But that may not be correct. I thought an ultrasonic test may show butting but that is inconclusive. Reynolds 531 plain gauge should be thinner than HM or A quality, but cannot prove that either.

It's always a potential minefield with old frames, there are many frames now carrying stickers they never left the frame builder with, so it is good you are trying to authenticate what yours should have.

Mercian will not supply period stickers (and they have an agreement with H Lloyd that he will not supply either) unless you provide them with photographs of the frame, BB and serial number – good for them. There are probably twice as many Mercians around than there were when they were originally built!

[David Standing 1Participant @davidstanding1]

Posted by Henry Buckeldee on 11/07/2017 21:48:45:

Referring to old Grubb catalogues of the period, I have only ever seen reference to Reynolds HM & 531, and A&P. If you say A&P did butted tube, then need to double check Grubbs catalogues.

A&P definitely supplied butted tubing in that period, scroll down the ads on the right side of the link below:

**LINK**

[egaParticipant @ega]

I have put some photos of a friend's Grubb in my album in case anyone is interested; it seems from the seat tube transfer to have plain gauge 531.

My own classic road bike is a Tommy Godwin which has been refinished with TG transfers but no tube ID.

[Tim StevensParticipant @timstevens64731]

I think double butted tube was made thus:

Start with a tube made by rolling steel between angled conical dies over a cylindrical mandrel a bit larger that the desired max internal diameter. Vary the radius at which the angled dies are set to vary the OD of the tube, so you produce a tube with a fixed internal diameter but thicker at both ends. Then draw this tube through a round die of the final OD you need. In stages, of course. And with the steel hot.

Unless, of course, you know different … ?

Tim

[Tim StevensParticipant @timstevens64731]

There is a maker's or inventor's name which escapes me for the process of rolling tube with angled dies – Mannesman, perhaps ?

Tim?

[David Standing 1Participant @davidstanding1]

Posted by Tim Stevens on 11/07/2017 22:27:15:

I think double butted tube was made thus:

Start with a tube made by rolling steel between angled conical dies over a cylindrical mandrel a bit larger that the desired max internal diameter. Vary the radius at which the angled dies are set to vary the OD of the tube, so you produce a tube with a fixed internal diameter but thicker at both ends. Then draw this tube through a round die of the final OD you need. In stages, of course. And with the steel hot.

Unless, of course, you know different … ?

Tim

I linked the process in Reynolds's words in my post of 20:02 this evening, above

[David Standing 1Participant @davidstanding1]

Posted by Tim Stevens on 11/07/2017 22:28:48:

There is a maker's or inventor's name which escapes me for the process of rolling tube with angled dies – Mannesman, perhaps ?

Tim?

Yep, the Mannesmann process, named after its inventors, the Mannesmann brothers.

[TrickyParticipant @tricky]

I find it interesting to see the enthusiasm for F H Grubb cycles as Freddie Grubb was my wife's great uncle on her mother's side although I don't think he was as good a businessman as he was a cyclist!

Richard

[David Standing 1Participant @davidstanding1]

Posted by Tricky on 12/07/2017 08:19:03:

I find it interesting to see the enthusiasm for F H Grubb cycles as Freddie Grubb was my wife's great uncle on her mother's side although I don't think he was as good a businessman as he was a cyclist!

Richard

That's interesting!

And things were different in the bike business then – no internet, a totally different way of advertising, and every bike shop had a frame builder, all of whose products were allegedly better than each other!

[Neil WyattModerator @neilwyatt]

Simple summary, squeeze the tube onto a shaped mandrel. then roll it to a large enough diameter to slip off, then through a die to size the outside accurately.

Sounds easy enough

Neil

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