NDT of thin wall tubing

Yep, but isn't over a fairly short distance, say 1/4 inch? You should be able to feel that?

Here you go, I'm sure you could feel the change if this picture is realistic. Right click to see image full size:

Neil if you went to spec savers you would see that it says 2" taper above both tapered sections

Hard to feel 6" down a seat tube with an old coat hanger

You need to remember my uncle was a frame builder and also built the bike I designed for myself

Edited By JasonB on 11/07/2017 19:45:22

And Neil, you are going off at a bit of a tangent regarding double butted tubing.

Both Columbus and Accles & Pollock (to name just two of the better known tube producers) made double butted frame tubing in period, so whether or not it is double butted doesn't answer the question of whether or not it is Reynolds 531.

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

I wonder how they made it?

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

**LINK**

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!

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

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?

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.

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!

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.

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!

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

**LINK**

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.

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

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

Tim?

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

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

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