[meddlesomebilly]

Hi Winold,
If you can find a non-destructive testing company such as those servicing the oil, gas and power industries they will be able to ascertain tube wall thicknesses very quickly by ultrasonic means, the only preparation required being paint removal over a very small area.
Regards, Tony.

[Rick Parkington]

Good work, Winold!
Bear in mind where the tube bends, it stretches on the outside so it may come out thinner there, maybe that's why you got 1.4mm there not 1.6mm like the tank tube. I would be surprised if the tubes are swaged at the ends ie get thicker where they enter the lug (unless of course the tube has corroded). That would be an expensive process meaning the tubes had to be made in sections to suit the frame rather than cut off full lengths. I think CD2 is the grade most people use for frame tube here, if that means anything in NL.
Interesting to hear about Reynolds history!
Cheers Rick 

[Winold]

Hi Rick,

Thanks again for your useful tips! The sand filled bending looks very interesting. I will use some bits of pipe to practice and see how the material behaves. The measuring tip is a clever one but unfortunately it doesn't work on my frame. There is a hole in some places in the lugs but they are way smaller than the inner diameter of the tubes. I decided to drill a small hole in each frame tube in a spot that you don't really notice. I brushed the paint off around the hole and measured the depth with a caliper and calculate the wall thickness. I tried to measure as accurate as possible and this is what I've found;

Front down tube 1-1/8" OD, wall thickness 3,2mm  measured by drilling a hole at the top of the tube
Seat down tube 1-1/8" OD, wall thickness 2,7mm  measured at the bottom of the frame, at the top 1" ID to allow for the seat stem to 7" deep, there it tapers to about 23,2mm ID
Above petrol tank tube 1-1/8" OD, wall thickness 1,4mm  measured by drilling a hole at the bend near the seat
Under petrol tank tube 1-1/8" OD, wall thickness 1,6mm  measured by drilling a hole in the middle of the tube (will drill another hole near the lug to see if the wall is thicker there)

I found a dutch supplier for seamless S235 steel 1-1/8" tubes with wall thickness 1,5mm and 3,2mm, although I haven't contacted them yet to ask if I can buy only a small quantity. And I'm also still looking for other suppliers. Reynolds is still in tubing business from Birmingham (quote from their site; the Patent Butted Tubing Co. was set up on December 20, 1898) and making special stuff, also used by motorcycle and car builders.

I've found two bicycle frames with 1-1/8", 1" and ½" tubing. Wall thickness of the 1-1/8" is 1,4mm so could be used but it is way too short. I will keep the frame tubes, it might be useful later to have some imperial size tubes in the workshop.

More later, cheers Winold

[Rick Parkington]

Hi again Winold,
The thicker the gauge of tube the less likely it is to flatten on the bend - or show signs of the start and finish - but sand filling is the best way to avoid it completely - exhausts were certainly often done that way back then.
I had a bit of an idea, you may be able to measure the ID of the tube from the headstock - difficult to get in with calipers etc but maybe you can poke something inside to get an idea - a bit of tube (like a ring) on the end of your finger for example. Find a bit that goes in the hole, then cut it to open the circle and stratch ut until it is a good fit, then measuring across the widest part will give you a rough idea.
I measured the Bradbury vee twin frame I need to repair, not the top tube because it has been replaced with gas pipe already but I was able to get calipers into the saddle tube - which us 1 1/8" (1,125"). The inside diameter was about 0.912", suggesting a tube wall thickness of 0.1065". The nearest tube size to this is 12 gauge (0.104") so that gives a bit of an idea. BUT whether a saddle tube and top tube would be the same gauge I don't know; as I said before top tubs were sometimes reinforced - out of interest Blackburne used two light D section tubes back to back inside a steel skin, an aircraft method apparently. Also the Bradbury frame is incredibly heavy and I suspect Sunbeam would have used a lighter tube but if you can get in to measure your tube you may be able to work it out. I should add that tubing thickness is (or was then) sold in Standard Wire Gauge thicknesses. Finally, I don't think Reynolds were around in the 1920s (could be wrong) but there other companies were more well known then, particularly Accles and Pollock.
Good luck with it mate, I'm off back to the shed and my own bit of the Deep End!!
R 

[Winold]

Hello Rick and John,

Nice to hear from you, thanks for your replies, that's very helpful. I am very aware that this is a specialist job in multiple ways. But before I ask someone else to do it I'd like to investigate it thoroughly myself. At least to determine how 'specialist' someone really is. And the more I learn myself the more 'specialist' I become... To see who the real specialist is or maybe eventually do it myself. Although my Beam is a bitsa it is worth a lot to me. It will not be a show bike, I want to ride it and feel safe on it. And, for a good deal, my safety feel comes from knowing the bike I'm riding is engineered properly.

The 1-1/8" CDS tubing I've found at some bicycle frame builders in various materials and wall thicknesses. I'll have to cut the tubes of the Beam to know the correct wall thickness if it is not known. Reynolds has been a tube producer since 1895 and was and maybe still is located in Birmingham. Did Sunbeam make their own or got it at the neighbours? They have been top of the bill tube makers for racing bicycles. Somehow they still use a lot of imperial sizes in bicycles. Also the cycle thread BSC or CEI is still used a lot in modern bicycles. Just to do some investigation it came to mind that I could easily pick up a scrap old bicycle from the street (I live in a city in the Netherlands). I might get lucky on the tubes, 1-1/8" seems to be quite common as a seat and front tube, otherwise it's good fun anyway. If not I'll contact one of the racing bicycle frame builders I've found, he seems to know a lot about it. He might even be able to do my Beam or know someone.

I'm still curious on the shape of the bend and how they made the bend in the top tube. My experience with an imperial pipe bender is that you can always see the start and end of the bend because of the clear difference in cross section. Also it flattens pretty much in the bend and I think Sunbeam would have done a nicer job. As the bend in my frame is ruined I can't tell how it should look like.

More later, thanks again! Cheers, Winold

[Rick Parkington]

Hi John, yes it's a problem- trouble is you get people who are good at welding fabrication but may have on understanding of the way the bikes were made. The worst story I heard was when someone discovered the remans of what turned out to be a well known Brooklands Chater Lea of the early 20s and took it to 'a mate who's a good welder' to get the frame repaired. The mate ruined it.
Sleeving tubes is a little tricky because again it's hard to get the sleeve hot - I've seen repaired frames/forks where a strange noise turns out to be the sleeve rattling free, up and down inside tubes held together by just a butt joint!
As practice for the frame repair I mentioned before, last week I was busy trying to address another appallingly badly done top tube replacement. Regrettably I have to confess this one was my own work over twenty years ago. The frame had been pretty much scrap anyway, an expert wouldn't touch it so I had a go myself, I managed to get it together and straight but I don't know how strong it will be and it looked awful. I've tried to reinforce it and tidy it up - but whether it will support my weight still remans to be seen - fortunately it's a single speed belt driver, so if it goes wrong at least it won't be in the fast lane of the M25...
That too had a rotten patch on the top tube and knowing what I know now I think I would have let in a piece of tube (like a Roman's shield - only the top was rotted) because I rebuilt a Morris pick up chassis by cutting it out section by section, sides and bottom and welding in flat plates as I went - so at all times two thirds of the chassis was still attached and keeping things aligned but it ended up a series of plates welded together. A decade on that's still going strong and carrying loads so although unorthodox it seems okay. On a bike frame, I suspect the stress on the middle of the tube is much less - or at least dissipated - than at it's end joints - the headstock particularly.
However it's done I would always advise keeping a close eye out for cracks - it's unlikely for two tubes to snap like carrots simultaneously without visible cracks forming first. My old belt driver will be getting a thin wipe of paint so  I can keep an eye on it - I wouldn't want thick powder coat/filler on a repaired frame unless I was completely confident of its strength.
Cheers Rick 

[singleminded]

Well explained rick. A friend of mine took his Vincent rear frame to a welding company to get a rear frame lug fitted..they could not get the old one off because of the braze not 'letting go'..they did exactly what you said and fitted and internal tube to get it back together..I found that when i retubed a Sunbeam rear stand that the pins would have held the whole thing together forever with just the pins used to jig it together..Locating the pins to drill them out can be challenging..John

[Rick Parkington]

Hi Winold,
This is a bit of a specialist job as I'm sure you realise and in consequence it is often done very badly - I have a frame to try and sort here for a vintage vee twin, the top tube has been replaced with (I suspect) old gas pipe and because it was done without a jig (or a brain) the engine now doesn't fit - as the owner discovered after having it beautifully painted!
I will be getting some help with it because it is outside the scope of my ability or my machines - but here's what I understand about the job.
The tubing would be CDS - cold drawn seamless, not sure what gauge but I think it was considered in the day that the top tube was under more stress than the rest (possibly because it is not straight) so often it was a reinforced tube. Hopefully you can get an idea from the old one but on the other hand the bikes were made for harder roads and harder use than they get now.
CDS may be difficult to get in Imperial sizes but should be possible - I need to look into this further for my repair.  One important thing, when a top tube needs replaced you usually have to cut the tank rail too so you can separate the head lug from the saddle lug and insert the new top tube.
To remove the old tubes from the lugs it is supposed to be a very bad idea to try and 'un-braze' them - the amount of heat required can apparently cause the brass to alloy with the material of the lug rendering it brittle and useless. Instead you should saw off the tube and bore out the remains from the lug. AS you say the tubes were pinned (holes drilled through tube and lug with a nail or similar banged in) to keep them in place during hearth brazing and these pins would keep it from separating even if the brazing was to melt.   
The bend was probably done with an Imperial pipe bender, if the gauge of the tube is fairly heavy you should get away with it - the tube should never be ovalled or flattened on the bend, that's a sure sign of bad work. In the absence of a pipe bender, you can fill with dry sand, heat it and bend it by eye - you need to pack the sand down very firmly (hammer and drift) and firmly plug the ends - often they are welded - the sand needs to be really dry to prevent steam explosion. Takes a lot of heat to do it in my experience, maybe because you are heating the sand too.
As you say, lugged frames were hearth brazed. I understand the joints were fluxed and pre-filled with 'spelter' (braze flakes) so that in the fire the braze melted and flowed around inside the joint. The problem nowadays is that people fill the joint from the outside using an oxy-acetylene torch but it is very difficult to get the joint hot enough for the braze to flow all the way in  - obviously you are trying to heat a tube that is shielded inside a casting. It's common to drill the lug so as to feed braze into the inside but it's still a risky business, you can have a neat little bead of braze around the tube entry but nothing inside which is very dangerous. I have a picture from an Irish Rally of a Model 9 with the front end completely broken off; I can't see that happening unless the frame had been re-tubed in this way, very nasty although I think the rider was okay.
When my mate brazes frame lugs he uses a big oxy-propane 'roofer's torch', when we brazed the rear axle lugs to my Martinsyde frame he got the whole thing nuclear-reactor hot - but the braze flowed in beautifully and it's all stayed together perfectly.
That's my ten cents anyway. Hope all is good with you otherwise
cheers Rick     

[Winold]

Hello,

I'm looking for advice on partly retubing my 1921  3-1/2hp leaf spring frame. Any tips are welcome!

The tube above and under the tank have been partly replaced and straightened. Unfortunately they haven't done a great job on this repair. It is mig welded where the tubes meet and the bottom tank tube is badly brazed in the head stock, so this connection is loose. Near the seat casting they've tried to straighten the bend tubes but it looks like @#%#. The tank tubes are bent from the point where the tubes exit the seat casting. The tube that goes down from the head stock to the engine is bent on 2 spots, it might be possible to straighten these, if not a fix should be made. The rear frame has a slight bend in it that can probably be straightened.

The tubes are all 1-1/8" (28,6mm) outer diameter. Does anyone know what the wall thickness should be? And the steel quality? Seemless I guess? How should the bend be made in the top tube? Is it nicely bent originally? Or is the section a bit flattened or oval at the bend?

I heard that back in the days in the factory the frames were tubed, straightened, pinned and then heated in a huge oven to a very high temperature, and after that bronze brazed. And therefore very hard to retube.

Does anyone have any experience or knowledge or tips about how to solve this? Any advice is very welcome! If you need more information please ask.

Thanks! Kind regards Winold