Brompton project

[12boy]

I have followed this journey with some interest, being impressed with your craftsmanship and persistence in achieving a goal so completely opposed to how mine is set up, but completely right for you. I look forward to seeing each step realized, but have to wonder if the the seat post crack was ever resolved properly. I have often wondered why the strategy of a plastic seat post insert was adopted for these bikes when others which use the sliding seat post idea do not. This issue and the process of replacing the rear triangle bushing are the two things I like least about these fine little bikes since I don't think I could do a good job myself.

 

[JhnBssll]

Thanks for your comments. I love the process of analysing a design and working out how I can modify it to better suit my requirements. It's very satisfying to see it come to life and can be equally frustrating along the way

Regarding the cracks in the frame these are indeed still there. It's a job I haven't gotten round to yet, but might have a go at it this evening if it's not too cold in the garage 😂

I've got a new seatpost and a saddle is on the way but haven't bought the nylon insert yet - as soon as the frame has been welded successfully I'll get one on order I understand they're bonded in to the frame, I assume it's an epoxy used for this but would be interested to hear if anyone has any experience in doing this job

 

[12boy]

My experience was I botched it. I then sent it via mail to a bike shop 1200 miles away and they redid it with a new one and reamed out the insert. The inserts are superglued in place, I believe.

 

[JhnBssll]

Thanks to @12boy I was spurred on this evening to tackle the main job - the cracks in the frame. To recap, this is what they looked like when I bought the bike...

So first stage was to strip the bike back down, which was a shame as it was starting to look like a real bicycle at last with all the bits that had arrived recently

Next step was to remove the paint around the affected joint. I wanted to check that the brazing was in good shape before I started to make sure it was actually worth saving I had tried sand blasting the stem with limited success so went straight for the Nitromors. It makes a mess but it gets the job done

Once I'd let that blister for a while I scraped most of it off with a metal scraper and then went over it with a rotary wire brush until I was left with this...

Super shiny, and all of the brazing looks spot on So with that confirmed I moved on to stage three, cleaning up the area around the cracks. I managed to fashion a lever out of a very small screwdriver and an allen key that allowed me to put just enough force on to the area to pull the cracks back in to alignment - they weren't perfect but they were much better. I then ground the metal around the cracks to make sure the welds would be as clean as possible.

As you can see there really isn't a lot of room for maneouvre with a welding torch in there I had a few practice goes with the welder turned off and then bit the bullet and turned it on... Spoiler - it went pretty well! Unfortunately I got carried away and banged all four welds in before I thought to take any photos I took it pretty slowly, welding a bit then blowing air over it for a few mins to take the heat out and repeating until they were all done...

There was a bit of spatter but honestly they're much neater than I expected to achieve in the space available. I've now started filing them down so it currently looks like this...

Theres a bit more filing to do as you can still see the edges of the welds. I don't know how tight the tolerances are on the fit of the seatpost shim but the most important thing is the cracks are no more If you're worried that you think you can see cracks in the image above, I assure you they're gone - the edges of a couple of the welds look like cracks with the camera flash. This tricked me at first, I had to go back down to the garage and double check to make sure I hadn't very neatly welded alongside the cracks

It couldn't really have gone much better

So on to paint! I think I've made a decision I really like @woodenspoons suggestion of desert camo so I'm going to attempt to recreate something like this, matching the colours of the grips and saddle plus another couple of similar shades. Maybe even a rogue bright colour but I haven't got that far yet

Next job is to finish stripping the paint off the frame, forks and rear triangle. That will take some time in itself so I have a while to think about it

 

[tom73]

As for colour rhubarb and custard combo. Go wild you know you want to

 

[Justinitus]

What about lacquer, so you can see all that lovely brazing? Maybe a tinted one like ruby?

 

[12boy]

I know this is probably nuts.....I have been shellacking bar tape and twining tape ends on my bikes for about a decade and use twining for other things like stainless steel water bottles, knife handles etc. In the course of this since I am too lazy to mask the bar and brake levers next to the twine, shellac gets on the metal parts and I've learned it does not come off easily. Shellac is available premixed or in a dry form which is mixed with alcohol since shellac in insoluble in water, only alcohol. Normally comes in clear, amber and garner. When applies it is transparent, sort of. It sort of self levels so is naturally smooth. If scratched or beat up it's very easy to just apply a fresh coat. I don't know if this is the same as the expensive lacquered finish on high end Bromptons but I really love seeing the brass in the brazed joints. If I have occasion to strip another frame I will mix some amber and garnet shellac and do the frame that way, creating a tangerine color. Hopefully, the metal, including the brazing, will shine through. Rattle canning is another option and can look pretty good if done with care and allowed weeks in a warm environment to achieve full hardness. Obviously powder coating is the most durable but a camo powder coat, if doable, would require some skill. I am very impressed with that seat post repair and am looking forward to seeing whatever paint job you come up with as I am sure it will be amazing.

 

[JhnBssll]

I had a look at colours this evening. These are the grips I would like to match:

I had a look on the RAL website and went through some colour charts. The closest I can get are RAL 1002, Sand Yellow, and RAL 1013, Oyster White:

Next I checked a few more colour charts out and chose a third camo-esque colour, RAL 8028, Terra Brown as it seemed to match the first two quite nicely.

For colour number four I have decided to go rogue - I had a look through the brighter RAL colours and settled on RAL 230 60 35, so wild it doesnt have a name Here it is...

One of my friends is following my build and I ran the colours by her. She suggest I send the camo pattern and colours over to her and a short while later she sent me this back after some digital wizadry

I think it looks pretty cool I'll use less of the rogue colour in the final camo design but will probably paint the stem in that colour only. I'll lay it down as the first coat and intend to make my own stencils so I will try and recreate the Brompton logo in this colour as well Might as well give myself a proper challenge afterall

This evening I've ordered a cutting board and some A4 sheets of stencil vinyl and sent an email off to paints4u to ask a few questions - all being well they'll come back to me early in the week and I can order up the rattle cans

I should really think about stripping the rest of the paint

 

[12boy]

The blue in the camo reminds me of what one of my friends said many decades ago while tripping on LSD..purple woul be such a nice color if there wasn't so much orange in it.

 

[CXRAndy]

Consider sleeving the down tube. drill holes and puddle weld

 

[JhnBssll]

A bit of progress today as wind and rain put me off the club ride this morning and wifey is away until tomorrow

I took the opportunity to strip the rest of the paint off the main frame and forks...

Plenty of Nitromors and a rotary wire brush attachment in the grinder made it fairly light work, if a little noisy

I had ordered a long wire brush attachment for the drill to try and take the majority of the loose rust off the inside of the seat tube, it seems to have worked quite well. Once the frame is painted externally I'll mask it up and get some hammerite down the inside of the tube before the insert is glued in place to try and prevent it rusting further.

Next job was to pop the headset cups out of the frame. The bearing surfaces were a bit lumpy and needed replacing anyway so I didnt have to be too careful but they came out fairly easily.

Next up I thoroughly cleaned and degreased the frame and forks a couple of times using new, clean cloths each time to dry them down and then on with some etch primer!

I'm pretty pleased with how it went on but there are a couple of imperfections that I'll need to flat back and touch up before the first colour coat goes on. Pretty good for rattle cans anyway

Next job is to move the frame and forks to one side once they're dry before stripping the paint off the rear triangle and stem and priming them I hope to get on to that later this evening after I've had a bite to eat

 

[JhnBssll]

Managed to get the paint stripped off the stem and primer applied, I'll have to do the rear triangle tomorrow otherwise I'll upset the neighbours

Theres a small dent to fill in the stem, also one on the forks and one on the rear triangle. I'll do them tomorrow too if I get a chance

 

[ColinJ]

Theres a small dent to fill in the stem, also one on the forks and one on the rear triangle. I'll do them tomorrow too if I get a chance

Ah - I thought I'd noticed a dent or two in some of the pictures! I had intended to ask.

I am enjoying following the project. It would have been easier (and possibly cheaper? ) to buy a new Brompton but if I had the skills and equipment I would have a go at something like this.

 

[JhnBssll]

I think it will come out at less than £600 all in, including the original purchase price. So slightly cheaper than a new one, but that's not why I'm doing it Its more about the journey than the destination, I'll be a little sad when its finished

 

[Gunk]

£600 will be a bargain, you’ve done a great job, really high quality work.