C's StreetFox (my first project)

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Apr 5, 2020
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Hi everyone! I'm excited to get involved with what seems like a great community that you have here! I'm a software engineer from the west of Ireland, and this is my first time attempting something like this, so I want to keep a bit of a build log here so I can see how far I get. Hopefully posting here will keep me motivated to work on this project, as it feels like a massive undertaking. If I can get something rolling around, I will be extremely happy.

About a year ago I bought plans for the StreetFox and the Warrior. I purchased my first welder (cheap DC arc welder) to start the project. I tried welding some steel plates together and had very unsatisfactory results, which put me off trying for a while. Then one thing led to another, I got a new job, the world locked down, and the project was never started. Fast forward to a few weeks ago Ireland went into lockdown again and I was looking for a new project. I figured I'll make it happen! I am fortunate to live in a house with a back garden where I can have a bit of space to work. Unfortunately, I do have quite limited space and no indoor room for working or storage. My steel is starting to get very rusty from sitting out in the weather on the west coast of Ireland (for those of you unfamiliar, lots of rain).

I spent a lot of time looking for 20" wheels with disc brake hubs before I got started, as I figured these would be the hardest components to find. Eventually I came to the conclusion that many have come to before me, that I'd have to build them myself. So I decided I would try it but I couldn't source hubs for a reasonable price from an EU supplier (anyone in the UK have any tips for finding these?) I ended up ordering a pair of 20mm Novatec hubs from AliExpress. There seems to be varying schools of thought on hub sizes but I'd rather overbuild for my first project. I also managed to get my hands on two scrap mountain bikes with rear suspension locally. The local scrapyard is closed due to the lockdown.

Last weekend I had a spare day and I spent it taking the bikes to bits. I cut out the headtube of one of them and the rear pivot (not sure what the correct term for this piece is!) I thought that the headtubes were the same on both bikes but in fact they are different, one is threadless, 1 1/8" and the other is threaded 1" steer tube. They are both 120mm long, I might cut one in half. But I'm not sure what to do about the steerer tube. I will have to get another one that is the same as one of the ones that I have, I don't really have the space for another scrap bike though! I'd rather not have different ones on either side.

Today I got going on the chassis proper. I took a deep breath and went at a few bits of tubing with the welder. To my surprise, I was able to get them to stick together. After fiddling around with scraps for a while I was able to weld two 1-meter lengths of square steel box section (40mm, 1.6mm) end to end to make the main boom. I feel like this will be ok as the only thing forward of the weld will be the bottom bracket. I attached the pivot point and the seat tube and everything seems pretty much straight! I am very surprised. I could have put the seat tube further back but I doubted myself lining everything up so I pushed it forward a few more centimeters than what was needed. I might add a small basket or something there later to use up the space.

When I started out I wanted to build a StreetFox with the front end of a Warrior, but I've changed my mind now due to the timing of making that happen. My hubs won't be here for another few weeks and I reckon I'll have to give myself a weekend to build the wheels once they arrive. I can only really work on the trike at the weekends as I work during the week, and then only if the weather isn't terrible, so this will probably add two weeks to the project. I was able to get my hands on a pair of 14mm 48 spoke BMX wheels so I think I'm going to press on with the standard StreetFox build. It's not what I want, but I don't want my steel to rust away while I wait for the wheels, so I'm keen to keep the momentum going and go with calliper brakes for the moment. One is a rear wheel so this will look a bit funny but if it keeps me going I'm not too worried. When the new hubs arrive I can build up the wheels at my leisure and eventually swap them on if I'm inclined to.

So in closing, that where I am. Next weekend I will try to build the steering boom tubes. I need to think about what to do with the headtubes - I think I will have to get a second matching one as I'll need the steerer tube too. Maybe I could get away with this using the threadless one, but the bottom is very slightly wider than the top and I'm not sure the bearings would sit right. I could cut the threadless one into two 60 mm tubes. But I'll need to do some calculations to see if that will let me get the required angles on the end of the steering boom. I like the way that the warrior actually angles the steering booms instead of the headtubes to give the required angles, I think that it looks really clean. I don't think it's feasible with the long straight boom on the StreetFox though. I'll have to do some sketches to see what will work. Plenty of food for thought for the coming week!

Anyway it seems that you like pictures here, so here is an image of what I have done so far: (Please don't look too closely at the welds, I think they're strong but I haven't yet learned how to make them pretty)

If anyone has any tips or advice for a total beginner I'm all ears! I will post an update when I make a plan around the steering.

Thanks for reading my rambles!
C+ (Seep).
 
Joined
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Welding tips. Turn your work to make the weld as easy as possible (this will mean flat - avoid welding vertically) and get a floodlight on it to aid in seeing where you are welding. If you're using a cheap handheld welding mask get a head mounted one as you'll need that other hand to hold various bits together at some point. Until you get proficient hold the rod along the line of the weld at 30 degrees or so with the tip just lightly brushing the work once you've struck an arc. As the rod burns down allow the rod to follow the line of work whilst maintaining the light brushing. ie you aren't moving the rod yourself but as it gets shorter the weld comes towards the rod holder. Practise this technique on scrap. Use as little power as you can get away with to avoid blowing holes in everything. Check you have enough power to make a decent weld by welding scrap of the same thickness and trying to break the weld with a large adjustment hammer and vice. When you lay a good weld the slag should shell off very easily in large flakes. If you're having to whack the slag off with big effort you're still needing practise. I've been welding for decades and still do some dodgy looking welds so don't dispair if your still struggling after lots of effort. ARC is the hardest to use on the thin metals we use but it can be done.
 
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Joined
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Thanks for the tips Popshot!
ie you aren't moving the rod yourself but as it gets shorter the weld comes towards the rod holder
This is something I haven't heard before but it makes a lot of sense.

I found it tricky to get the technique down for attaching the seat tube to the boom. I practiced on some scrap first which made it easier. Trying to get good penetration into the corner of the main boom without blowing through the bottom of the seat post was difficult. I was able to make it work by increasing the amperage and staying slightly more on the side of the main boom, "pulling" the weld over onto the seat post as I moved along. Not sure if that's the recommended approach! I did give it a few whacks with a hammer in all directions when I was finished and it seems solid.
 
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By keeping away from the cut edge and nearer the main boom where the corner effectively equals a bigger mass of metal you definitely reduce the chance of making holes. So long as the weld pool flows to the right place it's a good technique to use.
 
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Holding a welding rod too far from the weld is almost guaranteed to blow holes. All other things being equal, lower amps and/or closer to the work makes blowing holes less likely to happen.

Another tip: Only tack weld at first, enough to hold the work together. Makes it easier to pull apart if/when you need to scrap or reposition it.
 
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The corners are where I tend to burn holes. I think welding at higher amps in the the rest and then turning it down for the corners is what I'll try in the future. Also, clean your metal really well before welding.
Are you approaching the corners in a contiguous weld ?

That allows a build up of heat in the parent metal and by the time you reach the corner the metal is to hot to stand the rod as well and blows through.

Try tacking all 4 corners first do one then it's opposite check all is still square then do the next pair.

Once they are done just weld from one corner to the middle of the piece and move to the opposite side and repeat till you have gone all the way around , that will be 4 tacks and 8 small welds.

Effectively you will tack weld all the way around but change sides after EVERY weld , keeps the heat down.

Paul
 
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I move my electrode in and out. That way, you don't get holes that fast
I assume this spreads the heat over a bigger area when out than when in ?

Don't do stick so only guessing ?
 
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I assume this spreads the heat over a bigger area when out than when in ?

Don't do stick so only guessing ?
By moving it in and out, you keep the temperature lower than as you keep it in.
By just moving in and out, you can keep welding it in one line.
I tried to weld on a lower amp, but I didn't like that. For me, welding with a bith higher amp. Works better.
 
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When I did try stick if the amps were to low the rod kept sticking ...

However that was years ago !

Paul
 
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I learned stick welding with 5mm and thick mattirals. So when I got thin plates and a 1,6mm rod, it wasn't that easy as I was used to.
I also used the given settings, but I couldn't get any good welds with those settings.
The rod also sticked very fast as I moved to fast.
With a bith higher setting, it goes a lot better, but the risk on holes is a lot bigger.
 
Joined
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Thanks a million everyone for all the advice, it's really useful being able to hear everyone's experiences and tips with the welding.

I haven't had time to do too much extra work on the trike over the past week or so. I have been in touch with a local bike shop to get front wheels built with 20mm thru axle disc brake hubs. I also built a quick CAD model of the front end to check if I would have enough room to chop one of the headtubes in half, and I did. It'll be a bit tight but it should be ok.


Another reason for the CAD model is that it shows me the exact cut I need to make in the box section to get the angles right:


The idea is that I can print out the image of the bottom and top views to scale and trace it onto the ends of the steering booms. Then cut it out with the grinder and it should be pretty much aligned. I'm sure this won't work nearly as well as I want it to but I'm optimistic :)

I got my hands on another fork so I was able to get two tubes built up. One of the forks was attached on slightly differently so the ends are a little different, but I think this should be ok once I get the axle mounting tabs built.


Speaking of the axle mounting tabs, I don't have any steel plate to hand. Instead I'm thinking of using the ends of some steel cranks that I have to make the tabs. I'll just chop off the end and drill out the hole for the pedals a bit bigger to fit in the axle, then continue as per the Warrior plans to built up a bolt for the axle. I've seen this done before on youtube, but the guy actually used the axle in the pedal as his wheel axle. Anyone here done this before?
 
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I've seen this done before on youtube, but the guy actually used the axle in the pedal as his wheel axle. Anyone here done this before?
Oooh loads wrong with this !

On here we are ' long term ' we try things and document the successes and failures ?

Did the guy on Youtube come back after a few miles/hundreds miles and report whether it worked or not ?

A pedal has very few ball bearings and they are very small , compare them with a wheel's bearings ?

A pedal has to cope with no sideways forces at all , a trike cannot lean and so the sideways forces on a wheel are considerable , enough to bend a 9mm axle !

I think the idea is dangerous , but that is only my view.

paul
 
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Sorry I wasn't clear on my post - i was planning to use just the crank for the axle tab and drill out the hole to take probably an M15 bolt, and from there do the same thing as in the warrior/streetfox plans. Not planning to use the pedal spindle itself, just saying I saw someone do it before!
 
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Sorry misunderstood.

Should work there is plenty of meat on some of them.

A file maybe all that's required to get the hole out bigger ?

Paul
 
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For getting the angles right for those head-tubes it is very easy to use simple Trigonometry to establish the correct offset between 2 holesaw-cut holes top & bottom of the square tube; then just cut straight lines joining top/bottom holes, slip the headtube in and weld it up. ;)
 
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