First MIG Welded Cro-Mo Steel Frame

[LI-ghtcycle]

Can you tell us what the pros use for mitering the tubes? I found that was the biggest amount of work in my bike builds by a substantial factor.

In the class I took they say extra large arbors (3/4" for stability) with standard bi-metal hole saws using a vertical or horizontal mill is the best solution.


Sure you can just use a drill press, or a set-up like Spinning Magnets posted, but the problem is you won't get the accuracy that a large solid mill can, since the hole saw will want to walk all over the place in a typical drill press or other ad-hoc set-up.

(Which means just a bunch more hand filling when a good cut means 1 min deburring and you're ready to weld)


And the main reason for using the hole saws instead of just an end mill is cost, especially if you plan on doing different size frames, it's a lot cheaper to buy/maintain/replace hole saws instead of having the different sized end mill (bits?)

that are very expensive, and easy to drop and ruin.

 

[LI-ghtcycle]

Do you take paypal? No but seriously, do you? I'm not sure what gravitates me to the frame. The Cro-Mo, or the dropouts, really, the stuff you search for when looking for a suitable host. Can't wait to see what you make of it!

Hehe, you are very kind!

I will have to see what I can do once I have my own equipment first, you don't wana see what I just welded yesterday with the HF $300 MIG welder!

It's structurally sound, but pretty ugly compared to the perfect beads that a $3000+ Miller Maxstar 200 that I got to use in class.

For now, I will just try and decide what I want paint wise, I really am leaning toward a clear coat, but I don't want something that will yellow on me, might just end up doing the typical flat black rattle can since this will be a

work-horse frame for testing something like a GNG mid-drive and possibly the new Magic Pie 3 (The ones with a built-in cooling fan!) at somewhere around 74V or so.

 

[LI-ghtcycle]

I've never MIG'd a frame, and my stick-welding looks like bird-droppings. Now that that's out of the way...If I was going to make frames in my garage, here's the jig that I would copy. its from recumbents.com website (I will crop and re-size the pic when I get home):

http://www.recumbents.com/forums/topic.asp?whichpage=10&TOPIC_ID=2510

Nice! I might have to steal some of those Ideas for some home-brew projects, but if I were to build anything to sell, I would hit-up the local machine shop and see what kind of deal we can work out.

My first purchase will be a good set of hand files, and a the best welder I can afford (looking into some grants atm to get started ... might have some shop space available soon too!)

 

[LI-ghtcycle]

When it comes time to buy a welding machine, check out HTP. I bought one of their new TIG machines. Post-sale support is WAY better than what you get with the big companies. Great machines, too.

Kewl! Thanks for the tip, I will check them out.

 

[Samd]

That's awesome. Interesting to see you can buy the Surly dropouts - do you buy the headtube and bottom brackets also, or fabricate yourself? Sorry if it's a noob question - but when it comes to frames - I am! :?

 

[waynebergman]

That frame looks real nice. The photo attached shows these drop outs for sale from Amazon, are they the units you welded on to you frame? They just don't look as thick as yours but I am guessing they are the same ones.

When you get to shopping for your welder I would like to recommend the Everlast tig welder I picked up few years back. Seems to be good value and a nice combo unit for welding Aluminum with ac/dc options, pulse, foot pedal, stick and also plasma all in one little unit. I think it was under 1500 bucks delivered to the door and works well.

 

[spinningmagnets]

I don't know whats in the product "tap magic". It's a fluid thats spritzed on steel on which you're drilling, tapping, or using a hole-saw. Damn stuff works awesome, well worth the price. I've used WD-40 before, and it helps a little to cool and lube the cut, but...TM is in a completely different league.

 

[LI-ghtcycle]

That's awesome. Interesting to see you can buy the Surly dropouts - do you buy the headtube and bottom brackets also, or fabricate yourself? Sorry if it's a noob question - but when it comes to frames - I am! :?

The BB is something you buy and weld in, and you can get pre-cut lengths of tube, but it's expensive, and more for a true bicycle that is only going to see pedaling forces, not ideal for an E-Bike unless a pretty low powered one.

I'm going to buy 4130 Cro-Mo tube when I am able to start doing things with my own welder, but that will be a while.

For now I will just use cheap "found metal" and recycled frames to build things out of (I have built the motor mounts for my current mid-drive cruiser bike with square tube from out-door planters my friend was going to junk! I'm sure it's just mild steel, but it's plenty strong for what I am using it for, little 4 inch sections to allow a place for the motor to bolt down).

I will get better with the HF cheap welder, but it will never be a easy to weld with as the Miller!

 

[MadRhino]

Will the frame also house batteries and controllers? A fork with reinforced dropouts for hub motors sounds good, doesn't it? I usually use
https://thetigwelder.com/miller-syncrowave-210-review/ to weld this kind of work

That was 10 years ago, and we haven’t heard of it since.

The fact is, most who are building their own bike frame have very limited knowledge of frame design and engineering. They either copy an existing frame with slight mods, or work from plans availabe on the web. But, the best frames are built at high cost, lots of R&D, and years of racing team feedback/mods, to achieve a winner sometimes.

 

[nicobie]

The jig he used to weld that frame still blows me away.