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View Full Version : Do you tack weld everything first or completely weld a part at a time?



Tradetek
10-02-2012, 09:12 AM
So... when you are welding your frames do you tack weld your entire frame first until you have a rolling frame and can ensure all your alignments are corrects before you start doing finish welds.

Or...

Do you weld each piece/part together and then weld that compound part to the next part and so forth until you have a completely assembled bike?

And...

If you have switched from one method to the other, why did you switch and which do you like better and why?

Thanks!

Radical Brad
10-02-2012, 09:22 AM
I always use plan B. I found that to be more reliable since you can never fully predict heat distortions.
I like to use the wheels as a guide. If they all hit the road in perfect alignment, you win - even if there may be a slight deflection somewhere in the frame along the way.

Brad

river
10-02-2012, 09:43 AM
Plan B and i use the wheels as guide. Wheel alignment the most important. I'll tack main sections together and if they align good with tacks i'll finish the welds

Radical Brad
10-02-2012, 11:27 AM
I will also offer a 3rd method that I have tried several times and find it to be the worst method... making a frame jig.
I have tried heavy wood jigs and even steel jigs, and every time, I found doing by eye to be far better.

Perhaps because you just trust things too much with a jig? Sure, the jig was straight, and after welding so was the frame (while still in the jig).
But as soon as the jig was removed, tension caused from distortion pulled the frame out of alignment.

So for this reason, I find a DIY jig to be a waste of time.
Even if I was into production, I would still only use a jig to tack weld and then use the "look at it" method for the final welding.
A good welded learns how to anticipate the distortions induced into a part when welding.

Brad

Ticktock
10-02-2012, 12:09 PM
I am not in the profesional welder class, and therefore assume that whatever I weld will distort to some place I never even knew existed until the last weld was completed.!
I weld each piece as I go, getting it as straight as I can. . The final welds must determine where the wheels are, and that is all that counts. The rest of the frame can look like a banana--so long as the wheels are in the right place.
Actually, if you see some of the trikes and bikes here, you would not even worry enough to ask the question, there are not enough degrees on my protractors to measure the bends in the frames--but they all steer OK!
Same goes for wobbly wheels! Makes you wonder why we try sometimes. I have only seen one trike where the wheel wobble s were so bad that it had an effect on steering, and we would not even think of putting any of those three wheels on anything!
Final result must be wheels in right place.
Steve G

river
10-02-2012, 08:01 PM
You won't have any warped or distorted joint if you have good tack weldsaround the joint from back to front side to side then just do small welds on opposite side to keep it from getting to hot and warping Don't try to weld it all at once it probably will warp you have to spread the heat around to keep it from getting to hot in one spot. sometimes you just have to take your time. I like jigs and to me its easier, but nothing will replace a good eye either

graucho
10-02-2012, 11:59 PM
Everyone has their comfort zone with technique. We all get to the same place if you roll straight at the end. Jigs, eyeballing, tacking, I use them all. I love to tack. Yet it is very dangerous if you think you will be cruising the neighborhood for a test run with everything "just" tacked.

Your final decision will end up being personal preference in the end. I like using a jig for the tacking. I take it off of the bench for a roll walking beside it with one hand on the handlebars to see if it rolls straight. If it rolls balanced and straight it goes back on the bench (without the jig) for some massive tacking. Meaning the tacks will hold my body weight for one first roll. If its a thumbs up, I also follow "river's" advise above. Welding the tube sections switching from front to back not to causing warping.

A few vids of first rolls with tacks only. Notice its for balance and tracking only. Nothing crazy to snap the welds. The last vid is after full welds were completed. Pushing it hard.

http://www.youtube.com/watch?v=Lctcd0rkW8g&list=UU6xPKv5ZqNZxoya8GdsRSdQ&index=7&feature=plcp

http://www.youtube.com/watch?v=eFSFRfx6G08&feature=autoplay&list=UU6xPKv5ZqNZxoya8GdsRSdQ&playnext=1

http://www.youtube.com/watch?v=rcvEbjGoQUY&feature=autoplay&list=UU6xPKv5ZqNZxoya8GdsRSdQ&playnext=1

savarin
10-03-2012, 08:52 AM
I use both methods but the use of a precision eyecrometer is essential and as Ticktock stated as long as the wheels are where they should be the bits in the middle can go all over the place, aesthetics allowing.