Welding and rewelding Aluminum bike frames

[glockdoc]

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[HAWK]

Tanner,

I have a 30 amp 240VAC for my Dynasty 200DX. It works great! Also spend the $200 extra for the DX model with pulse and sequence. You will be hating life if you don't!

[Tanner]

HAWK,
I found out another thing about the 200DX that makes it almost perfect for me - the low current draw. It only draws 20 amps at 100% duty cycle on 120v. I like that, especially because my house only currrently has 200amp service. The 200DX also does not draw a lot of current when SMAW welding - my favorite type of welding. The reviews of the machine and the specs makes the price easily worth it!

[HAWK]

Tanner,

Thanks for the information on GT. I bought my bike 2 years ago and it had been it the guys garage for several years. It is an original GT. I remember the dealer talking of the bankruptcy, but did not know who would be picking them up.

I can't imagine the room you must take up with 19 frames! The Dynasty is a small unit. It is hard to believe you can get all that power and advanced option settings from such a small machine! If you do a search , you will find a number of posts on this forum about the machine. Here is a copy of one of those posts.

HAWK
Senior Member

Registered: Jul 2003
Location:
Posts: 753
DOHC330MustanGT,

As Grampa stated the Syncrowave 250 has been a Miller Mainstay in the TIG line for 25 years. The Syncrowave 180SD is its little brother and is a very fine machine. However, it really pales in comparison to the Dynasty 200DX in a number of ways:

Amperage is the first difference: Even though there is only a 20 amp numerical difference on the top end it is more like a 70 amp difference in the real welding world. Why? The Syncro 180 is a transformer machine using 60HZ AC line frequency to produce the welding arc. The Dynasty 200DX is an inverter type machine using IGBT's to boost the machines operating frequency well above 60HZ. This does 2 basic things: It takes less welding output to do the same job. The 200 amp Dynasty will weld 1/4" material easily. The Syncro 180 will max at 3/16" stock. Also the ability to add a premium pulsing system is the other great thing about inverters.

On the other end of the scale the Dynasty goes down to 1 amp on DC and 5 amps on AC. The Synco 180 bottoms at 10 amps AC/DC. This may not sound like much, but when you have to have it makes all the difference: You just can't weld .005" stock at 10 amps.

Both machines have the ability to adjust the electrode negative balance to compensate for material defects and get the right amount of cleaning and penetration. The Dynasty is adjustable from 30 to 90 percent on the electrode negative side. I am not clear on the amount of adjustment available on the Syncro 180.

The Syncro 180 does not offer any way to adjust the arc fequency to help focus the arc into a tighter area. It also does not offer any readily available pulse option. The Dynasty offers both in the DX model. It is adjustable to 250HZ in arc frequency and the pulse options are absolutely mind blowing. The adjustable frequency is available on the SD model as well.

The Dynasty is a highly portable machine at 50 lbs and will operate on 100-500 VAC single or 3 phase input power. It is an all around premium package for the professional TIG welder needing the best in arc quality and adjustability. The Syncro 180 is a high end light industrial machine filling the void between the Econo Tig's low duty cycle and no adjustability and the Syncro 250 industry standard for the professional TIG welder.

Both are good machines and designed for different purposes. To me the Dynasty rocks on aluminum. I do not have the proper facilities for titanium or beta titanium, but understand the Dynasty rocks here as well. It's hard to find that quality in just any machine. Given the right gas mix, settings, and operator experience this machine will do it all. If you believe in multipass welding and a little patience, .750 aluminum is not a stretch for this machine. I am talking 90% Helium and 10% argon, 200 amps, 250 HZ,500 PPS, ear plugs and a 13 shade. The Dynasty is a bit noisy on AC, but not really irritating. My ears are very sensitive. The Syncros are not exactly quiet either.

The Dynasty 200DX is an awesome unbeatable machine!

Tanner,

One more thing: Most people use the air cooled torch with the contractor's kit. I did this for a while, but found 2 problems-the torch got warm after exrtended weld times and the stiffer power cord on the air cooled torch made long hours tediuos to say the least.

I bought a DB20M25R Diamond Back water cooled torch with super flexible braided hoses and a small, lightweight, maneuverable body. Add a Coolmate 3 or 4 and it is a killer combo. The torch and cooler add about $650 and add another $65 for a good flow meter and regulator, $50 for ground and electrode leads. The total going this route is around $765 and the contractor's kit about $500. The kit has the air cooled 150 amp torch with tungsten collets, bodies, back caps etc., regulator, and leads with torch adapter.

What I am telling you is spend the extra $300, buy the separate pieces with the cooler and you will be much happier if you plan to spend any time at all under the hood making those tubular welds! I have the Coolmate 4 because it is more portable, but the Coolmate 3 is a great shop unit.

[Tanner]

Yeah, GT bicycles were a great brand, and I only say were because they went bankrupt, and were bought by Pacific Cycle (they make the Pacific) brand frames that are typically sold in Wal*Mart, Target, etc. Since then, all the frames that used to be welded in the US have been since outsourced to Pulo manufacturing in China. The welds that have been coming out of Pulo have been so shoddy recently, that many bike makers are pulling out and trying to get their frames welded in the US again. Chances are you got the frame before they were outsourced, so you lucked out. I was one of the few people who bought a frame from GT before they were bought out. Heh, I guess I did luck out with all my bike frames (all 19 of them in my garage). I'll probably end up getting the 200DX this summer, and update once that happens. Thanks again everyone!

[HAWK]

Tanner,

I take it you were able to open the .zip file. It is a MS word document. It also shows what filler has the best color match after anodizing. I think I forgot to mention that category. Best of luck. I, like Blondie, am getting older and having a fit with arthitis especially in my right hand. I think it has molded itself to a TIG torch and a coffe mug! I still ride a GT trail bike retrofitted with a front rock shock. I bought it used from a guy who wanted it out of his garage. I paid $250 for it even though I was not familiar with GT. I called the local dealer and they said I stole the bike. So far the welds are holding up well. I do not know what AL alloy the frame is made of. It is bright orange. It seems to be prety well adjusted for me. Downhill is bumpy, but never bottoms out. Keep us posted!

[Tanner]

yeah, I can't get it working. I have winzip, winrar and everything, but, this file just won't open. I even tried resetting the extension. that didn't work.

EDIT - Hoho! My reverse engineering skills paid off! Thanks HAWK!

[Tanner]

Thanks a ton HAWK. Err, it doesn't seem to have the right file extension on it. I'll try and get it working, if not, I'll let you know

[HAWK]

Tanner,

Most information I have found on heat treating 6061 and 7005 alloys does not recommend PWHT (post weld heat treating) as it requires heating to a temperature that causes loss of the alloy's mechanical properties. My guess is your heat treating will be in the form of incremental pre-weld treatment. Be thorough in your research for the welding of these alloys. Don't get you or someone else hurt or killed.

Attached is a filler guide with respect to strength, ductility, and crack resistance.

[Tanner]

Originally posted by pjseaman
Tanner :
If your employer would have a demo model you might be able to take it home for a weekend and try it out make a few fixes and take it back on monday. Make friends with the guys and you never know who will jump in to help you out, It could be like some of the guys here and just say comeon over and try it out! Also don't forget there is an educational discount available on some equipment.

Yeah, the guys let me come in and weld some stuff back when I was in 4th grade, and when I went back in to buy some gloves and a helmet they couldn't believe I stuck with it for so long. They also couldn't believe bow tall I was! (I had to duck to walk in the store!)

[HAWK]

Tanner,

First of all the Dynasty 200DX is the machine of choice for your work. Specific aluminum alloys are reweldable and re- heat treatable. You will have to do some research on the specific alloys as to what can be done. Also the filler rods for post treating of once welded aluminum can be more than a pain. They are expensive, hard to fine, and sold only in quantity.

[Paul Seaman]

Tanner :
If your employer would have a demo model you might be able to take it home for a weekend and try it out make a few fixes and take it back on monday. Make friends with the guys and you never know who will jump in to help you out, It could be like some of the guys here and just say comeon over and try it out! Also don't forget there is an educational discount available on some equipment.

[Blondie_486]

Tanner,

I'm old and have arthritis so riding a conventional bike is out for me. But I have been thinking about building a recumbent similar to the Easy 1, re-engineered to hillbilly specs of course. I'll most likely make a prototype frame out of mild steel and then think about either an aluminum or chrome moly frame. After I git all them thar bugs worked out of it!

Blondie

[Blondie_486]

Tanner,

Yeah that's the ticket go to work for a Miler dealer then get the employee discount plan. Or perhaps a demo machine or a reconditioned machine or a trade in. Any of those should net you a decent discount.

Good luck and keep us posted

Blondie

[Paul Seaman]

Tanner
When I was younger I rode pretty hard and only broke a couple of welds at the BMX track near us. Sound of it is pretty agressive, as blondie said I don't know about heat treating Al but I think all you can do is stress relieve it! Give it a couple of days and Andy will verify one way or the other.
Keep on, keepin on