Amperage needed for Ti and cromo?
I'm looking at TIG welding machines.
I've read a few articles about welding Ti and cromo and with cromo I want 1amp per thousand apparantly but for Ti almost all articles say I need upwards of 250 amps.
Now they are probably talking about welding big thick pipes and such and I wonder how big of a machine that is really needed when welding a frame out of Ti/cromo, including dropouts, disc mounts, a fork and such parts that are maybe upwards of 5-6mm thick.
When joining a typical Ti 0.039/1mm tube to another what is a typical current for this to work? I'm guessing a lot lower than 250 amps.
Is a 150 amp machine enough for all bike related welding? Cromo and Ti?
I've also found machines with 180, 200, 220 and 250 amps, but the prices go up to like 25-50% more quite fast.
Which of the functions are more or less useless for welding a bike out of these?
* wide adjustability of pre and afterflow of gas ( I know this is important for ti at least. some have up to 5 seconds preflow and some much longer, some have up to 25 seconds afterflow and some much longer, longer is better here or?)
*be able to set frequency and duty cycle of the pulses and dc bias when its in the low amp region (not just off).
*be able to use less than 5 amps.
I'm currently looking at these, we have a few at work (not tig) and they work well. MinarcTig Evo | Kemppi
MasterTig MLS | Kemppi
MinarcTig™ | Kemppi
150 amps is plenty for steel and ti. Like you said though, with ti you'll want some adjustability on the post flow. The pre-flow doesn't really matter because you can just kick the pedal and get the gas going (basically the machine goes into post-flow so you have plenty of time to start an arc).
I have a basic Lincoln Square Wave TIG 175 transformer machine and it does everything I need it to do at this point in my learning. All the machine has on the front is an amp dial and a switch for DC-, AC, and DC+. Nothing extra to cause confusion. It has a nice pedal and HF start. I would say a pedal is a must for good heat control on our thin wall tubing. The machine is hard wired at 15 seconds post-flow, so i've been able to mess around with some ti scraps that Rody passed along (thanks again, my friend!) without any contamination at the end of the bead. But I've been primarily focused on steel and aluminum.
You don't need many frills at all in a machine. Practice and having some folks to help you are key.
SF 29er by Zanconato Custom Cycles, on Flickr
Last edited by zank; 05-14-2012 at 05:06 AM.
I would say a bigger machine for aluminum, but the articles you have read suggesting a 250 amp machine for Ti may be concerned with duty cycle.
zank, that is a fine looking weld
Every once and a while along comes a natural...............
Originally Posted by zank
Dude, you're making me blush. But I have a long long way to go.
I see the colors blue and brown in there!! What are they doing there??
Originally Posted by zank
No just kidding looks good to me. I would ride it.
I had a chat with a guy at work today. He welds tig (tubes) and is licenced. He tought I should buy one with pulsing (but it would still work perfectly good without it), because its easier to control when you have thin tubes, especially pulsing with bias offset. Like eating the cake and still having it. But hf ignite was a must. Can't really remember what he said about pedal, he didn't use it at least, and since I can't remember it wasn't that important probably. He welds quite a lot of ti but thicker stock.
200 amp machine is a good middle ground unless you want to do aluminum. Ideally you don't want to be pushing the limits of your machine consistently. Plus it's always nice to have some amps in reserve for welding tooling that is going to be <1/4"
Pulsers are nice but you need to learn to weld without one so it doesn't become a crutch like it is with most builders.