DC Tig with engine drive machine help needed

By Ironman82 Date 03-10-2007 01:28

I recently purchased a new Miller Bobcat 225 engine drive machine for my own business. I want to do some TIG work but I don't really want to spend the money on a stand alone TIG machine nor do I want to carry around 2 machines with me when a job requires some precision. I know that there is a high frequency unit I can buy for the bobcat to do TIG, but with all the TIG work I have done in the past, I've only needed to use high frequency when welding aluminum. I 'm not sure if I'm correct but it seems to me that all I would need to do is connect the tig torch to my electrode post and connect my gas and go. It seems like this would be the way to do lift arc (although I've never performed TIG welding using the lift-arc process, only remote pedal starts). If anyone has any additional information or tips for me on this matter, PLEASE contact me by responding to this post or e-mail me at tearsofthefrail@aol.com with a subject of tig welding info.

Thanks for your help!
Bruce

By 357max

Date 03-10-2007 02:00

You are correct. You may connect the torch to the electrode terminal and the work clamp/cable to the work terminal. Set the machine for TIG DC and set the Coarse Range Control at lowest setting to get the required weld amperage by setting the Fine adjust control at or near maximum. Very carefully/gently rest the nozzle edge on the workpiece without touching the tungsten. Rock the torch to very quickly & gently touch the tungsten to the workpiece, establish an arc by rocking the tungsten to make & break contact. Lift torch to maintain arc length.
By the way, my Miller distributor says the High Frequency Arc Starter/Stabilizer with contactor lists out at $1300-1400 US. There is no remote amperage control capability, only a contactor closure.
Because I own a three phase welding arc 301 Trailblazer and getting ready to make new; the 275 DC with its TIG features sounds like for about 8-900 dollars more than a Bobcat 225 to be a better deal.

By makeithot (***)

Date 03-11-2007 16:05

I have a miller big 40 diesel (Deluxe) has all the bells and whistles tig contacter etc is build into the machine and these features are also available in the smaller machines. To weld aluminum the hi freq is still required. the advantage to it is you can use a foot pedal instead of a lift start. There are however two different hi freq units and both do not offer the same options.

By Kix

Date 03-12-2007 12:36

Don't ever touch the tungsten to the work piece unless u must. Place the cup on the workpiece like said above with the tunsten a bit off the workpiece. Then take your filler rod and flick it real quick across the tungsten touching the workpiece and tungsten at the same time. Wamo you go a clean start and a brand new sharp tungsten still. Thats if your not going to buy the hi freq unit and foot pedal. Also scrap the dc tig setting on your machine and just hook your stinger into the electrode neg bung. That works the best with the info i stated above.

By 357max

Date 03-12-2007 23:54

Depends on machine, The Bobcat 225 has a work connection & electrode connection. The polarity is set on the process selector switch. DC negative would be DC TIG selection.

By Kix

Date 03-13-2007 12:01

Ok i should be a bit more clear in the discription. Put the machine to stick welding on reverse polarity and swap the leads. Put your stinger in the work connector and your ground in the electrode connector. Works the best for that method