Manual for HF Tig?

I picked up one of those HF Tig units (#91811), but do not have a manual with it. I've checked the HF website, and can find no download.
Would anyone have a pdf version available?
I've done a bit of stick welding with it, and should have the regulator/gas to experiment with TIG work shortly.
Thanks, Roger.
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HF is pretty good about manuals that are missing. If there is a store near you, stop in, they will take the time to photocopy one for you. (If you can't find one here on-line that is.) They did this for me on a powdercoating machine I bought off E-bay. Sans manual of course.
Rob
Fraser Competition Engines Chicago, IL. Long Beach, CA.

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I have a paper manual and it is not much for information. You need to get some good tungstens and just use normal DC tig technique. Jury is still out as to whether it is a true lift arc or just scratch start. I have welded coffee cans with mine after much practice.

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Thanks to all for the information. I've purchased some 1/16" and 3/32" thoriated tungstens, and will have an argon tank and regulator/flowmeter shortly.
The Harbor Freight website has links to manuals for many products, but I could find no link for the infamous 91811 welder. Unfortunately, I'm a few hours drive away from a retail store, so that option is out. By looking at the site location for the other manuals, I was able to determine the link to this welder. Here it is:
http://www.harborfreight.com/manuals/91000-91999/91811.pdf
It looks like they just forgot to link to it on the product web page.
Glenn, you are right, there really is not much information in the manual. I sure am glad I didn't take up one helpful guy's offer to mail out a copy if I sent him $25!!!
BTW, I've read past discussions about retrofitting a foot-pedal current control. Has anyone done this yet?
Thanks for the info, Roger.
Glenn wrote:

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I have one of these welders, and it is easy to add an external pot. You need a pot with a linear taper, and resistance of between 5k and 10k ohms. The cable to the pot on the control panel has a three pin connector. You will need to provide a switch to select which pots slider is connected to the internal electronics. I used a small stereo phone connector with an internal switch. These are available at Radio Shack. You must drill a small hole in the front to mount the jack, and make a cable assembly to the remote pot.
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Mike,
Thanks for the info! That's exactly what I was thinking. What did you use for pedal assembly? I wonder if an electric guitar or sewing machine pedal be suitable. Obviously they'd aren't designed for the shop environment, but with a bit of care, they might work OK for the hobbyist.
Roger.
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I have yet to build the remote for mine, but I picked up a nice slider pot I intend to attach to the torch so I can control the current with my thumb or finger. IMO a foot pedal would sort of kill the benifit of the portability of the little jewel. YMMV Glenn
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wrote: | | > Thanks to all for the information. I've purchased some 1/16" and 3/32" | > thoriated tungstens, and will have an argon tank and | > regulator/flowmeter shortly. | > | > The Harbor Freight website has links to manuals for many products, but | > I could find no link for the infamous 91811 welder. Unfortunately, I'm | > a few hours drive away from a retail store, so that option is out. By | > looking at the site location for the other manuals, I was able to | > determine the link to this welder. Here it is: | > | > http://www.harborfreight.com/manuals/91000-91999/91811.pdf | > | > It looks like they just forgot to link to it on the product web page. | > | > Glenn, you are right, there really is not much information in the | > manual. I sure am glad I didn't take up one helpful guy's offer to | > mail out a copy if I sent him $25!!!
Thanks for finding that for me! I was asking about it the other day to see what it would take to make it do more tricks, and to see if the schematic would allow it. What a pleasant surprise. I learned a couple interesting things. First, it rectifies the high 220V input (and lower current) then creates AC out of again it to drive the output transformer. After the transformer, it's rectified to DC. To pull AC out of it, it seems (to me, who knows so little!) that you could leave the DC part alone since it's used for feedback (I assume) and just add two terminals for the AC right out of the transformer, before the diodes. The diagram doesn't say what goes on inside the circuit board, but it seems reasonable that you could rig up a way to add variable frequency. I was thinking that you could drive a electronic potentiometer with a chopper circuit or oscillator to trick it into thinking HF, but I'm sure there's some filtering there, so I don't know how that would work, but it's an idea. The on-board oscillator that creates the frequency that drives the IGBT's that drive the output transformer might be modifiable, but reverse engineering would definitely be in order. Would be a fun project to see how little you can spend to make a $220 welder do tricks of more expensive ones. I'm just gonna have to budget some money when the wife isn't looking and play around with it myself. Hmmmm..... I got rid of a lot of my electronics stash, but not most of the good stuff..... Where the hell did I put my scope? Where do I put this on my to do list??
Slams, criticisms, or compliments? Anyone wanna contribute to my project fund?
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carl mciver wrote:

I think the center tapped transformer or folded bridge would limit you to 1/2 the DC current for A/C. I looked at it when I first bought mine and decided it was not feasable for reasonable money. I think you would have to change the output transformer and switch to a 4 device full wave bridge for DC, then you could bypass the bridge and use it for modifide A/C output. I think the squarewave output is fairly high frequency for better efficiency in the output circuit. I would be interested in any ideas though. Glenn
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The AC out of the transformer is probably in the range of 20 kHz and fixed. For all of the AC tricks needed for Aluminum you would need to place a full bridge on the output to generate the pulse polarity and widths for an AC machine. It could be done, but its a fairly major project.
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