Metal cutting - oxyfuel cutting, plasma cutting, machining, grinding, and other preparatory work.
TheCatcher
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    Sat Apr 20, 2013 6:08 pm

I've got a few Plasma Cutter and TIG welder newbie questions, though the answers might be a bit complicated. I recently picked up a Chinese 3 in 1 Plasma Cutter / TIG Welder / Arc Welder combo machine.

The machine is working great and I'm not interested in starting a discussion about whether or not Chinese machines are worth purchasing or not. For what I purchased this machine for, it has already saved me more money than it cost. I've analyzed the circuit diagrams and I feel fairly confident I can repair most problems. So even though I can understand why a more robust machine is a most likely a requirement for professional welders, I'm happy with my decision to buy the Chinese machine.

Going forward with my Chinese machine, I can see some additional projects around the house where it could be very useful. But I'm starting to run low on the Plasma Cutter consumables. Like most Chinese welders the documentation is fine if you never intend to use it. But if you do find you need it, you are out of luck. (Documentation Example: The machine shipped without a plug on its electric cord. The machine is listed as 110v/220v compatible. The cord has Black, White, and Green conductors, standard 110v power cord. This is the only reference to the connecting a plug to the machine, in the entire manual... "2-a Connection of the input wire. The wire at the back of the welder is connected to the 220V AC power supply, no wrong connection." - does that mean, you can't hook it up wrong, or Don't do it wrong or you will be sorry... The first hit when doing a google search for "Chinese Plasma Cutter" is a YouTube video of a Chinese Plasma Cutter exploding... the unit has good paint, but there are bubble dents in the cabinet from internals being pushed out, so I suspect this particular unit had a pretty rough ride from China... but none the less, it did prompt me to open the unit and do a fairly complete analysis of the components, how they work, and how I would go about fixing the unit if I had similar problems... but I digress...).

The manual lists nothing about the type of consumables the welder requires. I've done some web research and based on the dimensions and pictures I've found, the Plasma Cutter consumables appear to be compatible with the ESAB PT-31 Torch.

There appear to be at least 2 different sizes of Plasma Cutter consumables for the ESAB PT-31 Torch (a shorter tip and longer tip). I've measured my current torch head and it should have no problem handling either size. The shorter tip has a 28.65mm long electrode and a 10mm long tip. The longer tip has a 38.2mm electrode and an approximately 16mm long tip. My welder came with the shorter tips. I suspect the longer tips might help protect the ceramic piece from blow-back (right term?) when doing plunge cuts, but that is only my guess.

So my first question is... What are the advantages and disadvantages of the shorter and longer Plasma Cutter tips?

My next question is about Plasma Cutter Torch Heads. My Plasma Cutter is a 50 Amp cutter. I've run the numbers and based on the number and type of Mosfets and transformers it should theoretically be able to handle generate the full 50 Amps. It came with a 40 Amp ESAB PT-31 look alike Torch Head and consumables.

From what I've been reading it appears as if the maximum severance cut that the ESAB PT-31 look alike Torch Head consumables will do is about 1/2 inch. I've also read that a 50 Amp Plasma Cutter with a 50 Amp Torch Head and the proper consumables should be able to do a 1 inch severance cut.

So my second question is... If my Plasma Cutter is capable of generating the documented 50 Amps, could swapping out the ESAB PT-31 look alike Torch Head with a 50 Amp Torch Head (with consumables that are rated to do 1 inch severance cuts) potentially increase the maximum severance cut depth (maybe not to a full inch, but just increase it in general)?

My third question is about the TIG welding consumables... Here I'm even more of a complete novice. I have never done any TIG welding. I have a Chinese HF MIG welder that I have been over using and abusing for the last couple of years. But (so far) I've never fired up the TIG welder functionality of my Chinese 3 in 1 Plasma Cutter / TIG Welder / Arc Welder combo machine.

Now I'm thinking about trying some TIG welding... I noticed when I was researching the consumables for the Plasma Cutter that there are a LOT of differences in the TIG welder consumables. It appears to be pretty common to buy TIG Welder consumables in lots that include several assortments of Ceramic Nozzles, Collets, and Collet Bodies.

My third (and final) question is a multipart question... Can all these different size components be mixed and matched, or should they always be used with their corresponding components? If they should always be used with their corresponding components, which Ceramic Nozzle goes with which Collet pairs (assuming the collet pairs are paired based on similar dimensions)? And if they can be mixed and matched or only used with their corresponding components, what are the advantages of having different sizes (I suspect this is a very newbie question and would probably be best answered by a reference to a reference to a "So you want to TIG weld web page")?

Thanks for any help anyone can offer, and if possible for not turning this into a lesson on the pros or cons of purchasing a Chinese Welder...
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Wow, what a read!

You're not on anything like weldingweb, here, and you don't need to defend your purchase like that... No one's going to flame you. We don't behave that way. There are several here who own various Chinese machines, and if you'll give a brand name and model, you might find that someone can answer your questions very specifically.

I'll answer the TIG question... It's good to have a variety of cups, for different welds. Larger cups give better gas coverage, smaller cups let you get into tighter spaces. Different collets and bodies allow you to use different size tungsten. a .040 tungsten is available for very high-precision work, up to 1/8" (even larger than that for specialized heavy work). Your best arc and puddle control comes from using the smallest tungsten that will do the job.

Everything in a "set" of TIG accessories will mix-and-match, unless you have a broad set including both gas lenses and standard collets... The cups won't interchange between the two.

Hope this gives you at least a starting point...

Steve S
TheCatcher
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    Sat Apr 20, 2013 6:08 pm

That exactly what I was looking for to make my TIG welding consumables purchase and give it a try.

I think I might have got one of the rarest 3 in 1 Chinese Welders ever made. I bought a MTN Gearsmith CT520D. I haven't been able to find company information or a web site for them. But I did find their MTN Gearsmith Trademark registration information online. So if I ever really need to get in touch with them, I can probably track them down, using the information for their Trademark registration (prior to finding a place that gave Plasma Cutter consumable measurements, I was pretty sure I was going to have to track them down...).

The MTN Gearsmith CT520D has 2 knobs on it. One is marked "A" with a range of 1 to 200, and adjusts the amperage. The other one is marked "S" with a range of 1 to 10, I'm not sure what it adjusts.... When I was using the Plasma Cutter, I just left it on 10.

Like most of the posts I've read from people who bought Chinese Welders. When I opened the box and tried to read the manual, I got hit with major buyer's remorse... But as soon as I got over the fear of plugging it in, turning it on and having it explode. I tried it, saw what it can do, and my buyer's remorse turned to complete satisfaction. These might take a little more work to figure out how to use, but if they didn't exist, at their current prices, I wouldn't have a Plasma Cutter...

I found a web site that sells a video for how to repair your Chinese Plasma Cutter circuits. The guy selling the video said that there were very little differences between any the guts of the Chinese Plasma cutters he had worked on. So I made a giant leap of faith that the difference between the stand alone Plasma Cutters and the 3 in 1 units wouldn't be too bad. From what I saw when I opened it up, I think it was a decent assumption.

I bought this to do some redesign on a trailer. Part of that redesign entailed shortening twenty 1/4 inch steel boat bunks and putting forty 1/2 inch holes in what was left of them. If I had to do that with a grinder and a drill, me and the drill would have been dead, and I probably would have killed another $20 HF 4 inch grinder (fortunately I got the 2 yr warranty after the last one died)...

With the Plasma Cutter, I clamped a piece of angle iron on the supports to help me make cut them off straight. And I made a template from a 1/8th inch thick piece of aluminum by putting 1 1/4" hole in it (with a metal hole saw drill bit). And used it as a jig to cut the 1/2 inch holes. I couldn't believe how quick and easy it was.
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    Tue Jun 26, 2012 8:05 pm

Is this your machine? if not, can you post a photo?
Many of these machines are made in China and marked with different distributors names on them. Its just a sticker...
http://www.tosensechina.com/en/product/2012-5-19/47.htm

Here are your consumables... http://www.tosensechina.com/en/products/list-40-1.htm

http://pt.aliexpress.com/item/NEW-50A-C ... 32962.html

http://www.amazon.com/Industrial-Invert ... B008OM4FWK

http://www.ebay.com/itm/3-IN-1-50A-Plas ... 3054717%26
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noddybrian
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    Thu Jan 24, 2013 12:13 pm

Hi -
the PT-31 torch started with short tips on early inverter cutters generally rated in the 25 to 30 amp range and is adequate for the job though quality varies - when the Cut.40 sets appeared in various names / brands they wanted to keep the same common consumables but the extra power overheated them very quickly so the longer tips were made to try to alleviate the problem, I think the PT-31 is being stretched to its limit even at 40amps & it is easy to overheat the torch even at 40amps unless used in very short bursts so it is unsuitable for your machine unless at less than 40amps & short cuts - if you only cut thin sheet at lower power then fine - it's a cheap to replace torch with cheap parts ( Ebay user " Shop River" has evrything you need )
So quick answer - use short tips upto 30amps on thinner sheet - use extended tips upto 40amps - allow adequate cooling time.
the price difference is so slight though I'd just buy the extended tips.

If you want to use the full potential of the 50amp cut I would look at a better torch - most torches on 50amp sets are larger than a PT-31 & generally cover upto 70amps - again check out " Shop River " for something affordable that uses a common consumable. Generally 50amps on a Chinese set will cut 12mm giving a fairly good cut & severe 15mm - maybe slightly more - the torch does effect this as the allignement of the torch parts & finish quality of the nozzle plays a part. I do think it's worth investigating - but don't expect 1" cuts !

The " mystery " knob marked 0 > 10 is going to be post flow time ( time gas solonoid remains on after process is stopped to allow torch parts to cool down ) so just leave it on 10seconds for everything .

Tig consumables - yea - minefield without knowing a little on what you intend to weld ! - however your set will likely have come with a generic WP17 torch so takes the larger parts - when looking for collets/ etc anything listed for the WP 17 / 18 / 26 torch fits - all standard ceramics / collet bodies should interchange & the tungstens are all the same.
So its DC only machine so plain cheap old fashioned 2% Thoriated is your best bet - or Ceriated if your paranoid about glowing in the dark - Jodys beloved 2% Lanthanated is also fine - but hard to find & more expensive - if your not going to weld regularly over say 150amps & longer runs then 1.6mm would likely cover all your needs - just adjust taper length slightly to suit - if your only going to use it for thin sheet then maybe 1mm / 1.2mm would be better - if your looking at long runs over 150amps then 2.4mm is as big as that machine will need - just to try the machine I'd suggest getting a 1.6mm red tungsten & a No.6 cup - this would cover nearly anything at a push - if you get on with Tig welding & you can justify the money then the stubby gas lense kit is a great way to go though very hard to find ( at least in the UK ) the only way I can order one is from "the other" Tig guys website !
Hope this helps.
TheCatcher
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    Sat Apr 20, 2013 6:08 pm

Thanks WerkSpace, that's my machine. It's nice to get confirmation that the consumables I'm about to order will fit. And the E-Bay link you referenced is from the same seller I bought mine from. The seller never responded to my original question asking for clarification about the plug wiring. But I won the auction around noon and the machine was on my door step the very next day, so I'm not going to hold anything against the seller for not answering my email question. (the seller's address is Apple Valley California, but the machine was shipped from Cerritos California, I live right between those 2 places).

Thanks noddybrian, great info about the consumables, the torches, the mystery knob. Now I just have to decide if I will go for the longer tips for my PT-31 look alike and a second torch to use for the higher amperage cuts. Or just replace my torch with a higher amperage torch for everything. I think I am leaning towards replacing my torch with the higher amperage torch and consumables. Then maybe I can use my current PT-31 look alike, down the road as the torch head in a small DIY CNC Plasma Cutter... (wouldn't it be nice to have lots of free time - and an income)

I have a feeling the ebay seller I found "River-Weld" and the "Shop-River" seller you referenced might be the same seller with different names, or at least associated with each other in some way. Their item pictures all have the same "River-Weld.com" water mark on them.

This is the 50A torch I'm planning to order...

http://www.ebay.com/itm/SG-55-AG-60-PLA ... 3a6c406df1

In addition to being 50 Amps it is also much nicer looking than the 30A torch with the zip tied-on switch that I received with the welder. I might do a little more EBay shopping, to see if I can find one with a cable attached. I will need to replace the switch cable connector, since the cables I am seeing just have 2 pins and my unit has 7 pins.

The information about the tungsten and consumable combinations is very helpful. I'm getting up there in years, I doubt I will be doing enough TIG welding or be around long enough for a little radiation to do me in (famous last words...) So for now, I will probably just go with the cheapest tungsten rods I can find, in the sizes you recommended.

Thanks! I think I now have enough information to jump on EBay and buy my consumables without worrying if I'm buying the wrong things! And now it's time for me to get back out to the driveway to do some more Plasma cutting on my trailer!
TheCatcher
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    Sat Apr 20, 2013 6:08 pm

While doing my due diligence to find the cheapest consumable prices, I ran across RiverWeldStore.com. Does anyone have any experience purchasing from them? Their prices seem really good, they have everything I was looking for, and then some. But their S&H prices seem a little high. For an order weighing under 8kg the ePacket shipping price came up as $10,000.00 USD. And the Hong Kong Post price was $100,000.00 USD.

I haven't found any reputable reviews of them... So I thought I would ask if anyone has had any experience ordering from them...
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I've been buying my supplies with FREE SHIPPING from these guys,
http://www.ebay.com/sch/3shop-river/m.h ... 7675.l2562

and very reasonable shipping from these guys,
http://www.ebay.com/sch/weldingcity/m.h ... 7675.l2562
TheCatcher
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    Sat Apr 20, 2013 6:08 pm

TheCatcher wrote:... their S&H prices seem a little high. For an order weighing under 8kg the ePacket shipping price came up as $10,000.00 USD. And the Hong Kong Post price was $100,000.00 USD.
It turns out these outrageous values for S&H are the values actually returned by the carriers. Apparently they only carry small packages and to discourage people from trying to send packages that weigh too much, when the weight goes over their limit, they return extremely high shipping costs.
TheCatcher
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    Sat Apr 20, 2013 6:08 pm

You guys were 100% correct about a 50+ Amp plasma cutter torch head doing a better job on my 50 Amp machine than the PT-31. My RiverWeld-store order arrived today. I included a new SG-51 plasma torch head (and some consumables for it) with the order, and it is severance cutting between 3/4 and 7/8 deep on my 1 inch test bar. The severance cut doesn't look pretty, but if I turn the bar over and cut from the other side, the cut goes clean through. My PT-31 torch head, with new consumables wouldn't even severance cut 1/2 way through the 1 inch test bar.
Drwoods72
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    Mon Nov 18, 2013 12:33 am

Related question for the discussion........I bought the MTN Gearsmith CT520D and had a similar thought of buyer remorse when I saw no plug. left it in the box for a couple of months and only just now decided to figure it out. I got the plug installed and seems to work but am struggling with the air connections. Turns out I am missing the gauge That screws into the back. First question, any idea where I can find parts? Second question, would it be possible for someone with a similar unit to post a pic of the back so I am sure I have it set right? Lastly, thanks for the above posts, I was struggling and it's nice to find a wealth of knowledge.
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@ DrWoods.

From reading different posts on Chinese welders (i.e. HF) I've come to the conclusion that they are not on the same page when it comes to fittings. I haven't seen the back of this type of welder, but I'm guessing it has an Oxygen fitting on it and not the standard Argon thread. There are adapters, they are not common and for good reason. You would never want to send Argon to a patient in a hospital bed and you would never want to send Oxygen to a Tig torch. So we use different threads for a reason. That being said, you'll most likely have to find an adapter from Argon to O2.

You can try to find a cheap flow meter of Chinese origins and see if it has the right connections on it, but I don't have a supplier in my mind to steer you towards.

Len
Now go melt something.
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Len
Drwoods72
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    Mon Nov 18, 2013 12:33 am

After some further digging and some help from YouTube, I find that the guage I need is built into the front and what is missing on the back is a 90 elbow. So I'm a little closer .....Thanks @Braehill
noddybrian
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    Thu Jan 24, 2013 12:13 pm

@ Dr Woods.

I don't have that exact model to look at - but pretty much all the Chinese cut 40 / 50 / 60 & the derivatives that are multi-process welders share a common design - the cheaper models will have a single fitting on the rear that goes to the gas solonoid valve inside & according to whether your using the Tig or the plasma function will need connecting to compressed air or argon which then comes out of the common torch fitting on the front of the machine - ( I hate this design as you will contaminate the argon with residual moisture & crap from the compressed air ) the better machines have 2 solonoid valves & input for the gas / air separately - below is a picture of a typical cut 40 - the air parts are all threaded 1/4" BSP & available pretty much anywhere - the regulator is needed to control the cut pressure for the plasma function - but on a mulit-process you should put a 3way ball valve where the elbow is screwed into the machine so you can select gas / air - then just go to a barbed fitting & run flexible pipe to a regular PCL fitting or whatever your compressor uses & an argon regulator fitting ( 3/8" BSP in the UK )
plasma rear view.JPG
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Hope this helps.
Drwoods72
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    Mon Nov 18, 2013 12:33 am

@Noddybrian....thx for the photo. I have narrowed it down to needing the 90 degree fitting in your pic. Any idea where I can get it, what it might be called, or if there is anything special about it?

Thx
noddybrian
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    Thu Jan 24, 2013 12:13 pm

@ Drwoods

1st off if I'm right about your machine the gauge on the front displays the cutting pressure on plasma - but if there is no knob to adjust pressure you DO NEED the filter / regulator as per my picture - the exact fittings you use don't matter - they are nothing special & most import sets just come with barbed fittings & a short piece of flexible pipe - the pictured machine is one I fitted the regulator with what I had in stock - it's not the only way it can be done.

Where to get the fittings - I'm in the UK so any truck parts supplier as the same fittings are used on truck brake systems - any hydraulic parts / hose supplier or most bearing suppliers - they all deal with pneumatic fittings - not sure where you live or if this helps.

All the parts that are threaded are BSP - but if your in the USA I imagine they are NPT
the top fitting is 1/4" male > 8mm compression ( 90 degree )
the lower fitting is 1/4" female > 8mm push fit.

Hope this helps.
RhatterNTatter
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    Tue Feb 25, 2014 11:24 am

I originally had questions about consumables, torch size etc...that have been answered within this thread. I did have additional questions though and hope this does not violate any policy by posting the questions in this thread.

I am working on building old shop trucks using 50's era trucks, doing frame swaps, bagging etc.

I run into issues with old rusted bolts and have already tried many of the things that others have suggested...including getting those special sockets from Sears, using propane to heat the bolts, using various rust cutter solutions etc. Many years ago I worked on a project with an old timer who used an oxy acetylene torch and he popped those bolts. I was hoping that a plasma cutter would do essentially the same thing. What I am looking for specifically is that I would cut the bolt head thus freeing up the holding pressure supplied by the bolt being threaded into a nut.

Figured I would pose this out there for those of you who have maybe already experienced this and you could maybe provide some tips or tricks or advice etc.

I do realize that I will be destroying the bolt and will still most likely have to work out the threaded portion if it is still in a nut that is part of the body part I am wishing to put back on the vehicles.

I have already lost skin and run out of cuss words to use on this type of stuff....it is actually meant to be fun but getting those old parts off is the un-fun part....it is mostly fun after that though.

Any advice is appreciated. I have a Mtn Gearsmith Cut 50-DX plasma cutter and am not sure how effective this is running on 110v vs 220v....couldn't find anything on that subject. This is new and would prefer to go 110 and increase the torch capacity and consumables if that will work to cut those bolt heads off. By popping...I am referencing using a process of cutting directly into the middle of the bolt head where it pops off. Would use oxy acetylene but sometimes more preferable not to have gas heat going with some of the areas those bolts are in.

Any advice is appreciated....I also am doing media blasting using dustless blasting and really need to get some dismanteling done so that I can remove paint, rust, etc from some of these old projects.
noddybrian
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    Thu Jan 24, 2013 12:13 pm

Oldish post now & your question is directly related - so I don't see any problem here - we're all mates.

You probably had all the advice before - but a good air chisel will take nuts off fast if you have access to the other side of the bolt - sometimes an air impact wrench will move or snap the bolts off - heat from a localized source like an oxy / acet welding torch helps - mark the bolt head center & drill the bolt diameter in the depth of the head can work.

if none of these methods work then an oxy torch is better than a plasma for this type of work as the plasma does'nt tolerate blowback & reflected heat well - assuming you have cheap consumables on a cheap to change torch it will work to a degree - like any pierce cut lay the torch over to maybe 45 degrees when starting the cut so the metal has somewhere to go & does'nt blow back at the nozzle - then gradually bring the torch upright on the bolt keeping a small distance off the tip - try to get a cut established in the center then draw concentic circles outward until the bolt diameter is reached - there will be some collateral damage around the hole most likely - your machine appears to be a generic cut 50 dual voltage so will be limited to 30amps cut usually when on 110 volt - this is quite low for a pierce cut - depending on the supplied torch a bit - only expect a cut of 5/16 maybe 3/8 at best.

It may not suit your job - but I have " washed " off bolt heads on various chassis parts on rock trucks etc with an air-arc gouge & it can be quite effective for this without causing much damage - even gouging rods do OK on this sort of job .
Arizona SA200
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I have never owned one of the "Chinese" machines and to be honest don't think i ever will. I am not saying this to bad mouth them but 9 times out of 10 my welding is production based. I think and correct me if i am wrong, these machines outputs are rated at their max output. The "brand name" machines usually have a higher output than stated but you must also take in to account the duty cycle of the machine. They can be great hobbyist/home use machines but don't expect them to be what the high dollar ones are.
I stack dimes for a living so i can stack dollars for a paycheck.
RhatterNTatter
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    Tue Feb 25, 2014 11:24 am

Thanks noddybrian.....hadn't tried the air chisel route yet. I have several of these project trucks and have tried various things on them depending on "where" the bolt is and how accessible. In this case, I am trying to remove the inner fenders on a 68 El Camino and those clips that I can't get to just turn...so the bolt turns but doesn't back out of the threads on the clip. May try my air chisel on them. As you can probably guess, I am trying to get some faster ways to get the dismantle process done so I can move into the media blasting, metal working, painting, re-assembly.
I bought a cheap plasma cutter only cause I don't really know if I will have all that much need for metal cutting other than to get something off of one of these trucks. I just spoke to a customer for my blasting and he said he had the same issues removing bumper brace bolts on his 47 Mack truck....saw a video about heating them to red hot then trying to break them which might work for what he was doing but won't help me with those bolts that don't come out because the clip is rusted and won't hold in place for removal.
Thanks again....
noddybrian
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    Thu Jan 24, 2013 12:13 pm

Sorry - I thought you meant heavier bolts on truck frames - if it's as small as sheet metal screws then the plasma will blow enough away to release them - may not be pretty & you will get some "collateral " damage - just start with the torch angled so the metal has somewhere to go & get a bunch of consumables ordered from " Shop River " - how about grinding the heads off ? even if an angle grinder won't fit you could put a small wheel on a die grinder or use one of the small cut off air grinders they use on exhaust parts .
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