Tale of The Franken Torch

[islander261]

Hello All

This is my tale about the creation of a "Franken Torch" for my old Torchmate (TM) 4 X 4 table. Now for the boiler plate so someone's widow or a corporate lawyer with a wild hair doesn't come knocking. This tale is intended for educational purposes only, do not do this! You can be exposed to things that can kill you. You may also violate various patents and end user agreements you have with others. All references to manufactures and their vendors are based on my experience and in no way should be taken to be representative of their official or unofficial policies. Wew, now that all of that is out of the way we can get down to business. This will take several installments as this is still a work in progress.

Now because this is bound to come up as part of the my perceived problems here is the equipment list and general operating conditions. I am mostly concerned with cutting 14ga hot rolled steel used for yard art and other decorative purposes, never do I cut simple rectilinear pieces as you do in a routinely in a fab shop. My air is dry, precooler, water trap/filter, refrigerated dry, desiccant drier, filter and onto the plasma unit, a Thermal Dynamics (TD) A-60. The air pressure at the input to the plasma unit is 120psi and drops to about 110psi when cutting. I use a TD AVHC box with the blue screen for torch height control. The torch is a TD SL100SV machine torch. I always default to book setting when trouble shooting problems. I have never knowingly used non OEM consumables. This whole system is about 7 years old now, I bought it used in 2010. I didn't know a thing about CNC plasma cutting when the system was purchased, my wife wanted me to make rusty steel knick knacks to sell at our local flea, excuse me, farmers market. It took a year to get a building built to hold the equipment with all the permitting and building season crap we have to go through here. The building is on it's own 200A service and is supplied via oversized (350mcm)conductors from the disconnect at the road, the starting current for the compressor was the deciding factor. As this was a new construction all the electrical work was permitted and inspected. I hope you all get the picture, plenty of power and clean dry air.

I am a tinker, always looking for a better way to do things. I also live on a fixed income so I can't just go out and replace major pieces of equipment. The work I do is small with lots of fine detail so kerf width and dross are big concerns. Later I discovered another big concern, consumable life. The life of the parts was never long, several hundred to 1000 pierces typically, some sets lasting longer than others. Some of my work has over 100 pierces per part so this can get expensive in a hurry. When I am busy in spring and summer I can blow through two or three sets a day. This isn't helped by the method my torch height controller uses for sensing the plate. Smashing the torch tip into the plate until it stalls to zero it's self for each pierce. Yes, I know about the torque setting in the AVHC and run it at the lowest recommended setting.

I found Plasmaspider.com a few years ago and it has been a tremendous help in figuring out how to work my equipment and suggestions for process improvement. One thing that became apparent early on is the prevalence of Hypertherm (HT) equipment used by the locals. The other thing I noticed was the apparent lack of factory involvement by TM and TD as compared HT. I asked for suggestions for improving the performances of my gear and received many well intended replies from the few TD and TM users here. Believe me I tried them all, some of them I really worked the problem. Different tip sizes and types, current changes, cutting height changes, singly and in combination. I swear I've cut a few thousand speed test lines doing this. Yes with some combinations I can get smaller kerfs and with some combinations less dross. But overall the best performance and highest tolerance to consumable wear and production cutting conditions always occurred at or near the book recommended settings.

The quest for better cutting performance and increased consumable life continued. Cutting to the chase it became apparent that the current industry "standard" for air plasma cutting thin plate is one of the HT power supplies with a Duramax torch using the HT Finecut consumables. So I looked at replacing my A-60, torch, and AVHC. This was way to rich of a proposition for me. I couldn't even get .25 on the dollar as trade in at the local welding supplier, they sell both TD and HT equipment, for gear that looks brand new with all original docs and packing. There had to be a way!

I kept looking around and found that TD sells a torch they call the "One Torch" that can be adapted to many different manufactures power supplies by purchasing a connection adapter kit. The "One Torch" is very similar to the torch I have. It even uses many of the same parts and consumables! Well I wondered if you can use a TD torch on HT power supply why can't you go the other way and use a HT torch on a TD power supply? Then I discovered that both torches use blowback parts for arc starting in a similar way. So off to find an aftermarket Duramax torch to fit to my setup. Sticker shock has a way of being a repeat surprise around plasma cutting equipment. I just couldn't justify nearly $750 for an experiment that I didn't know would work. I kept looking around and downloading lots of manuals for different torches and power supplies. More to come.

John

[I Lean]

I'm paying attention....

[islander261]

Hello

Well as I mentioned in my previous post I really wanted to try out a HT Duramax torch with their Finecut consumables. But there is a little matter of cost for an experiment that I don't even know will work.

I started researching (lots of PDF downloads) everything I could find on the web on both the TD torch I have (SL100SV) and the HT Duramax torch. What I found was that both these torches had parts with similar functions, both have a torch head that connects the consumable parts to the air and current by way of a housing that also can carry the shield. The TD torch has an extra part that is the blowback arc starter. The HT torch moves the main electrode instead of using a separate part. I never had any problems with the TD arc starter part and am still using the one that came with the torch. The big difference is that the TD automation torch has an air at the torch. Does mean that torches without a solenoid will not work with my TD A-60 power supply? Panic is setting in, looking on line and at my manual convinces me that non solenoid equipped torches will work with my power supply.

Now that I had looked at various manuals I was ready to see actual parts, or at least photos of them. The TD torch was easy as I had one, so I took it apart for a look! See photos below. The solenoid is a pretty generic looking one with push connect air fittings (SMC I think). The torch head is a molded plastic with metal inserts for electrical connections and strength. The part that I need to know was what are the threads that connect it to the mounting tube? Got out the measuring gear and low and behold the thread is 1-3/16-16UN or near that, the same as the butt stock on a AR-15, used a spare lower for a final test. Now this leaves the funny grey piece with the brass fitting on the right hand side in the middle of the photo. The obvious part is that it connects the air solenoid to the torch head and provides electrical connection to the torch head from the torch lead, see permanently attached blue wires. The connection to the torch head appears to be a proprietary connector by TD or someone else. The piece is also mostly covered by a piece of heat shrink tubing. I didn't cut the heat shrink off to look underneath because I didn't want to risk killing the torch. The part is not listed as being available separately but only as part of the torch lead assembly ($$$$$). Using a light and looking through the grey piece it appears to be the same small diameter (1/4"??) all the way through. Now why does this part have such a thick wall or is there something else going on here? Does anybody know why this piece is made this way? I am sure TD has a proprietary reason to go all the trouble instead of using a piece of off the shelf tubing. I still didn't have any photos of the HT parts.

Now I am normally adverse to any form of gambling but I really wanted to get a look at the HT torch parts now. It was very unlikely that anyone was going to disassemble their torch and photograph and measure the parts for me. So I got out the PDFs and started a shopping list.

1 ea. Retaining Cap 220854
1 ea. MRT Main Torch Body Replacement 228793
1 ea. MRT Mounting Sleeve 228735
1 ea. Duramax Sensor Switch Replacement 228720
1 ea. Finecut Consumable kit 850920

Everyone here knows how to use the internet to find the best deal so I won't bore you with the details. The parts came to less than $210 with shipping so I rolled the dice so to speak. While I was spending money my wife was out selling cut outs so this ends today's installment, time to put the torch back together and cut some parts.

John

[jimcolt]

I would have been happy to answer any technical questions about the Hypertherm, short of sending you the prints! Sounds like an interesting project and it may/may not work, but I am curious. Keep in mind that the open circuit DC that is present in the torch (Electrode negative, nozzle and work cable positive) can be in the 300 to 400 VDC range.....and at the max current rating of the power supply you are using. Dangerous, and probably why you are seeing some rather heavy insulating materials....to meet CSA and CE safety specs.

- Victor/T-D uses a start cartridge that was originally designed so they could end run around Hypertherm's blowback electrode starting patent. The original patent has expired (although there is a new one for the spring electrode) so there is no reason why they could not simplify their design.

-In a blowback torch...in order to re-fire while the torch is in postflow....the air solenoid has to close, and air pressure has to allow the moving electrode to seat itself against the inside of the nozzle. Hypertherms torch designs can do this rapidly even though the solenoid is back in the power supply.....the T-D start cartridge is sluggish at reseating the electrode....so they had to add a solenoid at the torch. At least that is what it appears to me that it is doing!

-The Hypertherm torches are carefully designed with the Hypertherm power supplies. There is ramp up current and ramp up air pressure at the beginning of every cut cycle that lessens the thermal and chemical effects on the electrode hafnium. The levels and timing are critical and are controlled by the microprocessor in the power supply. I suspect that the starting mechanism on the T-D power supply is quite different.....it will probably fire and run the Hypertherm torch just fine, however I expect a fairly substantial difference in electrode and nozzle life. I am guessing the Hypertherm consumables not last nearly as long as they do when in a complete Hypertherm system. I have no idea if they will last longer than the T-D consumables in the original torch. There also is a timed ramp at the end of every cut cycle with the Hypertherm.....I would expect similar issues related to not having this when operating on a T-D system.

So, just be careful! If you have questions about Hypertherm, fire away. I can'y wait to see the results!

Jim Colt

[islander261]

Hello

Now for today's installment I must apologize to everyone because I failed to take photos of the HT parts as they arrived. Their arrival coincided with me having to take an unplanned two week trip on very short notice. Looked at the HT parts and I am impressed at having a mostly metal Torch Main Body. I wasted no time installing the Cap Sensor Switch (Parts in Place Switch) onto the Main Body with the supplied screw. Now the HT Torch Main Body is attached to the Front Mounting Sleeve with 3 screws. My main interest here is what I will call the back side of the Front Mounting Sleeve which is where I will need to attach to. This area is threaded with what appears to be a 1-1/4- 16UN female thread. Since both the TD Mounting Tube and the HT Front Mounting Sleeve have female threads I will have to make a nipple with two different threads to join them. So to the lathe, the resulting nipple is shown below in the photo with the HT Front Mounting Sleeve. What isn't apparent in the photo is that the nipple is bored through with a 7/8" diameter hole.

The next problem is how I attach the cutting current and air to the Torch Main Body. Again out come the trusty measuring tools, the connection is a typical 45 degree flared tube fitting. Time for a McMaster-Carr order because the local hardware store doesn't have one of these for 3/16" tubing ( a #3 size for you hydraulic guys). Please see photo below of the Main Torch Body with the Cap Sensor Switch installed next to the Front Mounting Sleeve ( I have already cut off the HT supplied connector for the Cap Sensor Switch and soldered on extension wires in photo).

Next was to build the kludge to connect the Main Torch Body with the solenoid from my TD torch. From what I could tell this thing had to do several things. It had to connect the air from the solenoid to the Main Torch Body, it had to connect the cutting current from the TD torch lead to the Main Torch Body, and it had to insulate the solenoid from the cutting current. Again sorry there are no in process photos, I was on a run. I decided to use 1/4" tubing for all the connections because of availability and that is what TD used. I had to bore out the 3/16 (#3) tube fitting nut to take the 1/4" tube. The tube was flared for a 45 degree flare and the nut installed on it. The other end of the tube was slightly flared to help the 1/4 high pressure Tygon insulating tubing hold onto it. I tinned a large spot on the copper tube assembly and bound on 5 pieces of 16awg teflon insulated wire ( only high temp wire I had) with soft buss wire before soldering. Then the insulating tubing was slid onto the copper connector and the male hose barb to push fitting was installed in the other end. Both ends of the insulating tube where bound with soft wire wire to make a lock (I didn't have any mini hose clamps) and covered with heat shrink to help insulate every thing. Please see photo below of my connecting kludge.

The time had come pass the point of no return (or maybe easy return). Out came the cutters and the TD kludge was removed from the torch lead. I then spiced and extended some conductors and attached my kludge in its place. Please see photo below. I next started to reassemble the torch, again more photos. Final is torch mounted to table. I have more in process photos of the assembly if anyone is interested just PM me.

Jim

Thank you for the offer of help with HT products. I am aware of the high voltages present when the system is open circuit, hence my caution in first installment. I do have a question though, what is the recommended air pressure to operate the torch head with Finecut consumables? The TD power supply has a manually adjustable air pressure for the torch and is not preset like the HT units.

Till Next Time
John

P.S. Sorry for the out of order photos.

[jimcolt]

John,

The pressure (for the Duramax torch, all consumable power levels) is set at the upstream end of the torch leads....and is different based on the length of the lead. 68 psi for a 25' lead, 71 psi for a 50' lead and 74 psi for a 75' lead. We rely on this pressure and the lead fill volume for proper ramp up and ramp down of air flow....which is co-ordinated with amperage ramps. This is used to resolidify the hafnium emitter on the electrode at the end of each cut cycle....which greatly enhances electrode and nozzle life. Since yours has the solenoid near the torch....bets are off as far as that timing goes. I would suggest running at 68 to 70 psi.

Jim Colt Hypertherm

[islander261]

Hello

Now the question on everyone's mind, did it work? Well yes it does work, at this point it is not the silver bullet I was looking for.

I ran the torch at what I understand the correct conditions are for the Finecut consumables in the speed limited mode. The torch height is as close to .075 as I can get. This means I can slip a #49 (.073") drill bit under it but can't slip a #48 (.076")under it. The pierce height is set to .10". I ran at 150ipm speed. I set the air pressure on my TD A-60 power supply at 70psi. I set the cutting current to 40A on the power supply. The pierce delay was set at 0, and as you can see by the cuts this is still plenty long, I have real doubts about how fast the TM controller and software work.

The photo of top of the sheet for the speed test has the slowest,52ipm, on the right side and the fastest, 170ipm, at the left side. The cut direction is from top to bottom. The plate was still wet so that is why it appears the cuts didn't go all the way through. The photo of the bottom of the sheet for the speed test has the slowest on the left side and the fastest on the right side. Again the cut direction is from top to bottom and there is water in the cuts. I did a number of these tests so I could get a good feel for the arc voltage to set the AVHC. I set the AVHC to 70V for the lines about at about 150ipm. All of the series of speed test lines looked about the same.

Now for real world cutting. See below for the pile of parts I cut before burning up the nozzle and maybe the electrode. To put things in perspective this will be almost $1,000 of finished goods at wholesale and we will sell some of them at retail our selves. My cutting session ended with the dreaded green arc and no more cutting, a change of consumables and all worked again. The dross was manageable but still there, the parts are small and my table can only accelerate at about 16ips^2 so it takes about 1" to get up to full speed on a straight and may never get there on short curved segments. I got a total 2,137 pierces out of the consumables before they died. Remember I have a TM AVHC which smashes the torch into the work piece to find it for every pierce, I am sure that this had a significant effect on the nozzle life looking at how beat up it is in the photo.

Jim

Thanks for the tip, I guessed about right. I am going to make a new kludge connector and try without using the torch mounted solenoid an see how things work. I know the other TD torches that can be used on the A-60 power supply do not have a torch mounted solenoid.

[East German]

Hallo

Congratulations good work.
I once tried a another Torch on a China Plasma Cutter.
It has cut but very poorly.

Regards Peter

[jimcolt]

Make sure you are using this shield (220948 near the top) ....and try to get the height to .06", I know that the Torchmate AVHC leaves a little to be desired, but the Finecut parts are very sensitive to height, as well as speed. The 948 shield will not allow the nozzle to touch the material...and will further improve life. Still....decent number of starts. The nozzle looks like it has too much pilot arc current....

Jim Colt

all finecut cons.jpg (25.59 KiB) Viewed 2465 times

[islander261]

Hello

Short post tonight. I am using the suggested consumables, they came in the boxed set I bought.

Well I tried not using the torch mounted solenoid today. The whole sequence and what happened was very different from what I have seen before, not that I have ever run anything other than my TM set up. I will try and make a video, a big leap for this fossil, and up load it tomorrow if I can. I think that what is actually happening will get lost in my words if I try and describe it. Bottom line is that it did cut but with a decrease in cut quality, much more dross. I tried higher, lower, tweaked speed, arc voltage and lowered water level to no avail. I really tried to vary cut height and couldn't get any visible improvement. Maybe if Jim can tell me what to photograph I can get some visual feedback for the experts here that will be meaningful.

This is one thing that is definitely happening. I cut 14ga hot rolled. Not the stiffest stuff you will put on your table. I have tried many things to get the sheets supported well. Right now I an trying 6ga expanded steel ontop of my slats to support the flexy stuff but it is changing shape with every sheet I cut as well. The TM AVHC just keeps pushing the sheet down to find the surface and then it rebounds ruining the set cut height. I have the torque setting as low as will work reliably, yes I can set it lower but the air fires ruin the TD consumables on the first air fire and the HT ones are only good for several air fires.

I am getting to the point point that the real problem is the hardware and controller software I have. I have found the TM controller SW very intuitive to use and the manual is very good if you read it. The problem is when you get past basic loading DXF files and accepting the cut you get things get a bit wierd ( I now use external CAM to generate g code because the TM generated code is so bad). The TM AVHC was most likely a good unit in its day, certainly simple to use, but even TM seems to have abandon it now. I am now faced with much bigger problem, at least in bigger $ terms than my franken torch experiment. I think that CANDCNC has one of the most sophisticated low end hardware/SW setups available now and certainly has many satisfied customers, I am still very leery of Mach 3 coming from a machine control background. Every machine tool builder except Tormach I know has abandon it in favor of a closed system for reliability if not other reasons. I still read almost weekly on the pro machining forums of folks abandoning Mach 3 for much higher priced proprietary solutions because of reliability and other squirrly behavior problems. I want to find a good stand alone torch height controller that will work with my TM setup, though I am not get overly hopeful at this point. I can fix a post processor for SHEETCAM to generate any required code. I have much experience in PP work fixing modern CAD files to old machine controller solutions, MasterCAM is not one of them, I am an old PROE hand from way back. If I had an extra $7K I would buy an HT PM 65 and CANDCNC setup in a heart beat.

This reminds me of when I used to work as a systems engineer and had to work with corporate management. The old proverb of you can have any two out of three was always lost on the MBA ears. You can have it fast, or high quality, or low cost but never all three. Then again these where systems that had thousands of unique parts and hundreds of thousands total parts.

Edit. THE MBAs love the SW guys because their margins are so high. There is only development and maintenance cost, most of which you can charge for, no recurring cost. Well maybe what does a DVD cost? Well you have no idea how many quarterly review meetings this was crammed down my throat. They always seemed to forget the program cost and lost opportunity cost from the SW being late, really late like over years, in the development cycle. Ever had an ass chewing over a part costing $1 VS $.99?

John

[islander261]

Peter

We have seen some of your work. Please post more details. While being a native english speaker my last class was in 1972.

Regards

John

[OTHill]

Just gotta love the thinking out side the box.

[islander261]

Hello

Here are links to video of the Franken Torch running. The first one is the AVHC display showing the cutting voltage. The second one is cutting. Sorry for crappy video, i don't have an editor.

https://www.youtube.com/watch?v=UMF8ja4 ... e=youtu.be

https://www.youtube.com/watch?v=IJ4wGcI ... e=youtu.be

This is with no torch mounted solenoid. As you can see below the cut quality isn't very good in this configuration.

John

[BTA Plasma]

Look at your ramping/acceleration/decelleration rate and youll find them very anemic. Any change of direction or small tool path ends up taking more hammering/grinding work the lower the acceleration rate is. What is your rate and your cut speed. That will determin the areas you will need elbow grease on.