Hello everybody, I have had my Dynatorch for a couple years now. I have the downdraft table but I have not been able to find a good deal on an exhaust fan and I'm not really sure where to start with the setup. The smoke and dust is starting to get kind of old. I have thought about selling the downdraft part and building a water table as well as just building a tent around the table out of welding curtain with a smaller exhaust fan connected to the top of it.

I also need to get a larger air compressor and figure out why this thing likes to crash like once per sheet of cut and mess up the entire sheet, I think thats caused from a tip or electrode goin bad but I'm not sure I usually just replace them and its good to go but the damage has allready been done. It just crashes and drags along the sheet and usually moves the steel and I have to hit the E stop as soon as it happens( if I'm really lucky I can get through a sheet without it crashing, biggest sheet I have cut so far is 4x4). It's mainly the reason I have to babysit this thing while its cutting, and the fact that I have to pause the feed to let the compressor build up more pressure every couple min. Thanks for the help.

I have the air handler also, for the time being i have just used a old furnace fan and some cheap homedepot duct to vent it outside, its not perfect but better than nothing.
Have you talked to anyone at DT about the crashing? What are you using for a plasma and what are you settings for the steel you are cutting?

EDD

I haven't really talked to them about it I've only called really cause mine fried a couple motors. hasn't done it since i spent a ton of money to get a new servo board thing though.

How does the furnace fan work? I wonder if I found 2 old ones if I could T them out of the air handler into 2 seperate lines and if that would help keep the shop a bit cleaner(plasma dust outa my lungs and off the computer)

my plasma is a hypertherm 1250

Mine works ok when cutting 1/16th or 1/8th steel with fine cut consumables, there isnt much smoke or dust and the fan keeps it cleared out, in the winter when all the doors are closed i spray water on the sheet as i am cutting and it makes a huge difference combined with the air fan, but i cut up some 3/16 aluminum a few months ago using a 80 amp nozzle ( it was all i had and wanted to try it ) and it was like a shuttle launch in here, there was no way the fan could keep up...even with spraying water on it... eventually i will build a new shop designated for my cutter, at that time i'll spend the money and install a proper vent system or convert my table to water, or combo..

I bought a 60 gallon 3.2 hp compressor from home depot, i had to change the psi switch as the original would let the psi drop to low before kicking on, but it works great now, i have a cheap motor guard filter and just recently installed 2 desicant air dryers, i run 40 feet of air line up and away from the compressor and back to the dryers and then the filter and i dont have any moister to speak of...

I have the 1250 also and the only time it crashed on me was when i play around with the settings as im cutting, so i try not to do that anymore.. or if i am cutting to close to a edge and run off the plate a little... i found that if doing fine detailed cutting, close to a edge that if i turn off the thc it cant dive, that after a year of cutting...lol... learn as i go...

I havent used my table for a little while now, been away and now doing some other little jobs around the house, but next week i hope to fire up, will gladly share what ever little experience i have with you. When i get going again i will send you my settings for the gauges of steel i cut using fine cut..

What are you using for CAD CAM ? i use corel draw 3x and sheet cam... its taken awhile to learn corel but i am getting the hang of it now..

Regards
EDD

slamedxonair, If during your cut you have a momentary drop in air pressure below the requirements for your Hypertherm the torch will crash.

that could be part of the problem. Most of what I cut is 3/16 and 1/4" plate once in a while some 1/8" or 16 ga. In post #41 here I use alof of these as good starting points http://cnczone.com/forums/showthread.php?t=26227&page=4 I have to keep my THC at around 138-140 sometimes though or it will crash. It used to crash alot more than it does now. And would any moisure in the air effect the thc as well? I have like 3 water traps on the line in different places before it goes into the plasma. I thought about taking a big tote bucket of cold water and tossing the coiled up hose in it to see if it helps reduce moisture as well as a temp fix. I wish I had the $ for this thing lol http://torchmate.com/air_filtration_system/index.html

Does anybody know if a 16" 2500-3000 cfm 12v exhaust fan would work? Like if I work the ducting to it and run a power inverter to it?

Mine works ok when cutting 1/16th or 1/8th steel with fine cut consumables, there isnt much smoke or dust and the fan keeps it cleared out, in the winter when all the doors are closed i spray water on the sheet as i am cutting and it makes a huge difference combined with the air fan, but i cut up some 3/16 aluminum a few months ago using a 80 amp nozzle ( it was all i had and wanted to try it ) and it was like a shuttle launch in here, there was no way the fan could keep up...even with spraying water on it... eventually i will build a new shop designated for my cutter, at that time i'll spend the money and install a proper vent system or convert my table to water, or combo..

I bought a 60 gallon 3.2 hp compressor from home depot, i had to change the psi switch as the original would let the psi drop to low before kicking on, but it works great now, i have a cheap motor guard filter and just recently installed 2 desicant air dryers, i run 40 feet of air line up and away from the compressor and back to the dryers and then the filter and i dont have any moister to speak of...

I have the 1250 also and the only time it crashed on me was when i play around with the settings as im cutting, so i try not to do that anymore.. or if i am cutting to close to a edge and run off the plate a little... i found that if doing fine detailed cutting, close to a edge that if i turn off the thc it cant dive, that after a year of cutting...lol... learn as i go...

I havent used my table for a little while now, been away and now doing some other little jobs around the house, but next week i hope to fire up, will gladly share what ever little experience i have with you. When i get going again i will send you my settings for the gauges of steel i cut using fine cut..

What are you using for CAD CAM ? i use corel draw 3x and sheet cam... its taken awhile to learn corel but i am getting the hang of it now..

Regards
EDD

Hi,

If you are using the DXFTool with CorelDRAW there is a FREE upgrade available that you really should give a try.

-James

k thread jacked lol. but does anybody have an answer to post #7?

Not really an answer. But what are the specs on this? Does it show a duty cycle? 12V (to me) seems like an intermittent duty voltage. Is it a blade type or a impeller fan or even a hamster cage? That is a lot of volume to move with 12V, what was the previous application? Just throwing it out for thought.

WSS

its like the ones that go on cars to cool the motor down Ive seen some with those specs. It was just a idea I thought of for something temporary for a while. I really need to build some kinda filter or exhaust or soemthing before the winter. It gets pretty cold trying to build parts with the doors open to vent the smoke out lol.

If its the the type of fan i think you are talking about i have my doubts it will work or last long, not only for output but because the if fan motor isnt sealed and is within the dust flow it will probly get clogged and burn out. Just my thoughts...

EDD

Yea thats the only thing I was thinking of, the motor gettin caked all up. I just eed to get something figured out before winter. Last year sucked.

slammed,
If you have 3ph, here is a good one, and if your close to Ohio it would ship cheaper as well.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=110395689348&ssPageName=STRK:MEWAX:IT

It doesn't list the cfm but I bet it is close to 4000. I know it takes a lot of air movement to work on a down draft. With a welding head you can get away with 1200cfm because you can get at the source (top). I can see were the volume of air moved would be a problem in a cold climate. Our shop air gets changed every 60 seconds which is helpful to us. I had a 2" plate that was 650 degrees sitting on a table all day today. I ran a fume extractor over it just to keep the temp in the shop down. It is hard to believe that other shops have a problem with a water table freezing over the weekend!

no 3phase here my old shop had it. I think I need 2500-3000 cfm. Thats not a bad deal either and about 45 min to around 1 hr away from me :(

Check out my thread on Air and Exhaust.

This is money well spent and everyone should add these items to the budget.

http://www.cnczone.com/forums/showpost.php?p=315215&postcount=195

http://www.cnczone.com/forums/showpost.php?p=338275&postcount=228

Medical bills later in life will be way more than the dollars it takes to add safety.

My setup allows me to regularly run at 95 to 105 THC voltage. I to have three seperators 10/4/1 and have had no problems with the little I get to run my system.

I still have a lot to learn and I like the new designs coming from DT. I need to get my system at least to a dual X drive setup. I have some issues with slop on the drop side of my table. I purchased the tube cutter and I am not really using it. I am going to call and see what I need to make my system dual X drive.

MetalHead

Good to see you posting again, thanks for the links...

EDD

yea I bought a 3m breathing resperator filter thing and it seems to work great for my lungs anyways. but I still need to get something setup. eventually before winter so i can do something with the smoke.

I also have an Air dryer you'll see in the theads. The Metal dust that is in that smoke is what will get you. I am sure Jim Colt has some threads or comments about it also :) I know he's out here......

But if you think about it a Plasma vaporizes steel... Where does it go? Into the air as tiny particals in the smoke. That in turn will not only get in your lungs, it will stick and build up on anything with a static charge (Think Magnet) ... and think Electronics among other things. Once enough of it gets built up on stuff in the shop all sorts of wierd "Unexplained" things will quit working. Computers and Monitors are among the first to suffer since they are close to the machine. Just some thoughts.

I saw some very basic skirts with big fans that would help that is basically sheets of duct screwed to the legs of the table with one of those big fans from a Big Box store. Probalbly can do that for less than a grand.

In the Air front

http://www.pattonsinc.com/

http://www.ingersollrandproducts.com/IS/Product.aspx-am_en-12878 (Tractor Supply has a good seletion of IR stuff)

I went IR, but doing it again (Found them after I installed) I'd talk to Patton. But the main thing you want in your air system is an air dryer and filters. Clean air is KING :) . I would also not go below a 7.5 HP unit on either brand. My unit had a motor failure as it had a 5hp unit in it. After the fact my sales guy told me my unit was an entry level unit (Not happy about that for sure) anyway the 5hp fried and I hade to have a motor then so I ended up buying one at a shop here in town to the tune of about 300 bucks. Moral of the Story..... You will spend the dough on good stuff weather you do it the first time or not.

Search out either and tell them what you are doing and see what they can offer. Do not go below a two stage unit and add a muffler. (You can see the blue one on my unit in the thread I posted before). I can stand beside mine and cary on a conversation while it is running.

Yea I try to keep a cover on my laptop when I'm cutting and I keep the control box covered all the time as well.

Does anybody know if this will work? I have been emailing the guy about it, he didnt know the CFM rating but gave me a part number that I cant seem to find online anywhere. http://sandusky.craigslist.org/for/1400234965.html Model # 4C639A

I generally am pretty fried by the end of a day so I don't often get to these forums BUT.. tonight I was curious. Some ANSWERS for you.

1 FANS - The downdraft air table was designed based on area. A 4x8 table requires 3500 CFM @ 2" static pressure. A 5x10 table requires a 4500CFM fan @ 2" static pressure. Best choice for efficiency (smallest motor) is a backward inclined fan. This type will be quiet and lowest amperage.
For a 4x8 A Grainger model 7H165 or equivalent is needed. (2 HP)
For a 5x10 A Grainger model 7H166 or equivalent is needed. (3 HP)

If you find a used backward inclined centrifugal blower with a 15 to 20 inch wheel, it should work. Call me however to size the drive for proper RPM.

2- THC crashes. This is most often a problem of too low of a voltage setpoint. If it just randomly "jumps' then we have a problem with electrical static getting into the voltage line. This can usually be filtered out easily. Call me for instructions. It's a $2 fix.

Leon - Dynatorch Inc. Tech line

well that blower for my 4x8 table won't work. I don't have 3 phase electric....

That part number was just an example. However any fan used to move that volume of air will have to be 3 HP. Basic laws of physics and efficiency levels of fans. You may find a 3HP motor in single phase and just buy a fan without the motor. Then get pulleys and a belt to run the fan the required RPM. Otherwise, use a phase converter to get 3 phase from your single phase for the fan.

I was just wondering has anyone ever attempted installing a close meshed electromagnetic field under the cutting slats that can be turned on during the cutting process to collect the "plasma dust" while cutting steel. I realize this would not work with stainless or aluminum, but if it helped 90% of the time it might be worth a shot.

Hey slammedonair,

Slow day in the shop, I came across your thread while I was trying to look busy. Here's a couple of pics of our set-up. We have a 4x8 table running a 1000 hypertherm. I regularly cut thicker pcs. up to .50 thk, every once in a while I've had to cut .75. It works, but you have to play with the settings to make it work.

The table is a downdraft witha pull out drawer for the slag. Not sure what the exact specs on the fan are. If you need them I can search around for them. Pretty sure we picked it up at Grainger, and if memory serves I told them I needed a big "barn fan". It moves enough cfm's to suck all the heat out of our 140' x 60' shop though. THe duct work is 24" x 24", and we mounted the fan inside the duct. Easier to work on if we ever have a problem....especially in the winter.

hope this helps ya
Mike

Forgot to finish typing!!

The fan is mounted in the darker steel box you see in pic 2. My advice on the fan choice is to go with the biggest possibility that you have power for. If it doesn't perform the way you need.......get 3phase or open the door!

Mike

Water table-

No electric bill
No 3ph
No ducting
No heat loss in building
No warping

No, No, No...........

Just a thought!

WSS

Yea I wish I would have known all of this before I got my downdraft table... off Dynatorche's web site "Uses a low volume customer supplied vacuum source (exhaust fan)."
I wouldn't call a 3 phase 3500 cfm blower a low volume exhaust fan....

what is static pressure and why does it need to be 2" ?

All fans are rated by CFM and Static pressure. Both must be specified as the fan has a performance curve. As static pressure (back pressure or suction pressure) is increased, air flow volume decreases. Maximum pressure (or suction) is acheved at zero CFM (blocked inlet or discharge). On the other end of the scale, maxiumum flow CFM is acheved at zero static pressure. The air table system has a small amount of static pressure loss that must be overcome. This is the 2" water gauge pressure. Low pressures are rated at inches of water column. That is the pressure required to lift water in a tube by X inches.