[Torchhead]

:cheers: .... I have been searching everyone else builds trying to decide on mine... I'm wanting to build a 3x4 or a 4x4 table very much like yours, just scaled down a bit... Question is... I'm going very low budget, If i done my gantry pretty much like yours (except for the Z)... Could i not go direct drive for my X&Y-axis?.... This 3 axis kit i'm looking at has either NEMA 24's 382oz or 425oz steppers... This would be enough "muscle" to move everthing i need right?... What would be the Con's to direct drive over gear reduction?..

Also, and i hate to ask, i'm sure this is pretty stupid.... but searching, i came up with nothing.... Buying a 3 axis kit.... = 3 steppers.... so, If X runs 2 steppers and Y runs one...... well, I'm out for my Z!.... would i just buy another for my Z... or buy a 4 axis kit?.... I guess what i really want to know is do i run both steppers for X off the same stepper driver or do they require there own???

I would like to hear from anyone on this... Thanks for taking the time to right me before i wrong!!!

1. The important factor in plasma cutting (besides the cut speeds) is the acceleration. To get sharp turns and square corners at higher speeds you need acceleration. Acceleration is provided by FORCE (linear force converted from the rotary torque through the drive mechanism) TIMES the MASS (equals the weight on a horizontal load). Without going into Physics formulas here are some things you should know:

A pinion gear presents a speed INCREASE and corresponding TORQUE and RESOLUTION DECREASE. So a 1" pinion rolls 3.1416 inches per rotation. You will have LOTS of speed (Up to 1800 IPM) but for that you give up 2/3's of you Torque and 2/3's of your resolution. So your 425 oz-in motor suddenly becomes a 140 oz-in motor. The only good news is that at the low RPM's you will be moving for normal cutting speeds you will get most of the motors rated torque from it.

If your gantry is light enough then it will hit the 20 IPS/sec acceleration rates you need for good plasma cutting. If it's too heavy then you will have to roll back the acceleration setting and live with rounded corners.

You cannot run two stepper motors off one driver. Motors are generators so they tend to cross talk badly and mess up things like microstepping. You could maybe run them in series (the coils) BUT that changes the power characteristics and does not yield double the torque.


A twin drive (with two drivers) will give you double the torque on moving the gantry so you will have a much better shot at getting the good acceleration you need.

TOM caudle
www.CandCNC.com

[Weldtutor]

Well I am in the process of building a skirt that will wrap around the torch/tip to help stop water splashing and sparks shooting sideways...

What do you guys think of the skirt idea?? Help stop water spraying, sparks shooting, helps save rails and equipment on the machine etc....

Dustin,

A skirt should be a good addition, to work as you suggest.
The sparks that skip sideways across the surface of material being cut are actually tiny metal particles. They certainly do accumulate on equipment leading to problems and as well are not normally captured by a water table, resulting in more air borne plasma dust in the work area.

"Go for it.":idea:

[low79fx]

Finished painting/primer.... I cut my v-rails to length/Drilled every 8" on C, I decided to go with 1/4"- 24 button head bolts. Going to drill my 1/2" X 1/2" 20 pitch rack gear this week and hopefully start the gantry build on monday. Trying to hurry with the build because I have two large bids in process....

Dustin407,when you say cut to length were able to find rack strips and v rail strips that were the total length or did you butt joint them?And how does the machine react as it transitions past and thru the the joint if thats what you had to do? The reason I ask is I cannot locate any rails longer than 6 ft could you help me out as I'm trying to start a bill of materials and parts list to try my luck at a build. By the way I am very impressed with your craftsmanship and attention to detail on your build very high quality!!

[Dustin407]

Dustin407,when you say cut to length were able to find rack strips and v rail strips that were the total length or did you butt joint them?And how does the machine react as it transitions past and thru the the joint if thats what you had to do? The reason I ask is I cannot locate any rails longer than 6 ft could you help me out as I'm trying to start a bill of materials and parts list to try my luck at a build. By the way I am very impressed with your craftsmanship and attention to detail on your build very high quality!!

You probably wont find to many precision rails over 6' because there are a couple of reasons for that. One, the precision rails are not precise the longer the length (short length=precise tolerance), factory reasons for machining... Two, most companies have to ship this stuff so ups and Fmail charge double or triple over 6 to 8 feet in length. My table is 10' long for the rails so I ordered (4) 5' sections and then just milled the ends perfectly for a butt joint. The joints after playing with them and machining them for a few hours are perfect... Way more accurate than a cnc plasma could ever be (tolerance). As for the rack and pinion I ordered a 6' and 4'. This was a little more tricky to machine, the rack butt joint. The pinion gear flows right over without any glitches at all when done properly. Most of my cutting happens at one end of the table but I do get some larger parts 7-8' in length sometimes, and you cannot see any side chatter on edge quality from any joints....

[low79fx]

dustin407


The floating torch assembly on your z axis,what exactly does it do and how does it adjust and maintain its height? As does it have some kind of preload tension, I don't see a motor for adjustment other than z axis motor. I do note that when torch touches work and rises there is slight movement on vertical torch slide. How is this achieved? I sound like a little kid asking the same thing over and over but I just gotta know how it works.

[millman52]

dustin407


The floating torch assembly on your z axis,what exactly does it do and how does it adjust and maintain its height? As does it have some kind of preload tension, I don't see a motor for adjustment other than z axis motor. I do note that when torch touches work and rises there is slight movement on vertical torch slide. How is this achieved? I sound like a little kid asking the same thing over and over but I just gotta know how it works.

I'll try to answer your questions in general terms.

The floating head part of the "Z" axis allows the Z axis to move the torch into contact with the plate & trip a micro switch. This micro switch tells the "system" you have touched off on the plate & in turn moves the Z axis back up a pre determined distance, or to pierce height above the plate surface. (depending on your particular build. No two machines will be exactly the same)

The height is then most usually maintained by arc voltage. If the gap between the torch tip & plate surface increases or decreases the voltage varies & "the system" adjusts automatically up or down to maintain desired voltage. This value is pretty much proportional to gap or distance from tip to plate.

[low79fx]

millman

Cool so once micro switch is trip goes to predetermined height or gap,upon rising to this setting gravity allows torch assembly to drop down to its resting place on small vertical slide leaving the z axis set and in full control from this point on thru the cutting process.Of course relative to all the other factors you mentioned,am I understanding this correctly? Oh thanks for responding to my questions I am trying to grasp the mechanical aspect in relation to the control concept. You guys have made this cnc concept attainable to almost anyone willing to take the plunge. It is making a believer out of me.Thanks again!!

[joedesu1]

Dustin,
Your machine is clean as hell. I am about ready to start my own build. Most likely a 4X4 but I might go with something different like a 5X3 or 5X4 table. I am a grinder so probably going to make my own linear rails and such. I was wondering if the bearings for the rails are a must? I ways thinking about grinding a groove into some hardened steel and bolting it to I-beams that are ground flat and parallel to <.001 and grinding the opposite profile into the another piece of hardened steel then bolting them to the gantry arms and just lube the ways up as a means of keeping location. The fit would be about .0005" maybe tighter if I can get away with it. Is this a bad idea? I am trying for the ultimate DIY build to save myself the $, and my system seems a bit more accurate and true then vee rails, I am thinking rack and pinion on the y and x axis and acme screw on z. Is that a good idea as well? Any input would be greatly appreciated. Thanks

[Richard Honey]

joedesu1,

If you're looking at grinding your own rails have a look at this site: MechMate CNC Router - Build your own with our detailed plans

The guy (Gerald D) is based in South Africa and has made an outstanding machine not dissimilar to a ShopBot router. A lot of very capable and smart people have added their collective brains to the discussion and the results from these builders are pro quality.

The design utilises affordable V bearings that run on home made vee rails.

The web site details how to create your own X, Y and Z rails from flat bar. The various alternative grinding processes use bench saws fitted with an abrasive disk, 4 inch angle grinders and (gasp) conventional surface grinders.

Given that you have the skills and access to grinding equipment following the MechMate advice you should have all of the rails finished by lunchtime ;P .

Due to the dusty nature of routing and plasma cutting I wouldn't put sticky grease on any exposed bearing surface lest it becomes a nightmarish dust magnet.

Cheers,

Richard

[low79fx]

Dustin,
One question other than cost do you think servos would have made any difference on resolution and accuracy results after everything has been said and done.I was just wondering whether this cool build of yours would have a next level if any that one could take it to.I am sure you are happy with the final outcome but is it possible to make a good thing better? I am just wondering if servo ever crossed your mind.So far the one of the best builds I've seen yet.Still picking it apart!!

[Dustin407]

Dustin,
One question other than cost do you think servos would have made any difference on resolution and accuracy results after everything has been said and done.I was just wondering whether this cool build of yours would have a next level if any that one could take it to.I am sure you are happy with the final outcome but is it possible to make a good thing better? I am just wondering if servo ever crossed your mind.So far the one of the best builds I've seen yet.Still picking it apart!!

Hi Low,

Servo vs Stepper.... servo crossed my mind for about 3 seconds and that was all... I dont think it matters on a plasma build because there is" no cut force on the head". Alot of people forget this, I see some gantrys that weigh like 200 lbs + using 4 x 6 1/4" steel... Why???? I think if you had a router table and torque issues were a problem maybe I would consider servos but on a plasma table I think its a waste of money. Basically the motors are just moving the weight of the gantry around. The steppers on my machine have about 3,183 steps per inch on x y and a axis, that is very good resolution. Even if the system/stepper missed a few steps you would never even notice on the cut parts. I think there are alot of other important things to focus on a plasma build than the motors to have a great design and mechanically sound machine. (BTW im glad I went with 5 to 1 ratio, if i had to do it over just to fine tune some things I would use a 1-1/4 dia pinion gear to)

[low79fx]

Dustin thanks for the insight and the info I will sure take all this into consideration when I approach my attempt at a plasma build.As I said earlier your build has really inspired me to try my own build.Really dig the complexity and attention to detail that you took yet keeping it simple.Thanks again for an awesome display of mechanical engineering and craftsmanship.

Hi Low,

Servo vs Stepper.... servo crossed my mind for about 3 seconds and that was all... I dont think it matters on a plasma build because there is" no cut force on the head". Alot of people forget this, I see some gantrys that weigh like 200 lbs + using 4 x 6 1/4" steel... Why???? I think if you had a router table and torque issues were a problem maybe I would consider servos but on a plasma table I think its a waste of money. Basically the motors are just moving the weight of the gantry around. The steppers on my machine have about 3,183 steps per inch on x y and a axis, that is very good resolution. Even if the system/stepper missed a few steps you would never even notice on the cut parts. I think there are alot of other important things to focus on a plasma build than the motors to have a great design and mechanically sound machine. (BTW im glad I went with 5 to 1 ratio, if i had to do it over just to fine tune some things I would use a 1-1/4 dia pinion gear to)

[Dustin407]

Hello All,

Looking to purchase new machine come Monday or Tuesday... I sold my old TD unit to my father for a reasonable price of $800 so I am plasmaless right now ... I have been researching the 45 and the 52 both awesome machines but I have to make a decision very soon for a Bid that was awarded to me to cut out 650 brackets... I know there are alot of people on here with hypertherms so ill take that into consideration on my decision making... I have read nothing but good things on the 52 over the 45 price is better, can severe cut thicker, better warranty, lighter unit... Please tell me why I should get the H 45???? I would love to listen to any input at all...... Lets not have a arguing match on this subject just pros and cons... Thanks (group)

[I Lean]

I can't directly compare the two since I haven't owned both--but my Hypertherm PM45 has exceeded my expectations in every way. Cut quality, consumables life, and duty cycle.

When I was researching, I found quite a few people complaining about their TD units, and wishing they bought Hypertherm. (and found none the other direction) Those posts, combined with Jim Colt @ Hypertherm's unparalleled support on several forums, convinced me to go that direction. I haven't regretted it for one second.

[Dustin407]

Thanks for the relpy Ilean I appreciate it.... So I decided to buy the TD 52 yesterday with shipping and tax plus everything I needed it came out to $1,582.00 Thats pretty good for what the machine is capable of, plus the 4 year warranty parts and labor is nice also... They said it should come in on thursday... woohooo...

[Dustin407]

Hello All,

So I finished fabing up the plasma skirt with the water/flame resistant (flame2) material. I tested it out a little and it works awesome, I highly recommend that everyone install one... I left the front open a little just to check and see how things are cutting plus helps me locate 0 on the xyz... I used contact ahesive to attach the fabric to the alum. ring.. 1) because it is easy 2) this acts as a safety feature just in case the fabric gets caught on a sharp corner of metal the fabric will pull away from the ring without hurting anything... Also I may add a small airhose with a 3/4" vacum line to the top of the alum. ring to grab any extra smoke. It will be small enough where I can run this into my e chain for a clean looking finish. Small vacum should do the trick, beats the hell out of a 5 hp blower/downdraft table...

Help!!!!!!!!!!!!!!!!!!!!!! :drowning:

So I picked up my cutmaster 52 the other day and hooked up the thc sensor card (rev 12 board, mach 3, candcnc 4 axis, mp3000) and get everything dialed in correctly... I connected to the J10 pins inside which is a bank of 8 pins (1 & 3 is ok to move, 6 & 8 is torch on off) pretty simple.. connected the tip volts to the work and electrode, done ( second machine ive done so not a complete noob lol)... So I went to do some test cuts and it will cut fine for about two pierces and then on the third or forth the torch will almost fire but doesnt and the g code continues to run like the torch is on.. Plus the torch symbol on the mach 3 program says its on but not...?? (help) Also sometimes the torch will fire for a millasecond and then turn off and the external e button will come on... Anyone give me some Input Please until I can talk to Tom, or TD tech support... Also my compressor I am using right now sucks so it only gets to about 80 psi, when it drops down the red led light shows up on the machine for low air... Do you think this could be the problem from the torch firing or not????

[Torchhead]

Hello All,

So I finished fabing up the plasma skirt with the water/flame resistant (flame2) material. I tested it out a little and it works awesome, I highly recommend that everyone install one... I left the front open a little just to check and see how things are cutting plus helps me locate 0 on the xyz... I used contact ahesive to attach the fabric to the alum. ring.. 1) because it is easy 2) this acts as a safety feature just in case the fabric gets caught on a sharp corner of metal the fabric will pull away from the ring without hurting anything... Also I may add a small airhose with a 3/4" vacum line to the top of the alum. ring to grab any extra smoke. It will be small enough where I can run this into my e chain for a clean looking finish. Small vacum should do the trick, beats the hell out of a 5 hp blower/downdraft table...

So what do you do with the smoke that forms under the cut piece and drifts around until it finds a hole to waft out of? That is not going to get sucked up in a concentrated spot at the torch. If you watch on a complex piece the smoke comes out all over the place; even the edges...just saying....

So I went to do some test cuts and it will cut fine for about two pierces and then on the third or forth the torch will almost fire but doesnt and the g code continues to run like the torch is on.. Plus the torch symbol on the mach 3 program says its on but not...?? (help) Also sometimes the torch will fire for a millasecond and then turn off and the external e button will come on... Anyone give me some Input Please until I can talk to Tom, or TD tech support... Also my compressor I am using right now sucks so it only gets to about 80 psi, when it drops down the red led light shows up on the machine for low air... Do you think this could be the problem from the torch firing or not????

I don't think you need to talk to me to figure this one out You HAVE to have adequate air. The unit is tying to tell you it is starved for air. It happens after the first few cuts because the compressor can't keep up and the pressure starts to drop. You need about 10 lbs more going into the regulator than you are going to get out (especially if you have a dryer in the line.)

TOM caudle
www.CandCNC.com

[Dustin407]

So what do you do with the smoke that forms under the cut piece and drifts around until it finds a hole to waft out of? That is not going to get sucked up in a concentrated spot at the torch. If you watch on a complex piece the smoke comes out all over the place; even the edges...just saying....

I don't think you need to talk to me to figure this one out You HAVE to have adequate air. The unit is tying to tell you it is starved for air. It happens after the first few cuts because the compressor can't keep up and the pressure starts to drop. You need about 10 lbs more going into the regulator than you are going to get out (especially if you have a dryer in the line.)


TOM caudle
www.CandCNC.com

You are probably 100 percent correct about the smoke, it was just one of those spontanious ideas that I had while typing... Just like the plasma skirt.. But the skirt does work well keeps the sideways sparks and water isolated in that area to help save the equipment for long term use... (rails,bearings etc...)


Well it did that a few times but then after the compressor charged up all the way and turned off I ran the g code right away.... It did not even fire ( about ten times), so thats y im questioning if it is the compressor or not?? Plus it has never fired with the THC on only off... IDK still hacking at it.. My large kellog American compressor that makes 27 cfm is under valve work..:violin: So thats y im stuck with this piece of **** compressor and its drivin me crazy. How I miss the little things....

[Dustin407]

Hello All,

So I decided to upgrade my new cutmaster 52 to the 82 (80 amp machine) it cost me an extra $520 but it is nice to know I have an extra punch when it is needed sometimes, plus the duty cycle is great... I was having a problem with my torch firing so I did a bunch of tests. I rerouted the grounding wires and drove in a new grounding rod 10' into the ground and tadaa... fixed all problems, cutting good now.:wee: Here is a few pics of some western art work I cut out for myself to hang around the house ( I think it is 10 ga ms)... Enjoy....

[Weldtutor]

So I decided to upgrade my new cutmaster 52 to the 82. I rerouted the grounding wires and drove in a new grounding rod 10' into the ground and tadaa... fixed all problems, cutting good now

Dustin,
Looks as if you are back to having fun again!
A bad ground can bite your b**t :tired: even when everything else is set correctly.
Thanks for the update & enjoy your new Thermal Dynamics 82.
WT