Machine Choice Confusion ! ! !

[i_r_machinist]

Yes, what is the conclusion? Inquiring minds want to know.
i_r_

[plasmapros]

Our system DOES NOT use CandCNC. We use Mach3, but our controller and THC are much more robust than CandCNC. Mach3 is just motion control software. CandCNC is just one of many companies that use it. There are a lot of industrial machines out there using Mach3. One of the most critical components in a plasma system is the THC. CandCNC and SoundLogic (Now TX Micro) are hobby level THC's as they use Mach3 to control THC motion, which has severe limitations. Our THC operates outside of Mach3. Mach3 controls X and Y. The THC controls Z.

Check out our THC page.

http://www.trucutcnc.com/trutracthc.html

After reviewing the link you provided there was no reference to these "severe limitations" and I have seen CandCNC THC operate with no "bounce" at higher speeds and it has no trouble holding an accurate torch to workpiece distance. Please elaborate on the "severe limitations" of the THC system from CandCNC.

[plasmapros]

Cindy, still curious, please explain the severe limitations of your competitors thc systems.

[cindy carlisle]

That's great, guess it is all in what your expectations of a THC and controller performance should be @ entry level It is operating inside of Mach3 that causes the limitations. Mach sets the limitations. Our old THC worked fine as well customers are using it everyday, but this one is so much quicker to respond (operating outside of Mach).

I will try to explain in a PM The link goes into the same details as I will provide you.

[jimcolt]

Here is a copy of a post I wrote a while back in response to questions about the necessity of a Torch Height Control system on even the lowest cost cnc machines. It describes the necessary functions of a THC system.

Need for height control on entry level machines?

Torch height control is the single most important aspect of any cnc plasma cutting system...if you are concerned with cut quality and consumable parts life. A properly designed plasma height control system must work in conjunction with the cnc control as well as the part program in order to achieve the correct pierce height, pierce dlay time, cut height, and must have the means to ignore voltage anomalies caused by kerf crossing as well as machine slowdowns due to cornering and fine feature cutting.

All industrial quality (read more robust, more expensive) cnc plasma machines have full featured , well designed height control systems.....you cannot buy on of thes machines without height control. Unfortunately...many of the low cost, entry level cnc plasma machines that are designed for hobbyist or small shop applications offer height control as an option....which allows these machine builders to offer their products at lower prices. It is not a good idea to buy a cnc plasma cutter without height control....it will not cut as well and it will eat up consumables....resulting in higher cutting costs as well as poor cut quality.

A basic height control will automatically locate the surface of the material to be cut, will retract to a user set pierce height (always higher than the best cut height), will then fire the torch at the pierce height and remain in place for a pierce delay time (to allow full plate penetration before the cut starts), then will index down to the torch manufacturers recommended cut height. Once the x and y axis get to the programmed best cut speed....an arc voltage feedback control takes over the real time control of torch to work distance by monitoring arc voltage (as measured from the torch electrode to the plate), and adjusting very accurately in order to maintain the correct torch to work distance. The cnc has to be able to "freeze" the arc voltage control during normal corner slowdown and kerf crossings, as well as at the end of the cut when the arc extinguishes...this height freeze is to prevent torch diving. More sophisticated height controls also have the ability to auto - calibrate torch to work distance to compensate for normal consumable parts wear....thus ensuring that cut quality will remain constant throughout the life of a set of torch consumables.

A typical plasma height control system consists of a z axis motorized slide with mounting configuration for the plasma torch, a voltage divider /isolator circuit (to reduce the DC arc voltage signal and filter it to a usable level), an electronic control box that monitors the input, output (from CNC and plasma, and voltage divider), as well as associated cables and user interface panel. Some height control systems are "standalone" (will work with any plasma/cnc machine configuration) and some are integrated (designed to operate as an additional axis of the cnc machine.....and is operable through the motion control system software.

They are typically a fairly high price addition to an entry level cnc machine.....but make the system cut like a cnc machine should.....in a hands off automated manner.

Jim Colt Hypertherm

[cindy carlisle]

Jim I think you should take a trip to Jackson , TN. and see our system.

[trucutcnc]

I need something turnkey that my wife can run as well. She will never learn all the intricacies of Mach3.

Not sure if you're aware, but Mach3 does not really come with an "off the shelf" screenset. The screenset is the user interface and it is usually designed by the table manufacturer to meet the needs of that particular machine. Because the user interface is not set in stone, it's complexity depends entirely on the person who designed it. We've even made custom changes for customers who wanted to sort of put their own spin on it.

Before you decide that non-Mach3 controllers are easier to use, you need to do some hands on demos.

[trucutcnc]

Our system DOES NOT use CandCNC. We use Mach3, but our controller and THC are much more robust than CandCNC. Mach3 is just motion control software. CandCNC is just one of many companies that use it. There are a lot of industrial machines out there using Mach3. One of the most critical components in a plasma system is the THC. CandCNC and SoundLogic (Now TX Micro) are hobby level THC's as they use Mach3 to control THC motion, which has severe limitations. Our THC operates outside of Mach3. Mach3 controls X and Y. The THC controls Z.

Check out our THC page.

http://www.trucutcnc.com/trutracthc.html

After reviewing the link you provided there was no reference to these "severe limitations" and I have seen CandCNC THC operate with no "bounce" at higher speeds and it has no trouble holding an accurate torch to workpiece distance. Please elaborate on the "severe limitations" of the THC system from CandCNC.

The limitations are clearly outlined in the text on our THC page. The limitations are in Mach3 and it's ability...or inability...to operate at high speed with no acceleration/deceleration. THC's such as CandCNC, Sound Logic, Proma, etc. rely on Mach 3 to handle the motion control through it's THC UP and THC DOWN input signals. Since Z moves under THC control are simple ON/OFF commands, if it were to make THC corrections at max feedrate, it would overshoot and bounce like a pogo stick. Anyone who has tried raising THC FEEDRATE to get a faster response has seen this.

To make these THC's work (1) a programmed dead zone is needed and (2) a reduced feedrate must be used. The right combination of the two results in system that works OK under normal conditions cutting relatively flat material. The problem is that a dead zone and a reduced feedrate both start to become an issue when your cutting becomes not so normal, like high speed, light gauge material and corrugated. Both effect the THC's ability to react quickly to changes in height.

A dead zone work by setting voltage range in which the THC will not react. This basically allows the Z to overshoot the target arc voltage without causing it to react and correct in the opposite direction. The reduced feedrate minimizes the over-shoot, but it also slows the reaction time of the THC.

All of this is governed by the laws of physics. You can't stop a moving mass instantly without some degree of deceleration. The same theory applies to any moving object. When you approach a stop sign in your car at 60MPH, you see the sign and you decelerate as you approach it. Now take a run at the stop sign at the same 60MPH and have your wife yell "STOP" as you pass the stop sign. How far past the sign di you stop. Now back up at full speed and have her yell "STOP" again as you pass the sign in the opposite direction. You can see how that end up.

Now slow your speed down and add another stop sign 20 feet from the first. Now instead of stopping at the first sign, the goal is to stop somewhere between the signs. Now you're stopping within range, but the exact stopping point may not be the same every time. You reduce the chance for oscillation at the cost of accuracy.

[plasmapros]

I understand the laws of physics and your example of the car at the stop sign however I fail to see how you can compare a car travelling at 60mph toward a stop sign to a torch moving up and down a few thousands of an inch in a THC system...there is such a small distance travelled with each small adjustment of the torch. Your example would be much better compared to the X or Y axis which moves more weight over long distances at higher speeds....but OK...some may buy it I was just shocked to see you bash other brands and use this information as your reasoning.

[trucutcnc]

I understand the laws of physics and your example of the car at the stop sign however I fail to see how you can compare a car travelling at 60mph toward a stop sign to a torch moving up and down a few thousands of an inch in a THC system...there is such a small distance travelled with each small adjustment of the torch. Your example would be much better compared to the X or Y axis which moves more weight over long distances at higher speeds....but OK...some may buy it I was just shocked to see you bash other brands and use this information as your reasoning.

The amount of distance you move doesn't matter. Mach3 makes THC moves at a fixed speed. When the THC says move, Mach3 turns on the Z motor with no acceleration. Whether it's moving 1" or .01" it is moving at the same speed. When the THC says stop, Mach turns the Z motor off with no deceleration, which makes it overshoot the target voltage. The torch is also not moving a few thou. The dead zone is probably 10 times that.

PID controlled systems don't operate at a fixed feedrate. The feedrate varies based on arc voltage. As the gap closes between TipV and SetV, the feedrate slows down, effectively decelerating the load so it stops at it's target. PID controlled systems can respond to changes in height as small as a few thou because there is no dead zone.

The slower the feedrate and wider the dead zone, the less bounce. Any of the Mach based THC's can be tuned to run with no bounce, but at the expense of accuracy and response time.

If you don't believe it, in your THC settings, set the THC Feedrate to 100 and the deadzone, if it's adjustable, to 0. If the same laws of physics don't ally simply because of the small adjustments being made, everything should work fine.

I'm not bashing competitors. CandCNC is not a competitor as we do not sell controller kits. I'm simply stating a well known fact regarding the workings of Mach3's THC feature. The brand of THC doesn't matter. Mach handles the motion and that's where the limitations are.

[cindy carlisle]

I understand the laws of physics and your example of the car at the stop sign however I fail to see how you can compare a car travelling at 60mph toward a stop sign to a torch moving up and down a few thousands of an inch in a THC system...there is such a small distance travelled with each small adjustment of the torch.

Ross tries to make it easy to understand, he does it for me all the time. I understand Physics as well, but it helps to have simple example. As I told you before, it is all in your expectations of your THC. The TruCut THC is integrated in our controller while working outside of Mach. Thus making it capable of being one of the BEST THC's available at an affordable price when comparing it other more costly THC's.

Get's back to this simple statement

"WE BUILT IT, WE ARE PROUD of WHAT WE BUILD"

. Just ask our customers

[plasmapros]

Thanks for taking the time to explain it over and over again, I do get it, just don't agree with it. One thing I learned that may be true is that Mach is more limiting than I originally thought and that you guys found a way to possibly "improve" upon its limitations. As for bashing...that may have been a harsh term however specific manufacturers were mentioned by your company with claims that their THC was inferior with "severe limitations"....sounds like a bash to me but let everyone else can be the judge of that. It's one thing to show off what you have but when you start to compare it to others and make claims about their inferiority that's another thing, very unprofessional in my opinion.

[trucutcnc]

Thanks for taking the time to explain it over and over again, I do get it, just don't agree with it. One thing I learned that may be true is that Mach is more limiting than I originally thought and that you guys found a way to possibly "improve" upon its limitations. As for bashing...that may have been a harsh term however specific manufacturers were mentioned by your company with claims that their THC was inferior with "severe limitations"....sounds like a bash to me but let everyone else can be the judge of that. It's one thing to show off what you have but when you start to compare it to others and make claims about their inferiority that's another thing, very unprofessional in my opinion.

I thought I was pretty clear in saying that the limitations were within Mach3, not the actual THC. A specific manufacturer was not singled out. We do our best to try and educate the buying public and it's not intended as bashing. We improve upon Mach3's THC feature by not using it. Mach controls the X and Y and the THC controls the Z axis drive directly.

Just because you don't agree with it, doesn't dispel the science behind it. From my post above.....

"If you don't believe it, in your THC settings, set the THC Feedrate to 100 and the deadzone, if it's adjustable, to 0. If the same laws of physics don't ally simply because of the small adjustments being made, everything should work fine."

[CNCCAJUN]

When I started this thread it was to get some input to assist me in my selection of a CNC PLASMA TABLE, so since it has somehow moved away from that to a "who has the best THC", I will offer my thoughts / opinion.

As to who has the best THC, that would be a company call Hypertherm and for about $15,000.00 you can be the proud owner of it. Now all you need it a table and an operating system.

I feel more comfortable giving $10,000.00 to $30,000.00 to a company that has been around a long time that has also developed it's on control software (motion & THC). Some see that as proprietary and a negative. I don't as long as the table can easily be revised to run on another software system should something happen to that company.

As to Mach3, (my opinion) I see it much like Arduino microprocessor, it can do everything, just not anything really well.

Much of this will be a moot point by the latter part of 2014. I know of two groups that were campus incubators attempting to design the "greatest" 3D printer. They lost out on the grant they were chasing and turning their attention to developing a X,Y, & Z package they can market. My understanding it will be aimed at CNC Water Jet, Laser & Plasma. The idea is to bring CNC to the masses . . . Target price is less than $1,000.00

As to building your own machine, I think if your intention is to work the machine in a full time business, it is a poor idea.
The most you can save by building a comparable machine is a 33%. So on a turn-key machine selling for $20,000.00 you are looking at a savings of less than $7,000.00. Since all the build threads I have followed by the average Joe not owning a fab shop is approximately 4 to 6 months, I see very little advantage in building my own. If I can not earn $7,000.00 working everyday in my shop over a 6 month period, I would probably be better offer with a broom stick with a nail in it picking up cans on the side of the road.

So, I will be buying a CNC Plasma Table at the 1st of the year. I'll keep you guys posted as to how it goes.
If the machine I buy performs like promised, I will cheer for them everyday, if it does not, I will give them hell twice a day.

Thanks for all the input,
Steve in Louisiana . . .

[trucutcnc]

The original comment was to just point out that a good THC is critical....and I agree that Hyperthem probably has the best industrial THC on the market. You can't go wrong with any of their products. The Sensor PHC is a great unit and if memory serves, is in the $5K range. In your search for a table, just realize that there are table manufacturers who offer THC's that operate on the same principles as THC's from Hyperthem, ProMotion, Burny, etc. and offer similar performance.

[CNCCAJUN]

In your search for a table, just realize that there are table manufacturers who offer THC's that operate on the same principles as THC's from Hyperthem, ProMotion, Burny, etc. and offer similar performance.

NO, say it isn't so . . . .

Steve

[cindy carlisle]

Good Luck Steve in your final decision
If your wife ever needs any help, I have a group of women who run
CNC for artistics projects when their husband is not using it for the business.

[CNCCAJUN]

Thanks . . . my wife, heck . . . .put me in touch with anyone that has an imagination . . .

Everything I design has Zerk fittings or just plain square & boring . . .

Steve