Hi…I was simply contemplating whether anybody on here has one and can answer two or three brisk inquiries for me. Here is some foundation, we are seeing getting gear to do our spaces in house going from .060 right to .125 5052 H38 Aluminum. What is the base thickness you can cut or would .060 twist since it is excessively slender? Additionally what amount completing would be needed to deburr it? Would a snappy crushing of the surface normally get the job done?
Hey Kevon,
I am going to be honest I am having a hard time understanding your questions. Could elaborate and re-word?
Thanks!
I watched your open builds CNC video. Is it plausible to increase the size of the table just by increasing the length of the drive screws or are there any limiting factors in the motors or software? I’m a fabricator and this will be first foray into anything electronic so I’m just curious if increasing the tables capacity is a purely physical matter or not.
Hey Mitch!
There are diminishing returns when using a longer lead screw. A lead screw that is 1m in length doesn’t require any special consideration, but lead screws that are 1.5m and 2m long will experience a lot of whip (the lead screw wobbles up and down when jogging the axes - not good at all). To get rid of some of the whip, you can tension the lead screw (see product description of OpenBuild’s tensioning system). However, at >2m you have to apply too much tension and the aluminum rails will box.
So to answer your question succinctly:
Not plausible due to limitations of the lead screw. If you want a really large table (>2m x 2m) look into rack and pinion transmission
hello i have a couple questions about the cnc plasma build.
i just need a few things cleared up to make sure i understand things correctly.
i’ve used grbl in the past so im good on that end.
i see that you have a post for fusion 360. so i assume that has the probe cycle coded into it, ie head moves down till it trips the limit switch. is that limit switch just wired to the standard probe pins?
when you start up the control software like universal g-code sender do you just set a random z height as datum point for a safe retract height, program starts probes and resets the z to the correct height for cutting?
do i need a special version of grbl?
how is height after probing set, combo of placement of limit switch/change in the post possessor?
if i understand correctly not having thc the biggest issue is if the plate starts warping ?
also if any one can suggest a good cheap plasma cutter that be great i know some of the cheaper ones can cause issues. i help run a non profit maker space, every thing is done by donations so it would be easier to get a better plasma cutter later on as members start to use it and see its full potential.
Yes the limit switch is wired to the standard probe pins.
The retraction and clearance heights are going to be set in fusion360. You can see some images below of the “retract” and “clearance” planes. The Initial Height Sensing (IHC) is a limit switch that gets triggered when the plasma cutter comes in contact with the metal will set that as the Z=0. When the torch needs to move to separate tool paths, the Z-axis will move the torch up 5mm (in my example).
Nope. The pre-loaded GRBL on the BlackBox is fine.
The post possessor outputs a G38.2 Z command and it will use that IHC limit switch to probe.
Yes with thin gauge material (especially aluminum) the plate will lift off the table as it warps. THC is really important for large tables, but if you build a 1000mm x 1000mm table, I found that no THC is perfectly fine.
Yes I have an entire guide on this: click here.
so when you start up the machine,
you home it, then set you g54 xy and do nothing with z since since the probe cycle will take care of that if i understand you correctly?
let me reword this.
how do you go about setting what the gap between the torch and surface would be after the probe cycle is done.
do you just shift the limit position , or edit a line of code in the post. ie limit trip move z some many inches. like how where do you fine tune this.
thanks in advance.
I just wanted to put my 2 cents in here. I have built a small cnc plasma and purchased a larger one. Both had THC and I would never build one without. The quality of the cut on any machine is very much tied to an continuously accurate torch height. I won’t go into how this works. I know that LinuxCNC is a popular choice for DIY but I get really frustrated with the constant issues of these systems. You get what you pay for. (Sometimes) I recently purchased a 5x5 table that uses a very simple control interface by Proma. It is called the MyPlasm (not misspelled) Anyone who wants to jump into plasma with a simple and inexpensive control system should consider it. To be fair, be aware that this system is extremely simple. It really cannot manipulate the cut path beyond changing the order of the cuts, kerf width, and leads. It also comes with THC. I haven’t had it long but so far the THC is working well.
The MyPlasm control system is fairly new and a work in progress to make it more customizable so if you want to be able to control every little detail of your system, it is not for you. After I put my table together and filled it with water, I cut my first part within 1hour. Import dfx, set kerf width and leads, set cut parameters and zeros and go.
I believe that the software, motion controller and THC is less than $350. It has an interface for on and off control.
I believe that you can import .tap gcode from sheetcam which would give you some extra control of your cut path. It will however ignore any speed, pressure and amperage code. These are a constant set in the control software itself.
One last item, if you want 100% control over the plasma cutter, including air pressure and amperage, the only way that I am aware of is with a Hypertherm PM 45XP (or higher) and one of 3 control systems.
CandCNC is a high quality control system with the option for complete control of the above mentioned plasma. These use linuxCNC and commandCNC software. I have used it and it is very robust but I found myself working on it more than with it. These systems will run you about $3-4k including the steppers. They also have a nice Zaxis you can add.
Flashcut is another one. I have not used it but it has rave reviews. Just about anything imaginable is available. I am considering this system for my table. It is a substantially more expensive system but well engineered. This one will run you $8-10k for a stepper system. They have servo system too.
The last one is one I’m not really too familiar with. I believe there is open source Linux CNC code out there that will allow you to communicate with the Hypertherm 100%. This does not provide you with the hardware but I’m sure it is possible. This is basically what CanCNC did.
Be aware that the Hypertherm XP’s don’t all come with the ports to make the communications possible. There is a CPC port for on and off. And the serial port for air pressure, mode and amperage control as well as fault codes. Both ports can be added to any XP machine. If you are not going to go to the expense of complete control, you do not need the serial port.
Hope this helps. There is a lot of information (and opinions) out there and different ways to get to a functioning system. If you plan on cutting a lot of thinner metals (16ga and less) you need to really make sure your motors and drivers are high efficiency and have enough power for the speeds and acceleration required to cut these metals. (Sometimes 400 IPM+) I know the Hypertherm has a nozzle system to for fine cut low speed parameters which helps lessen the need for high speed equipment. It will not help with aluminum however since the fine cut nozzles are not recommended for aluminum.
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Thank you for making it clear on how to connect up the cut50L.
Do you by chance have a list of parts you used for the z axis you built for the table you built and took to Florida?
I’m using a lot of parts from openbuilds.
i was thinking of adding a Compact THC SD. since its stand alone and i could use it if i switch between grbl, linux, mach 3/4
I have heard good and bad stories about the proma THC 150. Most say it is slow. I have the one that comes with the proma myplasm system which is supposed to be different. It seems to work fine but I haven’t really put it to any real test like corrugated metal.
Hey Richard,
I apologize for my delayed response, but the Z-axis from the table that I took down to Florida is the same as my first table. You would need the parts for the Z-axis of the lead CNC from OpenBuild’s website and the floating head components listed in the BOM section on my project page.
However, all the red plates in the design used for the X and Y axes are not yet available on the OpenBuild’s website.
Follow this link for updates
Thank you for your help. Your YouTube are very helpful and I very much enjoy them.
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This is excellent information. Thank you for taking the time to explain some of these different commercial systems.
I do think it should be pointed out that with the lead screws used in the OpenBuild’s table that the maximum speed you will be able to achieve is 6000mm/min (250 IPM). However, I am still able to cut 16ga and 18 ga material with minimal dross. I have to decrease the amperage of the plasma cutter slightly for the lower speeds. You will need to make sure that you use the appropriate consumables for this lower amperage - using a set of 40A consumables when cutting at 30A can mess up the dynamics of the plasma stream. HyperTherm offers some lower amperage Finecut consumables.
When is a THC neccessary?
In my opinion a THC is only needed when cutting material prone to wrapping, like thin material (20ga and up) or when you have a large plasma table. For my small 1000mm x 1000mm table the parts lay flat enough that they stay in that plasma sweet spot. Keep in mind that to use a THC you need dry air because moisture can result in erratic voltage readings causing the torch to dive into the material. Multi-stage air dryers are expensive and that combined with the need for a more expensive controller and the THC unit itself, this upgrade can cost a pretty penny. It may not make sense to have a THC if you are just doing some hobbyist cutting on a small table like I am. Just my two sense. If you are making money off your table, then the upgrade is a no brainer.
I agree with everything you said here. I just want to point out that warping is not the only thing that can cause fluctuations in torch height. After using your slats for many cuts it can cause an uneven surface as well. Most metal isn’t 100% flat either. That being said, you can still cut without THC it just may have some variation in cut quality. I watched my Z axis motor yesterday while cutting some 16g and it was constantly making small adjustments.
I plan on cutting quite a bit of .016 aluminum. Cut speeds will be very high even with lower amperage. Fortunately there won’t be many sharp corners, just long sweeping curves. Getting the metal to lay flat will be a challenge. If I can’t get the steppers to do this I will be upgrading to Teknic servos. This along with stiffening the table legs etc should help. I’m a little disappointed that Hypertherm doesn’t have lower amperage consumables for the XP’s. They do have the fine cut consumables but they are not recommended for aluminum for some reason. I will just have to burn up my 45 amp consumables running them at lower amperage so I can get the speeds down below 400IPM.
Todd Candee
Todd@thecandees.com
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Would you mind sharing some pictures of your plasma table(s)?
It would be awesome to see your setup.
Hi, I’ve seen that grbl is not compatible with thc. how do you have solved this issue with blackbox?
have you ever try planet snc usb snc mk3/4?
Unfortunately, you cannot use the Blackbox (and as you pointed out GRBL) for THC. You need a new firmware/controller.
I have not. I do plan to try out LinuxCNC with the OpenBuild’s table, which does support THC. This would require a Mesa board. Check out some of my CNC Mill videos for info the Mesa boards.
Hi David, I bought a Cut50L for my CNC plasma but I am having a hard time determining the correct air connection fitting to screw in the built-in air dryer.
How did you connect yours to your compressor?
Thanks in advance for great projects!
Hey David #2!
Welcome to the forum. I used these 1/4 inch NPT, quick connections from amazon: see here. Is that what you were looking for?