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LOL!!! I'm sure I have a lot more of those moments to come!
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LOL!!! I'm sure I have a lot more of those moments to come!
I want to give a HUGE thanks to BBchevy for taking the time out of his day to help me thru some of the set-up of my table! Getting closer every day to lighting the fire on this thing!.....now I just need 85A worth of power to my Hypertherm and I'll be set!
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Well, I've gotten this far:
Finally worked up the courage to push the "Run" button.
vacextar - I like the design of your table a lot - could you point me to "Ron's drawings"?Originally Posted by vacextar
Thanks!
Library Mark
I think all of the drawings can be found at the precision plasma website. If not, you can contact Ron thru that website and he can point you in the right direction. Still running the table on a daily basis (even in freezing temps) and no problems so far. The only thing I've had "go wrong" is one of the set screws on one of the X axis pinions came loose and I had to retighten it. If I had to do it over again, probably the only thing I would have done differently is go with the bigger (600?) kit from candcnc over the 320 kit....for no other reason than to get the bigger motor with a bigger shaft so there would be a bit more for the set-screws on the pinions to work with. I have not found that I need the additional torque of the bigger motors, but over the long haul, it makes sense to me that the bigger motor with a......I think 3/8" shaft would just plain last longer and have more bearing surface than the tiny motor shafts that the 320 motors have.
Vacextar: If you have a Hypertherm 45/65/85 plasma cutter than I have posted a FREE Cut Profile Library for the DTHC based systems, that has all of the settings fot those models. There is a readme in the folder but all you do is copy it over to your MACH3 folder. If you have already setup some of your own Cut Profiles then read the README first. It's on the CandCNCSupport Yahoo Forum in: http://groups.yahoo.com/group/CandCN...UT%20PROFILES/
Open the HYPERTHERM PROFILES folder to get to the files and README
Saves a lot of time inputting values.
TOM caudle
www.candcnc.com
Thanks Tom! I do have a hypertherm 85, and for thicker material, the numbers out of the ht manual work pretty well. The problem I have is running pretty much anything over 200ipm. Thinner sheet metal is about all I cut, and the values in the profiles you linked to......well, for what I cut, it is calling for 300+ipm on most.......so I'm still stuck making up my own profiles......but for the thicker stuff, I will definitely keep my eye on that file.....thanks!
One thing I would like (now that I have your hand controller) is a way to use it to turn the torch on and off, and also a way to turn the "tip saver" on and off. Do you have a solution for those? Thanks!
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The feedrate is only "informational" in our profiles. It is there as a reference (so you don't have to go look it up each time) but feedrate is set in the G-code.
I would suggest you switch to the Fine Cut tips and drop the feedrate to 225. We cut a lot of 14ga and 16ga with a 65 and don't have motion issues. one thing that gets overlooked is that acceleration and velocity are interlated. Acceleration is a function of time and distance. The LENGTH of the acceleration curve is determine by the top speed (velocity) you have defined. That curve remains the same even if your feedrate is lower. Yes, the time becomes compressed BUT the SLOPE of the curve is the same. When you have higher feedrates and matching acceleration then the mechanics of your system start to be a factor. At higher RPM steppers lose torque which in turn forces acceleration to have to be lower or you get the dreaded "lost steps" The Z needs to be rigid enough to keep the torch from vibrating on sudden direction and spped changes. Grab your torch at the bottom and try to move it back and forth then side to side (motors on and locked) too much play will cause toolpath deviations. A tight table is required for tight cuts.
In a lot of circumstances there are adjustments on a table for the bearings that can take out slop. Some designs do not allow for that.
Another consideration is that mechanics designed for router may not work as well for plasma cutting (and vice versa). Speeds, and forces are a lot different. A lot of "kits" list plasma as a check off item but do not understand the true dynamics of plasma cutting.
There is no magic number I can give you for the optimum velocity and acceleration for a table. It even varies somewhat from table to tale with the same design. We do know there are minimum numbers for acceleration below which you get rounding. That minimum number will be a factor of the velocity. Also remember that the SYSTEM velocity and acceleration are based on a BLENDED number. What that means is that a coordinated move requires you to move the two horz axis (in plasma) at the whatever it takes to make the tool arrive at and follow a toolpath based on the slowest axis.
There is another phenomenon. Your actual surface speed can be faster than the either axis speed. Why? because of vector math the speed is the vector sum of the two axis. If you move X at 100 IPM and Y at 100 IPM then the resulting track is a 45 deg line that is moving a further distance (sin of the 45 deg angle times either side) It is my understanding MACH considers the surface speed to be the target feedrate......
Anyway it needs a bit of empirical tweeking (you gotta do some trial and error) A plasma table should be able to cut at the top speeds for thin material with the smallest tips and not have problems.
There are a lot of physics (remember that class you hated in school) and some trigonometry. Throw in some basic algebra and you have the tools to better understand the motion involved.
TOM caudle
www.candcnc.com
I do understand the physics and motion involved. My gantry is nearly 5' long. Unless there have some developments in materials that I'm unaware of, it is still impossible to make my gantry infinitely rigid while still being light enough for the motors to move it. My table is tight.....no slop. I can grab the torch head and move it slightly via the flex in the gantry. I would not expect any different. I can watch the table attempt to run at 320ipm all day long, and my common sense tells me there is no way I'll ever get an accurate cut on tight corners and small radius cuts at this speed......and the evidence is in the cuts. You can see the perfect vibration of the torch head on every square corner. Watching the table run at that speed, common sense tells me that is exactly what I should expect to see.
I have played with the accel settings for days. I am perfectly fine with cutting at 200ipm max.....doesn't bother me one bit. I am using the fine-cut consumables and they work great. I'm very happy with the way the table runs and the quality of parts it produces. I have no interest in hurrying the machine up to make bad parts. I'd much rather run it at 200ipm and make good parts.
Algebra and physics are great, and I use both a great deal and loved those classes in school......but they can be fairly time consuming to use in real life when you are trying to figure out how much flex is going to be in my gantry when it tries to turn a 90 degree corner at 320ipm.....especially when you consider that the flex in the gantry is going to change depending on where the Z is located on the gantry when the corner is executed....in the middle of the gantry or toward one end. In cases like that, I'll take common sense over physics and algebra every single time. Common sense tells me that the gantry is going to allow the torch head to flex more if the Z happens to be in the center of the gantry at the time, as opposed to being close to one end. If a 16 lb bowling ball falls from a 3' high table and accelerates at 9.8m/s squared, is it going to hurt when it falls on your toe? Physics is great, but I don't need to use it to answer that question.
Is there a way I can turn on my torch or turn on/off my tip saver with my hand controller?
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Last edited by vacextar; 12-15-2011 at 09:15 AM.
All outputs can be turned OFF (single button push) or ON (two button push for safety) from the PN200 Keypad.Is there a way I can turn on my torch or turn on/off my tip saver with my hand controller?
The Tip Saver (alone) cannot be disabled BUT the whole THC can be disabled/enabled simply by pushing the DTHC PRESET knob down once. You can also cnage the PRESET value while cutting by rotating the knob clockwise (increase) and counter-clockwise (decrease).
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