Change between Inches and millimeters on your CNC - CNCnutz Episode 245
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- čas přidán 7. 09. 2024
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I received a question the other day about running files in imperial on a metric machine and it seemed like a good topic to cover as it is not the first time i have been asked this. When you first set up your machine you need to choose the unit of measurement that you want to use on your machine. If you live in the USA you will most likely choose imperial and if you live anywhere else you will probably choose metric. Having made the decision are you stuck with your choice or can you change it easily? Fortunately Gcode has some commands built in just for this situation. G20 & G21
So the long and the short of it is that no matter what Native unit of measurement you set up in your machine you can machine any Gcode file given to you in any unit of measure.
Is it advisable? That is a completely different question. While I am not keen to run other peoples Gcode on my machine and any Gcode I make will always be metric I can see where this could be very handy. In these times of makers spaces where a CNC machine is a communal item it is likely that some people will want to work in Metric while others work in imperial. This is where the G20, G21 will shine. Users can design what they want in whatever unit of measure they want and can still machine it on the same machine.
Cheers
Peter
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I hope you enjoy.
0:02 looking good, Peter! Nice to see isolation hasn't got you rattled.
Stay safe!
Thanks Doug,
I like to look my best and I think I pulled it off.
Cheers Peter
Peter. Good explanation. As a Canadian baby boomer I was raised learning Imperial and then about 1970 Canada officially went metric (mostly). I spent the 1980's in Australia, Italy and Hong Kong and then spent about 25 years traveling to the U.S. every week or two for work. Fortunately I have a pretty good head for figgerin' and I consider myself to be fully metric/imperial bi-lingual. We still measure our lumber here in imperial units because a lot of it crosses the border with the U.S. in both directions. In my new exciting CNC world I tend to draw in Imperial and output the G-code in Metric. I have also learned to read and interpret the G-code (I have a programming background) and occasionally I will modify a line or two to suit my situation. Keep up the good work.
Thanks Ron
I grew up using both units myself and still do. Sometimes in the same sentence.
Cheers Peter
A great video Peter, it's good to see you Locked down in Southern California stay safe.👍👍👍🍺🍺😷
Thanks Lou
Look after yourself over there.
Cheers Peter
I hope you & yours are Healthy & Safe.... Another Great video, thanks for sharing your knowledge
Thanks Troy,
All good here, hope it's the same for you guys there.
Cheers Peter
Good to see you back Peter. Its hard not to touch your face when you are a thinker :-)
Thanks Dave
The more you try not to touch your face the harder it is. An itch suddenly appears from nowhere.
Cheers Peter
Thanks Peter.
I'll stick with my freedom units thank ya very much! 😏
Thanks for the video. When I looked in the mirror this afternoon I think I looked a tad dishevelled too, so much so for standing at the front gate this morning looking my best! And it looks like you haven't upgraded to Aspire 10. Cheers, David
Thanks David.
Still sitting at 9.5
I usually skip 1 upgrade unless there is some feature I really want.
Cheers Peter
Bless you. Hopefully, it's out of you for good :) Even easier in Fusion360. Units settings are in the model tree. You can switch back and forth very easily by right click select.
Thanks Stephen. I should really sit down and learn Fusion.
Cheers Peter
Hi,
What if I have a matrices plan/toolpath and I want to use a imperial router bit.
I wish if you can make a video explain it.
Thanks in advance.
Just and FYI, UCCNC doesn't process G20 or G21 (they're ignored) because it's a unitless G-code processor and everything is relative to the configuration file. Thus, don't run either G20 or G21 files unless your machine is set up specifically for those units.
That's right which is why you use the post processor that matches the Machine rather than what the drawing unit of measurement.
Cheers
Peter
Pete, very good video, I was just curious since the US and parts of Britain still use the imperial Neanderthal measuring system one foot in front of the other using the toes for better measurements. If you calibrate your machine in MM get it to the best accuracy in the millimetre measure and you then convert back to imperial figures, do you loose the accuracy? I can only see that if you are machining parts that need tolerances in thousands or microns dimension, but I doubt anyone here has such a machines with those tolerances.
There is no loss of accuracy changing between units. Not that you or I will see.
Cheers Peter
Peter. When we get a project from Vectric in inches and I output that in inches in my post processor does that mean it also outputs the feeds and speeds I have put in my tool database, presuming I have the right sized cutters equivalent to the imperial measurements.
It sure does. Half my tools are imperial and I always use IPM for speeds and feeds because I did that way when I first started and can't visualize metric for those items. All my Gcode is output as metric.
Cheers
Peter
2:28 - I beg to differ... if you run G-Code and it has G20 at the start... but you never issue a G21 afterward... you will get REALLY surprised when you MDI G0 X10 and expect 10mm. ALL my routines include G21 in them so that when a job is finished and I click my "Safe Go Home" button... it leaves the machine in G21 metric mode. If you turn off the machine, yes it will reset... but if not... please be aware that it will remain in the last mode set.
Hi Jerry,
I see what you mean. I should have phrased it better but I think people will get the idea. Hope that you are finally allowed out of your room.
Cheers Peter
Good remark. My machine is in mm native units. But for drilling friend's files I edited it and added G20 at the begin and G21 at end of each his file. I hope this is ok. I hope also Peter will comment this.
I’m a CBC virgin, and I’m having a problem with with the way my cuttings are coming out. I’m designing in Vcarve desktop, in imperial and using UGS to process. My jobs for example are 14”x14”, but when I run them they are coming out about 3”x3”. I’ve tried to find out what the problem is. I was hoping that you could help. What am I doing wrong?
Did you calibrate your axis? It you don't calibrate each axis it won't move the correct amount.
See my videos on axis calibration.
Cheers Peter
askjerry, good remark . My machine is in mm native units. But for drilling friend's files I edited it and added G20 at the begin and G21 at end of each his file. I hope this is ok. I hope also Peter will comment this.
Perfectly fine way of doing it. If it doesn't have the g20 in the file you can change it using MDI if you want and when you finish use MDI to change back. As with most things there are several ways of doing the same thing and it is a matter of finding what works best for you.
Cheers Peter
Thanks, Peter
Just watched your video discussing choosing MACH 3 or UCCNC and then this one. Great video wonderful explanation. Also I'm relative NeewBee so I chose UCCNC to start with but i am not able to understand how to change it to imperial. Am I correct that UCCNC is metric only? In reading below from qwert UCCNC is unitless and everything is relative to the configuration file. Does this mean that you can change the units in the config file. I would have sent to qwert but not sure he would see it. Thanks in advance
Uccnc is neither metric or imperial. It works in that ever unit you set it up as. You simply tell it how many steps it takes to move 1 unit and that is it. You cannot change between units. Once it is set up but you don't need to. If for some reason you want a metric and an imperial version just set up 2 different profiles and load the one you want.
Hope this helps
Cheers Peter
@@cncnutz Thanks for clearing this up for me. I just need to learn how to create a profile. Do you have a video on creating a profile?
Hello, I have created a new profile in UCCNC. What configs do I need to change or convert from mm to inches. The machine is in mm at this time.
You need to set up the machine using the inch as the unit if measure. When you calibrate the axis the steps per unit will be 25.4 times more that the current value. The soft limits will be 25.4 times smaller than the current ones. Each of the current units of measure will need to be either multiplied by or divided by 25.4 depending on what it does. In its most basic form steps per unit is multiplied all the other measurement settings are divided.
Don't forget to backup the original profile before you start.
Cheers Peter
will it change the tool setting as well. I use mm that`s what I learned in.
It changes everything. If the tool is 1/4 it will remain 1/4 but is treated as 6.35mm.
I got a dxf file that was in inches and it won`t change it to mm in my v crave pro
Maybe it is already open as mm. If this is the case you can always scale the drawing by 25.4
Select the entire drawing and use the scaling tool. This will resize it for you.
Cheers Peter
which program do you use for post processing?
Vectric Aspire and I use the Masso post processor to suit my controller.