So it begins... Cnc plasma table buid

[djreiswig]

Do I need/want the limit switches with the led light?

They're probably going to end up where you can't see them anyway.
The computer should have input indicators.

[acourtjester]

First off you do not need all the switches you are planning. My table has on for each axis and a floating head switch and ohmic sensor. I am using LinuxCNC with QTPlasmaC GUI. I use proximity sensors with a Mesa controller board, there are many inputs/outputs with this board. Attached are videos showing the proximity sensors in action, they come in 2 different configurations for mounting. The ones I use are the flat type, other are like a bolt in a longer configuration. As you can see in the video they have a built in LED to indicate when they are active (tripped). In the second video it is doing the start up homing action. The axis moves to the sensor trips it and backs away a short distance and stops. and move to the next axis. The sensors are sealed and have no moving parts to fail. They are powered by the Mesa card. I think this is the ones I used Amazon has the in a 3 pack for about $15.
TLW5MB1 Proximity Inductive Type ABS Shell DC12-24V 3-Wires Normally Open NO 5mm with Shielded Probe, Proximity Sensor with Induction LED Indicator

[acourtjester]

David I fairly sure the image I used was from your posting of the motorcycle.

[GoodB0Y]

Ok that's really helpful thanks!

I'm guessing that it's proximity switches I'm seeing in some of these videos where there's an led light that turns on when the switch is activated.

And I'm also reading that I only need limit switches on the home end of the axis... And guessing that soft/coordinate limits for the other ends.

Thanks again

[SegoMan DeSigns]

Ok that's really helpful thanks!

I'm guessing that it's proximity switches I'm seeing in some of these videos where there's an led light that turns on when the switch is activated.

And I'm also reading that I only need limit switches on the home end of the axis... And guessing that soft/coordinate limits for the other ends.

Thanks again

The light on / off is dependent on what type of switch you have and how its wired. I wired my table to the fail safe mode (NC) with the PNP type inductive switch. it stays on until activated and goes dark. I can not see the back side of the X switch but I can see the reflection of light from it.

PNP W Bump Stop.jpg

[acourtjester]

The way I have my table setup is the sensor is attached to the moving part of the axis. And there is a trip on each end of the axis, this is how I get away from having a switch/sensor at both ends. It the axis is moved to either end it will trip the sensor/switch, This is a safety too as the software knows what it is doing. If moving to a home it sees the sensor/switch as that home. If not a homing action is sees the the sensor/switch as a limit and stops motion

[tcaudle]

On all CandCNC controllers there is a "table I/O card that has the INPUTS and in some cases outputs. Each input has a an LED to show when its active (On) so testing is as simple as shorting that input to a common and the LED turns on. WHAT the input does when it turns on is defined by it assigned Function in the Configuration Program. Homes are important because they establish absolute (table ) zeros especially on X and Y. Without true homes you can't do software limits (the table does not know were the limits are)
You can make Inputs do more than one function. You can define more than one ESTOP input . Be aware that wile most inputs use "focus" (meaning they are looking to respond while a specific action is taking place). For example, when you hit a HOME bunion the system is doing a Homing Move and any input it gets that is defined as a HOME function causes it to act on that input. It ignores other inputs EXCEPT ESTOP. ESTOP does an ESTOP (Emergency Stop) not matter what (as it should).

If you make an input dual purpose it does the function that the current move is calling for. A HOme/Limit combo will home if its doing a HOming move and during normal jpg or g-ode moves it acts as a Limit/

Another word of advice: Do not set Soft Limits on an Z travel with MIN or 0 . It will see any negative (less than zero as a Limit and stop )

InputFunctionDropdown.png

Current controllers all sue the Table I/O 17 that is mounted with the input terminals and LEDS exposed on the side/front so its easy to hookup (16 isolated inputs) and gives you feedback without opening the case/

[tcaudle]

As part of troubleshooting the input LED is in series with the LED in the input opto isolators so they BOTH have tobe functioning for the external LED to light. here are also INPUT indicators in the DIAGNOSTICS tab that show you the LOGIC (Sioftare) input if its assigned

[GoodB0Y]

Ok that's great info everyone thank you!

So I've been thinking about the limit switches and my breakaway.

Really liked the ball bearings and magnets...

I'm thinking of something similar but using acorn nuts and magnets.

Is there a way to have the probe switch do double duty as a break away or collision switch? I read there are several ways to configure limit switches in linuxcnc... Would be great to have the probe and break away on one switch... While probing it's a probe switch. While cutting it's a collision switch. Going to dig into this when I get some time.

Thanks again for everyones input!

No cnc building this weekend. Apparently I have a wife and I need to spend some time with her... so took her out to a local resort for some couple time!

[GoodB0Y]

Now that I think of it there isn't a way to do that... Probe and limit in one switch... More thinking to do lol.

Wish I made my z axis a little bigger to accommodate all the things it needs to do lol

[acourtjester]

When thinking about things, look at what they are used for. A probe is used for locating the surface of the metal ( or maybe other things) and allows movement to continue. A break away switch is a safety or limit, both to stop the movement so no damage occurs. You doing research before taking actions saves making mistakes, but sometimes you need to do something to find out if it will work or not. If you had not started working on the Z you would not realize it needed changes after your table was complete. I have built 10 tables and the last one is different then the first one. Some things are similar and others were changed as improvements. I changed the shape of my axis sliders to make construction easier and function better. Change from micro switches to Proximity sensors. Changes to software and electronics which has effects in the cost and better operations. I sold 8 of the table to people that used them well and one given to my daughter, so none were failures. have fun and learn as you go.

[adbuch]

Tom makes a good point - this is a learning progression and ideas will evolve with experience. Everyone has to start somewhere and try to learn as they go along with their particular project.

David

[GoodB0Y]

Planning is a huge part of my buid absolutely!

I've put alot of thought into it and made the design to meet my expectations.

I'll be able to cut the full width and length on the table (less the y axis carage width) I'll have all the steppers mounted on the gantry (x and y axis) in a way to that they won't interfere with each other. I have the ability to have 3 inches of water depth if I so desire And I have a plan to make it so that it can be stowed away when not in use. I built my z axis to have 4.5 inches of travel and not add to much the overall dimensions (height) of the table. This was important for me as I want it to occupy the smallest footprint. And I'll have 5 inches or more (depending on the level of the water table slats) of head room from the cutting surface to the bottom of the gantry/torch.

If linuxcnc had the ability to use limit switches in a dual manor I could have the probe and collision use the same switch. It would just require the probe action to have the switch depressed or activated all the time during a cut and break the connection when probing or if the torch broke away. As a design or engineering concept it can be done.. I think it could be achieved...but may be too difficult for me with my small table.

I'm just trying to think outside the box. Not make a disastrous design decision and in the end have a machine that cuts metal.

I truly appreciate your guys help!

I've been on many many forums and you guys are the best!

And yes sometimes I post before thinking

[GoodB0Y]

Got a bit more done tonight...

Going to move onto the x axis this week

[GoodB0Y]

I gota admit that z axis stepper looks small... It's the same as the jd garage stepper... 40lbs holding power.

[GoodB0Y]

Just wanted to share a little video I made for some family that is out of country. It shows a little of my shop and some of the stuff were doing here. It's long at 4 plus minutes but ya have a look if you want... You'll see how full my shop is lol

[acourtjester]

Good show, room to get work done, like many of us you grow as you go After you build your table you project list will grow, buddies will be knocking on you door, Hey can you do this for me. I have a thought for you, how about having a pivot built into the cross rail support where you could fold it down for storage?? That would reduce the height of the Z assembly.

[GoodB0Y]

That video was for family honestly...I wouldn't describe it as a show, room lol...

But I am excited for the plasma table. I think it's a good fit for the stuff I do. Honestly it won't be used daily. But it'll be there when I need or want. I have friends who I powder coat for... But it's a hobby and I turn away alot of stuff. Have a full time job that keeps me busy.

And exactly! A pivot on one of the cross beams. There's a buid at linuxcnc called origami folding plasma table. I'm thinking something equivalent but instead of the pivot on the outside it'll be on the inside.

Lots to do before I start thinking about that haha

[acourtjester]

Interesting build he used the same Mesa board I used.

Mesa board.JPG

mesa 2.JPG

[adbuch]

Just wanted to share a little video I made for some family that is out of country. It shows a little of my shop and some of the stuff were doing here. It's long at 4 plus minutes but ya have a look if you want... You'll see how full my shop is lol

Congratulations on an very nice, large well equipped workshop. Everything appears to be very well laid out with plenty of room to work.

David

[GoodB0Y]

Well thanks for the kind words David...

Although I'd certainly like more room

[adbuch]

Well thanks for the kind words David...

Although I'd certainly like more room

You are quite welcome! I started out with a 300 sq. ft. building back in the day and gradually expanded it over the years - always wanting more room. But it seems as soon as I get the additional space - it fills up with tools/projects in no time at all. I expect it is the same for most of us hobby guys.

David

[GoodB0Y]

So true eh!

As soon as I make more room I find another piece of equipment that I "need"

I'm in my thinking stage again lol... Trying to figure out how to mount my gantry to the end plates. I'm thinking angle aluminum and bolts but because my rails need to go right to the end it removes some space for the angle aluminum... I'd weld a plate on the end but it's right at the limit of my tig welder and my aluminum tig skills aren't the best. And I always end up with warping... So idk Grrr!

*edit*


Actually the gantry beam is 1/8 wall so I should be able to weld a plate on the end and bolt it. It's just thin for Taping threads. Maybe rivnuts... My end plate is 1/4 aluminum...Mmmm....

IMG_0958.jpeg

[adbuch]

Nice! Those fully supported linear rails are great way to go.
David

[acourtjester]

Why not an angle to the side of the rail with through bolts???

rail together.JPG