[ger21]

Yes, you can have a single switch do double duty as both a home and limit switch.

[racedirector]

Yes, you can have a single switch do double duty as both a home and limit switch.

Excellent, I like the sound of that. One more question if I may. Using them this way would it take one or two inputs on the BOB, that is one for limits & one for home or one for everything?

Cheers
Bruce

[ger21]

A single switch only needs one input if used as both a home and limit. You can actually use one input for all your switches if they are wired correctly.

[racedirector]

Thanks again Gerry. I have my machine in bits at the moment rebuilding it. Have just finished the Z & Y axis's so will wire them up and test before putting the gantry back on the X. That way I can test things out before firing up a router

Cheers
Bruce

[brtech]

Those with small machines can use one input. This works because Mach will move one axis at a time when it homes, and so you only need one home. As a limit switch, you don't care WHICH axis hit a limit, you want the entire machine to stop.

You can configure Mach to work differently, but why?

There is one reason to use more than one input, and that is when you have a larger gantry and use two motors to drive X. If you have the X and A axis home on a different input, Mach will use that to self-square the gantry, which is very helpful. So you need two inputs on your BOB for that.

[racedirector]

OK, my machine is now running so it is time to connect up my switches. Before I do I have a question.

I am using one of James Newtons BOB on my machine (Break Out Board, Logic Power Regulator, Relay Driver, Indicators, Switches, Microchip PIC, LCD Panel, Current and Temp sensors.) and the switch attachment points exhibit 4.78V across them. There are places on the board to get 5V from if I need it to power the switches but I was thinking of just using 12V as I have done with the BOB.

I am unsure how to wire these given that the switch connectors have voltage. As I understand the wiring on the first page of this thread, the SS41 gets + & - voltage from a power source, be it 5V or 12V and the trigger leg gets connected to the limit switch position. This is what is confusing for me. Can someone take a look at the BOB page and suggest how I should be doing it? It would help me greatly.

Thanks in advance

Cheers
Bruce

[john-100]

Hi racedirector ,

as the 4 switch inputs that are connected to the LPT port pins 10 to 13,
are also connected to the +5V supply via resistors RP1
I would connect the SS441 hal switches to the BOB's 5V supply

you can parallel switches if you need to connect more than one
to any of the LPT inputs

John

[racedirector]

Excellent, thanks John. That is exactly what I was after. The GND connection is actually on one side of the connectors so that makes everything super easy. And while it was staring me in the face, I never twigged to use the centre 5V from the input connectors

BTW, how did you manage to see my hall switches on veroboard? Just kidding, that is exactly how mine are sans the writing on them, my switches have no writing at all but do have the angled face to tell me which way is up...

Cheers
Bruce

[RomanLini]

Greolt- Thanks for posting the photos, that looks like a good reliable sensor setup on your machine.

Thanks Ger21 and John_100 for helping Racedirector with the sensor wiring.

John_100- That photos looks like my hall sensor on veroboard! I left the ugly numbers on the side of the PCB just to make the PCB larger in area so they glued down better onto the machine.

And they have never moved!

[john-100]

Hi Roman ,


yes your right , they are your pictures of your hall sensor
whats more , james will spot his picture of the B.O.B

I just help when I can
at some time it could be me that needs help


John

[Ramcnc]

Just wanted to add my thanks to Romanlini and other contributors in this thread. Im a novice in both CNC mashining and electronics, and this DIY thread made it really easy and cheap to add homing to my mashine. Thank you!

[kinghong1970]

would it be ok to use PC 5v fan connectors for the Hamlin sensors?

[RomanLini]

John_100- Thanks for the help and thanks to everyone who has helped in this thread of course. That's one of the things I like about this (CNCzone) forum is the huge amount of people who not offer help and it is high quality help too.

Ramcnc- Thanks for the nice words and congrats on your home sensors.

Kinghong1970- The "PC 5v fan" type connector in your photo looks like a typical 0.1" pitch locking connector. Electrically that is ok, it can easily carry the very small currents the Hall sensors need. Being a locking tab type it is also good that it can only be connected one way around.

Just be careful soldering, they are a cheap lightweight connector and are normally kept cool (relatively cool) by the PCB during soldering. In line types are often crimped onto the wires and not soldered. Basically what I am saying is if you solder to these cheap little connectors be careful not to get them too hot or they will warp or melt, which can make the connection unreliable.

A good practice is to apply a little flux and solder or fresh rosin-core solder to the pins first, to "tin" the pins with fresh clean solder. Then pre-tin the wires in the same fashion so the wires are coated with fresh clean solder. Then solder the wire to the pin quickly and due to both items having fresh clean solder it will solder quickly and get a good solder connection. And all up will be much less time total the hot iron is applied to the tiny connector.

[kinghong1970]

Roman,

thanks for the tips!
i guess i have some soldering to do this weekend...

[riche543]

Hello all
Question regarding shielded cable, I have used good quality sheilded cable for motors & will do for hall sensors. but my question is about router cable, so should I use sheilded cable for my kress router the cable will be running along side all other cables in a track.
Cheers
Rich.


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[brtech]

Don't bother shielding the power cable to the router.

If you are having a really serious noise issue, sometimes shielding the source of the noise can help, but usually you shield the part that is sensitive to the noise.

[kinghong1970]

Ok, so i'm using the 3 pin connectors to connect cables to the hamlin sensors...

now on the other end, i don't want to hardwire direct to the G540 and want the option to remove when needed...

can i use 1/8" stereo plug and jack on the other end and then connect to the G540?
or should i just use RJ11 phone jack and plug?
but the RJ11 may not be compatible with the wires i ran for the sensors...

of course, the system will be turned off prior to removal of any plugs...

[ger21]

I think the more connectors that you use, the more you leave yourself open to potential problems. What's wrong with using the G540 screw terminals?

[kinghong1970]

nothing wrong Gerry... just wondering...
but what you say makes sense..

[riche543]

Mounting block with LED

I got a couple hours free today so I drew up my improved mount block design with the added LED indicator.

This diagram should have enough info, dimensioning etc for anyone to make these mounts. Sorry I don't use any standard CAD program so I can't offer CAD files or DXF, my machine works direct from Corel so I just work in 2D or write C code to do complex 3D cutting. Maybe someone who uses the popular CAD program (I don't even know which CAD program is most popular here!) can whip up a CAD design.



Cutting info.
The mount is cut from 10mm (3/8") clear acrylic, using a 1/8" (or 3mm) diameter end mill capable of plunge and cutting the full depth of the sheet.

1. Cut the shallow pocket 24x11 mm (2mm depth)
2. Cut the deep pocket 20x11 mm (to a total 7mm depth)
3. Cut the screw relief step, 30x10 mm (4mm depth)
4. Cut the 2 screw holes or elongated slots as desired
5. Cut around the mount 30x25 mm (to remove it from the sheet)
6. (in drill press) drill a 3mm hole for the wire (and deep enough for the LED if LED is to be used).


Mount design inprovements

This mount has a few small improvements from my design further up the page;
1. larger and thicker screw area for strength
2. shallow area for Hall switch is full 11mm width now; for better epoxy flow and less epoxy shrinkage there around the sensor
3. LED hole, is just a continuation of the wiring hole
4. deep pocket is not quite as deep now; saves epoxy, stronger, less shrinkage

At this point I can't see how to improve it much. Apart from redesigning it for special needs like miniature size, or changing the screw mounts to suit the equipment it looks pretty much done to me.


How the LED works

The design uses a 3mm LED, this is the smaller size (other popular size is 5mm). The 3mm size has become the most popular size these days and should be available anywhere cheap.

It won't matter too much which LED colour you choose, you can still use the same resistor values. You can even use different colour LEDs on different axes.

It would be best to use a "high intensity" LED, these cost maybe 50 cents more each but are MUCH brighter so will be much more visible when buried down between moving parts of machinery.

The resistor values shown below only run about 4mA through the LED, so the old style LEDs will not be very bright at that current but the new high intensity LEDs will be very bright at 4mA as they are really "high efficiency" as well as high intensity.


Other mount materials

If you want to use a different plastic than clear acrylic, like you may choose a high strength plastic like Delrin or just use plastic you have handy then it will be more difficult with the LED.

In the clear acrylic, the LED will light up the whole mount and be very visible.

But if using a black or coloured plastic, you have 2 options;
1. drill deep enough so the end of the LED actually comes out of the mount (this requires sealing before pouring epoxy)
2. drill ALMOST through, so there is only a thin skin of plastic in front of the LED

I would try method 2 first! Most plastics (even black) are quite translucent when they are very thin like 0.5mm (0.020") and the high intensity LED will shine out easily. If not, then just continue the hole all the way through.

Hi guys
After copying the wiring diagram (with led) I found I would only get a switch closed when I reversed polarity off my multi Metre so the +5v worked the right way , but when checking with multi Metre would only get closed switch signal by putting the positive (red) from multi Metre to ground & black from multi Metre to out, ? Sure this isn't right cuz it won't work that way once connected too g540 & Mach3 , just can't work out where I went wrong with wiring ?
I have ordered some more sensors so will try again, anyone got another map for wiring with led , I used 2 resistors in these , thinking the pic on first page with one resistor is more idiot proof ? Any reason why 2 resistors are used in later version.
Cheers
Riche.


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