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ravihotwok
20-06-2017, 10:45 AM
Morning chaps,

all being well I will be setting the machine up in its new workstation this evening and installing the licensed software from Planet CNC. When I was messing around with the jog I noticed I am able to make the machine go to the edge of the bad and make contact on the axis, what I mean is that the motor is trying to keep moving the axis but as the axis is not able to move any more is wont go and doesn't sound nice at all. Is there a way to setup some sort of parameter within the software so that it knows the limit of travel, basically ther machine will stop movement once it gets close to making contact with another part of the machine that is preventing from moving any further? I have seen limit switches but was wondering if there is anything else besides these as im not too sure how to install them. Any help would be great

Neale
20-06-2017, 11:16 AM
Typically you will have at least one switch per axis that is used for homing. That is, when you first fire up the machine at the start of every session, you "home" all axes. The software moves the axis in the direction of the limit switch; when it trips the software now knows exactly where the hardware is. A better-specified machine might have limit switches at the other end of travel as well that detect if the software tries to drive the axis beyond limits. Without these (and I'm talking Mach3 here although I assume that your motion-control software will do something similar) you can set up soft limits. That is, limits that enforced by the software rather than external hardware. Less reliable, depend on the initial homing being done, etc, but a lot of people will use both - soft limits set just within the hard limit values. Soft limits will often stop you doing something stupid but hard limit switches at both ends are the final belt-and-braces that will stop the machine if it all goes pear-shaped.

Depending on the type of limit switches your machine has, it is probably not difficult to add further limit switches at the other end of X and Y. Usually there is no lower Z axis limit switch as down travel depends a lot on tool length, etc. Z home/limit is usually at the top of travel. Most people probably have the home position at X=0,Y=0, but it is possible (Mach3 again) to set the home position at the other end of travel if that is more convenient. I helped a friend set up his machine where the orientation in the workshop meant that he wanted X=0 to be at the LH end, but the home switch was at the RH end. So we just reconfigured the X home position to be X=900 (or whatever it was).

ravihotwok
20-06-2017, 11:24 AM
right I think I understand that, I doubt my machine actually has limit switches installed, will have to have a look, but they do not seem to be expensive, just looks a but daunting in regards to how to install them and get them talking to the pc. I was hoping the software would be enough but if it can be unreliable then I will go with the actual switches

ravihotwok
21-06-2017, 08:38 AM
WHat do you think of these switches for the limits and homing?
http://www.ebay.co.uk/itm/10x-Mini-Micro-Limit-Switch-Lever-Arm-SPDT-Momentary-miniature-Snap-Action/252964260620?_trksid=p2385738.c100677.m4598&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%2 6asc%3D20160908110712%26meid%3De79fe06b14884c73a4e 66cde3800ca5a%26pid%3D100677%26rk%3D13%26rkt%3D13% 26sd%3D121762604573

ravihotwok
21-06-2017, 08:39 AM
and these

http://www.ebay.co.uk/itm/10-x-SPDT-Straight-Hinge-Lever-Roller-Momentary-Micro-Switch-KW11-3Z-5A-250V-AC-/152019788354?hash=item236515e242:g:RxwAAOSws4JW67H 8

Clive S
21-06-2017, 09:21 AM
WHat do you think of these switches for the limits and homing?
http://www.ebay.co.uk/itm/10x-Mini-Micro-Limit-Switch-Lever-Arm-SPDT-Momentary-miniature-Snap-Action/252964260620?_trksid=p2385738.c100677.m4598&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%2 6asc%3D20160908110712%26meid%3De79fe06b14884c73a4e 66cde3800ca5a%26pid%3D100677%26rk%3D13%26rkt%3D13% 26sd%3D121762604573

They are cheap switches but better than nothing. Surly the machine must have homing switches and if it has you should be able to set soft limits.

Take a step back and look at the machine and get to know it before you start playing with wires etc. How about some good pictures.

ravihotwok
21-06-2017, 09:24 AM
the machine is at my mates house but hopefully will be fetching it round to my workshop later tonight so will take a load of pics and post them up mate. Couldn't see any switches on it. It is a 3020t model

Clive S
21-06-2017, 09:28 AM
the machine is at my mates house but hopefully will be fetching it round to my workshop later tonight so will take a load of pics and post them up mate. Couldn't see any switches on it. It is a 3020t modelHow about a link to it then

ravihotwok
21-06-2017, 09:46 AM
http://essentialscrap.com/cnc/first_impression.html

ravihotwok
21-06-2017, 10:41 AM
http://www.chinacnczone.com/cheap-affordable-mini-cnc-3020-cnc-3020t-dj-router-engraver-chinacnczone_l66_p26.html

Clive S
21-06-2017, 11:32 AM
http://www.chinacnczone.com/cheap-affordable-mini-cnc-3020-cnc-3020t-dj-router-engraver-chinacnczone_l66_p26.html

According to their chat line limit and homing switches should be mounted already. But I am not so sure

ravihotwok
21-06-2017, 11:34 AM
not his is going to sound really daft. Any idea where lol
I not looked yet but nothing jumped out at me, especially on the z axis

Clive S
21-06-2017, 11:55 AM
not his is going to sound really daft. Any idea where lol
I not looked yet but nothing jumped out at me, especially on the z axis

Well post some good pics up when you can.

m_c
22-06-2017, 12:24 AM
Any 3020 I've seen, has not came with limit switches fitted.
Easiest way to home, is just to run the axis until it hits the end of travel. Doing that will be just as accurate as using cheap switches.

ravihotwok
22-06-2017, 12:54 AM
Any 3020 I've seen, has not came with limit switches fitted.
Easiest way to home, is just to run the axis until it hits the end of travel. Doing that will be just as accurate as using cheap switches.




Im not really keen on doing that as it may damage the motor or threads

m_c
22-06-2017, 12:57 AM
Im not really keen on doing that as it may damage the motor or threads

You won't damage the motor or threads by running it to the end of travel, as the motors don't have enough power to do damage. Far more problems will be had from the generally poor construction and design of these machines.

ravihotwok
22-06-2017, 09:03 AM
Well post some good pics up when you can.

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ravihotwok
22-06-2017, 09:05 AM
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ravihotwok
22-06-2017, 09:06 AM
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ravihotwok
22-06-2017, 09:09 AM
I cant see any micro switches so I have ordered some of ebay. I have also paid for the license for the planet usc controller registration which has arrived this morning :-)

There is also slight play in the z axis but this can be fixed by installing a washer