[engnerdan]

Many times its been brought up about the unreliability of using the proximity switches, that come on our machines, for limit switches. I have found a possible replacement that might even mount in the same brackets as the factory proximity switches.

Using some mechanical limit switches from Automation Direct this is what I have come up with.

Attachment 247600
On the left you have a roller/lever arm type switch. I wasn't able to easily re-position the lever arm in the 3D model but I think if you rotated it 90* and had the switch body horizontal it would be a cleaner mounting.

In the middle you have a model of the existing factory proximity switch

On the right you have a roller/plunger type switch. This type I think would work well too. Both this one and the lever arm type would require a custom mounting block to be made.

To use the roller limit switches the existing cast iron "flags" that are used to trigger the proximity switch would have to be modified with a 30* angle to the bottom of the flag. This is to give the roller an inclined plane to act against.


There is a third switch that I didn't model that I think might be able to be mounted in place of the factory proximity switch. It can be found here.
AEM2G22Z11-3 | 1 N.O./ 1 N.C. limit switch - metal plunger,metal roller w/ fixing nut


Additionally I think I found the solution to the Y axis limit switch bar from pushing out the front of the factory chip pan. By moving the bar back 100mm like the bottom picture. On my flag mounting bar there are 3 holes each 100mm from the previous. So I am just going to slide it back and re-adjust my single flag I use for homing.

Attachment 247604
Before

Attachment 247606
After

[Bubba]

The roller switch looks like the ones I used on my Mill/Drill and yes, it is easy to rotate the roller lever arm to different positions. If these are the "AAP series miniature DIN limit switches" not only can the lever arm be indexed in 6° increments, but the head can be indexed in 90° increments about the body. I have been using them as combination home/limit switches for nearly 15 years now and they are still very repeatable. The spec on repeatability is listed at "0.01mm on the operating points at 1 million operations"

Good luck with your mod.

[SCzEngrgGroup]

For purely limit switches, mechanical switches can be very good. But , good ones are expensive. The ones from China are absolute garbage - I bought about a dozen and they are so bad I will throw them away. Also, I've always hated the idea of separate switches for home and limit - it just clutters things up too much. So, I prefer a single set of switches that perform both functions, or an integrated switch that can do both in a single small housing. I've planned for some time now to make small enclosures that will house Hall Effect sensors activated by a magnet embedded in a spring-loaded pushrod. This will make the enclosures very small (as small as a 1" cube if you really pushed it), and could easily house two sensors a small distance apart, so the home position could be set just inside the limit. It would be totally electronic, so nothing to ever wear out. The pushrod would be sealed with O-rings, so no concerns about coolant. And, at $.50 each, the sensors are as cheap as you'll get. On the Pro, it will take two housings to do X and Y, and one for Z. All the existing home/limit hardware can be removed, in favor of small brackets to hold the housings and flags. In fact, I removed all the X/Y home/limit tracks, flags and switches from my machine a few days ago, while it was apart.

Regards,
Ray L.

[mklotz70]

With the switch on the left, you wouldn't actually need the ramp on the flag, would you? I guess it depends on just how far the arm has to travel to actuate. The arm could be clocked to the left a bit so that it tripped when close to vertical.

[engnerdan]

With the switch on the left, you wouldn't actually need the ramp on the flag, would you? I guess it depends on just how far the arm has to travel to actuate. The arm could be clocked to the left a bit so that it tripped when close to vertical.

You are right sir, I bought 3 of those switches and plan to rotate them 90*. Using the lever/wheel type arm actually gets me a little more travel which is a benefit being the limit switch mounting rail is too short on all the axes. I will add some info and pictures here eventually but the switches from Automation Direct are made in Italy, so none of the crappy 'ese parts like Ray had trouble with.

-Dan

[Windscreen]

/

[mklotz70]

You are right sir, I bought 3 of those switches and plan to rotate them 90*. Using the lever/wheel type arm actually gets me a little more travel which is a benefit being the limit switch mounting rail is too short on all the axes. I will add some info and pictures here eventually but the switches from Automation Direct are made in Italy, so none of the crappy 'ese parts like Ray had trouble with.

-Dan

Cool! I look forward to seeing them in use.
Mike