Home/Limit Switch Upgrade

[hdscarbro]

I'm just about finished upgrading the mechanical home/limit switches on our machine to proximity switches with solid state relays.

In my initial testing, the biggest variance that I've seen in homing Z is 0.0002. This is at least an order of magnitude better than what I was seeing with the mechanical switches. I'm waiting for some larger diameter flexible conduit and have not hooked up X, Y (or A ) yet.

The retrofit was straightforward, we only had to make two new trigger blocks for the Y axis and a new switch bracket for X. The new electronics (transformer, terminal blocks and relays) fit in the left side of the cabinet. If anyone is interested, please let me know and I'll post a parts list and some photos showing how we did the upgrade.

David

[titchener]

David, can you give the parts numbers and approximate cost for the proximity switches you used?

Thanks,

Paul T.

[hdscarbro]

I used (qty 5) PMW-0P-1H switches from Automation Direct at $38.00 each. Each axis needs a relay, I used (qty 4) 682-2322 from Allied Electronics at $14.44 each. To power the switches and relays I used (qty 1) 831-0231 power supply from Allied Electronics at $42.00.

[David C. Allen]

Hello David
Why was a relay required? I was wondering if you could have driven the limit's from the switches directly.

Edit:
After looking at the wiring diagram I understand the use of the relay's for the Z axis.

David

[titchener]

Originally Posted by hdscarbro In my initial testing, the biggest variance that I've seen in homing Z is 0.0002. This is at least an order of magnitude better than what I was seeing with the mechanical switches.

David, I didn't know you could get that kind of repeatability with a proximity switch. What kind of target are you sensing? Have you seen any temperature related variance? (ie hit it with a hair dryer and see if it still repeats).

Thanks,

Paul T.

[hdscarbro]

The target of the proximity sensors is the square edge of a rectangular block. This what tech support at Automation Direct suggested that I use. For X & Z, I flipped the switch ramps over and am using the back sides of them.

I haven't tried any temperature testing. I'll try a little heat on the electronics and let you know the results.

[jestism]

This sounds exactly what I need to solve my switch solution (you can see information on my table setup and why my X limit switches are being replaced to dry out about every 3 days at this thread http://www.cnczone.com/forums/showth...340#post714340 )

If you are willing, would you please email me any and all information that I need to replace my current limit switch with this solution?

jestism@prexis.com

It would be "Greatly Appreciated"...

Thanks,
Mike J

Originally Posted by hdscarbro I'm just about finished upgrading the mechanical home/limit switches on our machine to proximity switches with solid state relays. In my initial testing, the biggest variance that I've seen in homing Z is 0.0002. This is at least an order of magnitude better than what I was seeing with the mechanical switches. I'm waiting for some larger diameter flexible conduit and have not hooked up X, Y (or A ) yet. The retrofit was straightforward, we only had to make two new trigger blocks for the Y axis and a new switch bracket for X. The new electronics (transformer, terminal blocks and relays) fit in the left side of the cabinet. If anyone is interested, please let me know and I'll post a parts list and some photos showing how we did the upgrade. David

[flick]

Just thought I'd point out this thread for anyone who'd like to improve homing repeatability without investing in extra hardware. Standard disclaimers apply.