Alternate SO3 Z Limit Switch Mount

Assembly questions and answers for the Shapeoko 3 CNC Mill
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veng1
Posts: 250
Joined: Fri Nov 30, 2012 12:09 pm

Alternate SO3 Z Limit Switch Mount

Post by veng1 » Fri Jul 17, 2015 11:43 pm

In looking at the potential places to mount a limit switch for the Z axis, observe that the top Z-Axis Carriage Plate has a hard stop when that edge hits the 1/2" X 1" aluminum standoff. So I printed a limit switch mount that would sense the top of the plate adjustable to just before it hits the standoff.

The first one I designed was simple and flat so it could be either 3D printed or milled from an aluminum flat. I found, as did @kristenanne77, that is would "almost fit" but was hit by the top of the router. I'm also using a DWP611. I think that could be made to work but I decided to test out one that had a bend in it to solve the problem. The one with the bend was just plain ugly, probably because I don't really have the retract set just right of the filament has absorbed water. But in any event, I didn't like it. The last design, which seems to work fine, is extremely simple. It has a slot for a #10-24 screw that fits into the front of the standoff and can be adjusted by propping the carriage up until it hits the stop and then pushing the assembly down until the switch activates and then a little more to for the switch arm to over travel. It can be checked by moving the carriage up and down and insuring the switch closes (or opens) slightly before the hard stop is hit.

I used a switch with a roller that I had on hand but almost any one would work. The roller makes the switch fairly thick so the offset could be adjusted for a thinner one to exactly align it with the top of the Z-Axis Carriage Plate.

WP_20150716_006 Small.jpg
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WP_20150716_004 Small.jpg
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Z-Limit Switch Mount stl.zip
(70.61 KiB) Downloaded 63 times

veng1
Posts: 250
Joined: Fri Nov 30, 2012 12:09 pm

Re: Alternate SO3 Z Limit Switch Mount

Post by veng1 » Fri Jul 17, 2015 11:50 pm

Here is a top view. It's fairly clear, I think, that it won't interfere with the router.

The screws used for the switch are M2 and I think they were 16mm but 10-12mm would probably work.
WP_20150716_003 Small.jpg
WP_20150716_003 Small.jpg (232.64 KiB) Viewed 1964 times

veng1
Posts: 250
Joined: Fri Nov 30, 2012 12:09 pm

Re: Alternate SO3 Z Limit Switch Mount

Post by veng1 » Tue Aug 04, 2015 9:12 pm

The original intent was to make something that could be CNC milled on an SO3 but I got carried away and added nut traps. Without those, it could be milled although it is trivial to do with a 3D printer.
Z-Limit Switch Assembly Front.png
Z-Limit Switch Assembly Front.png (71.62 KiB) Viewed 1806 times





Z-Limit Switch Assembly Side.png
Z-Limit Switch Assembly Side.png (85.9 KiB) Viewed 1805 times

jayftee
Posts: 143
Joined: Tue Apr 14, 2015 3:47 pm
Location: Canada

Re: Alternate SO3 Z Limit Switch Mount

Post by jayftee » Wed Aug 05, 2015 12:36 am

I like the idea but, I'd feel safer having a piece using the 2 standoff so, It could never rotate.

Either that, or piggy back on the screw that holds the spring....

But then again, having it on one side and screwed it very tight would be probably enough :P

Jeff
Proud creator of Ike:Core, a 1 cubic foot work area FDM 3D printer based on CoreXY
Shapeoko 3 #00947, Aluminum Bed, Prototype Z Carriage, Porter Cable 450, Min/Max limit switches, Z-Probe, PreciseBits 1/4 & 1/8 Collets, Super-PID v2, IC Dust Shoe

veng1
Posts: 250
Joined: Fri Nov 30, 2012 12:09 pm

Re: Alternate SO3 Z Limit Switch Mount

Post by veng1 » Wed Aug 05, 2015 1:21 am

I can assure you that a #10-24 screw with a washer is not going to move when that carriage pushes against the arm on the switch. If one was really paranoid, a star lock washer might improve things but I think it's a waste of time.

The slot in the mount allows it to be adjusted to the point that the carriage can never hit the switch body.

I prototyped two versions that went across both screws one flat and one bowed, and realized that although it seemed like a more elegant solution, it was simply gilding the lily.

PM me with an address and I'll send you one to try. I am paying $0.015 per gram of filament and it takes 3 grams.

jayftee
Posts: 143
Joined: Tue Apr 14, 2015 3:47 pm
Location: Canada

Re: Alternate SO3 Z Limit Switch Mount

Post by jayftee » Sat Aug 08, 2015 1:10 am

veng1 wrote:I can assure you that a #10-24 screw with a washer is not going to move when that carriage pushes against the arm on the switch. If one was really paranoid, a star lock washer might improve things but I think it's a waste of time.

The slot in the mount allows it to be adjusted to the point that the carriage can never hit the switch body.

I prototyped two versions that went across both screws one flat and one bowed, and realized that although it seemed like a more elegant solution, it was simply gilding the lily.

PM me with an address and I'll send you one to try. I am paying $0.015 per gram of filament and it takes 3 grams.
Can't argue with that. As I over engineer most of my things, my first option would have been to make a bridge between the two standoff.

I don't have my SO3 yet, its waiting to be shipped with the new alu bed.

Thanks for the offer on the printed part, if you look at my sig, you should see a tiny link to the 3D printer I built for myself :P
Proud creator of Ike:Core, a 1 cubic foot work area FDM 3D printer based on CoreXY
Shapeoko 3 #00947, Aluminum Bed, Prototype Z Carriage, Porter Cable 450, Min/Max limit switches, Z-Probe, PreciseBits 1/4 & 1/8 Collets, Super-PID v2, IC Dust Shoe

veng1
Posts: 250
Joined: Fri Nov 30, 2012 12:09 pm

Re: Alternate SO3 Z Limit Switch Mount

Post by veng1 » Thu Aug 13, 2015 4:04 pm

My first option WAS to make a bridge between the two standoffs. Then I put a bow in it to allow room for the router. Finally, I realized with the forces involved screwing that big #10-24 screw and washer to hold that tiny little screw that it was way overkill and designed one to go on just one side.

The one with the bow looks like this:
Z-Limit Switch Mount Bowed.png
Z-Limit Switch Mount Bowed.png (32.51 KiB) Viewed 1666 times
Its designed for a roller arm switch but I've gone to a simple lever arm on the later designs as there is no lateral motion. The other thing I've added to the later designs is a slot for a tie-wrap because unsupported wires that can vibrate are just not good practice in a high vibration environment.

Here is the stl if you want to try it:
Attachments
Z-Limit Switch Mount Bowed.zip
(104.21 KiB) Downloaded 56 times

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