LitePlacer.com forums

I've never been too happy with how the liteplacer dragchains fly through the air, supported only by their own plastic joints.

Malte flipped his Y-axis dragchain to be the "conventional" orientation, and I copied that on my build.

Recently I've figured out how to flip the X-axis dragchain as well, although it's a bit of a tight fit.

First you have to take the uppermost pair of v-wheels on both the front and back gantry plate (total of four wheels) and replace the screws with low-head screws, and also flip their orientation around so the nut is outward. I used these, which fit perfectly and are super-cheap ($15 for a bag of 100).

This will create just barely enough room for a 10x15 dragchain underneath the z-motor. I used this one. It's a bit of a tight fit, and the heads of the screws do make a very soft "clacking" noise as they brush by the dragchain, but there's no real friction. If anybody knows where to get a dragchain that is just 1-2mm narrower, please let me know.

The 10x15 dragchain can fit a pneumatic hose, USB cable, and two shielded-Cat5 cables easily. I put the A+Z motors (four wires each) on a single Cat5 cable and it works fine since those are low-current motors, but I would never attempt something like that with the high-power X+Y motors. The other Cat5 carries all the data wires (limit switches, ADC, etc). But it certainly isn't as "roomy" as the dragchains that come with the liteplacer. I recommend moving the X-limit switches off of the backplate and onto the horizontal beam so those wires don't have to pass through the X-axis dragchain. I'm using nonmechanical inductive proximity sensors, you can see the one for x-max in the photo; I'm going to move them to the back side of the horizontal beam for a cleaner appearance once I'm done fiddling with them. Their wires still go through the Y-axis dragchain, but that's still a big fat one.

The final revision of my headplate PCB (which I will post GERBERS for when it is ready for the public) has only two wires in the dragchain: one for the motor wires and a USB-3 cable serving only USB-2 devices so the four additional superspeed conductors can be recycled for other purposes. My limit switches are daisy-chained and I'm putting a second (USB-native) AVR on the headplate so the ADC readings and solenoid commands are sent as USB packets. The limit switch is still a dedicated wire and I don't plan on changing that, it's important enough to deserve its own wire using simple electrical signals rather than something as complex as USB. Hopefully the extra four conductors will be used only for one limit-hit conductor and solenoid power supply (+12v/+24v) leaving two of them free for future use, although I still have some work to do there.

Photos below show both dragchains, I've been running this way for a while to make sure the new dragchain doesn't cause mechanical problems. Now that I'm satisfied with that I'll move the wires and take out the old dragchain.

Hi Adam,

nice modification

I just checked if I could do the same on my machine - but I seem to have differenz Z-axis motor... There is not enough clearance to run a drag chain between it and the and gantry beam.

I would need to modify front and back plate of the carriage which seems too much effort at this point. Even though I also dislike the "flying" chain, it has not caused any problems for me.

It might be a nice design change for Juha to consider: Just make the carriage plates a bit higher so the Z-motor moves up a tiny bit and leaves enough room for a chain. Use different screws for V-wheels as Adam did. At the same time, the top plate could be slightly adjusted to have mounting bracket + holes for a chain end piece.

Regards
Malte

P.S.: I am currently assembling the new X-carve by inventables - they also have a flying chain design; for small machines the chain is mounted in a different orientation which might be worth a try:



For larger area, they use more or less the same design as Juha did:

Hey guys I have CNC machine that has X Y Z axis and I like how clean they did the cabling using the chains.

Here is a link pictures of the machine which may or may not give you any ideas on how to improve your current setup.

https://picasaweb.google.com/1049219894 ... directlink

Hi RWB and thanks for sharing the photos of your CNC.

The Y-axis cable chain is routed just the way I have it on my machine

I also like Probotix' solution for the X-axis cable chain with the support brackets. Unfortunately we cannot use that approach with the maker slide profile as the moving X-carrgiage enclosed both sides of the gantry beam

So I think it is either "flying" chain, Adam's solution or something completely different.

I recently saw a picture by someone who mounted a vertical pole on one of the corners of his CNC, mounted a horizontal arm on top of it and basically let all the cabling hang to the head - like a gallow really.

By the way: The "flying drag chain" as Adam called it becomes much more stable if you mount a steel plate to the right Y-axis plate to lift the chain up a bit - see picture of my machine here:
You can further increase the stability by using "stiff" joints for the first few horizontal chain segments. I 3D-printed the drag chain and so I could simply make longer segments - the parts with "wire frame" design to save filament. If you bought a chain, I would assume a bit of cyanacrylat glue could permanently connect the segments that must not bend

mrandt wrote: It might be a nice design change for Juha to consider: Just make the carriage plates a bit higher so the Z-motor moves up a tiny bit and leaves enough room for a chain. Use different screws for V-wheels as Adam did. At the same time, the top plate could be slightly adjusted to have mounting bracket + holes for a chain end piece.

Agreed. If anybody does want to order a run of taller gantry plates count me in for a set.

RWB wrote: Hey guys I have CNC machine that has X Y Z axis and I like how clean they did the cabling using the chains.

Ah, interesting, your CNC has non-flying (conventional) dragchains, but they rest on a platform behind the horizontal X-beam rather than on top of it. I like the look of this too although personally I have most of my head-mounted electronics bolted to the back of the gantry and they stick out quite far, so they would get in the way of that.

- a