MJR7 said:

I was told that it is possible to replace an encoder cable which has braid shielded wires inside with one that uses no braided shielding but has wires twisted together in pairs for noise protection. Anyone familiar with this?

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In most cases this is not a good idea. The twisted pairs reduce cross talk between encoder channels. They do little to shield against outside noise.

The chances of having a problem depends on several factors. If you are using 5 volt single ended encoders then it is most certainly not a good idea. The presence of large contactors or a VFD are other reasons for shielded cables.

Shielded encoder cable is available in short lengths from McMaster Carr, I think in ten foot increments. The price is reasonable.

If you are really going for cheap then use good quality shielded cat5 patch cords. They are too flimsy for an industrial machine but at least they reject noise until they fail.

The argument over terminating which end or both ends of the shield is endless. Just do whatever was done with the original cable and you should be safe.

Doug

In most cases this is not a good idea. The twisted pairs reduce cross talk between encoder channels. They do little to shield against outside noise.The chances of having a problem depends on several factors. If you are using 5 volt single ended encoders then it is most certainly not a good idea. The presence of large contactors or a VFD are other reasons for shielded cables.Shielded encoder cable is available in short lengths from McMaster Carr, I think in ten foot increments. The price is reasonable.If you are really going for cheap then use good quality shielded cat5 patch cords. They are too flimsy for an industrial machine but at least they reject noise until they fail.The argument over terminating which end or both ends of the shield is endless. Just do whatever was done with the original cable and you should be safe.Doug

Standard CNC Cable Track Installation [Archived]¶

Please Note

These instructions are for Standard CNC machines purchased prior to September 2017. For cable track installation on current Standard CNC machines, refer to our Standard CNC Machine Assembly Instructions.

The first step is to attach the trays to the X axis -- the trays help route the cables and support the plastic e-chain guides. The x axis tray mounts using 2 metal U brackets, which connect to the inside face of the extrusion using 2 t-studs and hex flange nuts per bracket. If you have a longer machine (over 6 feet of travel), you will have received 2 x-axis trays, and 2 sets of metal U brackets.

After installing the brackets, attach the actual trays to them, connecting them with button head screws and flange nuts.

The gantry tray mounts directly to the gantry using the supplied t-studs and flange nuts. Note, for machines with shorter gantries, this tray may be shorter than the X-axis trays.

You are now ready to run your cable tracks and install your cables. Installation of your cables in the tracks is fairly easy, and is facilitated by use of a screwdriver to open the tops of the tracks:

The next section deals with attaching the actual cable track to the extrusion. The X axis connection is the most involved, so this is detailed out below.

Before you start make sure you have laid the cable track down so that the section with the end piece with the holes in it ends up next to the extrusion and make sure you have the following pieces from the CT- Fast hardware kit: (1) 5" hex cap screw, (5) 5/16 flat washers, and (4) 5/16 jam nuts.

At the beginning your set up should resemble this (possibly without the cables -- these can be added after the track is installed):

Working from the outside in towards the extrusion, start by threading the 5" hex cap screw through one of the flat washers and insert the screw in the outside hole of the cable track kit, then add another washer and a jam nut.

Continue by adding an additional jam nut and then a washer.

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Thread the hex cap screw through the inner hole of the cable track kit and add the following components in this order: washer, jam nut, jam nut, washer.

You should now have something that looks like the following photo and you are ready to attach the hex cap screw to the extrusion.

Screw the bolt the remaining way in, and the X axis track is connected.

The completed X axis track:

Next, connect the Y axis tray to the back of the gantry:

Next, connect the interface T bracket for the Y cable track and Z cable track to the open tapped hole on the gantry rack and pinion drive. Note, if you have a NEMA 23 rack and pinion drive using the turnbuckle tensioning system, you will use the same screw used to connect the R&P turnbuckle. Just un-thread the bolt and install the locking jam nut as shown in the photo below. If you have our low profile or other tensioning mechanism, just use the provided 5/16-18 x 1/2" bolt to connect the bracket

You can now connect the Y axis cable track to the interface T bracket using the supplied M8 button head screw and flange nut. You can also connect the Z axis cable track through the hole in the end bracket using the supplied M6 button heads and nuts.

With turnbuckle:

Without turnbuckle:

Finally, the Z axis cable track should be connected to the Z axis extrusion with the supplied 90mm hex bolt, flange nuts and roll-in t-nut. To install the roll-in t-nut, it can be helpful to use a screwdriver to rotate it into place

The completed connection should appear as follows:

All that remains is to route your cables through the system. For your X' axis motor opposite the X axis cable track, we recommend running the cable through the cable track on the primary side, and then through the hollow of the gantry. The sections of cables unsupported by energy chain can be fixed to the tray with cable ties, and this is recommended.

Any remaining questions, feel free to and we'll do what we can to get you up and going ASAP. Enjoy!

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