800w Spindle connector

I am currently in the process of setting up my 800w Gpenny spindle. The electrical connector on top of the spindle that came with it is quite small. It is an H17-4 “aviation” style screw on plug. The wire I have will only fit into it if I remove the outer insulation and shielding. Even then, the individual wire insulation gets really beat up when inserting the wire because of how tight it is. I looked for replacement connectors and could only find more of what I already have. How has everyone who upgraded to a spindle dealt with this problem? Here is a picture of the connector and wire:

I got my wire from here:

I also have some shielded 18g 4 conductor high flex wire that I could use but it still has the same issue of not fitting.

I cut off the crimping portion with my Dremel and then used F4 self fusing tape to wrap it up after putting it together.

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In altering the clamping arrangement, or removing sheath/shield from the cable, keep in mind that this cable can be carrying serious voltages - proper anchoring/clamping is important as otherwise you risk the constant movement of the spindle with the gantry (particularly Z) loosening the cable and causing the solder joints to be under stress… if one breaks free…
I saw other threads here where this same issue was discussed, the conclusion being to source a more slender cable that does fit. This was my solution when installing my GPenny 800W spindle, and it has been rock solid. https://cpc.farnell.com/pro-elec/pel01680/cable-cy-4-core-0-5mm-50m/dp/CB20789?CMP=TREML007-005

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The most important element is that the spindle and Z carriage not lose their solid earth connection as this is the only thing giving you any electrical safety downstream of the VFD. Fortunately the GPenny spindles generally have pin4 actually connected to the case (check this on your sample).

The “aviation connectors” are, IMO, not suitable for mains voltage and would not be acceptable for anything in aviation. The spec, build quality, lack of room to effectively clamp the cable etc. are all symptoms of designing to price not spec.

A cable rated to the current delivery required for an 800W spindle is definitely a good place to start, a smaller cable, of sufficient current capacity, which will actually fit in the connector will be better than an oversize which can’t be clamped properly.

It’s important to make sure you get good screening, braid and foil should be expected and you’ll be grounding the screening at the VFD or spindle end. The fourth core of the cable is the ground connection from the earth contact on the VFD to the spindle casing.

After watching the cable on my spindle flex back and forth every time the Z moved for a few months I finally gave in and put a drag chain on the Z axis. In hindsight, I should have done that as part of the spindle install.

Now the cable and hoses from the spindle don’t move at all as Z goes up and down and their bend radius is protected in the drag chain, which is what they’re designed to do.

I am at work right now, but I can take some pics of what I did to my connector to get the Belden 29501F wire to fit. But basically, I cut off the tapered portion with the screw clamps, then ground down the backshell and then rounded the edges of the backshell until the VFD cable conductors fit inside it.

Then, I used F4 self fusing silicone tape to put a couple of wraps around the wiring to make it a snug fit in the backshell.

I then wrapped the ground shield around the outside of the backshell and then wrap it tight with F4 tape and that’s it. My spindle is shielded and I don’t need to put a ground wire on my bits to zero, because the spindle is grounded.

That is some rather large cable. Is that what the manufacturer recommends?

It is high flex 16 gauge shielded motor supply wire. I selected it based on the max spindle amp draw of 7A at 110V. 18 gauge will also work but it is only slightly smaller.

Your cable does look quite beefy.

I chose “4mm² 4 Core CY Control Flexible Cable” for my 2.2KW spindle based on recommendations I found somewhere. It fits the connector absolutely perfectly. So perfectly I felt I’d done the right thing. But seeing your tree-trunk… hmmm.

if that’s really 4mm squared then it’s rated for ~31 Amps in three phase, assuming you’re on a proper supply voltage of 220V or more (not wiggly battery voltage) then you should be good for about 8kW even with an induction motor power factor.

Edit 16 gauge is 1.3mm square which is, as the OP says, rated to 3.something Amps only. Seems that cable has a lot of insulation and screening weight around it.

This particular insulation is rated for 1000V and the shielding is braided making it pretty thick. For those wondering how I got to 16 gauge, here is the math:

800W spindle / 110V x 1.73 = 12.58A - EDIT: I have since learned that this isn’t quite accurate. The correct math is this:

800W spindle / 110V / 0.75 power factor (approx) / 1.732 (3 phase magic because you are using 3 conductors to carry the current, not 2) = 5.6A

This is simplified and I am not the person to give more detail. An electrician will have to go into more detail

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Is that 4mm squared for each conductor or 4mm squared total? I don’t know how you fit it in the connector if that is for each conductor.

I made a mistake.

I recently bought cable for my new spindle, and I bought 4mm^2 and 2.5mm^2 since I tend to err on the side of caution and wanted to go bold first.

I ended up using the 2.5mm^2 cable for the spindle. When I checked my email for the purchase to attempt to contribute to this thread, I read the wrong order.

Sorry about the confusion (which was all mine).

(edit: the measurement is per conductor)

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