CNC Depot S30C Spindle - All the other parts!

Please be warned, this is a mega long post…

One of the things that I’ve noticed with the CNC Depot ATC spindle setups is that there isn’t always a lot of detailed information or conversation regarding the more banal components that go into these setups; regulators, fittings, solenoids, storage, etc.

I am in the process of figuring out all the other parts that I need to get air to the spindle and make things work. Here’s what I’m current working through, from compressor to spindle. Hopefully capturing this and the subsequent discussion might help others who are just getting started with one of these spindles and the things that need to go along with them.

First, let’s start with supplying good clean and dry air (5-6 delivered CFM according to CNC Depot):

  • Compressor: I went back and forth on this a LOT. I work in a residential basement and am conscious and sensitive to the sound of a piston compressor; I just can’t do it. I know there’s a lot you can do to help reduce sound levels of piston compressors, but I wasn’t thrilled about that path. Ultimately I decided to bite the bullet and purchased a rotary screw compressor, specifically this one: ELGI 5 HP Rotary Screw Air Compressor

It is WAY more compressor than I need, and I had extensive conversations with a few folks who own this type of compressor (including the manufacturer) and how to effectively mitigate condensation issues that can arise from these compressors not properly heating up and evaporating any condensation that accumulates in the oil. As I get some time on this compressor I’ll report back and let anyone who’s interested know how it works out for a small shop. Also, I’m not saying anything against good piston compressors, but after extensive conversations with my wife we decided we were willing to pay the premium for quiet(er). I’m sure any high quality piston compressor will work, but based on what I’ve seen I’d avoid the big box store compressors if you run jobs that are going to run “long”. I found this video particularly enlightening (and disapointing). !WARNING: Profanity laced educational video! Why are CFM ratings BS? Do not watch if you are sensitive to potty language :wink:

  • Air Drying: I’m considering going the route of an after cooler, but not the type that you usually see online where folks use copper pipe runs attached to walls. I’m considering a stainless steel HERMS Coil like you see in home brewing setups. It seems especially well suited to cooling the air to condense and trap water (with the right fittings), is more compact than the copper pipe runs, and if I choose I could place the coil in a water bath to even further lower the temperature to condense out more water. Of note, this coil would go between the compressor unit and the 60 gallon air tank. Here’s the one that I’m considering (NTP fittings pre-welded): HERMS Coil

Note: I did consider getting an actual Air Dryer, but thought to try an inexpensive chiller approach first and see how effective it is. My workshop is climate controlled to 45% RH year round (I primarily build guitars), so I don’t have high humidity to deal with.

  • Air Distribution: I’ve decided to go with the 1/2" Maxline system from Rapid Air. This is really pretty basic, and I did not opt to go with one of the kits. It was a bit more money, but the setup that I wanted to go with would have required me to buy more components AND have a bunch from the kit left over that I just wouldn’t need. For me, it felt needlessly wasteful so I just pulled together the necessary plumbing parts to connect my compressor tank to the Maxline.

  • Air Line Termination: My Maxline setup will ultimately run to the wall near my machine and terminate with a ball valve, manifold and two quick connect fittings. I went with the ball valve and two port manifold from Rapid Air and since I use Prevost quick connects for other things in my shop (with my small compressor), I decided to pick up a few more for the manifold. 1/2" Male Prevost Euro High Flow S1 Coupler.

So this is where I am in the planning and shopping phase of this project. What I’m left with are a bunch of questions that I’m hopeful some of you might be able to chime in on and recommend products, alternative approaches, or other considerations. So far in my build I’m trying to focus on quality components rather than the financial impact of decisions; I’m a buy once, cry once kind of person.

  • Air Distribution (quick connect) to Machine: I’m not really sure how I want to go from my quick connects on the wall to the rest of the components for the S30C spindle. For now I’m thinking of just a short 1/2" NPT air hose to connect the Maxline/quick connect to the regulator for the CNC.

  • Filter Regulator: Admittedly this is the part where my inexperience is really kicking in. There are a ton of different regulators and filter combinations to consider, and I’m just not sure what I want or actually need. I found a few options on McMaster that look good to me, I just don’t know which I’d go with, or if I’d just find something on Amazon and go on with my day: Festo Modular Compressed Air Filter/Regulator, SMC Modular Compressed Air Filter/Regulator, Norgren Modular Space-Saver Filter/Regulator

  • Coalescing Filter: I’m not really sure if I need this, but since the S30C spindle requires “clean, dry air”, I figured I’d look at adding a coalescing filter: SMC Air Filter, Series Afd40-A, 1/2 NPT Female

  • Drawbar: My understanding is that I’ll add a solenoid to the air line that will go to the drawbar inlet. I watched This video from Clough42 where he covers the solenoid setup he’s using with his spindle. I kinda like the footpedal idea, but I’m nervous that something will boop the pedal while things are running… cuz that’s how things go…

  • In the video from Clough42, he mentions installing a diode into the solenoid. This seems like an oversight from the solenoid manufacturer, no? Or am I just missing something here? Have any of you installed a diode in your solenoids?

  • In my S30C order, Alex included an AC-DC DIN rail power supply and a AVS-5111-24D Solenoid. How do the power supply, solenoid and CNC electronics get connected? The diagram in the online instructions isn’t terribly clear since I think it assumes you have the CNC depot control box (mine is the original AVID VFD box).

  • I’d like to manually actuate my tool changes since I’m not setting up full ATC at this time. Is this footpedal idea a good way to go, or are there other simple approaches for me to consider? I saw another thread on here somewhere where a button was installed in the dust shoe. Regardless, I was thinking of following the model from the Clough42 video, unless there’s a reason I shouldn’t.

  • What type of fitting do you use to go from your 1/2" NPT threaded filters/regulators to your 1/4" push to connect fittings? Ultimately I’d like to hook a push to connect manifold up to the air system to provide air to other tools (workholding, coolant maybe, etc.).

  • I’m thinking of just mounting the regulator and filters directly to the CNC frame / legs. I can’t fathom there’s anything to be concerned about with this, but thought to ask.

I think that covers Air…

I think it’s pretty well understood that getting into an ATC spindle represents a high bar of financial commitment. That said, I think I’m pretty well covered with tool holders and collets for my tools (18 to start). However, there are a few places where some recommendations would be welcome.

  • I purchased a simple ER32 collet wrench, nothing fancy. I am curious though, do any of you actually torque your collet nuts for your tooling? If so, what torque wrench setup did you go with?

  • I’m a bit lost on what tool tightening stand I want to go with. The prices seem to wildly vary, and I’ve never used one before. Any suggestions on a nice ISO30 tool tightener?

  • Tool storage is something I’m also a bit daunted by. I have several friends who are professional machinists and they all have these nice carts and racks and things filled with a gagillion dollars worth of tools and holders. Is it worth buying a cart at several hundred dollars, or just to CNC something out of ply and be done with it? I have no issue firing something up in Fusion, but I dont know if theres a benefit to one of the carts vs. just a stand I can put on a bench somewhere. I’m curious what you guys use.

  • Since I’m not really doing any automation (yet) with my system, I decided to ditch the AVID touchplate since for reasons I cannot figure out it doesn’t always seem to be accurate and is obviously limited to really only finding corners and Z. So I decided to go the route of a Haimer Zero master. As of now, I’m thinking to have tool 1 (one) be a 1/4" precision dowel pin with an arbitrary stickout (0" offset in the tool table), my cutters as 1 to N with appropriate stickout per tool, and my haimer as tool 99. Providing I use Mach 4 to precisely measure each tool offset, once set I imagine my tool offsets will work just fine. I would use tool 99 to locate the fixture offset(s), swap to the first tool of my operation and run the program, tool changing as appropriate.

Then, to add future tools I’d just zero Z with tool 1 (the dowel pin), and go through the tool measuring process with each new tool.

  • Not really a tooling thing, but this spindle seems a bit heavier than my 4HP unit. What have you done to reduce the load on the Z axis motor? I’ve seen some mentions about gas struts and things like that, but no concrete part or mounting recommendations (that I could find).

Finally, dust collection. I am asthmatic and allergic to pretty much everything (I should have been a machinist instead), and this is a big deal to me. I run an Oneida V3000 dust collector with a 35 gallon drum and it’s been great. The dust shoe I have, one made of clear plastic works “fine”. With the new spindle, I’m considering new options for a shoe since the old one won’t fit (obviously). For the short term, I’m probably just going to create an adapter ring out of BB ply to attach my existing shoe to the new spindle. With that in mind, and with dust shoe’s a near holy war topic, are there any units out there for the S30C that you’ve used and work well with a 4" hose? My vacuum trunk is 7", so in theory I could go up a bit if there’s say, a good 6" unit out there. I can design my own and either machine or 3D print it, but I think I’d rather just buy something that works and focus on other things.

Once I get all this pulled together, I’ll provide a full shopping list of the things I went with and some information of how it went together and things I’d maybe do differently.

Thank you for being patient with my long post here. I’m hopeful this thread will be helpful for those with, or getting into the CNC Depot spindles.



Wow that is a pricey compressor. I saw an ad for bambi silent compressors 40db from the UK I believe.

I’m DIYing the S30C too, so I’ll share my choices, as I’m a bit ahead of you in some steps (and behind in others)
Air intake and filtering - I went with a simple filter that met the minimum specs, running off my shop air. Nothing special. 3/8 polyurethane tube (the soft kind) works great:

Unlike the cncdepot setup[1], I elected to put all the solenoids at the spindle, and run only one air line to it. In their box, the one solenoid selects between “body air” and “release tool”, it’s powered by the given power supply and some relay that you provide. I have a four-solenoid manifold, so I can independently control body air, tool release, and two air jets:

Those are Nitra 3p2 AVS-3212-24D solenoids from Automation Direct, and they’re the most basic “on off” type. Also got a 4x backplate, exhaust silencers, and various quick disconnects.
At the electronics end, they’re controlled by four din-mounted relays:

In my case, the Mesa board’s field I/O couldn’t provide enough current for the solenoids, so the relays were needed.

To support ATC I elected to use modbus (RS485) to control the spindle, instead of discrete wiring, as discrete wiring was messy for the number of signals needed (like “zero speed indication”). Whether that works for you depends; I use LinuxCNC and it has built-in support for cncdepot’s WJ200 vfd.

As for the Z load, I mounted a pair of constant-tension springs on the Z rail. At 18 lbs tension each they almost perfectly balanced the moving load:

The springs themselves run on bearings with some bits of 3D printed adapters and some hardwood I had laying around. The springs are fixed at the top, the Z motion extends or retracts them at the bottom. McMaster-Carr

[1] In an image of their setup, follow the blue wires from the power supply at the far left, to the relay at the lower right, to the solenoid mid-right. The solenoid’s input is the bottom black tube, and it switches which top air tube gets pressure (the other one is left vented)

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Well, welcome to the club. Probably way more S30C in this forum than the 8 HP thing-uh-muh-bobs…

Interesting question. At $120 to $150 per ISO30 tool holder + $30 to $80 per tool it gets far more expensive than what you put into your AvidCNC and compressor.

I have stackable 1/4" plywood boxes I make that have U-shaped ridges that match the taper. I use Avery sticky labels to label them so I know what is what. I also 3D printed clips that snap onto the 40 series extrusion and I hang regular tools there (things like probes an markers). You can see them in the pictures of my tool carousel in the builds topic. They have the tool number in white on the top.

Oh, you have no idea. I loaded a file generated by Fusion 360 that I forgot to set the machine for and it used some generic machine instead. When the spindle had spun up to 20k RPM, it immediately tripped the relay #1 for the tool release and let go a 3.5" long 0.5" diameter end mill.

Strangely enough, guess cuz the spin on it, but it fell straight down and bored a hole through the MDF and then sat there spinning for about 60 seconds wobbling like a top… or at least it felt that long. It made a cone shape in the top and bottom of the MDF from the wobble. Since the tool was only 0.5" and the ISO30 is 50 mm it didn’t go all the way through or I would have been is serious trouble.

Turns out the coolant in the default Mach4 setup is wired to the relay #1.

After that I unplugged everything from the AvidCNC controller that operated the draw bar and wrote my own controller :rofl:

You will also find that you will drop tools during tool change because Mach4 does not stop the Lua engine when you hit the e-stop, cycle-stop or cycle pause. You can check for enable and e-stop but cycle stop or cycle pause are really hard to figure out. Makes for a rats nest of code.

Goof luck! You will need it!

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I saw one setup where the relay for tool release was hard wired with a bunch of other signals/relays, like spindle-zero-speed-detect from the vfd, to prevent software problems like that.

Of course, I shouldn’t talk, I still don’t have e-stop connected :wink:

Was that the Clough42 video? He does a similar setup to what you’re describing.


It might have been, I’ve watched most of his videos.

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If you have the VFD from CNCDepot I think you can set it up that way. I noticed that Alex removed the instructions from his web site. That right their should be all you need to know on the topic.

I would certainly consult with Alex and the guys at AvidCNC before following anything a YouTuber tells you, myself included!

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So, when you go the route of ATC spindles (or in my case, quick tool changes), you end up with awkward tools that require organization and storage in a less convenient way than a drawer with end mills in it.

I didn’t feel like dropping stupid money on a rack with plastic inserts, so I came up with a pretty simple 3D printed approach derived from numerous other things on the interwebs. It’s designed to be attached to 35mm DIN rail, and is printed in two parts; a bracket (multiple per section), and a taper base that cradles your tool holders with a matching taper. The brackets are printed perpendicular and vertical to the DIN rail (not sure that’s the best description), maximizing the strength of the bracket, and the base is printed face up to optimize the taper.

It’s rock solid.

Anyway, I smooshed together a youtube short to show it off, I’m pretty happy with how it turned out. 3D Printed ISO30 Taper DIN Rail Prototype


I have something similar for tools I will need but not right at the moment. So I printed a hook that fits on the 8020.

When you have 99 tool though, things can get mixed up so I printed them with numbers.

Pardon the mess, I have everything torn up right now;


Great post! The only thing I might reconsider is your air drying method. It may be perfectly fine, but I would hate to risk a 4K spindle. Hankinson (sp) makes a solid air dryer that won’t break the bank. We buy ours from McMaster carr or Grainger cant remember… You wouldn’t need a large one if your only trying to run the spindle head. I work on Medical equipment where clean dry air is a must, and any water in the system will wreck your world. The hank’s keep everything dry and I would guess you could get one for under a grand if you not buying from the guys I mentioned earlier.

Here in Georgia those passive dehumidifiers never work or simply don’t last but a single session so I use active drying, a Quincy refrigerated air dryer.

But you are right, nothing will kill a ATC spindle faster than water or oil cycling through it.

I ended up going with the Deltech 25SCFM Air Drier and so far its’ been great. Doesn’t seem to pull a ton of water from the air though to be honest, my workshop is a really consistent 70F and 42%-46% RH, so it’s not super humid or anything. Seems like most of the water ends up condensing in the tank and blowing out the automated drain valve before it gets to the drier.

I like the insurance though. For anyone interested, here’s the model I ended up with.

Deltech HG25, 25 SCFM, Refrigerated Air Dryer | Refrigerated Air Dryers | Compressor World

I’ve really noticed the power difference with my S30C 3HP setup vs. my original 4HP from Avid. It’s interesting since (in theory) the VFD really only supports a 3HP spindle as I understand it.

For example:

With the 4HP spindle I ran the recommended chiploads for my Vortex 3/8" single-flute compression end mill to profile 3/4" material. I ended up at about 18000 RPM and 297 in/min with full depth of cut (baltic birch ply), and it cut like butter; nothing where I was ever concerned. Cut quality is spot on, tools are room temperature to the touch after jobs… completely happy with how it was running.

Now, with the S30C spindle at 3HP those numbers bog the spindle down considerably, which is obviously undesirable. RPM’s drop, F&S stays constant and the chipload increases; perfect recipe for a broken endmill. For the first time ever, I had a “hotter than I’d want to touch” endmill when I’m used to running a long job and having a room temperature cutter with the other spindle.

I have had really good results running the recommended chiploads with the vortex bits. They cut cool, are quiet, stay sharp and aren’t’ screeeeeeetching like all the 2-flute endmills on the youtube. For cut quality I’d like to keep the RPM higher for these cuts and then drop the Feed Rate, but I’m not really sure how much I need to compensate for the less powerful spindle to prevent the bogging down (increasing chipload).

I’m curious for those of you who run this spindle… I’m assuming you adjusted your F&S to accommodate the less powerful spindle, or did you mess with the VFD to compensate? I am still running the out of the box VFD configuration from Avid.

Huh, didn’t know VFDs had anything to do with horsepower accept for current output. Mine just stated wattage and frequency on the box.

I personally follow the tool manufacturer’s s&f and their recommendation for cut depth. The number they give is for longevity which is important for running an ATC. The last thing you want to do is get all fancy with s&f and snapping a tool off in the middle of a run.

Yeah I had no idea on that either, until Alex mentioned it. I probably misunderstood something, because that’d be par for the course with me these days, but it was a curious statement regardless.

I avoid breaking tools, but still do like to push them and maximize the value of the machine.

Have you looked at the new line of CNC Depot spindles? I’m seriously considering getting something with a bit more oomph, and I like the fan cooled aspect of them. Maybe sell the S30C, maybe keep it as a spare. Not sure what direction I wanna go yet.

I wrote Alex late last week with a few questions, and I’m cautiously excited about the direction he’s taken these units. Interestingly, much of my questioning was on power and electronics compatibility; I wish I had a better and more accurate understanding of the torque curve of these units (new and old). It’d be nice to plug them into HSM Advisor and see if it would actually change how I run my machine.

At the moment I am heads down getting this carousel to market so I made a quick check and the new spindles are compatible but I haven’t taken the time to go more indepth with them.

I like the fact an American company it out there swinging in the midst of a flood of cheap foreign spindles. And they are price comparable when you get to that level of functionality to boot.

Also, be advised that there are new break in and warm up instructions for the S and FM line of spindles.

I didn’t know that there was a new warm up procedure, I’ve been using the one that was provided back in December of '22 when I bought it and installed everything.

I’m with you, I love that this is all American made, and that Alex is such a champ with all my questions (not that many tbh, but he spends time to answer them well). Where I’m stuck is which version of the new spindle to get. The American in me is like … “SEVEN HOASSEPOWAHHHHHHH!”, but I’m just not sure the Avid machines can really take advantage of that much oomph and wonder if the 5HP isn’t more, well, practical. Alex says they are essentially the same size and weight, and the cost difference isn’t crippling.

I love my Avid machine, but I can think of things that are more rigid. My gut says 5HP is the right power/value, but that’s all I really have to go on. I think the shop sabre pro models come in either 5hp or 10hp, and I suspect those machines are a bit more capable than mine.

I guess I just want the option to experiment with pushing the machine harder, and don’t want spindle power to get in the way.

I’ve been watching that project with a great deal of interest.

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I keep my mouth shut on the topic but since you started it :grin:, anything over 3hp will just highlight the lack of rigidity in these systems.