Seriously Considering Purchasing a Sienci Longmill MK2 for my company

Hello there! I’m David and as the title suggests, I am looking to purchase a hobbyist-grade CNC router for my company. We are looking for something that would be able to drill holes into a skateboard deck with reasonable dimensional consistency. Our goal would be to create interchangeable parts from deck to deck and have designed our holes to have some variation since variation in deck geometry is expected from deck to deck.

More info:

  • We would likely be making ~10 units per batch
  • The entire skateboard deck wouldn’t need to fit in the work area since we can create a fixture for the area of interest.
  • The decks are made of a fiberglass/bamboo composite
  • We own a Prusa i3 MK3S and a Voron Switchwire
  • This is the exact configuration that we are interested in:

Key questions:

  • Our impression is that a hobbyist machine such as the Sienci Longmill MK2 would be able to provide enough dimensional consistency to make our first ~100 or so units since dimensional variation seems to be less than 1mm. Is our impression correct, or should we increase our budget or look elsewhere to get a more dimensionally consistent machine?
  • What safety equipment and/or procedures are recommended, especially since we are also machining fiberglass? We are also considering buying this Dyson canister vacuum since it is the cheapest HEPA rated vacuum we found. [Link]
  • What maintenance tools and supplies are expected to be purchased?
  • What is your maintenance schedule for your machine if you own a Longmill MK2?
  • I live in Michigan. It is my understanding that Sienci is in Canada. For those in the United States, have you ever had to send anything back to Sienci, and if so, what was that experience like?
  • What software do you guys trust? I’m a 3D printer operator primarily and was very taken aback by the $600 price tag of VCarve Pro since slicer software such as Prusaslicer is free. I’m happy to pay for good software, but figured I should ask before shooting $600 at some software. I also use Fusion360 but haven’t looked into its capabilities yet.
  • Is there a way to estimate job time before purchasing the machine with software? Somewhat related to above bullet point.
  • If there were to be some geometry that I would need the router to navigate around, how would I specify these moves in software? I could manually edit gcode so that the gantry could go up and over, but I wondering if there was already an established solution for this.

I appreciate any insight you guys may have :slight_smile:

Edit: Added Dyson canister vacuum link and software-related questions

Hi David!

I’m sure the folks at Sienci and others on the forum can answer a few things in a bit more detail than I can, but I can offer you my experience on some of your points.

  • Dimensional accuracy: actually far better than 1mm - I would say easily 0.5mm or smaller. The accuracy and repeatability of your fixturing would be the main concern.
  • Safety equipment: wear proper breathing protection (i.e. a real P100 respirator) and safety glasses while running the machine. You will also want a cyclone in your dust collection setup, and perhaps some additional filtration. (This is a fiberglass thing - I would recommend looking more into that, it’s not my area).
  • Materials and tools - what you have listed sounds decent - but I would investigate additional / slightly different cutting tools. You don’t really “drill” with the machine, you more or less bore holes in a spiral - so having a smaller bit than your hole is necessary. Consider 1/8" downcut and upcut bits - and buy packs of 10, they do break. Downcut leaves a nice surface with no tearout; upcut evacuates chips better. I think Garrett Fromme (IDC Woodcraft) has a video that talks in depth about bits, but I don’t have it on hand.
  • Maintenance schedule: if your primary purpose is drilling, you could easily run 100 decks without any significant maintenance. End of every day, vacuum up any dust / chips, start of ever day check for backlash, check the motor couplings are tight, check the v-wheels are snug (basically 5 minutes of work).
  • US Returns: can’t speak for that, Sienci is located in my city - and I have never had to return anything.

We would love to see your work! If you have any pictures, feel free to share - and if/when you do get your machine, definitely show us your setup and fixturing!

(Edit - changed CNC to Sienci - it’s an easy slip)


Thank you for your quick response!
I found these bits, would these be adequate? [Link]

I am a hobbyist and I own a Prusa i3 MK3S and a Sienci 30x30 LongMill MK1. I have also had a cheaper printer and CNC. I think that both the Prusa and Sienci machines are really good especially for the price point.

I’ve made boxes, signs, cribbage boards and various other things with the LongMill. As Ed has said you can easily get sub mm precision with the LongMill.

I used to work removing asbestos so I know a little bit about the importance of respiratory protection. From a business perspective you definitely want to look into this both for health and safety reasons and possibly regulatory requirements in your state. Personally I would wear a P100 respirator if I was machining fiberglass unless I had air quality testing done to prove that the air was safe during operation. There are companies that can take air samples and then look at them in a microscope etc to see if the air is safe with your setup.

As far as maintenance there isn’t much needed with the LongMill. A little 3in1 oil for the linear bearings and keep the machine clean. Check that all is tight and right before use, it’s not hard and you assemble the machine yourself so you know where everything is etc.

I’ve had my machine for a year and a half and haven’t needed to send anything back or replace any parts yet but bear in mind I don’t use it every day. For a business it makes sense to have some extra wheels and probably some extra anti-backlash blocks as well because they do wear out over time.

Thank you for your response! I just found your files on Printables while browsing for Sienci files. I found extra wheels, but didn’t seem to find extra anti-backlash blocks, where would I find these?

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Hi David, I don’t know if it’s Amazon’s pricing into Canada, but those do seem to be quite expensive (when I see them - but sometimes Amazon goes a bit wild for Canada). They will do the trick - if you’re making an order with Sienci look at their selection of bits, they do have the same / similar, in packages of ten, at what I find to be very reasonable prices. I can also say the Sienci sold bits are of a known good quality.

Hope that helps!

On this page there are 2 sizes of blocks, I’m not positive but I’m thinking the larger one is just for the X axis on the 48" machine but would need to look at the assembly manual to be sure. It looks like the small ones, the ones I think you would want are out of stock. My machine came with one spare and I haven’t needed to use it yet but when time is money I would keep some just in case.

EDIT: The LongMill MK2 resource pages have a lot of information about the machine and assembly. Not sure if you found them yet.

I think if you know Fusion 360 you just have to learn a new part of it and you’ll be good to go. I stopped using F360 when the hobbyist version no longer allowed sales so I never learned the CAM part of F360. Fusion can output the G-Code and you control the machine with gSender which sends the G-Code to the mill.

This lead me to search the web for 3d printing skateboard parts and I found a fascinating world that I think I’m to old for :smile:

With that in mind Vectric, while great software, might be paying for things you don’t need? Do you plan to engrave or carve designs on wooden decks? I think anything can probably be done in Fusion but VCarve makes carving and engraving really easy. Also makes doing wood inlays pretty easy.

In this context gSender is like Pusaslicer, free, and VCarve is CAD/CAM software more like F360.

The control of the machines and the software is a little different but it’s not hard.


  • Make and slice model
  • Transfer to printer
  • Control from printer


  • Design and export GCode
  • Control the machine with gSender running on a PC

At least that’s how I do it on the printer side, not using OctoPrint or anything.

Your software analogy made complete sense! I wouldn’t be engraving into decks, at least not at this time. I’ll save myself $600 lmao. I have the startup license of Fusion 360 with CAM features.


As for software to “design” the gcode, you do not have to buy it. If you’re just doing holes, grooves, skateboard outline profiles, many free software options are out there. I use carbide create (version 6, —version 7 won’t work with gsender) and you can do a lot with it. You can’t do true 3d carved shapes, but you can do 2.5d, which means you can drill holes and grooves with extremely good accuracy. Carbide create looks basic, and it is simple, but you can easily do a lot with it. Do a you tube search. If you want to drill 8 holes for skate trucks in a board I have no doubt you could do this with less than .5 mm error. Once you make your gcode with carbide create ( or other program, like fusion 360 or easel(free also), then you can use a gcode sender program like gsender(by sienci, free, and easy and very good) or Universal Gcode Sender (also free and good, I used to use that before gsender) or some others. You don’t need paid software for drilling holes and cutting grooves or even cutting out outer profiles of board shapes with extremely good accuracy. Put some effort into designing and making a good and accurate jig to clamp your boards into the CNC machine in an exact and repeatable position, and then the software can easily drill and carve over and over what you designed