Buying a CNC router... need advice

How-Tos & Esk8 mechanics
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I am buying a CNC soon. I plan to open a DIY esk8 related business, with a focus of CNC machined parts. I need some help with selecting the right machine. I don’t have any CNC experience, but I have experience with laser cutters, 3d printers, and CAD design. (Just to clarify… I know I am not gonna get rich from becoming a vendor… mainly want to do it out of passion and to gain experience)

What do I want to make with the machine? Motor mounts, trucks, gear drives, wheel hubs, pulleys, deck protector X plates, onewheel rails… Esk8 mechanics basically, all machined in house. Mostly machined from 6061 or 7075 alu. I would however appreciate if the machine could be used to perform lighter or less critical tasks in steel as well… For example to cut pockets and holes in steel gears. Also in the future I might be interested in cutting some larger pieces of wood as well. Perhaps some decks… So ideally I would have a 125cm X axis, 50cm or 75cm Y.

And now the hard part. The budget. Ideally I would like to keep the cost of the machine without accessories around 3k€ EU VAT included. I could stretch that budget a bit if it’s required, but if it’s not required I wouldn’t want to. I know this is a though question. But are production quality parts possible with such a cheap machine? I don’t need the CNC to cut at the same speeds as a production machine.

My favourite option so far is the Ratrig Stronghold Pro, seems very robust for the price

Now in order to machine everything I want, I would pick the 1500x1000mm work area version of the advanced preconfig… 1000x1000 is the smallest. This is quite big though, so I might by sacrificing some rigidity. How much rigidity am I really sacrificing with that 50cm extra length in one axis?

TLDR of the machine: The machine is using 40 series aluminium extrusions, 16mm ball screws and HG25 linear rails on the X and Y, 12mm ball screws and HG15 linear rails on the Z, and has 12mm steel gantry plates. 2.2kW water cooled VFD with ER20 collet. “High torque” nema 23 steppers. CNCdrive AXBB-E controller

The other part that I am kinda worried about other than rigidity is this:
Full Step Distance - X: 0.05mm
Full Step Distance - Y: 0.05mm
Full Step Distance - Z: 0.02mm

Does this mean that no matter what I do, this is the best possible precision that I can achieve? Is this good enough tolerance for press fit fitment of bearings, for example in a 28mm wheel hub bearing seat?

Also, about how much should I expect to spend per drill bit? How much does it matter in your experience if I use good quality ones vs much cheaper chinese ones?

Tagging some smart people in this topic
@Savage1 @Creavenger @Boardnamics @Bavioze @MarkVa1 @ducktaperules @surfnacho

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Having just bought a Syil X7 and having gotten tens of thousands of machined parts made over the years, I will chime in.

Based on what you have chosen thus far, a gantry style lightweight CNC router, you will have no trouble making plate goods such as motor mounts or even decks.
However, parts that have multiple features on several faces that require tool changes and datum referencing will prove to be challenging and time consuming. Here is why:

Rigidity and accuracy:
An aluminum extrusion based router like that will have significant deflection on tough cuts. This can be “tuned” by your CAM however, by taking spring passes. However, it is very difficult to achieve the fits you desire on a router like that. Without getting too technical, CNC routers can achieve quite accurate “features of size”, but they lack the ability to consistently produce to precise geometric tolerances such as flatness and perpendicularity.

Tool changing and datum referencing:
A basic CNC router with no probing, tool setter, or closed loop servos means keeping a work coordinate system is much more difficult and time consuming. Part flips that require referencing datum features to accurately locate the next machining operations would be very difficult to do within a reasonable time frame.

Long story short, that is a good machine for simple flat plate based pieces and large deck work. A great machine to learn on but nothing I would want to make 80% of ESK8 related parts with.

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Don’t forget @SabreDynamics

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Totally agree. Speaking as someone with a similarish machine, there is definitely a trade off to be made between work envelope and high precision performance. If you prioritize making smaller but more complex and precise aluminum parts over the versatility of a large machine, you’re gonna want to go for a small mill instead of a router I think. If you go that route, I’d probably suggest doing something similar to what @SabreDynamics did. His machine is not really off the shelf but seeing as you wanna be an estate vendor I’d assume you like mechanical projects so maybe that’s something to think about.

I think given your budget it’s not possible to get everything you want out of one machine, so you’ll probably need to make a tradeoff.

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Ill second this too, maybe its good to invest in two machines, a cnc mill which can do small parts (3axis first) and also a cnc router for deck work etc, make sure to buy a good vacuum cleaner aswell. Especially for the router, that stuff gets dusty real quick.

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I also agree with @Boardnamics, the router will be doable for flat plate parts up to a certain thickness. I wanted to go this way too at first with the same budget as you. In the end I realised if you really want to make esk8 parts you will need a more rigid machine like a convential mill. I converted a (small) manual mill to cnc, in the end I was close to 4-5k for just the machine and electronics then I still needed all the tools, like toolholder, endmills and drills. Also measuring equipment like a dial indicator, a touchprobe and other tools. This is easily another 1-2k, typically 1/3 of the cost of your machine if you get decent tooling. And dont forget a lot of time to actually build the machine and get it up and running with the drivers and the software. Took me 2 years in the end to get to a point where I was happy. At the moment I can make most parts I want, even though the work area is quite small. There is still much to be desired like higher spindle speed to run the machine faster, at the moment its quite slow for production and often not worth it for bigger or more complicated parts. if I had the funds and space for a machine like the Syil X7 I would definitely get that, it makes complete sense for production. You want enough rigidity combined with a big enough workarea and good spindle power/speed. Also a touchprobe and a toolchanger to make it worth it for business.

If you really want to make decent esk8 parts without spending months or years to build a machine id consider to save up a bit more. Maybe also consider to buy an older commercial second hand machine. If id start over thats something I would definitely consider to save most of the building headaches. I have recently also seen this machine MR-1 CNC Gantry Mill | Langmuir Systems it looks pretty great for the price. But will probably set you back 6k in the end too and it doesnt have a toolchanger.

This will make a big difference, smaller routers often have much more rigidity.

I guess these are the minimum increments you can move so it will limit your accuracy. To give you and idea, I already struggle to get good bearing fitments due to backlash and tool deflection and I needa boring bar to make proper bearing holes. This tool is too long to fit on a router. Also I believe the minimum step distance on my cnc is 0.001mm. And If I realy try and do a test part I can get my parts up to ± 0.02mm tolerance

You can get some pretty good tools on Aliexpress, ive gotten some endmills that cut better and leave nicer finishes then quality german endmills that are 5x the price.

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I can add probing and closed loop servos to the machine quite easily. I haven’t seen anyone do a tool changer for this machine however so if I go with this one I would need to live without that

Even if I take a very shallow finish pass?

I am happy to DIY something, but I need to note that since this will be the first machine I have, I won’t really be able to custom make parts in house, so that would definitely drive up the cost of a DIY. Also, I would much rather follow a guide or a kit for a first machine rather than to design something from scratch. I don’t have the experience to know what works well and what doesn’t.

I definitely agree! But I don’t have the budget for that at the moment. I think I should try to downsize then… But I also definitely want to keep the ability to make onewheel rails, so I guess I will keep the X at the smallest stock length and modify the Y to 500mm or even 400mm later down the line maybe?

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I could do that but I haven’t seen any good ones on the danish used market. With that said it is probably worthwhile to look into the northern german used market as well because I am happy to drive a couple hundred km if that means getting a better machine.

That was really informative. Alright. Then I guess I don’t even have a chance for good bearing bores with this one. Backlash is a good point as well. No idea how tight of a tolerance I will be able to keep with this. As far as tool deflection, I could try putting in a 15mm drill bit, my collet supports that. Maybe that wouldn’t deflect as much

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Yes I would definitely look into that.

The larger the tool the more torque and power you will also need, routers normally have low torque but operate at high rpm to compensate. for example I run a 10mm endmill max on my mill. And the deflection is not only in the tool and collet/toolholder but also in the whole machine, like the axis gantries and the base. The MR1 is pretty great on rigidity. They pour epoxy granite into the base of the machine to make it more rigid overall, meaning you can uses larger diameter tooling and take bigger cuts with less deflection.

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I agree with the “namics boys”, @Boardnamics and @SabreDynamics. :+1:

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Some very good advice only thing I want to add is a cnc is a simplified 3D printer so if you build and design them you can use idea just beefed up.

Just look at old reppap software that’s literally what they’re useing no kliper, no ADXL no pressure advance,

Iv get a V core 3 I know their standards. Their CNC are good DIY for wood POM. I would not recomend ratrig for Ali or metal. You need a cooling set up pumping fluids and some thing stiffer. You may get by for motor plates but not for hubs, VESC boxes, trucks, gear drives need some thing considerably stiffer, accurate and more powerfull.

Think of it like a estate car vs a lorry both are about load space but one is way better at comershal.

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Kevin out here quoting GD&T

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Honestly, Kevin nailed it, but I will still share my thoughts. And since Kevin flexed his Syil, I’ll mention that I am in the process of buying a Haas VF2 :stuck_out_tongue:

I have a fair bit of router experience, on all sorts of machines, from $1000 China routers to the industrial shopsabre in my parent’s garage. And my non-profit actually owns several machines very similar to the one you posted.

I am a huge fan of CNC routers for sheet jobs, but anything with advanced geometry, required part flips, and/or thicker material will suck. You may be able to get some parts with these features to work, but your surface quality, edge finish, repeatability, and tolerances will not be up to par. Any reasonably thin and flat parts will be a breeze to make (in some ways easier than a VMC due to simple and dense workholding strategies like wood screws); gearboxes, motor mounts, anti-sink plates, etc.

Rather than me restating what Kevin said, just read this again lol:

The only parts from this list that you can actually make on a CNC router are the motor mounts and x-braces. And even those two parts will require solid feeds and speeds, good tooling, and some method of chip clearing (air blast or preferably mist coolant).

I totally get that you want versatility, but these machines are really meant for woods, plastics, and LIGHT ALUMINUM work, I would completely forget about steel.

Kevin used to whip the Chinese huaho single flute endmills (~$5) on his Omio. They are hit or miss. I used to run some Chinese endmills, but pretty quickly switched to Amana o-flute router bits once I was actually making money with the machine. Those will run anywhere from $25 to $45 per tool (depending on diameter, tool coating, cutting length, etc.)

If you do still want to buy a router, I would check out the Omio. I have never had one, but they are incredibly popular in the FRC community, and Kevin owned one for while.

I am happy to answer any more questions :slight_smile:

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Alright I am pretty much converted from a router to a mill now. The only issue is finding one that’s readily available EU side within my budget. Plus I need one that I can fit through a door in parts at least… And has to be liftable by 2-3 persons

The router I linked above is about comparable with the omio x8, just slightly bigger.

If I can’t find a mill that fits my criterias, what do you think about taking a beefy router (like the omio or the ratrig) and reducing it in size to a work area that’s comparable to a mill?

The ratrig can be shortened quite simply and after adding some features like a touch probe and closed loop servos could be fairly capable I think. Not as good as a purpose built mill of course

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I’ll add to this a bit. I’ve been machining for about 29 years now. I went to a trade school right out of high school to be a machinist. 2years. Then, did a 5 year apprenticeship to become a tool and maker. I spent my first 10 years making precision parts on manual machines. Then, I learned CNC using G & M code programming. In last 10 years, I finally became a mechanical engineer.
I think your ambitions are awesome! I would recommend getting your feet wet with a light duty machine, and learning how things work, and make fun parts for yourself. After a few years, you might be able to manufacture parts for sale.
For example, here are some simple clamp adapters I’m currently making to adapt 3 links to other gear drives. Looks simple right? How might you go about making this assembly?

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IMG_4959
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I’m not so sure of that. What are you factoring into your comparison? Just the machine specs page? From my quick look, the Omio is still considerably better.

https://www.langmuirsystems.com/mr1

The MR-1 is probably the cheapest “real” machine that you can kinda make your parts on. It will be pretty slow, and part quality will be alright. It has a probing option which is nice. However it is still running generic stepper motors. Edit: Saw this was already shared above.

You can try. I am sure you will end up with a great machine. But you still cannot really expect to make parts like wheel hubs. Many of those issues that Kevin explained will still exist.

I would just caution you from spending too much and not getting the capabilities you want. If you spend 10k and still can’t really make “mill” parts, that would be a bummer. Honestly since you are new to machining, I would just grab an omio and start playing. Learn as much as you can, make some cool parts, push the machine.

Screenshot 2023-07-25 at 4.08.51 PM
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Kinda unrelated, but my buddy just designed and put together this machine for our non-profit. This will be used mostly for education. Almost fully custom except for the extrusions, ball screws, and linear rails from the queen-bee kit. Just wanted to share :slight_smile:

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Have you heard of the millennium milo? Small DIY desktop CNC mill. May be worth looking into.

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I will add one more thing. If you really want to make good parts, you will spend around your said budget on a machine, just in tooling alone. Clamping and work holding, tool holders, cutting tools, and measuring tools.

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One more, If you do find a decent mill, it might be 3 phase power, so check that as well. If you don’t have that, then you will need a phase converter which is more money, and also consumes much more electricity, leading to higher energy bills.

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One more last one. If you are choosing a milling machine over a router, most likely it should be for a more ridged machine. If 3 persons can lift it, it’s no good for the application you want.

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