Created a new CNC router design, some advice needed

[vagearie]

Hi all,
First of all thank all you guys for posting on this forum i learned a ton from it. I am thinking about building a cnc router myself for a long time not, but recently got a bit more serious.
I made a first design (still not completly finished) and was wondering if you guys could comment on it and maybe give me some tips.

I wanted to design a machine that is suitable for wood. If it can cut aluminium at slow speeds then that will be nice too, but it is not the aim. I don’t have a clear budget, but my aim is to stay under 1000€ and have nice rigid machine.
At my work they have a lasercutter so i can ask them to lasercut a few things for me for free (only flat parts and not on a regular basis). I regularly model in unigraphics so i have acces to that as well. I also got 5 NEMA34 motors (PK299DW-A4) and 1 driver (RBD245A-V) from an abandonned project. Other than that i just have standard tools.

Please see the attached images of my first design draft and my partslist with prices from the websites where i want to order it. I made the following design decisions:
- The machine has to fit in a small shed so i tried to keep it a bit compact. I plan to rotate the machine in a vertical position when it is not in use (still have to add this to the design).
- I aimed at a 1000x70x10cm usable workarea (doesn’t have to be exact)
- I tried to keep all lasercut parts the same thickness (3mm) to keep it simple and easy to lasercut.
- I don’t have easy acces to welding equipement so i created a design that is fully bolted (see detailed image for an example connection). This gives me the bonus that i can still take it apart if needed and there are no
deformations from welding so everything should fit and adjust nicely.

I still struggle with the following questions:
- Is it smart to use the NEMA 34 for x and y and what drivers should i use for it? I have enough steppermotors, but only one driver.
- I used a NEMA 23 for z although i still have more NEMA34s. I thought the whole thing would be too heavy with a NEMA 34 on the z. Is this the good decision?
- What power supply should i use? I can probably get a 12V 60amps power supply for free, but is this usable with these motors.
- I chose to use a Makita RT0700C spindle? Would this spindle be proper fort his setup?
- Are there any parts that i am buying for too much money (see pricelist)? I can get the bearingblocks for my spindle a lot cheaper, but then the bearing block and spindle are from different suppliers. Is there a chance that this will
result in problems with tolerances?
- Any other design things i am doing wrong?

If helpful i can also share the 3d files.

Thanks,

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[wizard]

Hi all,
First of all thank all you guys for posting on this forum i learned a ton from it. I am thinking about building a cnc router myself for a long time not, but recently got a bit more serious.
I made a first design (still not completly finished) and was wondering if you guys could comment on it and maybe give me some tips.

Probably the biggest tip i can give is try to come up with the most rigid deign possible that fits the budget and tools available. It is fair to say that this is always a struggle.

I wanted to design a machine that is suitable for wood. If it can cut aluminium at slow speeds then that will be nice too, but it is not the aim. I don’t have a clear budget, but my aim is to stay under 1000€ and have nice rigid machine.

The feasibility of doing so depends upon the machines size and what you can get suitable materials for. In the end only you know local conditions as far as buying materials and services.

At my work they have a lasercutter so i can ask them to lasercut a few things for me for free (only flat parts and not on a regular basis).

Flat parts are of limited usefulness in my opinion.

I regularly model in unigraphics so i have acces to that as well. I also got 5 NEMA34 motors (PK299DW-A4) and 1 driver (RBD245A-V) from an abandonned project. Other than that i just have standard tools.

It might be a good idea to define standard tools! That is for both you and the guys reading the thread. Often it makes sense to take an inventory of your tools to see if you will come up short anywhere.

Please see the attached images of my first design draft and my partslist with prices from the websites where i want to order it. I made the following design decisions:
- The machine has to fit in a small shed so i tried to keep it a bit compact. I plan to rotate the machine in a vertical position when it is not in use (still have to add this to the design).

Any suitably rigid machine, even one made out of wood, will be heavy. A tip up machine will require some engineering thinking to assure safety. Totally doable but you need to make sure falling on somebodies head is impossible and you need to make tip up safe for your back. The other thing here is that the more rigid your machine the least likely you will have alignment problems setting it up.

- I aimed at a 1000x70x10cm usable workarea (doesn’t have to be exact)

Machine size can make or break a budget. If the budget is tight then keep the machine small and rigid.

- I tried to keep all lasercut parts the same thickness (3mm) to keep it simple and easy to lasercut.

Unfortunately unless you have access to a metal break to bend those flat pieces into usable assemblies i dont see a lot of uses for flat stock.

- I don’t have easy acces to welding equipement so i created a design that is fully bolted (see detailed image for an example connection). This gives me the bonus that i can still take it apart if needed and there are no
deformations from welding so everything should fit and adjust nicely.

Distortion can come from a number of realities in metal working even laser cut sheet stock can deform. Dont be surprised if you laser cut stock requires some wrangling to go to gether as designed.

As for bolted up construction, nothing wrong with that. Do plan on gussets angle brackets and so forth.

I still struggle with the following questions:
- Is it smart to use the NEMA 34 for x and y and what drivers should i use for it? I have enough steppermotors, but only one driver.

If you are on a budget it is always smart to work with what you got. As for drivers and power supplies you need to know the electrical characteristics of the motor. Each model is a bit different and properly matched drivers and supplies makes a huge difference in performance.

- I used a NEMA 23 for z although i still have more NEMA34s. I thought the whole thing would be too heavy with a NEMA 34 on the z. Is this the good decision?

Off the top of my head no. Assuming your Z is the vertical axis, that axis is working against gravity. That could be an issue with a heavy Z axis.

- What power supply should i use? I can probably get a 12V 60amps power supply for free, but is this usable with these motors.

That cant be answered without the motor specs. My gut feeling is that 12 VDC will be too little.

- I chose to use a Makita RT0700C spindle? Would this spindle be proper fort his setup?

Im not familiar with that model. Generally on a low budget machine you implement something cheap until you can upgrade.

- Are there any parts that i am buying for too much money (see pricelist)? I can get the bearingblocks for my spindle a lot cheaper, but then the bearing block and spindle are from different suppliers. Is there a chance that this will
result in problems with tolerances?

Sadly some of the cheap Chinese bearings are just that - cheap. On a cheap machine build you upgrade to higher performance stuff in the future.

- Any other design things i am doing wrong?

The basic design bothers me. The basic table design looks like it would be almost as rigid as cookie baking sheet. That isnt good.

The gantry construction isnt clear to me (on my cell phone). However it looks to be thin. Especially on the gantry, you would be just as well off to use a steel box beam. While they would be different sizes id use steel box beams (square tubing) for a good part of the remainder of the machine. For the most part, a bolted together machine from steel tubing is faily easy to do.

If helpful i can also share the 3d files.

Thanks,

At the moment im traveling so wont be looking at new files.

[awerby]

I looked up those motors: https://www.oriental-motor.co.uk/Pro...0876&dwn=artnr With 2.5mH of inductance, they'll want 50v DC supplied to run optimally. At 12v they'll run poorly, if at all. I'd suggest the Geckodrive G-540 to drive them, but I can tell you're too cheap, and will have to buy a crappy set of drives first before you're convinced it's worth the money.

That hand router will work for a while, but ultimately you'll want to get a real 3-phase spindle and VFD. I wouldn't worry about the weight of the stepper on the Z axis, since it doesn't have to go up and down - the effect of it will be negligible (unless you plan to operate the machine in a tilted-up position.) I'd use profile rails instead of the round ones, but again, they're more expensive.

The basic design is pretty standard, and it looks okay to me, but as Wizard says, you'll want to beef up the table underlying it. You can often save time (and even money) by finding an actuator to use as the Z axis. Good ones come with profile rails and ball screw pre-installed, lined up and mounted in a rigid extrusion.

[dpot]

have a look her https://www.ebay.com/itm/New-3-Axis-...8AAOSw5P9bBRpH sume good prices and if you ask him he give good info if you are just looking to cut wood my be have a look at the Vslot liner rail system price is beater than open close bar rails may be have a look her and pinch sum ideals https://store-itwgldve.mybigcommerce.com/

the hand router as awerby has said // i used a porter cable router 7518 and it is very noisy so if you have neighbors use good air cooled spindle

[vagearie]

Thanks for the replies so far, it has been very helpful for me. Here some extra information that was probably not clear from the initial post:

- I don’t have a big workshop and basically only hand tools. So no fixed drill, band saw or other big machinery.
- I have 5 NEMA34 steppermotors (PK299DW-A4) https://ciiva.com/part/pk299dw-2449814 , 1 driver (RBD245A-V) https://catalog.orientalmotor.com/it...phase-bipolar-
stepper-motor-drivers/rbd245a-v and oe 12V 60 Amp powersupply (which is probably not enough)
- I plan to fold the machine vertically when not in use, but downwards instead of upwards. It will then still take some room, but it will avoid having this big weight hanging in the air

I have some questions based on the replies:

About baseframe rigidity: I will try to make the base more rigid based on your comments. I also noticed that the baseframe design is probably not clear from the initial pictures, so i added some extra of the baseframe only and ganrty only. I plan to bolt the frame to a thick sheet of wood so that wil probably help with the rigidity as well. I also have looked at other entry level designs, but they look a lot weaker. For instance the shapeoko or xcarve. Practically the only rigidity there comes from the wasteboard itself. So looking from that point i should be fine right? I am not aiming for the very precise tolerances, but the parts i want to make with it should look visually decent.

About the lasercut sheet metal parts: We use this a lot at my work and i never noticed any significant deformations (i will at least achieve way better tolerances that making a frame with only hand tools). We regularly make designs from only sheet metal, sometimes even without bends. I can be very sturdy, but is of course all depends of the design. I saw that for instance bobscnc (https://www.bobscnc.com/products/e3-cnc-engraving-kit ) is made entirely out of flat sheets so this is possible. I understand that this wooden design is probably not very good in terms of rigidity, but i think a fairly rigid sheet metal design without bends should be achievable and that was my aim.

About the steppermotor on the z-axis: Your comment on this in not entirely clear for me. Do you advice to use also a NEMA34 there that i already own or buy and use a smaller one?

About the steppermotors + drivers: The Geckodrive G-540 really looks good. I saw a lot of complaints about cheap drivers not being up to the task However this one will almost eat up a third of my budget (at approx approx. 300€ incl shipping). I checked the TB6560 but i think it is not suited for a NEMA 34. Are there any options a bit more in between? And what powersupply will i need to complete the set?

About the spindle: I have neighbours so sound is definately a concern. Any suggestions for a good air cooled spindle? Is it possible to get one in the 200€ pricerange? What VFD would go withit? I thought that air cooled spindles still made a lot of noise and that the only option to limit the sound was to go for a watercooled spindle?
About the v-slot rail: I checked it.There is some difference in price,but it is not that big. When you add the leadscrew the difference becomes bigger, but it will require a complete redesign. I keep it in mind.

Thanks for helping me out.

[awerby]

I'm not clear on how this thing is supposed to fold up. It would be hard enough to make it without this feature, given your lack of tooling. Give us a more detailed drawing, showing the unfolded and folded positions, if you want comments on it.

How thick is the sheet metal you plan to use for your gantry? Unless it's a lot thicker than normal sheet metal, I don't see that gantry beam being a viable component for CNC routing. You'd be better off using plywood. You can decorate it with the sheetmetal on the outside if you want.

The NEMA 34 motor should work fine for your Z axis.

I thought you'd balk at the G-540, so try something else that's cheaper and buy one later, when it doesn't work. Don't get a TB6560 - those are the worst. You need something that will tolerate 50v, which leaves out most of the cheapest boards.

Get a power supply that puts out 48v with enough amperage for your motors. If you've already got a 720 watt supply, you can probably add a voltage converter that would boost the voltage to 48 for less than a whole new supply.

The inexpensive Chinese air-cooled spindles get good reviews around here for the most part. They usually come with a Huanyang inverter. I'm not sure how much they cost in Europe. Make sure yours has all its grounds installed - for some reason they're often left ungrounded, which can be dangerous.

[dpot]

all i can add is if you have a budget of 1000 euros then the very best is out of budget and there are lots of good cheep stuff that hobbyist are using all the time with no problem her is the setup i have been using for 15 years and it is still running now but it is not usb compatible so need old computer with printer port https://hobbycnc.glopal.com/en-GB/p-...ombo-kits.html for 295 $ and lots of good info there .

if it is for just cutting wood and aluminum you do not need something that can cut through 2" of steel and if you need more torque than think about gearing.

the box tub frame design is good but i would think about putting in blockheads that will help to stop it from twisting and make it stronger // if you can get the plat cut for free then that is good to.

liner rails are very expensive but your design is not that big so prices for under 1m long rails and shipping is good and you should get away with 10mm to 16mm railes and 8mm screws.

as i have already said diy routers do not last that long and are very noisy i would say a 2.2kW Water Cooled Spindle for more efficient, quiet CNC routing! Ships from the United States. Warranty & Support available now. High quality stainless steel casing. Speed: 0-24000 R/min but that is haft your budget. this i found on ebay euro Germany made ball bearing.New upgraded with adopt Germany imported bearing: three times useful time than ordinary spindle motor. More speed: 0-24000 R/min. More precis collet: ER11(3.175mm,4mm,6mm) Runout off: less than 0.005mm. Pass ISO9001 quality certification which means this item is the top quality item. for 109 euro thats is 125 $ but you would need a controller for it