First Proper CNC Router

[diycnc]

After building a couple of 3d printers, and building and struggling to do anything with an MPCNC, iv decided its time to make a proper cnc router.

Design criteria are,
Desktop machine with foot print no bigger than 1050 by 850 to fit on my existing bench.
Make use of the 4 750mm SBR16 rails, and 2 300mm SBR16 rails I have buried somewhere in the workshop.
Capable of cutting the end of sheet timber to make box joints.
Reduce costs where possible without affecting performance.

After alot of reading, and a few design iteration, this is what i have come up with.


Z axis,

Both plates are 15mm thick aluminium ecocast. 140mm travel, 1605 ball screw. mass aprox 7kg.
3.1nm motor connected by belt drive. (The motor plate inst shown in the image)
Tramming will be done by a eccentric bush and shims between the X axis plate.


X axis and Gantry

Gantry is made from welded steel box section. Bottom piece is 100x60x3, top 60x60x3, short connecting pieces are 60x40x3.
The two end end connecting pieces will be bolted in place so the ball screw mounts can be easily adjusted if needed. Also if at some point in the future i decide to swap the SBR16 rails for hiwin stile rails I will be able to easily move the ball screw back into the gantry to suit. Rail surface will be epoxy leveled.


X axis plate is 10mm thick ecocast. I dont think there is any need for anything thicker here as it will be bolted to the 15mm thick Z axis plate.
Gantry ends are 10mm thick aluminium flat bar or plate. The Y axis bearing are fixed almost directly to the underside of the gantry, so the gantry ends will only carry load in the Y direction, so no need for anything too thick.The gantry ends will be fixed to both the top and bottom steel gantry tubes. Two small pieces of 20mm thick aluminium ecocast are bolted directly to the underside of the gantry, these will be bolted to the Y axis plates. Shims can be placed between these two plates to level the gantry if needed.
Connecting the bottom of the gantry ends will be a piece of 60x20 extrusion. The Y axis ballnuts will be attached to this.
X axis drive will be 1610 ball screws, with 3.1nm motor connected with belt drive.
I plan to connect the motor to the gantry end plate with some long spacers. This hasnt been included in the model yet.

Total length 900mm, rail length 750, travel 600mm.
Mass approx 25-30Kg

Base frame and Y axis

Base frame is made from wedled 60x60x3 and 60x40x3 steel. Rail surface will be leveled with epoxy. 1610 ball screws are under the bed to reduce the machine foot print. Id like to drive this with just 1 nema 23 3.2nm motor. Is this possible with a gantry approaching 40kg?
The machine will sit on 4 adjustable feet which are not in CAD yet.



To give you an idea of the space constrains, this is a plan view of the current design with the workbench parameter shown.


Total machine weight is around 70kg.
Cutting area will be around 600x600.
Gantry clearance 140mm from the steel base frame. 120mm ish after adding a bed.

Id love to get some feed back on the design before I start ordering parts or cutting metal.
Also im struggling with where to buy the electronics and what to buy, any advice would be really helpful.
im also yet to choose a spindle. Id love a 2.2kw water coolded one, but they are bloody expensive and if possible id rather not have to bother with water cooling. Any suggestions?

[Desertboy]

Design is crazy simple this is a good thing! I can understand why you want to use the SBR16 BUT sell them and get 15mm Hiwin's you're router design is too good for SBR and it will be the weakest link.

Except the truth this is going to cost more than you think it will, if that doesn't scare you off and it shouldn't mostly your costs go up because someone tells you not to buy this but to buy that instead and you do but in the end you end up with a router not a Xmas cracker toy like the MPCNC.

I speak from experience my plan was to build an xmas cracker but along the way it turned into a router and the budget went to Honolulu for a holiday ;)

[diycnc]

Thanks for the feedback.
During the design I considered hiwin a number of times as I know they will be loads better, but to get things started at least I will stick with the SBR16 I already have.
If fully expect to upgrade to hiwin at some point, hence the x axis ball screw been fixed to a bolted in piece of tube, not welded, so it can be easily adjusted to suit the smaller rails. The y and z rails can be replaced buy just drilling some new holes in the aluminium plates and a few new spaces I can mill (probably slowly with the sbr16 rails) on the machine before I dismantle it.
This also helps cash flow a little! As you say I expect this to be a rather expensive project, and spreading out the cost a little will please the missus!

I noticed on your build log you mention you wanted to use arduino and raspberry for the controller. Did you do this in the end?

[Desertboy]

Thanks for the feedback.
During the design I considered hiwin a number of times as I know they will be loads better, but to get things started at least I will stick with the SBR16 I already have.
If fully expect to upgrade to hiwin at some point, hence the x axis ball screw been fixed to a bolted in piece of tube, not welded, so it can be easily adjusted to suit the smaller rails. The y and z rails can be replaced buy just drilling some new holes in the aluminium plates and a few new spaces I can mill (probably slowly with the sbr16 rails) on the machine before I dismantle it.
This also helps cash flow a little! As you say I expect this to be a rather expensive project, and spreading out the cost a little will please the missus!

I noticed on your build log you mention you wanted to use arduino and raspberry for the controller. Did you do this in the end?

No in the end I spent £300 on a toroidal PSU build and AM882's lol. Now I have I consider this the bare MINIMIUM for any router I would build, the arduino setup (If you use cheapo Polou or equiv) is not going to drive the motors quick enough and with enough torque I tried with mine and it was gutless.

An arduino can drive pretty much any stepper drivers but the question is do you want it to? I'm using a parallel port breakout board <£5 on ebay to connect to the steppers and my PC running linuxcnc is doing the processing which with grbl the arduino would be doing.

The PC even a really old one is a lot faster than the arduino so can drive more pulse per second more pulses== more speed.

Arduino is a really wicked little device and works for an xcarve because it's so flimsy you could never run it fast enough to matter but that steel beast you want to build can cut faster than the arduino will keep up with it and you will want to cut at max speed.

Arduino though might be a good fit for a laser cutter or a plasma.

If I had one word of advice on electronics if budget is the issue don't buy a USB controller for £100 and spend £200 on Mach 3. Instead spend £200 on 4 AM882's and £100 on PSU, Breakout board and sundries and use linuxcnc. I see so many people buying shit drivers and then a £200 controller (On cnczone) and I tear my hair out thinking such bad bad advice from people that should know better.

I spent ~£2k building mine but I also got all the aluminium in my build and a lot of other things already so it would cost me £3k to do it again.

Routers aren't cheap and when they are well you saw yourself with MPCNC, even the upper end like xcarve and shapeoko (Common history intersting read) they all at best finicky and at worst unsable. The age old adage is even more true here you get what you pay for.

If you think about problems you had with 3d printing at the beginning and then times them by 10 and you get to cnc routing lol.

One thing though my microswitches are not moving anywhere and that's what you need.

Although I still like to pay less just check my signature and you'll know where I want you to buy you cnc stuff lol.

[diycnc]

Whats so great about A882 drivers, Iv seen a number of people recommend them.
Do they offer any great benefits over something like this,
https://www.omc-stepperonline.com/st...it-dm860i.html

Both are capable of handling 80V and more current than my motors can cope with.

The only difference I can see is stall detection. Is that really worth £20 per axis, £80 for all 4?
Any suggestions where to buy a toroidal PSU? Id rather not make on.

The only PC I have are laptops, so no serial ports unfortunately. Which means i either need to buy a PC or an expensive usb or ethernet controller. Hence why i was hoping an arduino might do the job.

[Desertboy]

Yes it is worth £20 an axis, don't be scared of the PSU build I was then it turned out to be nothing but if you're near Leicester I'm happy to help build it with you to take the scary edge off with and you can check out my router so you don't make the same mistakes I did, you can make other ones lol.

I do love your design because it's just so raw but over engineered that raw becomes pure.

[diycnc]

Is there much of a saving when building rather than buying?
I see zapp automation sell a 68v one for £115.

Im in north Manchester, so Leicester is a little far. I do travel with work from time to time, so i might take you up on that offer if im in the area soon.

I tried to keep with the KISS (Keep It Simple Stupid) methodology when designing this. I find is often the easiest, cheapest, and quickest way to design and make stuff.

[JAZZCNC]

Is there much of a saving when building rather than buying?
I see zapp automation sell a 68v one for £115.

Depends on how many motors your running and motor size. Zapp 68V PSU only provides 6A which isn't really enough for 4 motors or leaves any room for upgrades with 3 motors.
Can make one for about £70-80 with exactly what you require and bit to spare for upgrades.

Regards the Drives then if your using slaved axis then go with AM882 for stall detection it's a Must Have feature really.
If not then save the money and put to motion control card it will be worth the investment.

[Clive S]

Is there much of a saving when building rather than buying? I see zapp automation sell a 68v one for £115.

Check out Joe's excellent vid.
https://www.youtube.com/watch?v=4OoQ...zD30sZjtp_VyqY

here is a shopping list from Rapidonline https://www.rapidonline.com/

I would go with a 45-0-45 V toroidal instead of the 50V

[Desertboy]

Listen to Clive I speak from experience lol
http://www.mycncuk.com/threads/10880...6816#post96816

get a 45v not a 50v, if you do insist on a 50v buy mine of me it's only had 10 minutes on time before I bought a 45v one lol. Luckily I got both 1/2 price so it evened out in the end and one day I shall find a use for it.

If you were in mainland europe 50v is fine as the mains is 10v-20v less.
Best thing about having screws under the bed is they're out the way so not crap can get into them, I also toyed with slinging the hiwin under the bed but too much hassle, for reference hiwin's are 95%+ efficient in sideways or upside down mounting vs horizontal it's for me their main selling point.