I’m after a little bit of critique for a build that I hope to start in a few months time (probably moving back to Australia from Europe next year and need a project to distract me!)
The ultimate aim is to have a slightly less than full sheet lowrider (probably ca 1.2x2m working area but since I don’t know what space this is going into that’s very flexible), using an 1.5kW Chinese spindle as the main tool but have it swapable to a foam needle cutter or a pen mount. I would be running dual endstops on both Y and Z axis, a single on X and probably a usb camera to help with registration.
Mostly I plan to work with wood (ply, mdf, balsa etc.) or foam board, not metal.
Due to the cost/availability of getting some of the things in Australia, seems like a good idea to order some of the bits when in Europe to keep costs reasonable.
Control electronics - as I understand RAMBo is limited for dual endstops for a lowrider? Does anyone have experience with Duet or Smoothiebords for CNC? What I would love is dual endstops and integrated spindle/brushless control. All the high level stuff with be done with either CNC.js or bCNC on a raspberry pi.
Steppers - reading through previous posts it’s clear there’s no love for NEMA23s. Is there any advantages or considerations for using more powerful NEMA17s though? Eg 65Ncm (92oz.in)? I know the motor cutouts on the Y plates would have to be made slightly bigger to fit that one.
Power - I know duet is really built and focused on 24v, and my Prusa has made that leap as well. Is there any reason not to go to 24v? I realize for the brushless motor foam cutter that’s provably better on a 12v supply, but the biggest use case would be the spindle anyway, so no problems running that on a dedicated PSU
Any advise on the three points above would be more than welcome!
The “official” version only has mounts for the DW611, AFAIK. You’d be making some new mounts to make these mount to a flat plate.
Rambo has 5 drivers and plenty of IO for a spindle or laser control.
Dunno, but the standard motors are working well.
I’m not sure what the benefit would be. It seems like the big benefit for printers is faster heat bed Warm up times. I don’t know any reason why you couldn’t.
I would like to know more about this. I’m a software engineer that occasionally uses CV in my job.
I’m not sure what your experience is, but keep in mind you can change any of this after the fact. I would recommend starting with the standard build first, until you have a good idea how it works and then apply your energy and money to parts that are lacking or interesting.
DW611 is only 110v, so sadly it’s not an option. The idea would be to perminantly sink some M8s into the bottom plate and then mount (home made) standardized rings for the spindle/foam cutter/etc with nuts. I say rings but I’ve not started to sketch it out yet. The spindles are a bit larger than the 611 but I obviously don’t want to change the spacing of the tubes. I haven’t bought anything yet so all open to change.
Ok cool, it might come down to what I can get my hands on in Europe/oz. I like the idea of full digital control of the drivers, which leaves me with trinamics. Features like stealth chop seem meaningless in this use case. Also since I plan to run a raspberry pi as the main interface things like LCD and Web control aren’t of much use either.
Its a feature of bCNC, which I’ve been using at the local hackspace. It’s nothing super fancy or automated, basically you mount a camera on the x plate, use the router to drill a small hole somewhere and then jog to line up the camera to the hole. The software calculates the offset between the two. Then you can realign it to that point as required, and help to home the stock (or the machine if into the wasteboard.) I’m not sure of the accuracy level compared to limit switches is but for double sided machining it might be helpful.
just an update, to fit an 80mm spindle I had to make the center plate wider by 30mm. Apart from losing some X travel, are there any other problems that could come up from this?
Even with this, the clearance is very tight under this design. I couldnt think of a way to 3D print it in one piece though - suggestions welcome!
Ryan called this part in his designs the 611 plate, so I take that as an endorsement of changing it if you need to mount another router :).
How are you going to make the flat parts?
My work for involves assisting the router up and down. I pull it completely out to change the bits. I drop it down when I am setting up a cut and up when I’m turning it off. You’ll at least want a hole in your table to drop the bit into when you’re done.
I like the way the back panel takes a step backwards to miss the pipes.
no problems to me on changing the internal mounting holes, I just wanted a sanity check that there was no other issues with making the plate a touch wider! The other option was to make the rail spacing wider, which just has so much knock on effect that its not worth it.
The intention for the flat pieces would be to make them on the local makerspace’s x-carve using 6mm MDF. The chamfers will have to be done on a router table, and for the box joints will need some help from a chisle or predrill some mouse holes into the corners. The design will change a little for this spindle to try and reduce weight (not that it will have any real effect but old habits die hard). The chamfered bit was the only way to get clearance! I just hope that 6mm is enough section there for bending.
For changing bits mid job the idea at the moment would be to lift to ~z max and then rest the assembly on a perch (or just full power to the motors), and hopfully have enough space to get to it from underneath. Certainly whilst it is height adjustable with the clamps, at the moment I am thinking just to clamp it once and be done with it. With the way the spindle is crammed in there when it gets changed out for a needle cutter/pen/etc the bolts are all undone from the bottom anyway, so this has to be factored into the design.
W.r.t. the box joints, adding overcuts or dogbones would be easy in cam and wouldn’t hurt the strength enough to matter. Butt joints in mdf would be almost as strong, but wouldn’t give you automatic alignment like the box joints.
I was expecting you to not want to unclamp the spindle, that’s why I mentioned having all that. You’ll probably want a hole where you start the machine (at machine 0,0,0), so you can let it drop when the power is off.
