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Does it happens with ballscrews ? Or is it related to weight ? I've been working with ACME screws on CNC and 3D printers and never faced this problem.

I think this will require a second plate to fix the X-Axis rails to the V-Slots, am I wrong ?

I put them on the front otherwise the Y-Axis will be outside of the frame, so I'll be losing some precious centimeters (I'm storing the machine in my appartement, small footprint is important to me).

 

Thanks for your advice. Regarding the Z-Axis dropping, I added a little stand on the X plate where the Z-Axis can go resting outside of the work area.
It allows me to implement a macro to go there, which should be more practical than the block.

 

You're right, I'm using V-slots as they are easier for me to source (1 command on Ooznest and I can get all the components), actually any aluminium extrusion could do the job. T-slot should be even better as the contact surface with the rail will be larger.

Indeed, once again SFU1605 are easier to find, but there is no constraint in the design not to switch to 1610.

I will share the DXF for the plates as soon as I validate the design. I am now searching the right settings in order to cut the plates on my OX CNC.

 

Hello, during the week I beefed up the design for more rigidity.

MGN-15 rails have been replaced with HGR-15. The linear actuator have been reinforced with corner angles. They are now made of 1 20x80 V-Slot and 2 20x40 V-Slots. Aluminium plates have been thicken to 15mm. FK12/FF12 blocks have been replaced for BK12/BF12 which allows for bigger work area.

I should order the material very soon. I think the first implementation will be made out of MDF to confirm that everything aligns properly. I may keep it like this for a while if it works properly ...

 

That's definitely an easy and cheap update. Actually I put the flexible couplers because they are available in the OpenBuilds library on my CAD software ...

I cannot run those maths as I don't know of any formula ... I don't know wether they can be easily understood or a full mechanical engineer training is needed :/

 

Thank you for your precious help. I haven't quite yet understood all of the formulas, yet the documentation has been precious.
My biggest concern was regarding the side rails being vertical and not horizontal, but according to the documentation the loads are equivalent.
I ordered the pieces recently and am waiting for everything to arrive.
I started 3D printing the plates as I sold my OX CNC before changing the design ... The 15mm thick plastic seems quite robust and should be sufficient in order to cut the plates out of aluminium, as only the drill needs to be precise.

I'll keep you updates once the parts are ready. Definitely alignment will be a challenge ...

 

Unfortunately I have more money than time ...The issue is not about the maths but more about the variables. I have no idea about the forces that would be applied.

I'm quite confident with my Prusa doing a correct job. Let's see if I got you correctly, I should print them as follow :



Because I don't really like long prints, I'll go with the second solution. After some tests it seems better to have the inside facing down as the surface is a bit flatter. Also to avoid warping on such big pieces I print them without top/bottom layers, letting the infill pattern being exposed, this pattern being triangles.

It'll look something like this :



For sure this will flex, but I hope the 15mm thickness will be enough to hold the machine while cutting the real plates.

 

Hi everyone,

It's been a while but the project is not dead, the parts took quite a long time to arrive from China.
I eventually assembled the machine last week, and do some tiny modifications (regarding the Z axis for easiest mount). Here's a picture of the machine assembled :


Some features are still missing before the first cut (I need to retrieve some wood for the waste board). I am quite satisfied with the 3D printed part, yet the side panels are a bit too weak and the z axis wobble a bit if I force by hand. I created a new design to reinforce the part, I will give you the feedback once I receive the parts :

 

Hi Jacob,

DXF are already available in Files and Drawing, which format would you need ?
Which slots are you talking about ? If you're talking about the aluminum standoffs, the motors are offset in order to use standard size linear rails and ball screw. Also it turns out that if printed with flexible materials, they make great dampers to reduce the vibrations

 

Ok, I published the STEP file, the export might not be perfect but I hope it helps.

Regarding the slot, it is meant to pass the endstop cable, as shown in the picture.

 

Hi Mostafa,

The cost is around 1000€ for the structure and the electronic (without the spindle), for a 750x750mm machine (~550x500 work area).

I tried to cut aluminium with it, for sure the machine is sturdy enough but I think I don't have the proper federates/tools to achieve perfect results. You can look at the pictures, if you want me to perform any test let me know.

 

I'm using an Arduino with a CNC shield (like this one Kit CNC Shield + 4 Drivers DRV8825), but this is not robust for such a machine (The current limitation of DRV8825 is quite low, and it happens quite frequently that a connector would burn ).
I might upgrade it for a Gradus (Gradus M1 PRO GRBL CNC Controller), which has the same architecture with more robust components.
Otherwise most people would go for a Duet or a XPro, but I find those quite expensive with a lot of useless features for me.

Regarding the motors I use those : E Series Nema 23 Stepper Motor Bipolar 1.8deg 1.26 Nm(178.04oz.in) 2.8A 57x57x56mm 4 Wires
The torque is quite powerful, but the motors would stall above 2000mm/min, I expect more powerful motors to go faster.

 

The controller board I suggested is using stepper drivers, they are just smaller (DRV8825).
The one you choose deliver higher current, allowing them to drive bigger motors (Like the one you choose).

Your controller board should embed Mach3 controller, I'm using GRBL and never used Mach3, but it should do the job

Out of curiosity, what are the small modifications you made on the design ?