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Thanks for your reply Anthony! Yes, the milling part is also my greatest concern. I'm hoping that while in milling mode the Z will be at all times close to the base where it should be much more stiff. X movement in that position should be quite quite well supported by the Z axis's base. I don't think there will be any sort of bending due to the fact that I used 20x40 linear rails and Y wise I added another 20x40 (maybe I'll twick with it some more). But I've never built anything with openbuilds products so I'm not sure about the wheels and how well they resist. I'll keep trying to make it more stiff without needing to rob a bank at the end when I'll estimate the costs. I might also go with 500mm rails instead of 1000.

Thanks for the advice about the laser. Never worked with one before, I'll make sure to educate myself througly before starting to implement it. Any recommendation about specific hardware is welcome.

 

*UPDATE* (101)

- added a platform for the Y axis ~900x770mm reachable area by the head
- strengthened the X axis based on what I've seen on some other CNC builds
- added initial concept for the electronics (that's an ATX board mainly because I have a few ones laying around) (yes, that's a 240mm rad)
- grouped the Y and Z axis for easy movement in sketchup

Questions for experienced builders:
- What do you think about the stiffness of the machine? Any way to further improve it?
- Are 2 nema 23 motors enough for the X axis with direct extruder/mill/laser, etc weight wise?


On a side note: I might add a notebook screen to act like a monitor and make use of its motion hinges to cover the hardware when it's not in use. (this implies I buy an lcd controller)

Also, the Z axis requires me to drill 2 holes for the ACME lead screw plate into the middle of the gauntry plates. Any solution that doesn't involve drilling is much appreciated.

 

*UPDATE * (103)

- changed the X axis movement system by adding 1 more nema 23 motor and integrating the belt into the rail (similar to the OX CNC by @MarkCarew)
- changed the Z axis with a better version inspired by the actuator kits I've seen in the part store
- added filament holder
- initial sketch for an integrated pc + electronics
- added ventilation system for the extruder

 

Any ideas on how to improve the Y axis? I'm not confident that the Mendel i2 system would be adequate in this situation due to its size and weight (I also want to include a rotating platform in the middle). Also, what material would work for best for the platform? I was thinking about wood but I'm not sure.

 

@Julius, thanks for your reply. Could you please elaborate it further? I can't see any "weak" points in the XZ axis if I move the X slowly (the wheels should be full metal). Due to its rectangular shape I don't think there's any risk of bending and due to the double motor setup it should provide sufficient equal force. Or maybe you're saying that the whole structure could wobble under high tension?

 

@JustinTime extremely appreciated insight. I didn't think about it. Need to revise it a bit. Any wheels you'd recommend?

 

@Julius, could you be so kind to post some photos with the rails in question with a sign made in paint or some other program indicating the direction in which they tend to bend under pressure? This would really help me improve my mental image of the build. Thank you. (Also, noted the wheels, tnx!)

 

@Julius, I see what you mean. So the Z movement is the problem. I suppose I can increase it to double 20x60. If that doesn't do the trick either I'll go with double 20x80.

 

Took you up on that @Anthony Bolgar. I tried to design something that would fit well myself but at the end I realized that @Mark Carew 's design was the best (also taking in consideration that his is tested to work).
Here is a pic of what I got (the mill isn't fixed on the platform):



This implies I cut some mm off the C-Beam to make it fit between the 2 z-axis beams. Hopefully I can find someone willing and capable of doing this in my vicinity.

 

Hmm... I can't seem to get over something... Could someone tell me what they think would be best for the Z axis? The current Gantry with inside wheels or this exterior version that I brutally chopped off from the OX CNC?


Which should improve stiffness, stability and durability? The first one looks much cleaner but for now my main concern is reliability. Also, the first one uses mini wheels.

Tnx @Anthony Bolgar for the suggestion. I've seen it done by @Savvas but the problem is finding someone that has one. I'll pay a visit to a FABLAB in my vicinity that might have one.

Edit: The second option could allow for rotating 180 degrees the Z C-Beams and thus hiding the open ACME Lead screw from potential debris due to milling

 

Definitely an interesting result. Though I've sacrificed some mm from the X movement the overall stiffness of the build seems to have increased due to the added joining plates and the new 20x80 rails on the sides. Also, the fact that the screw is now shielded should increase the reliability by quite a lot.

 

You're right @Anthony Bolgar! It's like building with legos but much more complex, thus allowing for everyone to be able to build something at an affordable price due to mass producing of some of the most used parts. Hmm... speaking of affordable... I'll soon need to make my calculations... I started today by considering the basic stuff and I started sweating . Hehehe...

Back to the subject: I'm not very confident with this Y axis belt system I came up with... I feel like it must be changed immediately but I have literally 0 ideas on how to implement a better one. Any ideas are much appreciated!
Here are some pics:



P.S. I like the new look of the website! Awesome job MODS!

 

The last Y design doesn't give me any confidence at all (the belt seems too long the way I put it) so I decided to experiment with something else. Many people seem to love C-beams and I've seen in some videos that they can be pretty fast so I tried designing something that would fit well with the dimensions. After some tweaking I came up with this design:



Yes, the central C-beam sticks out of the frame. I'm considering shortening it. I also had a 2 motor design in my head which would reduce the height and be more sturdy in the Y movement but less in the X-Z.
This seems like an interesting solution but again, I don't have much experience so any advice is much appreciated.

 

Changed it again. Browsing some other builds I've stumbled upon @Bob K 's. I've noticed that his was pretty much similar to mine in therms of objective and structure. I thought about putting 2 motor driven c-beam actuators too for the bed at first but scrapped the idea in favor of a single motor design. But after watching @Bob K 's, I decided to give it a try since it had some things that I really liked about it. After some tweaking I made it into a single motor design with 2 c-beams. Oh, and I also meddled with some cable management while I was at it. here are some pics with the build so far:


Here's some cable management:



I'm still experimenting with the pc part, apparently the more I think about it the crazier I get. I might just build a full fledged pc case with transparent plexiglass on top of the mBOX. Still need to think about it but for now the main objective is the mainframe, pc modding comes second.


P.S. Cleaned and updated the sketchup model. Please check it out and tell me your thoughts on it
Edit: dunno why but I can't upload the sketchup model. It says: "security error". Will retry later on.

 

Hi @Bob K ! Happy we agree on the single stepper design. Interesting idea with the side supports for the bed (I have a half idea of how that might be implemented while keeping the clean cable management layout. This should also solve one of my concerns in regard to the front of the Y axis sticking too much out). Also, since our designs are so similar, could you please tell me of any other problems you have encountered since you've built it?

You might want to take a look at the smoothieboard with external motor drivers (that's what I'm looking at) in case you're not supplying enough current (25mm/s is not exactly what I have in mind). The smoothie also supports lasers!