Amazing build - the photography is also very professional!
I thought I saw a speck of dirt in your workshop, but it was actually on my monitor…
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That looks great CpNemo
I’m glad to see you have mounted a water cooled spindle. I have one not quite ready to fit but was slightly worried it might be too heavy. How has it worked for you? Any tips or advice you can offer would be greatly appreciated.
Jim
Hi Jim,
the 0.8 kW spindle is not too heavy, I believe it’s still ok for the MPCNC if you keep it small. My ground plate is 900mm x 600mm, which is kind of a sweet spot concerning the size of the machine. The spindle is extremely quiet, you can’t even tell it’s running some times. That’s why I have a “Spindle running” light in my front panel. Noise should be avoided when ever possible and it was the only reason I took the water cooled version. I definitely would choose it again.
I can very much recommend the CW-3000 water chiller. It just works and is sold for less than 100 € around Germany. Water temperature never exceeded 35° C so far, even after several hours of usage.
If you’re interested, here’s the 65mm tool mount that I designed (the standard mount has 70mm I believe): https://www.thingiverse.com/thing:4322931
To attach the spindle you just need a stainless hanger tape.
I was thinking about the usage of drag chains in the first place. But I figured the water hose is not flexible enough to bend in a small radius. I also tried silicon hoses, but those were too soft and tended to clog. So I ended up with polyurethane, which is quite stiff but ok to bend if you keep the radius big.
Very important: Don’t forget to ground the spindle! The spindle is not earthed as standard. Use shielded cable and connect the shield on both sides, but do not abuse the shield to replace the grounding cable.
Uli
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Pictures are beautiful, like professional photos from a magazine.
It seems that toothed belt holders are okay on one side but on both ends they can only be tensioned in increments of 2mm so I’m not sure if it’s a matter of luck to get the correct tension. I suppose you could shim the motor plate to slightly raise the motor to adjust tightness but that seems inconvenient. Is there some other procedure or factor I’m missing?
I’m not sure if it’s a matter of luck to get the correct tension
What is the “correct tension”? In my experience there is a certain range which is acceptable, but no way to determine it very precisely. Being restricted to increments of 2mm still enables me to choose a tension, which seems “correct”.
The advantage of this design is here: Both belts have exactly the same length. Thereby both steppers on one axis move exactly the same distance per step. This can not be achieved by tensioning both belts individually, it is for sure a matter of luck to get the same length (tension) on both sides.
My aim was not only to reduce flexibility by avoiding cable ties, but also to make the steppers move the spindle in a perfect rectangular.
Belts stretch roughly 0.35 mm per kg per meter of length, so each 2 mm of stretch should give approximately 5.7 kg of tension if you have a 1 meter belt length. If you have 600 mm belt length then the tension will be 9.5 kg of tension for each 2 mm of stretch. Ryan recommends approximately 2 kg of tension (3-5 lbs) but I think it’s common for people to use more. I don’t see an issue with maybe 5 kg, and 10 kg of tension is on the high side but perhaps fine. I’m glad you found tension that works for you but I would still say it is a fairly coarse control.
I would also say that if equal belt pitch is critical, then it would be possible to measure the belt pitch and adjust accordingly. Having fixed endpoints is elegant and looks very clean but it is not the only way to achieve equal pitch.
I wondered about the belt setup, too. Interesting discussion, here, but the proof of the pudding is in the tasting. Let’s see how it runs!
Ok, I get the point, but still have no clue how to measure the belt tension. What I can determine very precisely though is the distance each axis moves per stepper revolution. And here is something very interesting: These are the actual distances I measured on my machine:
X-axis: 31.91mm
Y-axis: 31.93mm
So I conclude the difference in belt tension between both axis must be just 0.06%. How can that be? Maybe I was just lucky, or it is a result of maintaining an aspect ratio of 3:2 (900mm : 600mm). I don’t know.
If belt tension is not satisfactory (too loose in one notch, too tight in the other), I guess the top part of the corner must be moved a tiny little bit. This could be done by widening the screw holes. But I admit this is not an elegant solution. I would rather have changed the design by moving the notches a bit and printing the corners again.
Uli
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There are a hundred things that can make a “difference” or that aren’t “optimal” or “best”. Go show this machine to “professionals” and they’ll tell you that how you manage the belt tension isn’t the problem because we shouldn’t bother using belts at all.
At the end of the day, if it cuts how you want at the precision you need, it’s a win.
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@CpNemo fantastic build, the attention level is incredible, could you share you’re corner/belt tensioner design?
It is totally fine and highly encouraged to share modifications, just choose the CC-SA-NC licence on TV or other sharing platform. So, please do post the file if you’re comfortable doing that.
I was actually not sure if it’s ok to share modified parts as I’m not familiar with all the licenses. So thanks for the hint!
Here we go: MPCNC modified corners - no cable ties by UliSchirm - Thingiverse
Uli
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Very nice! The water cooling seems not that difficult/expensive to implement as I would have expected.
I figured the individual parts like pump, hoses, reservoir and so on are much more expensive than the whole CW-3000 device.
I am never sure how a comment like that will be received. For the most part, people want to do the polite thing, and they just don’t know. Sometimes, it rubs people the wrong way though.
Remixing and sharing is a huge part of this community. Thanks for sharing.
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thank you, I will try it later this afternoon
Amazing build!! To you have a link to buy the water cooled spindle?
Thank you!
Thank you very much!! Do you also have a link for the VFD?
What do you think about that spindle? Do you recommend it for a new build?