My awesome wife bought me a 2.2kw water cooled spindle for my birthday.
I still need to buy some shielded cable to wire the vfd up. And get a pump sorted for the water cooling. However I wanted to test that the z axis would cope with the additional weight.
This spindle is nearly 5kg. And I had to dial the z axis back to 100mm/min to reliably move without skipping steps. But I think that’s fine for the moment, z axis movements can be slow without being a big problem.
Having proved that is going to work, I’m really excited to get the rest setup and start machining again. Hopefully this will be much quieter than my Bosch router and also not run the risk of burning out.
You have any awesome wife. But your probably already know that.
Is the original picture blurry or is what I’m seeing here the effect of Google’s enhancement?
@Paul_Frederick yeah that first one is blurry, I didn’t notice when I was selecting it.
@Daniel_Would
I wanted to see what kind of a lead screw you were using but I couldn’t quite make it out. Is it plain all thread?
@Paul_Frederick it is just a plain m10 threaded rod
@Daniel_Would
So M10 X 1 ? Or is plain M10 X 1.25? I come from one of those backwards countries that still uses Imperial threads for the most part. Either way that is pretty fine pitch.
10mm is somewhere between our 3/8s & 7/16ths which have a coarse pitch of 1.5875mm for the 3/8s and 1.8142mm for 7/16ths rod. I use 1/2 X 10 TPI acme for lead screws. That is a pitch of 2.54mm. Which is more than twice the pitch of even the coarse M10 metric rod. But even 10 TPI is kind of fine pitch. Some folks use 4 TPI ball screws which is more than twice the pitch I have.
I worry about these kinds of things because I never could get the rapid acceleration I wanted to out of my machine. In metric I don’t think my machine goes much faster than 183cm a minute. Not very fast. It doesn’t sound any faster using imperial units either. 72 IPM there.
That is all due to my cheap lead screws and cheap motor drivers I use. So what kind of motor drivers do you use? Or more importantly what voltage do you run your drivers at?
@Paul_Frederick I believe they’re m10x1.25 and it certainly is slow. I normally run at around 250mm/min which requires significant patience. That said for something like MDF which is quite forgiving, you can do deeper cuts. So rather than trying to double the feed rate for a 1mm cut, better to play date of feed rate but do 2mm (or more) of course that gives problems with plastic which just abyss to melt I’d you go too slow.
I have small cheap motors driven by sparkfun easydrivers. I run them at 24v which does get them quite hot, so I have some heat sinks (which are too small really) and some small fans blowing across them.
@Daniel_Would 250mm/min? I can see room for improvement there someday. It is tough at the outset to completely predict where a CNC build will end up. With that fancy new spindle you just got I can only imagine you’ve plans for future upgrades at some point in time.
@Paul_Frederick oh yeah… Starting to think about pretty much a whole new machine. Just trying to think about what I can get away with in terms of incremental build. So maybe a new extruded aluminium structure but with current electronics/lead screw’s. Then maybe upgrade the lead screw’s to something better. Possibly forcing an update of motors and drivers…
Ideally I’d like to be able to step towards a much better machine without having to buy everything at once…
@Daniel_Would
I’d get better motors and drivers now for your present machine. Even one of those imported TB6560 boards would be better than those little Allegro boards you have now. For motors try to find someone in the office machine business. They probably have access to lots of scrap electronics you could pull good stepper motors out of.
@Paul_Frederick interesting, the motors were not the obvious next step for me. Whilst better motors and drivers will certainly increase speed, my main issue is still accuracy. So I was thinking of improving the mechanical parts to reduce backlash etc.
With bigger motors and drivers, I have to figure out controlling new drivers from the arduino… or look to a whole new control board.
Slow is annoying, but not being able to get precise circles feels like the bigger problem right now.
@Daniel_Would
Arduino? I’ve heard of people using those as CNC controllers but I don’t know anything about it past that really. I use a plain old PC. I got mine in a thrift store for $5. Which is cheaper than Arduino usually costs. I use LinuxCNC on it which is free.
There are a couple of hardware solutions to deal with backlash and I used the simplest one I could think of. I made myself plastic lead nuts. Plastic is fantastic because it is so elastic! Sorry, I couldn’t resist.
Anyhow, one cheap source of plastic stock is plastic cutting boards. Buy them used for next to nothing. Buy them new for not much more. Tooling to tap with can be costly depending on the work you need to do. I made my own tap because tapping plastic is not exactly challenging. Not that I was looking for a challenge, but I figured I’d keep some cash in my pocket by doing things myself.
I made my tap out of a bit of threaded rod I wasn’t going to use for my machine.
@Paul_Frederick yup arduino running grbl which basically allows you to stream gcode to it over USB. So I run my normal laptop to send the gcode, but can use USB and not have to find an old PC with a parallel port.
As for backlash I have some delrin anti backlash nuts which I need to fit, buy at least some of the problem is with the heavy wooden construction I think. Things flexing that should not etc.
Realistically the next step is to fit the delrin nuts, and at a second steeper to the x axis so there is one for each side rather than one in the middle.
We’ll see how that goes, after that I will be tempted to go the extruded aluminium route.
@Daniel_Would
You can put a parallel port into any PC with a PCI slot so availability is not really an issue. Although the PC I got has one. LinuxCNC lets you adjust acceleration with its trajectory planner. That should allow for overcoming inertia to some extent.
If you think your wooden construction is heavy you should see the cast iron table on my milling machine. Actually there’s a lot to be said for mass damping machine vibration. A certain amount of mass is needed to keep things from chattering away on you.
I like dual driving axises so much I do it on X, and Y myself. I don’t offset drive Z either. An axis hanging off the side of another just looks too unbalanced to me.
