- November 20, 2016 at 9:29 pm #21263
Hey Ryan awesome design!
Built to fit on 900x600mm sheet of MDF.
25.4mm (Bunnings) galvanised steel, approx 1.6mm wall thickness.
Metric hardware. Nb. bolts holding bearings are probably best done using imperial – the 8mm bolts tap into the plastic (despite carefully scaling to get all dimensions right) – the equivalent imperial bolts will just touch without tapping in. I might change mine if it doesn’t stay square.
I have 20-tooth gears on the stepper motors and will need to adjust firmware to take this into account before doing anything dimensional.
Pictures to come. The printer is hard at work printing a pen holder, then once that is done I’ll adjust the firmware, then will do a dremel mount.
BTW the heat sinks on the stepper drivers get very hot even with just brief testing. Came at 0.5V from the factory, I left it at that for initial testing. I’ll adjust to the recommended 0.7V when doing the firmware upgrade. Do they normally get that hot even with minimal use?November 21, 2016 at 4:47 am #21277
Even if the machine isn’t moving, it’s going to send power to the steppers to hold position, at least for a minute or so, after that it will power off the steppers, so yea, they’ll get warm. I have a fan running on mine.November 21, 2016 at 9:32 am #21285
Are you using the drv8825 drivers? If not you need to adjust the voltage differently for the a49’s.November 21, 2016 at 4:33 pm #21329
Barry – thanks, I forgot the steppers stay on to hold position.
Ryan – 8825s. The voltage seemed OK so I didn’t adjust (0.5V) – but the multimeter batteries turned out to be flat, so will re-check with everything unplugged.
I hit a speed bump – forgot to re-zero the axes and drove the Z down too far and fast, and the threaded rod has stripped out of the pineapple coupler. So, some repairs to do!November 21, 2016 at 11:02 pm #21355
OK all sorted. Voltage on the stepper drivers turned out to be 1.6V – oops!
Adjusted to 0.777 (why not) and just warm to the touch on the heat sinks. I’ll work up once the belts are tightened (and the cable ties trimmed…) as it was smoother at the higher voltage.
Threaded rod epoxied in, seems fine now.
What a thrill to get it all working!
Next is a trim router or dremel mount, also software – I think I have an old laptop somewhere that will run Windows via parallels – otherwise I might see if LinuxCNC will work on a CHiP, that would be cool.
Attachments:November 22, 2016 at 12:08 am #21360
Congrats! I see you used 25.4 from Bunnings? couldn’t find the 25mm tube they have hey?
I am in Northwest suburbs, and after my move test last week, I am now focusing on cabling it up, and checking I have the correct steps per mm in all directions.
While I was going to try it with my dremel first, I think I will get a Ozito edge trimmer instead (I saw a personal blog with it working well, even for Al(at low speeds)).November 22, 2016 at 4:07 am #21365
Yeah, the Ozitos with the 3-yr warranty are the most affordable tools locally. Not sure I can justify a Makita or Bosch. Don’t forget to have a look on Gumtree, it is pretty good for 2nd hand power tools if you don’t mind used.
I already have a dremel, and I found a tool mount for the 525 on Thingiverse, so that’s what’s printing now.
The tubing I found at Bunnings was a fairly stiff, 1.6mm wall galvanised steel tube; I bought the 1m lengths to fit in the car, it is marginally cheaper in 3m. I’m pretty sure it is 25.4mm.
Some others have mentioned chrome rail, which is a bit more expensive but is spot on 25mm and smoother. That might be a good choice. It is more flexible.
I found the seam inside the tubing makes it harder to debur and limits where the nut traps can go on the Z assembly, also I had to re-scale the nut traps due to the thicker tubing. I bought an Aldi 2-speed mitre saw recently and the supplier (Scheppach) was very helpful supplying a blade suitable for steel (at the slower speed), maybe not the best saw but good enough and very affordable.
RE cabling – I ordered a few header connectors etc online, but found that I could re-use the ones I trimmed form the stepper motors, they fit better that way too. I ended up using a shielded 4-core cable from Jaycar for the cabling, and some printer filament to stiffen the cables that pass through the gantry tubes to keep the cables out of the way of the gears. I only needed 2m or so of cable, as I salvaged cable (and plugs) from some of the steppers.
My biggest remaining issue (apart from the deplorable state of the Australian cricket team) is software, I’m on a mac and haven’t found a good free option. Fusion 360 might be the only one without buying Parallels and Windows. Probably cheaper to find a cheap PC!!November 22, 2016 at 4:45 am #21367
See thats why I used the Chrome 25mm tubing from bunnings. it came in pre-cut lengths. I used 1200mm and 900mm. Yes I still had to cut the Z axis (and thats why I redesigned the Z nut trap), but the pre-cut lengths made it perfect for precut MDF size of 1800 by 900 for the table.
Also used a 3D printed mount for my dremel to angle grind the pipes when I did have to cut them (and yes for the middle X/Y pipes I did have to trim the ends down so they wouldnt stick out, but the the XY rails, I left them default size).
All my build pictures are in my post in getting started (and @vicious1 if you could shift that thread from there to this channel that would be more relevant.)November 22, 2016 at 9:47 pm #21388
Dremel 4000 mount by Fyleo
A bit fiddly to attach and uses M4, so another bolt size to keep track of – but works like a charm, rock solid. I used a spiral upcut / multipurpose cutting but that came in the kit; the tip is like a drill, not an end mill, but seemed to work just fine (softwood ply board)
Next, I need to track down some MDF slot board (probably an off cut from a shop fit out would be easiest to find here). Then software. Then I’ll try a trim router if I find the Dremel is not up to the task.
Attachments:November 26, 2016 at 11:11 pm #21571
M8 bolts fit fine, just quickly run a 8mm drill bit through the hole to knock the printed edge off to a smooth surface and the m8 bolt slides straight through. I’m using stainless button cap bolts for mine 🙂
I’m also using the Bunnings 25.4 Gal tubing, seems to be pretty good. Profile is not absolutely perfect through the entire length however no tubing is and it’s close enough that the rollers seem to roll on it well enough, i’m sure they will be even better once the bearings tram themselves out on their running line.December 11, 2016 at 1:42 pm #22509
Thanks to those who wrote the post processor for Fusion 360 – all working reliably now.
I did a hand-coded Z steps tester and for the moment am going super slow at 100 mm/min with a view to increasing to 300 (tested OK) when x/y speeds are sorted.
Next step is to fit a 1/4in trim router and get a larger V router bit (1/8in PCB engraving bits in the Dremel need a very slow feed rate, I think about 200mm/min as I’ve done the CAM at 600 and slow it down to about a third speed on the RAMPS controller).
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