- February 4, 2016 at 11:18 pm #7025
I’m in the process of printing the parts for a MPCNC build in Auckland, New Zealand.
I’m printing in PLA from DiamondAge through a Mendel90 printer. I’m using 0.3mm layers and Ryan’s recommended settings everywhere else. I’ll be using a the normal hardware kit
I printed the 4 corner blocks as one plate earlier and it took around 31 hours. I started it on a Sunday evening right before I went to bed and it was still going when I left for work on Tuesday!
I’ve been having particular trouble sourcing any 25mm tube, but I’ve found some 3mm wall aluminium tube available from a local supplier. 3dTI has used the same tube but anodised, so that’s the current plan.
Total goal for the project is to have a usable cutting area of around 610x610x150 so that in theory I can cut stuff out of pieces of 1200×600 ply or MDF that are readily available locally and easy to transport. This will likely make the table slightly more irritating to construct as the 600×600 stock can’t be used to make the table, but so be it.
For a spindle I’d like something that can work with Aluminium, even if only roughly and slowly for very ‘functional’ items, so I’ve ordered a 500W Chinese air cooled spindle with power supply/speed control. Alternative choices are somewhat limited here, given that we get different versions of most laminate trimmers etc. but once the machine is constructed I’ll have a better idea of what the weight/power requirements are.
Attachments:February 5, 2016 at 1:26 am #7034
Wow. I thought i almost was the only one with a Meldel90. Mine is about 3years old and still going strong. I have been printing for about 5days now. Think I am at about 75% of the printing
Attachments:February 5, 2016 at 10:53 am #7062
Sounds like you are on the right track. You have definitely done your research. I can’t say for sure how the aluminum will do, I have wanted to try some thick walled aluminum but I don’t have a good supplier locally. Hopefully the bearings actually work harden the surface relativity fast and you hopefully only need to snug things up once. Keep us in the loop, more rail options would be nice.February 9, 2016 at 8:03 pm #7343
Nice, Andreas! I think there must be quite a few of them in the wild because I’ve met quite a few people who have heard of them. Just over the past couple of weeks I’ve been helping someone who missed out on the last batch of kits and ended up with something a bit cheaper/crappier. I hope yours has been as reliable and bombproof as mine. I think mine is around 2.5 years old now (ordered end of 2013) and I’m not actually sure how much filament I’ve put through it. Probably around the 10kg mark, but mostly as large prints.
I like the reel holder. I’m in a pretty hot/humid part of the world so I keep the reels in a big plastic bin, each in their original bags with dessicant, etc. I’ve never had any change dimension on me noticeably, so that’s obviously working out ok. What’s the tape you’re using on the bed? I’ve never had to use anything other than bare glass for the PLA I’m using and glass + ABS juice for printing with ABS the few times I’ve done it.
Ryan: I’ll let you know. Still haven’t got the tube, but I might be able to pick it up tomorrow. Shipping was going to be half the price of the tube. Was also carless over the last weekend due to mechanics ordering the wrong parts in. I’ve transported some odd things by motorbike but a pair of 2.5m long aluminium extrusions isn’t about to be on that list!
As for the printing progress, the middle Z piece was the first decent part I had ever printed with support and it came out beautifully. I was actually quite impressed. I’d printed a few basic test objects before but the inability to remove the support cleanly etc. just led me to decide that it was better to just bridge and be careful with my part design. I’ve never run into a situation where I absolutely needed it, thankfully. I don’t know what other people’s experience with PLA and support was like, but Slic3r worked perfectly.
The parts had the support come off cleanly with a little encouragement from a box cutter and steel rule as a wedge. Nowhere near as easy as the peelable support on our Up Box or Up Mini work printers, but plenty easy enough that I’ll use it in the future without worry.February 10, 2016 at 9:38 am #7358
Anodizing the aluminum rails before assembly would get them hard enough to resist wear. Seems like it’s just better to use something harder though.February 10, 2016 at 10:53 am #7362
I agree that something harder would probably be better, but 25mm steel tube is completely impossible to find here. It gets tricky to verify, as well, as I’ve had several companies tell me they have 25mm but when checked it was 25.4mm OD. There is a thread about this ‘Australian Tube Options‘ in the Assembly section.
I also agree with respect to the wear resistance, but I’m wondering if flat spots might end up forming due to deformation of the underlying material, rather than wear itself. The anodized layer is only a few um thick (12.5um on the regular anodizing that I’ll be going with, but potentially 25-50um for a lot more money). Obviously, that layer isn’t strong enough to have any structure by itself, so it’s still reliant on the base material to provide the overall strength (in the same way that you couldn’t use a tube made out of tinfoil, no matter how hard it’s surface was). I guess it will act to spread the load somewhat (after all, it must be somewhat stronger than the underlying aluminium) but my assumption is that this effect has limits.
My hypothesis is that with enough time and pressure, this base material would cold flow until there are flat spots on the rails. What I don’t know is how much actual force the plastic pieces exert through the bearings etc. I assume that the round tube will eventually end up with a flat spot that is wide enough that the force exerted no longer causes it to deform plastically. It’s all just a question of how wide that flat spot isGiven the lack of options here, it looks like I’m simply going to have to try it and see! I suspect this could be directly measured using something along the lines of one of the standard indentation type hardness tests.
A quick google has just shown that it seems that hardness testing of anodized aluminium is indeed tricky in this regard as the macroindentation hardness tests (high force, large deformation) tend to reveal more about the underlying material hardness rather than the surface hardness by breaking through the oxide layer. http://www.practicalmachinist.com/vb/general/anodizing-hardness-202779/ post #4 has a comment on it.February 10, 2016 at 11:35 pm #7387
Have finished all the big prints now, just about to start one final pass to finish off all the little pieces.
Image shows it all arranged on the desk. Out of sight are the translucent orange pieces for the feet.
In order to use my filament relatively evenly, I’ve printed it all in varying colours on pretty much a whim. With the DiamondAge filament, I’ve never noticed any preference for different settings with the different colours and they all seem to print the same. The pieces are colour coded as to where they’re being used, apart from the red Roller Locks, which I might re-print in sapphire just to match the Roller F parts.
Also picked up 3x 2.5m lengths of 25mm diameter, 3mm wall Aluminium. $120NZ incl GST all up from Ulrich Aluminium, die number UA1248. This will give me enough for 6 lengths at 800mm for the frame rails, one length at 800mm that will get cut up for the Z rails and plenty spare for the legs. I’m going to end up with probably ~1.5m spare, but that’s not such a bad thing, so I’ll call the aluminium cost $100, even.
I’ve confirmed again with Anodising Industries in Onehunga that 7-8 pieces of up to 800mm long with regular anodising will just be their basic minimum job cost of $50 incl GST. For $60 they’ll do it as black. If there are pieces that are shorter then that will require setting up a 2nd jig which will make it $80-90ish so the current plan is to have one extra piece the same length as the X/Y pieces and then cut it down post anodising. The guy said that because it sounds like an easy job to set up, they might be able to run it as ‘Marine’ anodising for the same price, which would result in a thicker surface finish, I believe. The main reason to avoid >800mm long parts is that this company can’t handle them , which leaves me with the other companies that were charging pretty much double.
The downside of that is that 800mm lengths leave me short of my goal of 610mm cut width. Now that I’ve got the tube, it looks a lot flimsier than I original expected so I doubt the 900×900 machine required to run a >600mm cutting area would actually be a good idea. I figure I’ll stick with 800mm long rods and I can always shrink the machine later, if it doesn’t look like it will be rigid enough for what I want to do.
So assuming I can scavenge materials for an adequate table, the current total cost is:
MPCNC Hardware Kit + Shipping = NZ$490.65
Aluminium Tube + Anodising = NZ$150
Printer Filament, ~1.5kg = NZ$85
500W Air Cooled Spindle + PSU + Collets = NZ$188.46
Total: NZ$915 (~US$600)
So a bit more than I was expecting to spend at the start of this, but if you compare it side-by-side with no spindle, still about 1/3 the price of a Shapeoko.
Attachments:February 25, 2016 at 5:05 pm #8266
After a couple of weeks of being particularly busy and getting involved in a few other events, I finally found the time to drop the parts off to get anodized.
Given the minimum charge on the order, they’ve said they’ll try get it done in 25u ‘Marine’ anodizing, so should be a little thicker.
Unfortunately, the tubes were originally chocked in place in the car but over the week it took to get things sorted, they started shifting at some point and a few of the tubes have picked up some extra scuffs etc. Hopefully that shouldn’t be too much of an issue. I’m assuming the cold working of the material will likely smooth out any rough spots, anyway.
In addition, the 500W spindle arrived a few days ago. It looks pretty good and there’s no visible play/runout in the spindle when turned by hand. I haven’t clamped it up to check with a DTI yet but that’s on the ‘todo’ list. Given some of the things I’ve seen in other threads, it’s often the machining on the taper for the ER collet or the collet itself that lets the spindles down with respect to runout. I figure just chucking a new twist drill and putting the DTI on the shank where it comes out of the collet is probably enough to check that to within my likely requirements.
I’m leaving out printing a few parts (spindle mount, etc.) until I’ve got a better idea of how I want to mount it. The fan at the top of the motor looks like it might need a bit of extra clearance than the motor itself, so I want to check that out on the actual machine.
The other thing of note is that I forgot to check the GT2 belt for total length with the machine. It looks like I’m going to be short a bit, so that’ll result in another quick order to get some of that. I’ve got another little project (cartridge case annealer) that is currently in the works which could use some, so I’ll do a bit more work on that and then consolidate.
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