I expected even some moderate changes to get it into a workmanlike state. I judge that it made that standard. Different expectations.Quote
I bought this kit based on the above review. My risk was small, since I already have a good working printer (Original Prusa i3 MK2) and I also have a hardware design background. I expected to have to do a few minor tweaks to get this working. Wrong!
Didn't notice. Put in the supplied rods and bearings. They fit, and worked. It's a low end machine. If I wanted super-solid and super rigid, I'd probably design my own (which is actually in progress, and I have received the 12mm X-axis rods and bearings as well as the aluminum stock for implementing the axis). What I got works OK.Quote
1) The Z axis rods are listed as 10mm in both assembly and BOM, but the kit supplied 8mm rods. This is evidently the 'new' standard according to 3DPrintersOnline.
That would be annoying, OK. Mine don't fall out. I expect to take off the X-axis and drill/tap setscrews for the linear guide rods to fix this. This will also fix the issue with flexing inwards of the Z-guides and leadscrews when tightening the belt. I may not have hit this yet, because I have yet to print anything more than about 1/3 of Z-height capability.Quote
2) The X axis L&R ends REQUIRE that both the Z axis rods AND the acme screws are fixed at both ends, but the acme rods have no top supports. This results in the ends twisting when the X-axis belt is tightened, causing the bottom X-axis carriage rod to FALL OUT of the left-side end. There is an extended top support supplied as an STL file on the SD card, but! it is designed for 10mm rods and 10mm acme screws.
As I said, this hasn't happened to me.Quote
3) The bottom X-axis rod is evidently too short for the ends supplied (see #2).
I did go look, and none of my rod supports are off by 2mm diameter. I suspect that you may have received a machine that had the 10mm-printed parts with the "new standard" 8mm rods. One option for a quick fix would be to Loctite some 10mm bushings on the 8mm rod ends where they go into the printed parts, or to re-print the holders after magic-CADing them. I'd be happy to help with that If I can.Quote
4) The quality of the printed parts is horrible, especially where any of the smooth linear rods is concerned. None of the rod supports actually fit properly - they're all too loose.
Yeah, I wasn't all that happy with that, either. My solution after initial proving trials is probably going to be to use some high-temp and thermally conductive epoxy to fit them in. The aluminum block could be drilled and tapped for another holder, etc. There are a number of solutions.Quote
5) The MK5 clone hot end is a fire just waiting to occur. The instructions supplied manage to skip over the hot end assembly entirely, and the online copy shows the thermistor simply placed in the hot end without anything holding it in. This heating element is held in place with a single grub screw that applies absolutely NO clamping force around the element at all.
Hasn't hurt me yet, but then I never intended to stretch it to the last millimeter. I was very happy and my Prusa-friend was envious of the ease of setting up the belts and tensioning, though. One man's fish is another man's poisson.Quote
6) The heatbed - a MK3 (nice!) - only has 180mm of usable travel in the Y direction due to the design of the belt routing off the Y-axis stepper.
Yeah, I didn't partlcularly like that, either. However, it does work. And the heat bed and support frame are getting some design attention, about which, see below.Quote
Also, the heatbed support frame is acrylic, which WILL sag after a bit of use due to the MK3 heatbed being all aluminum.
Maybe. This chart wire sizes and ampacities shows the ampacity of 16ga (mine is; I was worried and measured) as 22 when used as "chassis wiring", which is what this is. I've worked in power supply design for a number of years, and I'd say that 16 is OK, but nothing smaller would be. If the power was changed to 24V, the current would drop by 4, and the wires would be overkill. So for 12V, it's marginal or OK, depending on the heatbed resistance. It just has to stay under 22A, and that means the heat bed resistance has to be more than 0.545 ohms. Most of them are. Mine measures 1.2 ohms, and the wires do not get noticeably warm with the bed at max continuous heating; about which, see below.Quote
The wiring is insufficient gauge and yet another fire waiting to happen.
Frame, stepper, heatbed, yes. The RAMPS board is of mysterious quality as opposed to questionable, using the normal USA English connotations of those words. Both of mine worked without a hitch when I got them plugged up correctly.Quote
7) The frame is nice. The steppers are adequate. The RAMPS board is of questionable quality. The heatbed is a MK3.
My axes work, but admittedly they are not military grade. Of course, I didn't pay for mil-spec, either. Let's talk about a couple of issues I did have and worked around. That will hit a couple of these points.Quote
All in all, I'm able to salvage the frame, the steppers, the heatbed (after replacing the hot leads), and the endstops. I've had to redesign all three axes, source a support frame for the heatbed, replace the hotend entirely, and buy another controller board. Now, I admit that I could probably get by with the RAMPS board supplied, but my confidence in the overall quality of the kit is so low that I'm not willing to trust it.
Makes sense. I can stuff the STLs into Freecad and "trace" them if that would help you. It might be worth looking for some suitable bushings for a temp fix til you could print new fittings. I did correspond with an FLSun buyer whose nozzle carriage had drooped so that the nozzle would not fit in. A friend printed her a new one from the supplied STLs and it worked for her. The quality of the printing is likely to be ... variable...Quote
Re the 8mm/10mm issue, the printed parts supplied are for 8mm rods, but the print quality is so poor they might as well be designed for 9mm. Yes, there is that much excessive clearance - my comment about the bottom X rod falling out is not exaggerated. The STL files are all for 10mm rods, so you cannot simply reprint the parts with the files supplied, and if I'm going to have to CAD up new files I might as well fix the design so it actually works.
Again, reasonable. If you have spares, it makes sense to use them. I just haven't run into issues with these boards yet.Quote
Re the RAMPs, I've already admitted that it is probably okay. However, clone RAMPs boards vary widely in quality, and one of the known failure symptoms on poor quality boards is a catastrophic failure of the flammable variety. I already have a spare 4x Smoothie and GLCD I can use for this build, so this RAMPS goes into the spare parts bin until I can give it a proper QC check and BVT.
It's a pleasure to deal with someone who's experienced.Quote
I may not have as much hardware experience as you do, but I do have 10 years previous experience as a product design engineer in embedded processing for industrial and machine controls to draw from.
We'll see. Of course, I did mount a battery-powered smoke alert on top of the frame, too.Quote
Counting the clone V5 that came with the kit as a total loss is not a big deal since I have a spare E3D V6-Lite (original, not clone) from my Prusa MK1 to MK2 upgrade. However, even if I didn't have a ready replacement I wouldn't trust the one from the kit under any circumstances - the design deficiencies are *that* bad.
The supplies I have are hanging in there. I may not have as high a current bed as you're seeing. Or just be lucky. Could go either way.Quote
One additional thing I failed to mention is that the PSU is inadequate for the parts supplied. The kit comes with a 200W PSU (12 @ 16.6A). The MK3 heat bed draws anywhere from 8A to 12A, the hot end 2.5A, each stepper is rated for 1.5A, so you have a potential peak draw of 18A to 22A even before you add in any of the controller and display electronics. A 300W PSU is the minimum for this build and this may account for your heatbed's inability to reach a usable ABS temp. 4mm cork tile is a good alternative for insulation if you don't want to replace the acrylic carrier. I'm tempted to cover the MK3 with a sheet of adhesive PEI since the MK2 has shown that it works well for my prints. Adding a BLTouch to the hot end mount allows for grid compensation and helps minimize the leveling requirements.
Good, I'd like to see them.Quote
As soon as I get some free time I'll post some pics of the mods that I've done to this build. I'm still working on redoing the Z axis and X carriage assemblies and this is not a high priority project, so it may take me a few weeks to complete the conversion.
There are several things going on here. First is the tendency of Chinese manufacturers to be very NON-integrated. If they need power supplies, they buy from a power supply company and include that. If they need metal castings, they sub out the casting to a metal caster. This is what USA manufacturers have come to view as the very, very best in "integrated supply chain" tactics. It allows for very "agile manufacturing", which is another thing I was beaten over the head with as a design engineer. So products **can** be improved very quickly as needs change.Quote
I would be curious when you guys purchased your kits as there appears to be a lot of upgrades and improvements made over each. I believe this is supposed to be a new design so perhaps this is more an indication or either a work in progress or parts bin picking or whoever is handy at the time. For example my power supply is rated higher 320w(new and improved sticker? :-)) and the rods I have are 8 mm and the caps top and bottom were a very snug fit and required a bit of surgery.
The heater block assembly is a very common item, probably made in huge quantities by several companies, but not FLSun. I'm guessing that they go buy several thousand at a time from a number of suppliers. Suppliers of subsystems are added to or removed from the "qualified supplier" list based on performance of the finished subsystems. This technique was pioneered by USA automobile makers, and is how most remaining USA industry works.Quote
Your remark about the design deficiencies of the supplied extruder has me curious. What exactly are they? In regards to the comment about grub screws mine had two. The Chinese version is a larger diameter and would have a slightly larger thermal mass making it more stable (in theory) for temperature.
See above rant.Quote
While I was expecting/dreading typical Chinese quality
That is my assessment as well.Quote
for me the kit was quite a bit better than that low standard.
That's why you have me wondering if this is a work in progress. I was expecting a all metal frame and was annoyed to see use of acrylic for mounts and end stops on a "metal" framed printer. Sort of defeats the gains made from the extrusions
It was the XYZ version, not the Kossel/Delta. Yes, this one. They had a bad print. A reprint of the provided file fixed it. Mine both came OK.Quote
Was the drooping extruder mount on this model or another?
I've got my first real complaint with this printer. The set screw that holds the heater cartridge in the hot end doesn't reliably do its job. I've had the cartridge come out twice. The first time I noticed that Repetier host was pausing to heat the extruder. It normally doesn't do that so I investigated and found the cartridge dangling and glowing red hot in the middle of a test print!!!! I cleaned everything up and reassembled the hot end. The second time I left a 5 hr print unattended for a couple of hours. I return to it to find the heater cartridge out of the hot end and laying in the print, ruining it.
This obviously has to be addressed before I continue using this printer. I have wondered about using red RTV silicone to glue it into place. Is this a good practice? It stands to reason that you would want to be able to remove the heater cartridge for service and repair situations on the hot end. However, if the cartridge and hot end need to be permanently affixed and treated as an assembly, I can deal. What say the masses? I cant be the first person with this problem. Are there other accepted solutions I'm unaware of?
Very worthwhile tidbit.Quote
[...] some red RTV [...] holding the cartridge and the set screw both.[...] holding up well.
Also good tidbits. I'll add those to the enhanced instructions file.Quote
>20$ on ebay will buy a 33A 400 watt unit
>pair of 45mm linear bearings to replace the 24mm units on the Z axis
>3mm set screw on the upper rod [...] to final tension an already snug X belt by spreading the carriages and locking the rod in the left carriage[...] It would be nice if they would have detailed this in the build instructions.
Looking into the causes I noted that the Y axis rests on the front and rear extrusions. I also noted that depending on which corner you're looking at that these two extrusions could be flush, proud, or below the mating extrusion. It became obvious that this is a source of Z dimension error in the Y axis. I tried to loosen the angle brackets and tighten them with a clamp holding the pieces. This worked until I tried to do the same to the other end, which would invariably twist the first out of position.
This "problem" looks to be relatively easily solved. The corners need to be braced through two different dimensions. So I dug through my scrap and came up with a piece 1" by 1/2" "U" channel that could be cut into four 40mm pieces. I then drilled 2 holes in each 10mm inboard from the corners to center the bolts in the 20mm extrusions with the overhand towards the inside. The corners were rounded over to prevent any scrapes and snags and then each piece was bolted over the joint where the extrusions meet. This locks both pieces into the same plane. The corner bracket is snugged into place as the brace is tightened to keep one from binding the other.