It should be noted that most concerns with the 8020 linear motion bearing pads had to do with binding issues using them in the Z-Axis rather than X and Y. I have been playing with them and I find them to be pretty good all round, in the Z axis you need to address binding but I believe that can be solved with careful consideration to rigidity and symmetry, for example driving the axis with 2 threby goinreverse - General
The currently fatal problem with the mcwire is that there isn't really an extruder design that can extrude SLOWLY enough for the very slowly moving threaded rod driven planes. This pushes printing time through the roof (to perhaps 200-400 hours for the mendel depending on how good you get, not only printing time but time to take the stl's, tweak skeinforge and print all the mendel parts) becauseby goinreverse - General
I meant the amount and time to wear down is speculative and material dependent rather than the concept, sorry I was not more specific. I don't know what the co-efficient of friction of printed abs (or pla) on printed abs (or pla) is or if it could be modified by some sort of lubricant to further reduce wear and maintain 2 point contact for a sufficiently useful duration. It does seem to me to offby goinreverse - General
I think a lot of that is speculative, It could potentially taking a very long time to wear down if it where plastic on plastic. It wouldn't be very hard for someone to print and compare the bearing vs. non-bearing construction and the respective tradeoffs.by goinreverse - General
I look forward to Sebastian's response about repraps potential growth in the US, I would love to be persuaded to change my mind on that. I've been working in open source projects for 20 years and my personal opinion is that currently reprap has little to none of the crucial philosophical and practical project management infrastructure I see in a linux kernel, ubuntu, apache, debian, etc. Others dby goinreverse - General
I'm not looking to be belligerent here, clearly I have very different goals than some other contributors and I am forking a project to focus on what I think is important. That being said if reprap has a leader who has set goals then I suggest he/she step forward... I think the project has a severe lack of any goals and leadership. If there was ever a project in need of a 'Linus' I think it is thiby goinreverse - General
Why do you NEED bearings for the roller? I think you could get by with static rod/spacers mounted in the hub. VXD generally has any size small-medium sized bearing 10-packs for $5-$15.by goinreverse - General
The problem with screw driven planes is that it will take 200-300 hours of printing and babysitting time to print all the mendel parts. If you can find a way to drive the plane using belts and pulleys (which you could reuse in mendel) or rack and pinion. Not sure what you were planning for an extruder but the pinch wheel generally produces too much extrusion for the slow moving planes of a screwby goinreverse - General
Actually what I was posting is in response to that, the "roller" and pinion, rather than the rack and pinion (as that blog shows), is a slightly different design which I think would be particularly well suited to printing. The roller could have the "teeth" elements as bolts with spacers screwed between 2 printed hubs or possibly 100% printed. The herringbone is fine but very complex to model anby goinreverse - General
Viktor, Just post the parts list and specifications in detail. That way individuals can acquire the parts completely independently of you and you won't incur any liability. Mouser, Digikey, Alltronics, Mcmaster all sell heaps of dangerous parts that when put together can become even more dangerous, there isn't a big issue because they sell it as parts (also for example makerbot sells unassembledby goinreverse - General
Not that I want to encourage more dependency on printed parts but this seems like something higher performing and more easily printable and easy to manage than the herringbone: Could easily be a printable replacement for standardized nylon rack and pinion (which would be the boot strap option).by goinreverse - General
Sebastian, I am still working out what media and formats I am going to be documenting with but I have no problem whatsoever with it appearing on the reprap site and will most likely license it under creative commons SA which I think is compatible with repraps documentation license. There should be a pretty foolproof 8020 repstrap coming from me forthwidth. I am talking to them about making it iby goinreverse - General
Greasing the threaded rods (don't go crazy) can also make a big difference in the amount of torque needed. Not sure how you are linking the shaft to the rod but I use vinyl tubing with a hose clamp on the joint and it works well while still allowing for slight misalignment and wobbleby goinreverse - General
After looking at the 8020 system (8020.net) in detail I don't have any interest in a mendel or mcwire and pretty happy to just be done with that, For 70% the cost of a makerbot I can put together a 2'x2'x2' device. That is without a doubt the best system I can possibly conceive of for doing a wide range of things including this. I am going to be focusing my energies on building an FDM with thatby goinreverse - General
Not sure if I have seen bothacker in the forums but his design here is the same as the t-slot version I have as gantry-only (rather than cube): 8020 looks like a good source for aluminum rail in addition to mcmaster. Some parts mcmaster has 8020 does not like the 2 and 3 way corners, some things 8020 like the raw bearing pads.by goinreverse - General
I don't think that material will have the finish and tolerances needed. Also as mild steel it will rust, distort and is generally not easy to make into a square cage. For high accuracy printing we are talking about getting to tolerances under hundredths or even into thousandths of an inch, that means the planes and gantry need to move predictably on those tolerances. Something like the mcwire hasby goinreverse - General
You will be ok with 1.8 degrees per step. Here in the US lin engineering and interinar seem to be the best sources of steppers. I would strongly suggest the highest torque (within reason) Nema 17s you can get for your budget.by goinreverse - General
@JohnnyCooper I just don't agree and what I have seen from my perspective here in the states doesn't line up. Makerbot literally can't make enough units at the $950 price point, clearly there is market demand here at that price point. For me the electronics were the easiest part, point, click, credit card, 5 days later they were here ready to go. If they had already assembled machines (I don't tby goinreverse - General
The problem for me is installing chrome/chrome frame on tons of different computers and OS's, just not something I have time/energy to deal with right now. I have used wave, seems like a lot of people say the opposite, that etherpad has some things they are waiting to be added to wave... YMMV.by goinreverse - General
I should get wave setup but I am jumping between computers and OS's all day long so standard web works better for me at the moment. Etherpad might be a good option. In terms of safety I should point out that pretty everything about FDM and laser sintering is bad, those ABS fumes from the extruder, bad, PLA, slightly better but still bad. Check out the MSDS sheets for these plastics. Pretty muchby goinreverse - General
***safety warning*** Be EXTRAORDINARILY careful with lasers, you can't necessarily see the output that will make you blind and it can happen in a fraction of a second. I would strongly urge you to get proper high end eye protection from someone like wicked lasers and make sure you validate that it is covering the correct wavelength of light. I see kids on youtube playing with those and the potentby goinreverse - General
Kevin, Sounds good to me. I need to think on it for a few days but I think the best way I can contribute to open hardware 3d printing is with design and implementation of a new device separate from reprap. I have already put in over 300 hours of effort to the point where my mcwire is printing objects. Those will now take what looks to be almost another 200 hours work/print time to complete, It hby goinreverse - General
Your thought with the sawdust raises a really interesting idea with a micro-misting extruder head delivering catalyst and a power based of epoxy (or anything else) that would harden. I think that is definitely worth exploring. Laser wise you can also use UV responsive liquid resin, you just need to move the laser really fast. The hardened material has a slightly higher density so sinks in the flby goinreverse - General
Thanks, yea, those mm2 to cc just don't work well in my american brain. So that makes the theoretical maximum speed to build a set of mendel parts almost 15 hours, approximately 1300cc I think. At least I didn't cause a satellite to crash a la NASA. Realistically that might be more like 25-35 hrs including all the various setup/teardown/babysitting. That really seems like too long to me...by goinreverse - General
For now excluding filament/heat dynamics... I think heated bed or heated airspace can address some of those issues. So if I have my math right you can push out 2.5 cubic centimeters per second or is .5 the circumference of the extruded material? It doesn't seem to me that belt driven planes can move that quick or at least there will potentially be inertia issues in direction changes. Do you havby goinreverse - General
I did give the search a go but I really couldn't find anything in all the noise. Any advice on search terms or possible date range? Or maybe you just recall the conclusion, how far is mendel from the theoretical max today? Is it 10% of max, 50%, etc?by goinreverse - General
Do you yourself have a laser cutter or access to one? If so what make/model, I have been looking to invest in one for work. I really appreciate your contribution, if you are ever in Phoenix ring me and I'll buy your a beer.by goinreverse - General
My last post just started showing up, actually written this morning... weird. I saw your detailed post rick, ignore my query for more info. After reading the makerbot forums I think I may be contributing my efforts to the wrong project... that looks like division A to me and possibly a better fit for my perspective. Thanks Rick!by goinreverse - General
Thanks, that's good information on motors but I am all about the standardized parts. If it isn't available off the shelf (or at least in chinese batch manufacture) I don't think it is a good fit for what I am trying to do. Commercially there are a lot of hollow shaft motors, they are just giant, such as 2HP size. That would probably be overkill I played with dies a little bit, much to sharp andby goinreverse - General
I was hoping someone had already done some hard thinking on this. What is the maximum theoretical print speed of FDM using a material like PLA or ABS? What are the primary factors effecting speed or is it as simple as speed of plane movement and speed of extrusion? Take something like the stratasys FDM machines, how fast are they in comparison with something like a properly tuned mendel?by goinreverse - General