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rack and pinion versus belt?

Posted by goinreverse 
rack and pinion versus belt?
January 22, 2010 01:14AM
I am wondering if there is a specific reason and rack and pinion type drive (nylon) would not be better/cheaper/easier than all the belts and pulleys currently in use on mendel ? For example mcmaster 57655K63 . I was just thinking maybe I was overlooking something obvious.
Re: rack and pinion versus belt?
January 22, 2010 01:25AM
My understanding is that people are working on a reprap printable rack and pinon
type drive with a nice V in it to make sure that the pinion does not fall off the rack.

see [blog.reprap.org]

I am sure this will be incorporated into the next reprap as Adrian is very keen on
maing the reprap build itself.

Grin

Stephen
Re: rack and pinion versus belt?
January 22, 2010 01:31AM
I am trying to create a "mendel" with 100% standardized parts. So if they are going that route then maybe I am not missing something.

To me the whole print itself thing is a gimmick, 80% by weight threaded rod... Design changes so frequently there will never be enough printed parts to go around.
Re: rack and pinion versus belt?
January 22, 2010 06:29AM
I think we'll be printing a lot of rack in the future. I've created [[RBS/Rack]] as a stub page.

[objects.reprap.org]



To me the whole print itself thing is a gimmick, 80% by weight threaded rod...
It's been discussed before. The most important thing right now is to make it harder, better, faster, and stronger:
[www.youtube.com]
What part would you like to focus on and make better?

Design changes so frequently there will never be enough printed parts to go around.
We're not sure how to sort out the versioning issues or track improvements yet. That's where people like you come in, according to policy:
[objects.reprap.org]

Also, the agitprop committee tells me we're expecting to saturate the market for 3D printers in the next few years, maybe. The low end market, that is. The high end will take another decade or so.
Re: rack and pinion versus belt?
January 22, 2010 10:13PM
Hi

goinreverse () said
To me the whole print itself thing is a gimmick, 80% by weight threaded rod... Design changes so frequently there will never be enough printed parts to go around.

My reply.
It's a work in progress and it's fast becoming a reality.
Take the reprap I am currently building. It's a darwin design and only has four threaded rods and three un threaded rods. The main structure is MDF (cheap) and is so strong I can sit on it. (I weigh 95kg). I don't use nuts and bolts much as I have replaced them with self taping screws which again are cheap. I hope my next reprap will be a CNC machine and reprap. I see no problem with this as the structure is rock solid. Hopefully it will be able to cut out the MDF parts as well as make my rack and pinion. Grin

Stephen
Re: rack and pinion versus belt?
January 22, 2010 10:17PM
Cool.thumbs up

If it's better than the McWire thing, want to wiki it up? Most of the wiki is world-edittable.
Hi SebastienBailard ()

You said
If it's better than the McWire thing, want to wiki it up? Most of the wiki is world-edittable.

My reply
I would never say my reprap is better than anyones as most of the ideas
have been stolen from other people.

However will have a "coming out" party when I am satisfied with the design and it's functionality. As I said currently working on the following technologies.

1) use 50mm self taping screws. (cheap and plentiful but requires hand drill)
2) use only 3 threaded screws on darwin Z axis. (25% less friction and cheaper)
3) use MDF instead of steel rods. (More stable and cheaper and very CNC able)
4) Replacemnet of $5 bearings with tube/pipe,washers and a little silicon spray

5) Multiple tool design. (very much in my head at the moment)
6) Automatic feeder. (again very much in my head at the moment)

My reprap has a base of 800mmx600mm for stability and a working area of 400mmx300mm. Note I did not choose these dimensions it's just that the MDF came in this size and I am very lazy.

Problems I am still having.

Does anyone know how to drill a 6.35mm hole into a 10M bolt which is perfectly
in the middle of the bolt when spinning? It's driving me nuts.

Stephen
Re: rack and pinion versus belt?
January 24, 2010 06:44PM
I would never say my reprap is better than anyones as most of the ideas
have been stolen from other people.


If you cite what you remember, if you think it's important, it's merely borrowed. smiling smiley
Also, I think the only good RepStrap or the good RepRap is the one with good documentation, but that's the RepRap librarian in me talking.


However will have a "coming out" party when I am satisfied with the design and it's functionality. As I said currently working on the following technologies.

Once you're clear on the design, you may want to photoblog it on the [[wiki]] page as you fabricate, and then talk it up in a new forum thread, etc. Retrodocumentation is 10x harder than getting down initial impressions the first time during the build log.


-Sebastien, RepRap.org library gnome.

Remember, you're all RepRap developers (once you've joined the super-secret developer mailing list), and the wiki, RepRap.org, [reprap.org] is for everyone and everything! grinning smiley
Re: rack and pinion versus belt?
January 24, 2010 06:46PM
Also, shiny acrylic panels and computer "case mod" aesthetic design features help sell things, but that's the RepRap agitprop committee gofer in me talking. smiling smiley
Re: rack and pinion versus belt?
January 29, 2010 11:52AM
To get a 6.35mm hole exactly in the center of your 10mm bolt, you need to put the 10mm bolt in your hand drill, the 6.35mm drill bit in a table vise, and drill into it that way. You can easily tell if it's precisely centered or not, as it will shake/vibrate if you try to drill off center. It will also auto-center to some degree when you try to hold it steady.

If you don't have a table vise, you can use any sort of vise that will hold the drill bit solidly, though having it at table level is about right.

If you don't have a hand drill, you'd have to get one. But if you're using self tapping screws you already have one. Unless it has a smaller chuck that won't go up big enough to hold a 10mm bolt, in which case you have a problem.


--
I'm building it with Baling Wire
Re: rack and pinion versus belt?
January 31, 2010 06:00PM
Jgilmore

To get a 6.35mm hole exactly in the center of your 10mm bolt, you need to put the 10mm bolt in your hand drill, the 6.35mm drill bit in a table vise, and drill into it that way. You can easily tell if it's precisely centered or not, as it will shake/vibrate if you try to drill off center. It will also auto-center to some degree when you try to hold it steady.

My reply
Of course !!!! You are a legend.........

Thanks will try tonight when I get hope from work.
Re: rack and pinion versus belt?
February 03, 2010 02:55PM
goinreverse Wrote:
-------------------------------------------------------
> To me the whole print itself thing is a gimmick,
> 80% by weight threaded rod... Design changes so
> frequently there will never be enough printed
> parts to go around.

It's not a gimmick, it's a design goal. These machines are in their infancy, so to speak, and they're working under the open source mantra of "release early, release often". The design will stabilze over time, and at that point, pieces that have been printed will have a longer "life", which means that there will be more machines. More machines means more part printing capacity.

The Rack and pinion design, in my mind, opens up the possibility of a larger print area. A larger print area means that you can print more parts per run, further reducing print time.


And aside from all that, older generation machines can print newer generation parts, so the old designs don't go to waste. 4 Darwins can print Mendels, which will be able to print the next design. The whole system just has to reach a certain critical mass of working machines, such that there is spare capacity to print more spare parts. As it stands, there's an 80+ hour print time, plus about $300 in electronics per machine. That creates a pretty high barrier to entry, but it'll drop fast. Heck, it's already a lot lower than it was a while ago.
Re: rack and pinion versus belt?
February 03, 2010 07:16PM
Reasonable people can and probably do disagree on this issue. I think having as a fundamental design goal a requirement for non-standard specially printed parts is a gimmick and virtually assures that the project cannot reach mainstream adoption in the near term. Furthermore all designs to date are substantially non-printed parts by most useful measures (weight, cost, volume, functionality). As clearly evidenced it is not possible to produce enough parts at a fast enough rate to meet an exponentially growing demand for new machines. Certainly once everyone everywhere already has a machine, that is not the case but we are possibly 10-20 years from that point.

My position is that in order for the project to be sustainable and successful it must move to a single design that can be built with either standardized OR printed parts. I actually don't think doing this is that hard either, just a little more forethought in some of the part designs would go a long way. I do think it needs to be made a fundamental consideration of the project. Requiring separate standalone bootstrap devices means that very soon the bootstrap device meets of exceeds the value of the actual device and the bulk of users no longer make the actual device. This is already happening with makerbot... When they offer a larger form factor, which I think is very soon, I see reprap having a very hard time reaching mainstream acceptance without significant adaptation in design and process. As it stands today reprap is being dwarfed by makerbot success though I don't think this process is irreversible as a lot of folks are still using makerbot as a stepping stone to reprap.

I am going to make a separate thread about costs as I think what you stated and what appears in various places are dramatic understatements as to the real costs of building the device both in time and hard materials.

For example makerbot is currently shipping at least 100 units per month, I don't think it would be crazy to say that by the end of the year they could be at 250 units per month. At their current volume in reprap terms that would require 8,000 print hours per month... Best I can tell there are under 200 people with fully functioning repraps/mendels worldwide. To continue at that pace would mean that every single reprap owner would need to contribute 40 hours per month just printing parts for new users, I think it is ludicrous to expect that. I doubt that you could reliably get reprep owners to contribute more than a single or possibly 2 complete sets of parts for redistribution in a year. I do think that making that a requirement of the license (build 1 share 1 or build 1 share 2) would be a significant and positive step forward in assuring growth and adoption.

That being said I certainly am 100% in favor of design elements that can both be printed and are available as standardized parts. I think rack and pinion is possibly a great example of that and could solve a lot of problems, either 1) buy the rack and gear from mcmaster, etc or 2) use a functionally equivalent printed part which may operate slightly differently such as herring bone in plastic versus straight steel from mcmaster but should use the same mounting holes, etc. In other words the parts are practically interchangeable though perhaps not functionally identical. This is not anywhere near the case today and again it is crucial that the folks designing the rack and pinion use mounting points and general measurements compatible with what is commercially available or the opportunity is squandered.

I also agree that increases in the printing area are crucial though to what exact size I couldn't say.

On the design stability issues I don't agree with you at all, looking at the interest curve and the innovation curve I think there are literally many more years of complete redesign and re-implementation ahead of everyone. Things have barely begun and I doubt anyone can predict with even moderate certainty whether repraps next year will be laser sintering plastic powder or "extruding" molten metals or something we can't even conceive of yet.
Re: rack and pinion versus belt?
February 03, 2010 08:54PM
goinreverse Wrote:
-------------------------------------------------------
> Reasonable people can and probably do disagree on
> this issue.
>
Indeed.
>
>
> For example makerbot is currently shipping at
> least 100 units per month, I don't think it would
> be crazy to say that by the end of the year they
> could be at 250 units per month. At their current
> volume in reprap terms that would require 8,000
> print hours per month... Best I can tell there are
> under 200 people with fully functioning
> repraps/mendels worldwide.
>
I used to think that way, too, not that long ago. In fact, however, BitsFromBytes alone has already sold over a thousand at last count. Rapmans get used, a lot typically. Over at the BitsFromBytes forum there is a lively effort to design and print replacement parts for the laser cut acrylic parts for the various models of Rapman. As best as I can estimate there is no market for BitsFromBytes for replacement parts sales for Rapmans. People are just printing their own. Ian at BitsFromBytes is even setting up a bank of printers to print parts for their machines, thus getting away from the brittle, laser-cut plastic that they are presently using. Personally, I am expecting that Ian will be selling packs of the non-printable parts alone within a year or two as the informal trade in printed parts increases.


A quick look in Thingiverse will also show you all sorts of people who are not only using what are, more or less, low-cost commercial units like Makerbot and Rapman, but also units they've cobbled together from any number of strange parts.

In that regard, Frank Davies down in Texas is a good example.

[www.thingiverse.com]

He built his reprap machine from old paper printers parts. The 3D printing work he's done with it is nothing short of awesome.
>
> That being said I certainly am 100% in favor of
> design elements that can both be printed and are
> available as standardized parts. I think rack and
> pinion is possibly a great example of that and
> could solve a lot of problems, either 1) buy the
> rack and gear from mcmaster, etc or 2) use a
> functionally equivalent printed part which may
> operate slightly differently such as herring bone
> in plastic versus straight steel from mcmaster but
> should use the same mounting holes, etc.
>
I've developed quite a few parts in plastic. Sadly, design realities are such that plastic and metal parts are rarely interchangeable unless the metal parts are massively overdesigned. Plastic is simply not the function equivalent of metal per unit volume. That doesn't make it inferior, just qualitatively different.
>
> In other
> words the parts are practically interchangeable
> though perhaps not functionally identical. This is
> not anywhere near the case today and again it is
> crucial that the folks designing the rack and
> pinion use mounting points and general
> measurements compatible with what is commercially
> available or the opportunity is squandered.
>
I wish that were possible. I fear, however, that it is impractical.
>

Edited 3 time(s). Last edit at 02/03/2010 09:02PM by Forrest Higgs.


-------------------------------------------------------

Hell, there are no rules here - we're trying to accomplish something.

Opportunity is missed by most people because it is dressed in overalls and looks like work.

Thomas A. Edison
Re: rack and pinion versus belt?
February 03, 2010 09:07PM
Forrest definitely has a good point on the impracticality of designing things so that printed and commercial parts are interchangeable. It might not be impossible or impractical to design so that smaller sections of the design change between using printed and non-printed parts, though. For example, say you have a rack and pinion system. Chances are you need a gearbox (you definitely do for printed parts, not sure if this is true for commercial but bear with me). If you design the system so that you mount the stepper to the gear box and the gear box to the frame, then you can standardize the mounting holes for the gearbox. If you set up the mounting so the gearbox can be raised or lowered to engage the rack properly, then you don't need for the printed rack or gears to be the same height/diameter as commercial to be able to retain the ablility to use either in your design. If you're building a gearbox using gears from SDP-SI or McMaster, you make gearbox panels with one design. If you're printing it, the printed design is a little different - but each gearbox fits the same mounting point.
Re: rack and pinion versus belt?
February 03, 2010 09:15PM
Corwin Wrote:
-------------------------------------------------------
>
> Chances are you need a gearbox (you definitely do
> for printed parts, not sure if this is true for
> commercial but bear with me).
>
I would have agreed with you two days ago. Since then, however, I've located an Allegro A4983 breakout board that lets you do microstepping. I've dumped the gearbox idea since then. With microstepping you don't need gear reduction to get the printing resolutions you need and better.

[www.pololu.com]

That bad boy will even let you design bigger, easier-to-print sprocket gears for your rack and pinion system.


-------------------------------------------------------

Hell, there are no rules here - we're trying to accomplish something.

Opportunity is missed by most people because it is dressed in overalls and looks like work.

Thomas A. Edison
Re: rack and pinion versus belt?
February 03, 2010 10:35PM
I don't agree with the attitude that you can't design a system wherein the parts are "practically interchangeable" between printed and standardized. Certainly I don't think it would be very easy to make parts identical and I didn't mean it that way if it was taken so. Overall the machines here are not that complex, there is a frame, 3 moving planes, and an extruder. Maybe the standardized parts route and the printed parts route take slightly different paths in the real specifics but they should be able to get you to the same place. What literally has me pulling my hair out now is that attitude towards the bootstrapping devices is an after-thought at best while at the same time it will be a year or more (if ever) before parts availability catches up for the mendel at which point V3 will probably taking shape.

That is just the problem, attitude. For example with rack and pinion, just mcmaster has something like 200 different configurations of gearing and racks. The idea that the mount holes couldn't be matched and some distances from how the shaft drive powers the gear, or even the sizes of gears be at least compatible is absurd. It is absolutely feasible to do that.

Seems like there is some irony in you selecting a standardized and widely available chip to power steppers like the A4983 from a widely available manufacturer like pololu, Why not use an FPGA and custom microcode? Ohh right, because standardized widely available parts make things easier for everyone and lower the barriers to entry.

Another potential avenue is something like the mendel extruder mount, with some minor changes it could easily be configure to be made using a drill press and either layered acrylic or solid block material. Sure someone can hack that together but I think the consideration of building from both standardized and printed parts needs to become a foundational element of the project. The current distance between the bootstrapping systems and the final system is maddeningly and arbitrarily large. And before someone says "why don't you do it then"... I am already in the process of. For me the critical question is how the community would or would not accept those types of changes and if not why I should bother.. Alternatively I can just focus my attention on a forked machine that does not take into account the need to self-replicate which as I have already stated I don't personally think is important or at least not for several more years.

Or how about make all the printed parts mold-friendly and include at inception laser cut diagrams to make the molds from multi-layer acrylic. That way one person could pay a service like ponoko/etc to make the molds, a machine for him/herself, mold many more parts and/or print many more parts.

I am not sure I really understand your point about bits and bytes selling one thousand units, I guess you mean just that there are a lot of repraps out there? I should have qualified more specifically, I meant to say that there are under 200 repraps which have been "built" rather than purchased. I think the distinction is important because someone who builds I think is much more likely to be part of the community than someone who buys. Again also coming back to the "build 1 share 1" idea, imagine for a moment that for every reprap sold Bits from Bytes or potentially the end customer had to provide a set of parts to a communal redistribution resource. I am not saying that is necessarily a good thing or a bad thing, maybe that requirement would have made their business impractical, I don't know but I think it is an important discussion point.
Re: rack and pinion versus belt?
February 04, 2010 12:26AM
Forrest Higgs Wrote:
-------------------------------------------------------
> Corwin Wrote:
> --------------------------------------------------
> -----
> >
> > Chances are you need a gearbox (you definitely
> do
> > for printed parts, not sure if this is true for
> > commercial but bear with me).
> >
> I would have agreed with you two days ago. Since
> then, however, I've located an Allegro A4983
> breakout board that lets you do microstepping.
> I've dumped the gearbox idea since then. With
> microstepping you don't need gear reduction to get
> the printing resolutions you need and better.
>
> [www.pololu.com]
>
> That bad boy will even let you design bigger,
> easier-to-print sprocket gears for your rack and
> pinion system.
If that's the case, then I absolutely have to agree with goinreverse. There's absolutely no reason not to choose a rack and pinion gear with the same radius as the printed gear and either match the mounting for the printed rail to the commercial unit or include mounting holes for both.

By the way, how long has that pololu driver been out? If it's been around for more than a year then boy do I have egg on my face for buying anything else. $13 is a lot less than I paid per axis for the EZ CNC driver board on my repstrap or the v1.1 reprap stepper driver board.
Re: rack and pinion versus belt?
February 04, 2010 07:13AM
I can't see goinreverse's point. An exponential growth will always beat a linear one, it's just a matter of time when it happens, why does it matter when that is?

The issue with the pololu board is that it does not have enough heatsinking so you have to add the cost of a heatsink and improvise some sort out mounting that gives good thermal contact.


[www.hydraraptor.blogspot.com]
Re: rack and pinion versus belt?
February 04, 2010 07:30AM
nophead Wrote:
-------------------------------------------------------
> The issue with the pololu board is that it does
> not have enough heatsinking so you have to add the
> cost of a heatsink and improvise some sort out
> mounting that gives good thermal contact.

that's true, and for many of us it still works out better than other offerings.

I'm experimenting with this in my extruder at the moment, and with a heatsink on the A4983, the motor is so strong that it's cutting gouges out of the side of my filament without even slowing down.. I think I will have to blunt my splines, make them more closely resemble gear teeth or something.


-----------------------------------------------
Wooden Mendel
Teacup Firmware
Re: rack and pinion versus belt?
February 04, 2010 11:01AM
nophead Wrote:
-------------------------------------------------------
> I can't see goinreverse's point. An exponential
> growth will always beat a linear one, it's just a
> matter of time when it happens, why does it matter
> when that is?
>
I'm not going to feed someone who appears to be bent on being a troll {not you Nop, that other guy} any longer, but just in passing I've recently made a Reprap friend in eastern Europe. He's tuned his printer/extruder to where it is printing effectively at about 50 mm/sec {I've seen video clips of it in operation}. It's a hacked Rapman.

So far he's printed up 8 sets of Mendel part and sold them in his area. He tells me that he can get a set of parts out the door in about four days. I asked him if he had to print continuously to manage that and he said most emphatically NO. He's going to keep track of the actual printing hours on the next set he makes.

The guy is a teenager. smileys with beer
>
> The issue with the pololu board is that it does
> not have enough heatsinking so you have to add the
> cost of a heatsink and improvise some sort out
> mounting that gives good thermal contact.
>
Popolu were quite upfront about that problem when I talked to them. I suspect that I can epoxy some sort of suitable copper finned heatsink onto the chip. I certainly have some copper shim that should do the job. I figure it it works, well and good. If not, I'm not out a lot of money. smiling smiley

Edited 2 time(s). Last edit at 02/04/2010 11:03AM by Forrest Higgs.


-------------------------------------------------------

Hell, there are no rules here - we're trying to accomplish something.

Opportunity is missed by most people because it is dressed in overalls and looks like work.

Thomas A. Edison
Re: rack and pinion versus belt?
February 04, 2010 04:18PM
Forrest Higgs Wrote:
-------------------------------------------------------
> nophead Wrote:
> --------------------------------------------------
> -----
> > I can't see goinreverse's point. An exponential
> > growth will always beat a linear one, it's just
> a
> > matter of time when it happens, why does it
> matter
> > when that is?
> >
> I'm not going to feed someone who appears to be
> bent on being a troll


I don't think Goinreverse is being a troll, to me that implies intent to stir up trouble. I think his problem is that of a narrow, and maybe myopic view. Self replication *is* a design goal. It is not (necessarily) a production goal. That's the whole deal with rapid prototypers, they're PROTOTYPERS, for one-off use, not for mass production. You'll always be able to mass produce faster and cheaper than a 3d printer will. But the idea of a machine that can, at any point in time, produce a replacement part for itself, is a goal to design toward. For mass production of these machines, once a stable design that is 100% printable is achieved, you'd still set up a production line. There are hundreds of iterations to get between here and there. New production techniques (like the tuning that Forrest's Eastern European friend has) will decrease production times. New precision methodologies will allow more complex parts to be printed, etc, etc. We're at the Bushnell, Jobs, and Wozniak in their garages level here, eventually we'll be at the iPad level, but it'll take a while.
Re: rack and pinion versus belt?
February 04, 2010 04:41PM
abrannan Wrote:
-------------------------------------------------------
> Forrest Higgs Wrote:
> --------------------------------------------------
> -----
> > nophead Wrote:
> >
> --------------------------------------------------
>
> That's the
> whole deal with rapid prototypers, they're
> PROTOTYPERS, for one-off use, not for mass
> production.
>
I think you are getting too caught up with naming things and not paying attention to what they do. It used to be that there were printing businesses in practically every medium sized and larger town. Production of printed documents was simply not possible on a desktop basis. These days you will struggle to find printing businesses.

3D printers can and do print real things. Ask the people at Lockheed's Skunk works

[defensetech.org]

...so do reprappers. Mass production is only useful and economic if you want to make many thousands of identical objects and can afford the distribution costs from an expensive, specialised factory. That's not the 21st century. It's the 19th and 20th centuries.
>
> You'll always be able to mass produce
> faster and cheaper than a 3d printer will.
>
Nope, not if you factor in distribution and manufacturing flexibility.
>
> But
> the idea of a machine that can, at any point in
> time, produce a replacement part for itself, is a
> goal to design toward. For mass production of
> these machines, once a stable design that is 100%
> printable is achieved, you'd still set up a
> production line.

Well, we'll have to agree to disagree. If you really believe this why are you here. You ought to be sitting back for 10-15 years waiting for HP's $15 3D printer to get cheap enough for desktop use... and then they'll stick you with outrageous costs for their filament, just like they do for ink for their printers.
>
> There are hundreds of iterations
> to get between here and there. New production
> techniques (like the tuning that Forrest's Eastern
> European friend has) will decrease production
> times. New precision methodologies will allow
> more complex parts to be printed, etc, etc. We're
> at the Bushnell, Jobs, and Wozniak in their
> garages level here, eventually we'll be at the
> iPad level, but it'll take a while.

Yeah, yeah .... whatever... eye rolling smiley


-------------------------------------------------------

Hell, there are no rules here - we're trying to accomplish something.

Opportunity is missed by most people because it is dressed in overalls and looks like work.

Thomas A. Edison
Re: rack and pinion versus belt?
February 04, 2010 07:46PM
Well, I guess I appreciate nopheads defense? of me. I don't think articulate reasoned discussion, however much it seems to disagree with the status quo, is trolling. I would also like to point out here that I have been intentionally discussing the project as a project (and I believe I have been successful), I have not individualized any particular person here while it seems like some have confronted me on a personal basis as being both a troll and as being "narrow and myopic"... You are free to agree or disagree with my positions, that is the nature of debate. Can we also agree not to make this personal? I am sure that all participants herein are intelligent, upstanding, gentlemen/women. I don't dispute my passion or enthusiasm, my only goal here is to try and improve this project and make it more accessible to as many willing people as possible.

I also don't have a problem with "self replication" as a design goal. What I have a problem with is self replication as the only design goal or at the expense of ease of use/construction, or as an arbitrary barrier to entry. From my perspective those things seem to be true as of right now. Both in this forum and with virtually every group of people I discuss this project with (LUGS, Hackerspaces, etc) the number 1 issue (if not the only issue), availability of printed parts.

I guess I can say that from the prototyping versus manufacturing distinction between you forest and you nophead, I split the difference. I think the primary value of a reprap like tool today is in creating the components and tooling of mass manufacture (molds, negatives, 3D design prototypes, tooling guides, etc) and dramatically reducing the cost to do so and to iterate. That being said I don't see any reason why in the near to not so distant future it can't also be a direct manufacturing tool.
Re: rack and pinion versus belt?
February 05, 2010 09:55AM
goinreverse,
I think you misunderstand the goal of the project. It certainly isn't to make a rapid prototyping machine for tooling mass production. It is to make a cheap machine that does distributed mass manufacture. A self replicating machine with exponential growth and intelligent evolution will eventually outperform centralised mass production and shipping, it's just a matter of when. Exponential economic growth and population expansion will always end in disaster for the same reason: simple maths.

All the activity around repstraps is because people are impatient to have the machines now. The number of people printing parts has increased dramatically since around the time Mendel was announced. Before that it was only about 3 people and five sets of parts. Now there are lots of people making parts. Repstraps will die out eventually because given a set of parts at cost it will be easier and cheaper to use them.


[www.hydraraptor.blogspot.com]
Re: rack and pinion versus belt?
February 12, 2010 01:57PM
goinreverse,
I think you misunderstand the goal of the project. It certainly isn't to make a rapid prototyping machine for tooling mass production. It is to make a cheap machine that does distributed mass manufacture.


I respectfully disagree. I think the idea is to
(1) Make a cheap machine that does distributed mass manufacture.
(2) Make a variant and bolt a laser onto it.
(3) Make it 10 x bigger and bolt a large router onto it.

(2) and (3) are not cheap. But if they are cost-effective to run they belong up on the wiki. If they are fun, they belong up on the wiki. If they aren't up on the wiki, the wiki is failing its purpose in life.

Doing one machine is fun. Doing dozens of machines with dozens of different features is even more fun.

If goinreverse tacks up a napkin sketch on the wiki, then goinreverse is an official RepRap Developer, by definition. And is helping decide "the goal of the project". By contributing.

Unless we agreed at one point that Adrian has the official goal of the project on some lab notebook page that isn't up on the wiki, or the Gada Prize is the official "goal of the project".

Inasmuch as I want to make a RepRap that doesn't fit through the average door and falls through the average floor, I respectfully disagree. Anything on the wiki is the official "goal of the project". Everything else ... doesn't really exist yet, in RepRap terms. RepRap nearly understands Heated Bed, for example, but I don't think the wiki page is there yet.

[objects.reprap.org]

Edited 2 time(s). Last edit at 02/12/2010 02:04PM by SebastienBailard.
Re: rack and pinion versus belt?
February 12, 2010 02:12PM
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 this one or alternatively a debian or ubuntu like community structure.

I honestly think that here in the states anyway reprap is going to have a really hard time getting additional traction and gain contributors as is. As soon as makerbot coordinates a design with a mendel sized printing format I think its game over. A brief survey of hardware hacking groups I found here showed 91 with makerbots and 4 with functioning repraps (based purely on a review of their websites), certainly some of those with makerbots are looking to build mendels but again for the larger print format I think.

Now the gen4 electronics are on the way out soon which will further fragment things, a total mess of a situation.
Re: rack and pinion versus belt?
February 12, 2010 03:15PM
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.

Congratulations! That's the first step towards becoming an official RepRap developer. smiling smiley (The second step is logging into RepRap.org and clicking "edit".)

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 this one or alternatively a debian or ubuntu like community structure.

Forking = Great, as long as it's documented on the wiki. smiling smiley

RepRap is definitely a debian or ubuntu like community structure. We get wiki space in 20GB chunks. Let me know if you're planning on using more than 20GB at a time, but aside from that, it's all good. I may be speaking humorously here, but I mean it when I say that the wiki is for everyone.
[objects.reprap.org]

RepRap doesn't have a Linus. We've got:

(a) Mendel - designed by folk who have little interest in bolting a Dremel onto it.
(b) [[Dremel Holder]] - a wiki page for folk to bolt a Dremel ono a Mendel.
(c) [[Gada Prize]] an 80,000 KUSD feature wishlist.
(d) [[Development Pathway]] the feature wishlist of everything that's not in the Gada Prize.
[objects.reprap.org]

The only hard part is making sure the wiki pages are clear that
"You are on the EMCRepStrap page. EMC is not the official RepRap software, but lots of folk use it."

I honestly think that here in the states anyway reprap is going to have a really hard time getting additional traction and gain contributors as is. As soon as makerbot coordinates a design with a mendel sized printing format I think its game over. A brief survey of hardware hacking groups I found here showed 91 with makerbots and 4 with functioning repraps (based purely on a review of their websites), certainly some of those with makerbots are looking to build mendels but again for the larger print format I think.

Hmmm ... I have a huge ax to grind there, and will only comment after I draft and redraft it to be polite and constructive.

Now the gen4 electronics are on the way out soon which will further fragment things, a total mess of a situation.

Development != mess. Development = feature. smiling smiley

Freezing electronic development, now that's bad. Making it all clear on the wiki, that's our job. grinning smiley


-Sebastien, RepRap.org library gnome.

Remember, you're all RepRap developers (once you've joined the super-secret developer mailing list), and the wiki, RepRap.org, [reprap.org] is for everyone and everything! grinning smiley
What the project is
February 12, 2010 03:29PM
From the front page:

Quote

Welcome to RepRap.org

RepRap is a free desktop 3d printer capable of printing plastic objects. Since a large part of the RepRap is made of this same plastic the RepRap can be considered a self-replicating machine - one that anyone can build given time and materials.

This is what I believe the project is as it has always said something along the same lines.

Adrian Bowyer is the Linus of RepRap. The project was his idea and he decides what goes into the official releases.

Sebastien seems to think RepRap covers every possible home made fabrication machine. I have no objection to a website that covers the world of homemade fabrication machines but I don't see how it should be the reprap site. Reprap is only a small subset of such machines. [email protected] is another.

I would have though Reprap.org should cover all the information about building and using Darwin, Mendel and the descendants, and any neat machines you can make with one. To keep that up to date and consistent is a massive task when things change so quickly. Mixing loads of unrelated machines and fabrication techniques seems to just make the thing impossible. Better to have separate domains and websites for projects with a different goal.


[www.hydraraptor.blogspot.com]
Re: rack and pinion versus belt?
February 12, 2010 04:46PM
SebastienBailard Wrote:
-------------------------------------------------------
> goinreverse,
>> I respectfully disagree. I think the idea is to
> (1) Make a cheap machine that does distributed
> mass manufacture.
> (2) Make a variant and bolt a laser onto it.
> (3) Make it 10 x bigger and bolt a large router
> onto it.
>

RepRap is NOT supposed to replace mass manufacturing!

It is supposed to be self reproducing (it's not yet, but that is the goal).
It is supposed to be able to create useful objects.
It can create optimized objects such as ... oh I really like the design but it would be better if ... so change it to what you want and print it out.
It is the ultimate beaming technology, friend in Japan designs a part and emails it to me, 1 hour later I am holding it in my hands!

You can do small batches of objects, 10's to 100's.

When you get into the 1,000's then you might want to think of more conventional methods such as injection molding.

Will this FFF (or FDM) be the technology used for 3d printing on every desktop in 20 years ... maybe yes, maybe no. I particularly like the use of plain paper, adhesive and a cutter that creates wood-like objects at a very low cost - the main cost being the special adhesive required. Others use a roll of plastic, adhesive and a cutter which makes even stronger parts but at a significantly higher cost (plastic vs plain 80/160 g paper).


Bob Morrison
W├Ârth am Rhein, Germany
"Luke, use the source!"
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