Price of child reprap About how much does it cost to clone a reprap? including printed and "nonprinted" parts? thanks. https://reprap.org/forum/read.php?1,16989,16989#msg-16989 Sat, 10 Oct 2026 13:21:34 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?1,16989,17238#msg-17238 Re: Units correction (Nit-picky, I know) https://reprap.org/forum/read.php?1,16989,17238#msg-17238 -------------------------------------------------------
> > Thus the slug
> > in the US common system is the equivalent of
> the
> > Newton in SI.
>
> Not quite.
> Both slugs and Kg are mass measures; both pounds
> and Newtons are force measures.
> Sorry to nit pick.
>
You're absolutely right. I got it muddled.]]> Forrest Higgs General Tue, 30 Sep 2008 17:20:28 -0400 https://reprap.org/forum/read.php?1,16989,17236#msg-17236 Units correction (Nit-picky, I know) https://reprap.org/forum/read.php?1,16989,17236#msg-17236 -------------------------------------------------------
> A slug is a unit of mass in the US common system
> of measurements. Most people think that both kg's
> and pounds measure the same thing.

All true.

> Thus the slug
> in the US common system is the equivalent of the
> Newton in SI.

Not quite.
Both slugs and Kg are mass measures; both pounds and Newtons are force measures.
Sorry to nit pick.

IMHO, the common fig Newton cookie really ought to weigh exactly 1 Newton in a 1-g field. (I don't think they do, but they're probably within a factor of two.)

-- Larry]]> Larry_Pfeffer General Tue, 30 Sep 2008 16:51:12 -0400 https://reprap.org/forum/read.php?1,16989,17228#msg-17228 Re: Price of child reprap https://reprap.org/forum/read.php?1,16989,17228#msg-17228
Demented]]> Demented Chihuahua General Tue, 30 Sep 2008 12:55:16 -0400 https://reprap.org/forum/read.php?1,16989,17201#msg-17201 Re: Price of child reprap https://reprap.org/forum/read.php?1,16989,17201#msg-17201 a slug... isn't that a "homeless" snail?
32.2lbs ? that'd be a pretty huge one ;)

uh wait.. here we go... thanks to dict.leo Now I get it, its a piece of metall,
who'd known :D

thanks for lighting things up Forrest.

'sid

No matter what it's strange to measure the power of a stepper in kg/m or slug/ft
cause that's not a constant, not even on earth! nevermind]]> sid General Mon, 29 Sep 2008 23:00:33 -0400 https://reprap.org/forum/read.php?1,16989,17179#msg-17179 Re: Price of child reprap https://reprap.org/forum/read.php?1,16989,17179#msg-17179
When I was in engineering school in the mid-1960's, we were still doing engineering calculations in the US common system of measurements. Even then, though, they were tending to want to use metric measurements. We only had metric in CGS (centimeter-gram-second) and MKS (meter-kg-second) systems. SI wasn't adopted till a bit later.

BTW, a slug weighs right at 32.2 lbs on the Earth's surface or 143 Newtons.]]> Forrest Higgs General Mon, 29 Sep 2008 13:56:11 -0400 https://reprap.org/forum/read.php?1,16989,17173#msg-17173 Re: Price of child reprap https://reprap.org/forum/read.php?1,16989,17173#msg-17173 just like lightyears measure the distance not the time...
how long does it take for a slug to move one foot...

Or its how many slugs fit in a foot what may depend on shoesize (what a bizarre imagination , i'm sorry for that.. btw it's 32 for sz 9.5 ;))

Well it may be just some oldschool babelfish translation error ;)
(p.e. hahnsauger is one translation bf offers very often; sorry for the rudeness)

'sid]]> sid General Mon, 29 Sep 2008 12:49:39 -0400 https://reprap.org/forum/read.php?1,16989,17172#msg-17172 Re: Price of child reprap https://reprap.org/forum/read.php?1,16989,17172#msg-17172 Forrest Higgs General Mon, 29 Sep 2008 11:29:41 -0400 https://reprap.org/forum/read.php?1,16989,17169#msg-17169 "Interesting" units and their application https://reprap.org/forum/read.php?1,16989,17169#msg-17169 -------------------------------------------------------
> Ooh, thats a dead useful page. Well found.
>
> I'd never even heard of the measurement of 'slug
> feet' before.


Slug-feet my be an archaic measure, but it's quite useful for quantifying sliminess -- applicable to lawyers, hedge-fund managers, and politicians. ;-)

For such applications, the prefixes mega, giga or larger may be required.

-- Larry]]> Larry_Pfeffer General Mon, 29 Sep 2008 09:59:23 -0400 https://reprap.org/forum/read.php?1,16989,17162#msg-17162 Re: Price of child reprap https://reprap.org/forum/read.php?1,16989,17162#msg-17162
I'd never even heard of the measurement of 'slug feet' before.]]> Ru General Mon, 29 Sep 2008 05:21:32 -0400 https://reprap.org/forum/read.php?1,16989,17125#msg-17125 Re: Price of child reprap https://reprap.org/forum/read.php?1,16989,17125#msg-17125 Forrest Higgs General Fri, 26 Sep 2008 07:30:35 -0400 https://reprap.org/forum/read.php?1,16989,17123#msg-17123 Re: Price of child reprap https://reprap.org/forum/read.php?1,16989,17123#msg-17123
[www.linengineering.com]]]> nophead General Fri, 26 Sep 2008 06:10:16 -0400 https://reprap.org/forum/read.php?1,16989,17069#msg-17069 Re: Price of child reprap https://reprap.org/forum/read.php?1,16989,17069#msg-17069 -------------------------------------------------------
> Now I've got to figure out how to draw wire. I
> can build a foundry that will let me melt recycled
> aluminum tin cans and lawn furniture into ingots
> easily enough. Once I've built my little EDM
> machine I could be able to cut dies to draw the
> wire from the ingots. Lordy! :P



Forrest - I built a foundry and do melt aluminum. Don't bother with the cans as all you will get is "DROSS" about 5% of the can will be melted metal and the rest will oxidize away and is not worth the effort. Melting lawn furniture and such solid item works fine. I do that all the time. I do sand casting and sometimes I even get what I designed in the first pass. The nice part of this is that all it takes is charcoal and a hairdryer to melt the metal.

Here is a link to the book on the foundry. Dead simple to make and works great.

[www.lindsaybks.com]

Bob Teeter]]> bobt General Tue, 23 Sep 2008 16:45:39 -0400 https://reprap.org/forum/read.php?1,16989,17068#msg-17068 Re: Price of child reprap https://reprap.org/forum/read.php?1,16989,17068#msg-17068
Darwin will easily work at torques less than 70% of the motor rating and the motors are 8 wire, so unipolar drive will definitely work. In fact I think Ian Adkins uses it. It does have the disadvantage of wasting power in the form of heat in the motor so if you are using motor mounts with a low melting point it may matter.

Unipolar electronics are more efficient than bipolar of course.]]> nophead General Tue, 23 Sep 2008 15:28:54 -0400 https://reprap.org/forum/read.php?1,16989,17066#msg-17066 Re: Price of child reprap https://reprap.org/forum/read.php?1,16989,17066#msg-17066 degroof General Tue, 23 Sep 2008 13:59:12 -0400 https://reprap.org/forum/read.php?1,16989,17065#msg-17065 Re: Price of child reprap https://reprap.org/forum/read.php?1,16989,17065#msg-17065 Anonymous User General Tue, 23 Sep 2008 13:54:03 -0400 https://reprap.org/forum/read.php?1,16989,17064#msg-17064 Re: Price of child reprap https://reprap.org/forum/read.php?1,16989,17064#msg-17064 -------------------------------------------------------

>
> Root 2 times less torque for the same power.
>
Um... You're the expert and I'm an idiot in these things by comparison, but isn't it

unipolar torque = bipolar torque/(2^0.5)

what with the square root of two being something 1.414? I'm probably just not understanding how you're expressing it.

:S]]> Forrest Higgs General Tue, 23 Sep 2008 12:32:37 -0400 https://reprap.org/forum/read.php?1,16989,17063#msg-17063 Re: Price of child reprap https://reprap.org/forum/read.php?1,16989,17063#msg-17063
[attachment 1088 fieldoffsetscut-out01.jpg]

I'm not quite sure why tin can stepper designers make the inner offsets pointy and the outer ones square, but I'm going to stick with conventional wisdom till I have something at least sort of working.

I discovered a little while ago that I can make lead screws by simply buying a cheap thread die cutter and running it down a rod.

Now I've got to figure out how to draw wire. I can build a foundry that will let me melt recycled aluminum tin cans and lawn furniture into ingots easily enough. Once I've built my little EDM machine I could be able to cut dies to draw the wire from the ingots. Lordy! :P

A later reflection.... You know. I just actually looked at that template and realised that it could be easily done with a compass and ruler. That's probably why they made the inner offsets pointy. Tin can steppers have been around since I was a child back in the 1950's. I remember having one to play with for a project then. :P]]> Forrest Higgs General Tue, 23 Sep 2008 12:21:39 -0400 https://reprap.org/forum/read.php?1,16989,17062#msg-17062 Re: Price of child reprap https://reprap.org/forum/read.php?1,16989,17062#msg-17062
Quote

I'm not at all certain about the disadvantages involved with unipolar motors vs bipolar ones.

Root 2 times less torque for the same power.]]> nophead General Tue, 23 Sep 2008 12:16:39 -0400 https://reprap.org/forum/read.php?1,16989,17060#msg-17060 Re: Price of child reprap https://reprap.org/forum/read.php?1,16989,17060#msg-17060 -------------------------------------------------------
>
> The steppers themselves are also none too cheap; I
> watch with interest your efforts to assemble your
> own!
>
Funny you should mention that. I resolved this morning that I would take a crack at making Tommelise cut the thin sheet steel to do the field offsets for the linear tin can stepper that I've designed.

[attachment 1087 02453.jpg]

I bought a little diamond cutting head for about $9 that works with my Dremel. It will be interesting to see how long it takes to cut the steel profiles that I need. I plan on using a 3/8-24 inch threaded rod for a lead screw for now till I figure out how to cut my own lead screws. You can buy that kind of threaded rod in most good hardware stores.

One of the gripes that I have with the Haydon linear stepper motors is that the 3 mm lead screw is far to flimsy for the lengths I'm using. Making my own linear steppers lets me fix that problem as well as controlling the costs.

Now I just have to write a little routine that will generate the profiles that I need to cut.]]> Forrest Higgs General Tue, 23 Sep 2008 10:10:16 -0400 https://reprap.org/forum/read.php?1,16989,17059#msg-17059 Re: Price of child reprap https://reprap.org/forum/read.php?1,16989,17059#msg-17059
Quote

There is no reason whatsoever that the electronics cost as much as they do with Darwin. Looking at the electronic parts, one of the biggest cost items is the stepper-driver boards

That is very true; I've made quite a few posts elsewhere talking about possibilities for replacing the L297 ;) I guess also that moving to unipolar motors would lend itself to replacing the L298; but I'm not at all certain about the disadvantages involved with unipolar motors vs bipolar ones. I imagine discrete components for the driver boards would not only be cheaper but also easier to source a suitable part and somewhat future-proofed into the bargain. I looked into h-bridge design though, and decided that it is a job best left to a more skilled engineer than I.

The steppers themselves are also none too cheap; I watch with interest your efforts to assemble your own!

Anyway, my original point still stands: the control logic and motors represent a major chunk of the cost of a CNC tool, cost which is shared by repraps and other systems. This leaves the cost of the structural components and materials which for reprap represent perhaps $100-150 dollars? plus a whole load of machine time. That seems pretty damn cheap to me, considering what you're getting out of it in the end.]]> Ru General Tue, 23 Sep 2008 09:50:30 -0400 https://reprap.org/forum/read.php?1,16989,17058#msg-17058 Re: Price of child reprap https://reprap.org/forum/read.php?1,16989,17058#msg-17058 -------------------------------------------------------
>
> The bulk of the price seems to be in the
> electronics right now; a cost that must be shared
> by any other design.
>
> Where do you see savings?
>
There is no reason whatsoever that the electronics cost as much as they do with Darwin. Looking at the electronic parts, one of the biggest cost items is the stepper-driver boards. While the L297/L298N controller chips are making designing the board easy and give you upwards of two amps capacity per phase in your stepper that two-chip ensemble also costs about $12-13 PER stepper motor from Mouser.

There are historical reasons for this to have happened. When Reprap began we were using the venerable SN75440 chip, which costs well under $2 to do the same job as the L297/L298N ensemble. The only problem with the 754410 was that it can't deliver more than 1.1 amps/phase. At that time it was very difficult to find bipolar stepper motors with enough copper in their windings to keep the current load at or under 1 amp. It is still not that easy, though it can be done cost effectively.

As well, in designing the Arduino/Sanguino the team restricted themselves to DIP chips as well as ATMEGA offerings because they were able, thereby, to access an excellent open-source (this being extremely important to them) firmware compiler. The downside was, however, that the chips that they had to use, as a result, could communicate with the outside world only through RS232 serial and a variety of that which required a small handful of additional components to talk to your PC. Shifting comms over to USB added even more components. All that makes the controller board both more complex and more expensive than it needs to be.

To give you an idea of the potential impact of this it was mentioned a few days ago that a complete set of controller electronics for Darwin costs about $180. The electronics for Tommelise, my variation on Darwin, which uses steppers drawing a bit less than half an amp/phase and a microcontroller with native USB comms rather than add-on bits comes in at around $40.

It wouldn't be a big deal to redesign Darwin's electronics with cost as the driving criteria and get the parts budget down to about what Tommelise does.]]> Forrest Higgs General Tue, 23 Sep 2008 08:55:21 -0400 https://reprap.org/forum/read.php?1,16989,17057#msg-17057 Re: Price of child reprap https://reprap.org/forum/read.php?1,16989,17057#msg-17057
Quote

I've always asking myself if self-replication/low cost is something that goes hand to hand

Are non-replicating designs any cheaper?

The bulk of the price seems to be in the electronics right now; a cost that must be shared by any other design. These other, non-replicating designs will not be capable of building spare parts for themselves. nor upgrading themselves, and so their 'total cost of ownership' is going to be greater as a result, and their up-front cost doesn't appear to be significantly lower. Cheaper cartesian bots do exist (like the McWire) but they seem to make many compromises, and haven't really taken off.

Where do you see savings?

Quote

I guess having something like a pick and place tool and a soldering iron ttachment would make it possible for the reprap to replicate its own circuits but would be complicated to replicate

Complex replication isn't so much of an issue; its more the non-printable parts which push up the price and the inconvenience.

Designing such a system has a whole host of prerequisites though... head changing, automated height compensation, etc etc, and these in turn require a fair amount of skilled brain power to overcome. When the problem has been solved once, it will become vastly more easy in the future.

Oh, and it might be simpler to cook the circuits yourself, rather than making a hot air soldering head for the darwin.]]> Ru General Tue, 23 Sep 2008 05:14:43 -0400 https://reprap.org/forum/read.php?1,16989,17055#msg-17055 Re: Price of child reprap https://reprap.org/forum/read.php?1,16989,17055#msg-17055 pingiscoolest General Mon, 22 Sep 2008 23:21:08 -0400 https://reprap.org/forum/read.php?1,16989,17054#msg-17054 Re: Price of child reprap https://reprap.org/forum/read.php?1,16989,17054#msg-17054 le_chiffre General Mon, 22 Sep 2008 23:10:30 -0400 https://reprap.org/forum/read.php?1,16989,17037#msg-17037 Re: Price of child reprap https://reprap.org/forum/read.php?1,16989,17037#msg-17037
A minor part of the problem is trying to get metric parts in the USA. McMaster's M8 rod is oil-hardening tool steel drill blanks, AND the length is only 914mm (36") each so you have to buy 16 instead of 9 (most of the pieces you need to cut are 500mm). That's $78.08 right there! You can save about $60 by going with zinc plated SAE sizes instead of metric. That would be 5/16" rods, 5/16-24 studs (all-thread), nuts and washers.

A big problem with McMaster is that you have to buy fasteners in bulk. If you want one cap screw you have to buy 100 for $5 or $10. At least you'll have LOTS of spares! The 8mm washers and 8mm nuts (or 5/16") are used in enough quantity that it makes sense to buy a box of 100. For the cap screws and grub screws it makes sense to buy locally someplace where you can buy by the piece. If you have to buy in quantity you can get the longer length of cap screw and cut some down to get the shorter lengths. For example the 3mm cap screws are used in 16mm, 25mm and 30mm lengths.

The moral of this exercise is: Nobody has a clue how much it is going to cost YOU to buy all the machined parts.]]> JohnWasser General Sun, 21 Sep 2008 08:40:02 -0400 https://reprap.org/forum/read.php?1,16989,17036#msg-17036 Re: Price of child reprap https://reprap.org/forum/read.php?1,16989,17036#msg-17036 JohnWasser General Sun, 21 Sep 2008 07:11:46 -0400 https://reprap.org/forum/read.php?1,16989,17035#msg-17035 Re: Price of child reprap https://reprap.org/forum/read.php?1,16989,17035#msg-17035 Gene Hacker General Sun, 21 Sep 2008 02:29:46 -0400 https://reprap.org/forum/read.php?1,16989,17033#msg-17033 Re: Price of child reprap https://reprap.org/forum/read.php?1,16989,17033#msg-17033 pingiscoolest General Sat, 20 Sep 2008 21:03:22 -0400 https://reprap.org/forum/read.php?1,16989,17031#msg-17031 Re: Price of child reprap https://reprap.org/forum/read.php?1,16989,17031#msg-17031 -------------------------------------------------------
> About how much does it cost to clone a reprap?
> including printed and "nonprinted" parts? thanks.

You'll need the electronics, Arduino and cable: $190 plus shipping from RRRF.
A posting from January lists the "Steel Frame Kit Subtotal:]]> JohnWasser General Sat, 20 Sep 2008 18:55:49 -0400 https://reprap.org/forum/read.php?1,16989,17028#msg-17028 Re: Price of child reprap https://reprap.org/forum/read.php?1,16989,17028#msg-17028
Also, at this point, I think the shipping charges are minor compared to the number of man hours I've put in building. This project is still very much in the experimental realm.]]> Wade General Sat, 20 Sep 2008 13:05:49 -0400