Actual costs of printing with a Reprap machine... October 11, 2009 06:41PM Admin Registered: 17 years ago Posts: 1,915
I recently started working seriously with Mathematica 7 and am also building up a BitsFromBytes Rapman.

In that a lot is known about the operating characteristics of the Rapman I decided to see if I could calculate what it would cost to run one.

Assumptions:

ABS filament - \$9/lb

Rapman built out - \$1500

Duty cycle - 50%

Service life - 36 months

Interest rate - 10%

Capital Recovery Factor - \$0.134/hour

Print output rate {assuming that the extruder is operating 75% of the time during the print} ~ 1.2 cubic inches/hour

Electricity usage/cubic inch - 0.05 Kwhr/cubic inch {negligible}

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Capital cost of printing = (\$0.134/hour)/(1.2 cubic inches/hour) ~ \$0.11/hour

Assume 20% in repairs over the life of the printer

(\$0.11/hour)(1.2) = \$.132/hour

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Cost of filament per cubic inch {assuming a 100% fill} = (\$9/lb)/26.6 cubic inches/pound) ~\$0.34/cubic inch

Note that I haven't included space rental for the printer.

Thus you are looking at paying for printing on a Rapman = \$.132 + \$.34 ~ \$.47/cubic inch

Note that a print shop charges about \$25 - \$30/cubic inch for retail printing.

Assuming that they have bought a \$30,000 Dimension printer, they are talking about about \$2.70/cubic inch capital cost for prototypes printed.

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Figuring that both the Darwin and Mendel use about 1.2 kg of printed parts, these would cost...

(1200 cm^3)/(2.54^3 cm^3) = 73 cubic inches of printed parts

(73 in^3)(\$0.47/in^3) ~ \$34.30

to print a set of parts for a Reprap.

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Now an interesting result is that ABS filament costs two and a quarter times more per cubic inch than acrylic sheet. When you look at the cost of nuts and bolts in bulk lots I don't expect BitsFromBytes to start shifting over to offering printed parts for their Darwin/Rapman printer any time soon.

Edited 3 time(s). Last edit at 10/11/2009 06:56PM by Forrest Higgs.

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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: Actual costs of printing with a Reprap machine... October 11, 2009 08:48PM Registered: 14 years ago Posts: 387
I wonder how the economics would be if they were to switch to a full mass-production model (injection molding, etc).
 Re: Actual costs of printing with a Reprap machine... October 12, 2009 09:59AM Admin Registered: 17 years ago Posts: 1,915
jbayless Wrote:
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> I wonder how the economics would be if they were
> to switch to a full mass-production model
> (injection molding, etc).

I think it has always been understood that you could mass produce a Reprap machine considerably cheaper than you could locally produce one. The question for me has always been whether the mass-produced machine plus shipping from China would actually be cheaper and, perhaps more importantly, could a mass produced machine be evolved in capabilities and materials used as quickly as a printed one.

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

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: Actual costs of printing with a Reprap machine... October 13, 2009 03:54AM Registered: 15 years ago Posts: 536
I wish I could get 1.2 in^3/hr and a 50% duty cycle over a few kilos of plastic; my current rate is about a quarter of that. I do hope to improve it though.
 Re: Actual costs of printing with a Reprap machine... October 13, 2009 05:43AM Registered: 14 years ago Posts: 387
"I think it has always been understood that you could mass produce a Reprap machine considerably cheaper than you could locally produce one. The question for me has always been whether the mass-produced machine plus shipping from China would actually be cheaper and, perhaps more importantly, could a mass produced machine be evolved in capabilities and materials used as quickly as a printed one."

Oh yes, for sure - But much like the Cupcake can be used to print out parts for, say, a Mendel, it might be interesting for a fully mass-produced model to work alongside the self-replicating one. The cost and challenge of building a RepStrap is, I think, probably the biggest barrier to people entering the Reprap community.
 Re: Actual costs of printing with a Reprap machine... October 13, 2009 04:05PM Registered: 14 years ago Posts: 2
some interesting calculations here was just wondering if you had seen the reprap economics script by Enrique? RepRap economics script
 Re: Actual costs of printing with a Reprap machine... October 13, 2009 04:19PM Admin Registered: 17 years ago Posts: 1,915
Nope! Would love to see the formulae behind the model.

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

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
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