Actual costs of printing with a Reprap machine...

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

I wonder how the economics would be if they were to switch to a full mass-production model (injection molding, etc).

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.

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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

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.

"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.

some interesting calculations here was just wondering if you had seen the reprap economics script by Enrique? RepRap economics script

Nope! Would love to see the formulae behind the model.

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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