3D Scan (Point-cloud) to ABS Rapid Model

Discussion in 'Software' started by sash.alexandre, May 1, 2013.

  1. sash.alexandre
    Joined: Apr 2013
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    Location: Melbourne, Australia

    sash.alexandre Sash.Alexandre

    I'm fresh out of Uni and have an interesting contract project I would like to tackle. Unfortunately my lack of experience calls for advice. A dash board design for a 6.5m ski craft is underway and as an junior engineer on this job I have an executive decision to make:

    a) Scan an existing suitable dashboard and mold it in Rhino to produce .stl file ready for 3D printing using ABS plastic (ready to go part)

    b) Scan same as above, but instead of printing actual part; 1st create a negative part of the dash in Rhino -> stiffen it -> make it into a mold and now submit .stl file for 3D printing to later produce fiberglass parts from it.

    See, the reason for creating a mold, is that this dash most likely will become a production part. Thus requiring few parts to be made. My questions are as follow:

    1) Cost wise: is it smarter to invest into a mold (my time in Rhino translating it from a pointcloud/meshing it/building up/stiffening) and down the track make cheaper in-house parts out of glass or

    2) Save time and NOT model the mold, but instead have a quality .stl and keep printing parts with 3D printer as needed.

    Also what is the approximate freelance hourly rate I should be charging considering my circumstances and being a junior for Rhino modeling. I have relevant experiences with advanced features of this package and regularly practice them on various jobs. However this is the first time I would attempt to prepare a correct watertight model for rapid 3D (quiet intricate design)?

    P.S. Preliminary quote i just received is approx. $4000 AUD for the dash to be printed.

    Regards
     
  2. Eric Sponberg
    Joined: Dec 2001
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    Eric Sponberg Senior Member

    Sash, welcome to the forum.

    First, AUD$4,000 for a dashboard part is really expensive, even for a mold. A traditional fiberglass mold would cost a lot less, and the fiberglass part less still. That price probably won't fly with your client. What would he typically do? Stick with what he knows because most likely he tries to build boats to get the most bang for us buck.

    Not sure about the adequacy of ABS plastic--maybe it's OK, but if 3D printing is what it takes to get the part, that's not the way to go. If ABS is the preferred material, then cutting it out of sheet stock would be cheaper and faster, even with secondary machining to trim corners and edges. If there are going to be a lot of these made, then NC cutting them out of sheet stock would make better sense, in my opinion.

    As for the fee to charge for your time--consider your experience at this stage in your career, compared to other professionals who have been in the business a lot longer. At the same time, you want to be respected for the education and training that you do have. Professionals at my level have hourly rates of US$150-US$200/hr. At yours, fresh out of college, see if you can find out what typical engineers get in your country. Or, here is another way: Let's say that typical graduate engineers get $50,000 a year starting salary. Divide that by 1,000, and then again by 2, and you get the equivalent hourly rate = $25/hr for a 40-hour work week for a salaried employee. Multiply that by 2 or 3 to get a reasonable hourly rate for a consultant. That brings you up to $50-$75/hr. That sounds reasonable to me. Over time, as you gain more experience, you can gradually increase your rates. You can follow this same formula even as typical engineers see growth in their salaries--the same relationship applies, pretty much.

    Good luck.

    Eric
     
  3. wet feet
    Joined: Nov 2004
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    wet feet Senior Member

    A few thoughts;it would take a lot less time to vacuum form ABS than to rapid prototype it.You can get away with a fairly rudimentary vacuum form and I have made a dozen parts from a wooden former.You could use your scanned data to create a solid and a CNC router would be able to shape the sections quite quickly.You could create a plug for a GRP panel the same way and again I would expect the process time to be less than rapid prototyping.Finally,is the part that was scanned made of a suitable material to allow lifting a GRP mould directly from it?This could get a bit close to splashing an unauthorised copy if the design's origins lie elsewhere and is the sort of thing that is frowned on here as I am sure you will appreciate.
     
  4. sash.alexandre
    Joined: Apr 2013
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    Location: Melbourne, Australia

    sash.alexandre Sash.Alexandre

    Firstly, I would like to apologise for a late reply as I have been catching up with another project parallel to this. Your responses are very valuable and thank you. After reading your opinions I have scheduled a meeting with 3D prototyping company and threw some ideas around in terms of material to use and its costing. The conclusion was that it is going to be cheaper to cut and shut an existing dashboard to meet our design criteria and will take an approximately same time in labor as printing it anyway. So that is what is going to happen.

    The next problem is this: If it was still to become a production part (even as little as say 6 more parts to be made); would it be cost effective to still take a mold off it (after it's been cut and shut) and try to produce fiberglass copies in the future. The answer to this would be a no brainier if the dash was a simple surface, but unfortunately instead a chosen dash houses all the extra electronics and is pretty intricate as you can see from an attached image of its console section (cannot be simplified):

    http://i1279.photobucket.com/albums/y521/Sash_Alexandre/SkiBoatDash_zps83647b74.jpg.

    "wet feet" I appreciate your concern and welcome any guidance on how to professorially communicate on this forum as I'm new to all of the above. Though, the image attached is of a similar/existing dash that was used in the design process and does not give away any unauthorised material.
    So, to sum this up: scanning and 3D printing was eliminated - making this process much cheaper, but has not simplified production process in the future as the cut and shut process needs to repeat and also, there is a danger of necessary "off the shelf" dash vanishing from the market. What would be the simplest option for its production allowing for initial setup costs - what ever they may be?

    Regards
     

  5. Eric Sponberg
    Joined: Dec 2001
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    Eric Sponberg Senior Member

    You certainly can make a mold from the "cut and shut" part, and if it is a simple enough shape, perhaps the parts can be laid up with fiberglass. The complication of the surface, whatever that may be, will deterline the process to use. The more convoluted the shape, the more difficult it is to use fiberglass layup, so maybe a resin-cast process would be better, or a vacu-forming process would be better. A lot depends on the number of parts to be made, too. If you are going to build thousands of these parts, then more expensive tooling is justified for a more sophisticated molding process. If you are only going to build a few parts, then making custom parts from scratch using the original "cut and shut" part is justified and you don't have to spend any money at all on tooling.

    I hope that helps.

    Eric
     
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