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Thread: Quality expectations of lost wax casting

  1. #1
    Join Date
    May 2020
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    Default Quality expectations of lost wax casting

    Hi All,

    I'm new to the forum and had a question about the qulaity that should be expected form lost wx casting for a professional casting company.

    I have been working with a 3D designer who has produced some amazing designs for me, which I shared with the casting house to check that they didn't have any concerns about casting issues. I then has this design 3D printed in wax and sent to the casting house, which cost a few hundred pounds as it was a fairly large piece.

    The casting house explained to me that they'd prefer me to finish the master, rather than them doing it. Which makes sense I guess, but I would have preferred them to do this based on detailed renderrings I shared. Is this normal?

    They let me know when they received the wax and send me the unfinished casting of the master pretty quickly, however the quality was no-where near what I was expecting.

    For the most part, the details has been captured very well and everything looked good, but they are numerous holes in the piece and patches. Some of them are small and on surfaces that will be polished flat, others are quite large and on areas of detail. Someone suggested that I melt wax into the holes and try to redo the details, but there are quiter a few holes and this isn't my speciality.

    I was just wondering if my expectations were too high. I thought that the casting would be a perfect replica of the wax. If you use casting companies, what are your expectations whenyou send them a high value wax? I am honestly quite dissapointed, but don't want to come accross as unreasonable, so was hoping for some insight from anyone with more experience of this process.

    If the wax was likely to have casting issues, I would have rather had a mould made of the wax as a backup, to avoid a lengthy repair or paying for a reprint. Is this a common approach?

    I look forward to hearing your opinions.

    Cheers,
    Steve

  2. #2
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    Hi Steve, and welcome to the forum.
    Yes, it's best not to part with your master without back up, partly because it can get lost in transit, and partly because casters a prone to occasional mishaps.
    The casting you receive should be a first class replica without bubbles or blemishes.
    No doubt the members will post their views in the next day or so, so keep looking. Dennis.

  3. #3
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    Mar 2011
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    When you say it was printed in wax do you know which machine was used ? How big was it approx. Sometimes you do get holes and things this is especially true from resin prints( I know you said wax) of large models. Its difficult to burn the resin out with out ash. Its difficult to say without seeing the cast but there will be grow lines from the printer and you do get porosity sometimes like little pinholes , laser welding is a way to repair this. It is usual for you to finish the master especially if its a detailed model as it can be very Labour intensive and probs not cost effective for them to do.

  4. #4
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    The issue of printing and subsequent casting can be fraught - I recently had an extremely large piece cast in sterling (once I could find a caster willing to take it on); given the size of the piece it had to be poured hotter than usual to ensure it cast fully. This in turn made for more cleanup...

    I could have printed & cold-moulded the piece, but the volume of RTV I'd have needed to achieve that would have been a couple of litres - which brings other problems (mould cutting being one of them).

    The quality of the print can have a massive effect too - just because it looks good in a render doesn't mean that the print will be a completely faithful reproduction; Solidscape printers, for example, despite their much-vaunted ability to print in wax (rather than a wax-bearing resin) leave significant growth lines on parts; there's also the issue of design for printability that needs to be factored in (no point putting tiny features side-by-side if the printer will blend them into one). If you want a top notch wax master, milling is still the best way to get it done.

    Porosity on castings happens more than I'd like; it requires some time sat finishing the part. People here won't be surprised to hear me talking of the value of a laser welder for sorting porosity issues. That said, they shouldn't be excessive, but that's a subjective judgement.

    Things happen. Best bet is to talk to the caster about your concerns and see how they respond. It's a bit difficult to generalise, but most of them tend to be reasonable.

    By way of comparison, I recently had a setting sent for me to work on where it was a complete pig's ear; rex setting with half of the cutouts filled in an growth lines that made it look like it was cast in cuttlefish. The company who cast it weren't interested in doing anything to rectify it. Once I started working on it I found sizeable areas of porosity that I had to fill with the laser too.

    (or, TLDR - pretty much what Joe said )

  5. #5
    Join Date
    May 2020
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    Hi All,

    Thanks for the quick replies.

    I tried to upload some images, but they kept failing, so there are some links below of the casting and what it should look like with dimension. volume should be ~8.4cm3 and it was cast in sterling silver.

    The printing company used a solidscape 3z pro i believe, they sent me some (bad) pictures, but I'm confident the printer can handle the detail of the model.

    The company that printed the wax was recommended by the casting company, and when I spoke with both of them on the phone, neither expressed any concern that there would be problems, and teh casting company said that the wax looked great.

    There were fine layer lines from the printing, as I expected, but I'm confident these would polish out. The issue was multiple big defects, one looks small and rectangular, almost like a tool mark on the wax. Too much tweezer pressure?

    My preference would definitely be to have the casting place finish the masters based on renders. I really just want them oxidised to bring out the depth and detail, then polished to shine up the surface. Any idea if there is a typical cost a casting house might charge for finishing a master like this?

    I'd really appricate your opinions on the quality of the casting from the pictures. If it was likely that the casting was going to have issues, it would have been nice to be advised and perhaps have them suggest doing a cold mould backup. This is my first time going through the process, and I'm still learning, but at >300 a print, it's an expensie learning process.

    Cheers.
    drive.google.com/open?id=16PSGxPWsxZh8vcDbkhgQlKrNiMsBgeWW
    drive.google.com/open?id=1BkUyT9Htb_R4ZeQMK77KcBH3VatvHgpn
    drive.google.com/open?id=10S7IRjAbt46f44RiBocgjyzbKmZnd1bT
    drive.google.com/open?id=1QVzHrt5ViH9V1MFSg_owR9iNwI02JYe9
    drive.google.com/open?id=1gItAqcmJT-Hs-HSOQ4--kzt5bBJHLIQP
    drive.google.com/open?id=1IdczeH-z2PEUq2x0mbyn4izn8SarLT-q
    drive.google.com/open?id=1bDNUfuKL8JPfJmnVFwpze9Bb2rX65rbo
    drive.google.com/open?id=1ggs32L93lZfvy-7E9DhUqfS60VYkpsSW
    Attached Thumbnails Attached Thumbnails dragon-master-12 (2).jpg   dragon-master-24 (2).jpg  

  6. #6
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    I wouldn't be happy with that its a bad cast.

  7. #7
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    May 2020
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    Quote Originally Posted by josef1 View Post
    I wouldn't be happy with that its a bad cast.
    Thanks for the feedback. Good to know that I was right to be disappointed. I guess thinks can sometimes go wrong, and it's bad luck for me that it happened with the master.

    Would I be right in thinking that with most casting houses, they would not send something of this quality out of they have a mould?

    I'm expecting to be ordering batches of 20 when we get everything going, and if any of them came through like this, I wouldn't be able to sell them. What are common arrangements like with casting houses regarding quality and failure rate.

    I want to think that if I order 20, they will all be high quality. Is that a fair expectation?

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