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| Mold Making (extension of pantograph discussion) http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=39068 |
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| Author: | Mike OMelia [ Wed Jan 23, 2013 9:53 am ] |
| Post subject: | Mold Making (extension of pantograph discussion) |
Well, I am punting on the Friendly Plastic approach. I have 8, possibly 16 molds to make, and making them individually is such a pain. So I made a form and filled the form with melted friendly plastic. Then a cover with the inlay pieces was pressed into it. All surfaces were coated with parchment paper, and oil on the inlay. This works to a point, but removing the shell invariably damages the edges, and worse, bubbles. These would occur randomly, but sometimes near the inlay edges which ruins the mold. Maybe I can be convinced to go back to one mold per inlay. Maybe I'm overthinking this. Hobby Lobby sells Amazing Silcone Mold and casting resin. Should I? Mike |
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| Author: | Mike OMelia [ Wed Jan 23, 2013 1:00 pm ] |
| Post subject: | Re: Mold Making (extension of pantograph discussion) |
Hmm. How do I get the block off of the inlay? Acetone? |
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| Author: | Mike OMelia [ Wed Jan 23, 2013 2:33 pm ] |
| Post subject: | Re: Mold Making (extension of pantograph discussion) |
OK, but still, how do you remove the CA? |
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| Author: | Ken Jones [ Wed Jan 23, 2013 11:01 pm ] |
| Post subject: | Re: Mold Making (extension of pantograph discussion) |
Without reading the other post, it does sound like you'd benefit from using a flexible mold rubber, either polyurethane or silicone, both of which are available from Polytek in small "trial sizes" available at a special introductory price. Or at least that was the case eight years ago when I did it for a living. |
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| Author: | Mike OMelia [ Thu Jan 24, 2013 2:45 pm ] |
| Post subject: | Re: Mold Making (extension of pantograph discussion) |
No, these are a bunch of different sized finger board markers. I probably could do this a simpler way, but I want to use take this opportunity to learn. Actually, there are two sets for two finger boards and there are subtle differences there as well (inlay is hand made). My initial thought was that if I could make a single mold for all of the pieces, then I could get the individual negatives lined up and avoid excessive setup between cuts. So, each mold would contain the 8 negatives needed. I have just about decided to buy that stuff from smooth-on. I watched their videos. It looks straight forward to me. |
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| Author: | Mike OMelia [ Fri Jan 25, 2013 12:32 am ] |
| Post subject: | Re: Mold Making (extension of pantograph discussion) |
I bought smooth on products. Release, sealers, casting resins, and the oomoo urethane rubber mold stuff. I also bought some hdpe parts from McMaster to build the molds like saw in the videos. If this works, I should be set up for this and future projects. Fingers crossed. Mike |
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| Author: | Barry Daniels [ Fri Jan 25, 2013 9:58 am ] |
| Post subject: | Re: Mold Making (extension of pantograph discussion) |
Content deleted to prevent further aggrevation. |
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| Author: | Mike OMelia [ Fri Jan 25, 2013 12:44 pm ] |
| Post subject: | Re: Mold Making (extension of pantograph discussion) |
Barry, I fully understand that you feel I am doing something in a manner that you would not do. I've gotten that from your posts on this thread and the other. Still, I intend to do what I am doing for my own reasons. This is a hobby, and I enjoy exploring alternate techniques. I do know that I am not very good at freehand stuff. What I am looking for in these threads is helpful advice. And useful criticism. That is all. Mike |
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| Author: | Mike OMelia [ Sat Feb 02, 2013 9:55 pm ] |
| Post subject: | Re: Mold Making (extension of pantograph discussion) |
Well, an update. The Smooth-on oomoo silicone mold material worked like a dream. I bought their release agent and mold sealer. Both of those products worked well too. However, the release agent destroyed the pump spray mechanism. I will complain about that. Surely they know their pump mechanism is incompatible! This is a small issue. I bought their 61D casting resin. That was a bad choice. The part came out flexible. It's gotten a little harder over the day, but still no good. Perhaps their 65D or 66D would be better. I went to Hobby Lobby and found a 10 minute casting resin. This stuff was awesome. Created a hard, white cast in less than 20 minutes. Reminds me of that Amazing Plastic. In fact, the brand name of the resin was "Amazing". I screwed that cast into the pantograph and cut 8 inlay patterns in about one hour. And all the shell inlay fit perfectly. Mike |
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| Author: | Rienk [ Mon Feb 04, 2013 2:30 pm ] |
| Post subject: | Re: Mold Making (extension of pantograph discussion) |
Mike O'Melia wrote: ... I screwed that cast into the pantograph and cut 8 inlay patterns in about one hour. And all the shell inlay fit perfectly. It took me a while to figure out what this thread was about (I'm a little slow on the uptake). It would be great if you can post some pictures of your process. Sounds like a time saver for anyone (considering) using a pantograph. And i assume it gives near perfect fit. |
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| Author: | Mike OMelia [ Mon Feb 04, 2013 7:47 pm ] |
| Post subject: | Mold Making (extension of pantograph discussion) |
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| Author: | Mike OMelia [ Mon Feb 04, 2013 8:02 pm ] |
| Post subject: | Mold Making (extension of pantograph discussion) |
Here are some (after I did it) pictures of the mold and cast making process. For the mold, I used Smooth-on silicone. The cast was a resin I bought at Hobby Lobby (Amazing 10 minute casting resin). The first step is to glue parts to be cast to grid plastic (to keep straight). Then glue that to Hdpe base. Then form an appropriate side form. Spray release agent, and pour the silicone.  
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| Author: | Mike OMelia [ Mon Feb 04, 2013 8:05 pm ] |
| Post subject: | Mold Making (extension of pantograph discussion) |
Next, frame that mold with 1/4 plywood, half the height of the silicone cast. Reframe, spray with release agent. Make sure all silicone is coated!!! Pour more silicone.    
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| Author: | Mike OMelia [ Mon Feb 04, 2013 8:07 pm ] |
| Post subject: | Mold Making (extension of pantograph discussion) |
Finally, use the sealer (2 coats) then one coat of release agent. Pour the resin.   Now, mount the cast in ur pantograph and carve away. Mike 
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| Author: | Mike OMelia [ Mon Feb 04, 2013 8:08 pm ] |
| Post subject: | Mold Making (extension of pantograph discussion) |
Please watch the videos at smooth-on for missing details!! |
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| Author: | Joe Sallis [ Tue Feb 05, 2013 8:44 am ] |
| Post subject: | Re: Mold Making (extension of pantograph discussion) |
Mike, am I right in thinking that you are trying to cast inlay pieces from a mould? I work in an art department of a university. If a student asked me how to do this I would advise using silicon rubber as a mould, for example http://www.tiranti.co.uk/EdgeImpactShop ... ne+Rubber+ and casting in polyurethane resin to which you can add pigments or fillers for metalic or stone effects. You obviously need a good original to work from which has clean edges square to the face. Casting my own inlays is something I've been meaning to do. As ever, please post pics... |
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| Author: | Joe Sallis [ Tue Feb 05, 2013 8:50 am ] |
| Post subject: | Re: Mold Making (extension of pantograph discussion) |
Mike,, ignore my last email. I studied your pictures and realised that you are doing something different to what I originally thought. You did a great job! |
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| Author: | Mike OMelia [ Tue Feb 05, 2013 9:49 am ] |
| Post subject: | Re: Mold Making (extension of pantograph discussion) |
I could cast pieces if I wanted from the first stage of the mold (which used the shell to form it). This was a time consuming process only because I had to build the pantograph, learn how to use it, and learn how to make the molds and final cast. If I were doing another (and I will be), you have to figure 6 hours for each mold stage (cure), and 30 minutes for the resin cast. Cutting 8 inlay slots took less than an hour. The hard part is behind me now. BTW, those bolt holes (10-24 1" allen hex head) were filled with 5 minute epoxy. You don't want the silicone going in there. Mike |
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