# Accidental Mold Repeatability Test on My Form1+ **URL:** \ **Category:** General Discussion\ **Created:** [February 11, 2015, 11:54am UTC](https://forum.formlabs.com/t/accidental-mold-repeatability-test-on-my-form1/3629 "2015-02-11T11:54:14Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![Steve\_Johnstone](https://sea1.discourse-cdn.com/flex025/user_avatar/forum.formlabs.com/steve_johnstone/32/998_2.png) [@Steve\_Johnstone](https://forum.formlabs.com/u/Steve_Johnstone)\ **Post date:** [February 11, 2015, 11:54am UTC](https://forum.formlabs.com/t/accidental-mold-repeatability-test-on-my-form1/3629/1 "2015-02-11T11:54:14Z")
Recently I printed and tested molds for [casting urethane expanding foam](http://forum.formlabs.com/t/sla-printed-molds-for-casting-urethane-foam-parts/3532) on the form1+ and had great results. I used Clear v2 resin for the core and cavity mold tools, but found that finishing the transparent mold surfaces difficult as it’s difficult to see surface imperfections. With FDM printing I’ve found that grey ABS is the best material for these types of molds. So printing mold tool parts, requiring good surface finish, in grey resin would be the better solution. In my case, having the other tool part clear is great, as it really helps been able to see inside the mold when casting. I have since printed the cavity mold tool in v1 grey and finished it in the same way as the clear mold tools. What amazed me was that the urethane foam part cast using the two clear resin mold tools, fitted perfectly into the new grey cavity moldl! **Why is this awesome?** - It shows how good repeatability is with the Form1+ is, especially considering it was printed in a different resin and different resin tray - If I need to modify the surface of one of my tool parts there is no need to print the corresponding mold tool which saves time and money. 😃 ![](http://forum.formlabs.com/uploads/formlabs/2467/06914bda80014741.jpg) ![](http://forum.formlabs.com/uploads/formlabs/2468/e7c674650979a806.jpg) ![](http://forum.formlabs.com/uploads/formlabs/2469/5e3f131d56bd1daf.jpg) ---
**Author:** ![Randy\_Cohen](https://sea1.discourse-cdn.com/flex025/user_avatar/forum.formlabs.com/randy_cohen/32/1500_2.png) [@Randy\_Cohen](https://forum.formlabs.com/u/Randy_Cohen)\ **Post date:** [February 12, 2015, 12:38am UTC](https://forum.formlabs.com/t/accidental-mold-repeatability-test-on-my-form1/3629/2 "2015-02-12T00:38:47Z")
Ducted fan 3D-printed fuselage to go with your 3D printed duct and fan? Nice! How robust is the foam part? ---
**Author:** ![Steve\_Johnstone](https://sea1.discourse-cdn.com/flex025/user_avatar/forum.formlabs.com/steve_johnstone/32/998_2.png) [@Steve\_Johnstone](https://forum.formlabs.com/u/Steve_Johnstone)\ **Post date:** [February 12, 2015, 9:49am UTC](https://forum.formlabs.com/t/accidental-mold-repeatability-test-on-my-form1/3629/3 "2015-02-12T09:49:08Z")
Hi @Randy_Cohen, they are surprisingly strong with a nice amount of flex in them. I’m using Foam-it 8 which self skins and forms a very fine plastic skin on the surfaces, with a foam core. Think of a sandwich, the skin is the bread and the filling is the foam. Independently the are very weak, but put them together and they are incredibly strong and light. The trick is to get the parts to release from the molds without delaminating. If that happens then “in to the bin they go”. This gets even trickier when you cast parts with super thin skins. The wing skins on this project are only 0.5mm thick 😮 ![](http://forum.formlabs.com/uploads/formlabs/2502/e75a5edb41f57dbe.JPG) ![](http://forum.formlabs.com/uploads/formlabs/2503/542b316a81824ef9.jpg) ---
**Author:** ![system](https://us1.discourse-cdn.com/flex025/uploads/formlabs/original/3X/5/b/5bc2bdf993ff27c2e0eecab5010b25626fbb327a.png) [@system](https://forum.formlabs.com/u/system)\ **Post date:** [February 26, 2015, 9:49am UTC](https://forum.formlabs.com/t/accidental-mold-repeatability-test-on-my-form1/3629/4 "2015-02-26T09:49:11Z")
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