I think CultTV Man is already working on a reproduction of the Sealab III model.The Sea-Lab is also a must have for SW modeler (as well as the Porsche)
Just got an Injection Molding machine and looking for Ideas
- Thread starter DinoDino
- Start date
joberg
Legendary Member
It can, but not sure how long it will last.
Every injection I saw in my activity, as worker, and also as mold maker, was made from steel.
I also worked on carbide tools but those were designed to shape steel, like the mystery bolt on Luke Ep6, it's cold forging process.
I was thinking about design a mold to make 100% accurate exactra bubble strips, that could be a good product as this is something I know well, the strip, but also the process to get all accurate finish on the mold to make a perfect one.
I was also thinking about working on a cast golden gun, with metallisation and final gold plating or titanium nitrid coating, but the tools required to make it are huge investment, as the design is very complicated, especially using injection molds, just the lighter bottom has many reliefs carvings on all sides and would require a 6 parts mold, same for the lid, same for the core, very expensive material, much easier to 3D print.
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be careful with the finish, it needs sometimes specific polish to get accurate surface, sandblasting can also be useful, but for injection molds, I never saw such a finish, as it gets gritty and it' getting much harder to pull the plastic out, also please consider the rods to eject the material once the casting is cold.
Normally, you will find where those rods were placed, by studying the original part, you will find some small round shapes here and there, sometimes the finish can be so clean it would almost be invisible, but my guess is on that piece, there are 3 ejection rods, unless the whole core has been designed to move and work as ejection rod.
drusselmeyer
Master Member
It hasn't come up before, so no files exist yet. Since I am a prototype sculptor, I have been working on developing patterns, not scans or files. Most parts would be around 25mm (1") on the longest axis. The main idea is to create double hinges for elbows and knees.
Which file formats can you accept?
belloq
Sr Member
Google for Cantina Dude's thread about the "gauntlet whipcord housing" on one the Boba Fett forums. He would need to approve of any use of his 3D model.
You are absolutely correct. I know where the ejector pins were on the original part and I am planning on adding those into the design later. So far we have used this small machine to make 2 parts and those released from the mold without the need for ejector pins. But this design is significantly taller so I suspect it will need the ejectors.
I am intentionally starting with the least complex mold design in order to see how the parts come out (or fail). Then I can study those and refine the mold. This way I will be able to learn how various aspects of the mold impact the finished parts.
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Molds can be made from many different materials. An aluminum mold typically will last between 3000 and 10,000 injections. But it really depends on the mold and the details needed.
Steel molds last up to 100,000 injection depending on the mold design and the tolerances of the part needed. Since I don't plan to run anywhere near these numbers, aluminum molds will likely be good enough for me. But if I do need a steel mold I could machine that in my shop as well.
A few other mold materials are possible too. Epoxy molds are sometimes used for prototyping or short runs. I also read a cool paper on using 3d printed resin molds for short runs. FormLabs has a white paper on this topic with their Rigid 10k material. Those molds lasted a few hundred to 1000 times. But again it really depends on the parts you are making and how accurate you need them to be. Here is a link to the white paper if your interested.
Low-Volume Rapid Injection Molding With 3D Printed Molds
With affordable desktop 3D printers and injection molding machines, it is possible to create molds in-house to produce functional parts for final products.
3d.formlabs.com
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I can work with just about anything. For 3d models .stp / .step or .iges are easy to use. For 2d models .svg or .dxf would be easy to use.
MPP shroud (accurate 1 step for Vader lightsaber)
Parts kit for Vader ROTJ stunt lightsaber (control box, shroud ring, ball latch, port plug, d-ring holder)
Panel indicator lamps (various colors) used all over Star Wars sets
Slide viewers for Death Star detention block cameras
Obi-Wan grenade for ANH lightsaber
Obi-Wan booster for ANH lightsaber
TI calculator bubble strip for lightsabers
Parts kit for Vader ROTJ stunt lightsaber (control box, shroud ring, ball latch, port plug, d-ring holder)
Panel indicator lamps (various colors) used all over Star Wars sets
Slide viewers for Death Star detention block cameras
Obi-Wan grenade for ANH lightsaber
Obi-Wan booster for ANH lightsaber
TI calculator bubble strip for lightsabers
Can't you buy the MPP shroud and the Exatra bubble strip from WannaWanga? I think those are already have a good sources. They also sell the T track which I mentioned wanting to do. So I can understand your suggestions.
I think the Obi-Wan Grenade lightsaber part should be machined from aluminum but maybe people would rather have plastic ones.
I dont know about the slider viewers? Do you have a link or something I can look at? Same for the panel indicator lamps?
Slide viewers and dome lights can be seen here: Detention Center Camera Greeblies
I had another productive couple of days. I finished up machining mold yesterday and today I shot it for the first time. I got a bit excited so I didnt take many pictures of the mold before I installed it. I machined a core to go into the mold. I left it a little big and then hand sanded it down to be a nice tight fit. It took a little time, but was worth it.
Then I installed the mold into the machine. The machine I am using now is relatively small when talking about injection molding machines. So there isn't a ton of room to work. Even though it is a small machine we used a engine hoist to take it out of the crate and rest it on the table. I think 2 people could pick it up if they wanted to, but it wouldn't be fun. I have another machine which weighs about 2000 pounds, but I need to move that machine before I can start using it. That is why I am using this smaller machine for now.
Here are some pictures of the mold in the machine.
Here is a picture of the injector side of the mold. you can see the core in the center and the four alignment pins that help to line up the two halves of the mold. You can see the center hole which is where the plastic is injected from. Right now it is a 0.25 inch diameter straight hole. More on that later.
This is a picture of the other half of the mold. One thing I learned while installing the mold was I want to make the outside corners of the mold more rounded to give more room for the pins in the corners of the machine.
You can see how the area to work in here is pretty small. It really isn't a big problem if you have everything set up and a nice mold design which automatically ejects the parts. But when installing the mold and if you are manually removing the parts it is annoying. I think it would also be a problem if you are doing over molding where you mold around another part. You would have to insert the first part by hand and that might be hard.
Then I installed the mold into the machine. The machine I am using now is relatively small when talking about injection molding machines. So there isn't a ton of room to work. Even though it is a small machine we used a engine hoist to take it out of the crate and rest it on the table. I think 2 people could pick it up if they wanted to, but it wouldn't be fun. I have another machine which weighs about 2000 pounds, but I need to move that machine before I can start using it. That is why I am using this smaller machine for now.
Here are some pictures of the mold in the machine.
Here is a picture of the injector side of the mold. you can see the core in the center and the four alignment pins that help to line up the two halves of the mold. You can see the center hole which is where the plastic is injected from. Right now it is a 0.25 inch diameter straight hole. More on that later.
This is a picture of the other half of the mold. One thing I learned while installing the mold was I want to make the outside corners of the mold more rounded to give more room for the pins in the corners of the machine.
You can see how the area to work in here is pretty small. It really isn't a big problem if you have everything set up and a nice mold design which automatically ejects the parts. But when installing the mold and if you are manually removing the parts it is annoying. I think it would also be a problem if you are doing over molding where you mold around another part. You would have to insert the first part by hand and that might be hard.
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Sprayed the mold with some mold release. Then I shot the first part in the mold and it only filled the mold about halfway. I was a bit worried but I removed the part and shot another part. To my surprise the second part came out pretty good. I guess it is a little like pancakes, the first one always sucks. I realized that the aluminum mold was at room temperature and the plastic being injected was hot. So it cooled off very quick, and hardened before filling the mold. It is not uncommon to have to let the machine warm up before getting high quality parts. With such a small machine / mold it only took 1 part to warm up. I bet on a larger machine it would take more parts, or some sort of pre-heating routine.
The last time I was using this machine I was working with TPE (thermoplastic elastomer). That is really just a fancy way of saying a rubbery plastic. I wanted to use PP (polypropylene) for these parts. So I had to shoot about 10 parts to purge the TPE out of the machine.
I was actually very happy to see that the part was remaining in the moving side of the mold. This made it very easy to us needle nose pliers to reach in and grab the sprue. I was a little worried about the part releasing from the mold since I didn't add any draft angle to the mold. But the part came out very nicely. So I don't think this part needs a draft angle.
I did notice a sink mark on the part though. This is caused by the plastic shrinking when it cools. Areas that are too thick will show sink marks like this one. I think this is because the sprue was so thick. I didn't pick this size sprue randomly though. This was copying the design on the sample part / mold that came with the machine. So I think I will have to make a new cavity for the mold with a smaller hole though. This should help with the sink mark, save plastic, and make it easier to cut the sprue off at the end.
The other thing I learned was the radius in the bottom of my mold has a slight lip on it and you can see that tiny lip in the part. It doesn't change the function of the part in any way, but it is a cosmetic one I want to fix. I don't think I have a great picture of the surface finish, but the TPU material didn't seem to pick up much of the swirls in the mold.
Here you can see how the TPU is more like rubber. For another project it would probably be very useful.
The last time I was using this machine I was working with TPE (thermoplastic elastomer). That is really just a fancy way of saying a rubbery plastic. I wanted to use PP (polypropylene) for these parts. So I had to shoot about 10 parts to purge the TPE out of the machine.
I was actually very happy to see that the part was remaining in the moving side of the mold. This made it very easy to us needle nose pliers to reach in and grab the sprue. I was a little worried about the part releasing from the mold since I didn't add any draft angle to the mold. But the part came out very nicely. So I don't think this part needs a draft angle.
I did notice a sink mark on the part though. This is caused by the plastic shrinking when it cools. Areas that are too thick will show sink marks like this one. I think this is because the sprue was so thick. I didn't pick this size sprue randomly though. This was copying the design on the sample part / mold that came with the machine. So I think I will have to make a new cavity for the mold with a smaller hole though. This should help with the sink mark, save plastic, and make it easier to cut the sprue off at the end.
The other thing I learned was the radius in the bottom of my mold has a slight lip on it and you can see that tiny lip in the part. It doesn't change the function of the part in any way, but it is a cosmetic one I want to fix. I don't think I have a great picture of the surface finish, but the TPU material didn't seem to pick up much of the swirls in the mold.
Here you can see how the TPU is more like rubber. For another project it would probably be very useful.
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After about 10 parts the TPU material was out and the PP material was in. Sadly since they are both black it really isn't possible to tell by looking at the parts. But the PP ones are much more rigid. They also stuck to the other side of the mold. So that was an interesting difference.
I think I will need some form of ejector pins in order to properly shoot this mold. I am going to have to do some design work for this. I have never designed injection molds so this is a fun project to learn about it. So that will likely be the subject of my next post. I also noticed a small void in my mold which is causing extra flash on the part. It is super hard to show with a photo though. You can also see that the PP material did pick up the tool marks / swirls in the mold more. So that might be a reason to try and polish the mold.
Well that is all for today. I want to try and order some more plastic in different colors and see what I can do with that. More to come, so stay tuned.
I think I will need some form of ejector pins in order to properly shoot this mold. I am going to have to do some design work for this. I have never designed injection molds so this is a fun project to learn about it. So that will likely be the subject of my next post. I also noticed a small void in my mold which is causing extra flash on the part. It is super hard to show with a photo though. You can also see that the PP material did pick up the tool marks / swirls in the mold more. So that might be a reason to try and polish the mold.
Well that is all for today. I want to try and order some more plastic in different colors and see what I can do with that. More to come, so stay tuned.
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Oh I forgot to post the best photo. I trimmed the flash off with a razor knife and tested the fit on the mating part. It actually fit very well. I think the latches need to be slightly longer for it to really fit, but all in all I count this as a success. I was able to design the mold, machine it and shoot the parts. I learned a ton from this result.
drusselmeyer
Master Member
Congratulations on your first test!
Well I made some more progress this week. I got ordered some more polypropalene plastic pellets from Ebay to use. There are not many vendors that will sell injection molding plastics in low volumes. The best place I have found so far is on ebay. I was able to buy a ten pound bag of white and a ten pound bag of yellow for about $100. This included this shipping. Based on what I have seen so far this should last me quite a while.
I plan to get some air tight containers to store the plastic and put some desiccant packs in with the plastic. Industrial molding shops have a dryer to remove moisture from their plastic before use. Moisture will turn to steam while molding and will produce bad parts.
I also removed my mold and added another set of bolt holes to make it easier to connect to my machine. This also allows me to leave the mold on the injector side slightly loose. When the mold closes the alignment pins keep everything aligned and push the plate into the extruder. But when open it creates a tiny gap between the extruder and the aluminum mold. This helps becuase the mold is not constantly absorbing the heat. You want to keep the mold cool an the extruder hot.
While the mold was off I used a tapered end mill to add a 3 degree taper to the core. This should help the part removed easier. I placed a 123 block next to the core to show the taper in the photo below.
Since I had black PP in my machine I needed to purge that out. I removed as much as I could from the hopper and added yellow PP. I have not had to purge my machine before so I thought I would just shoot the mold 10 or so times an that would work. I was also curious how the colors would mix. Well it took a lot more parts than I thought. I think I made 25 parts before it was mostly yellow and even then I sitll had a few black streaks.
If this was the effect I wanted it would be really cool. But sadly there were all just scrap parts. I saved them and maybe I will do something with them. I have since read up on a few better ways to change the material. Firstly I learned out to run the extruded without closing the mold and that will make the process 10x faster. But also it is recommened to use a special material to purge. I will have to see if I can get it in smaller quantities. So far I havent found any.
The last step was to print the decal on waterslide paper and apply it. Here is the final product so far. The part on the right is the original and the part on the left is my replica.
Next week I have some parts coming to try and design an automatic ejector into my mold. So there will be a major mold change next time.
I plan to get some air tight containers to store the plastic and put some desiccant packs in with the plastic. Industrial molding shops have a dryer to remove moisture from their plastic before use. Moisture will turn to steam while molding and will produce bad parts.
I also removed my mold and added another set of bolt holes to make it easier to connect to my machine. This also allows me to leave the mold on the injector side slightly loose. When the mold closes the alignment pins keep everything aligned and push the plate into the extruder. But when open it creates a tiny gap between the extruder and the aluminum mold. This helps becuase the mold is not constantly absorbing the heat. You want to keep the mold cool an the extruder hot.
While the mold was off I used a tapered end mill to add a 3 degree taper to the core. This should help the part removed easier. I placed a 123 block next to the core to show the taper in the photo below.
Since I had black PP in my machine I needed to purge that out. I removed as much as I could from the hopper and added yellow PP. I have not had to purge my machine before so I thought I would just shoot the mold 10 or so times an that would work. I was also curious how the colors would mix. Well it took a lot more parts than I thought. I think I made 25 parts before it was mostly yellow and even then I sitll had a few black streaks.
If this was the effect I wanted it would be really cool. But sadly there were all just scrap parts. I saved them and maybe I will do something with them. I have since read up on a few better ways to change the material. Firstly I learned out to run the extruded without closing the mold and that will make the process 10x faster. But also it is recommened to use a special material to purge. I will have to see if I can get it in smaller quantities. So far I havent found any.
The last step was to print the decal on waterslide paper and apply it. Here is the final product so far. The part on the right is the original and the part on the left is my replica.
Next week I have some parts coming to try and design an automatic ejector into my mold. So there will be a major mold change next time.
drusselmeyer
Master Member
I just saw this on Fbook:
I'm not sure how useful you might find it.
Injection Molded Parts in <24 Hours With 3D Printed Molds + Q&A
Use stereolithography (SLA) 3D printed molds in the injection molding process to lower costs, reduce lead times, and bring better products to market.
3d.formlabs.com
I'm not sure how useful you might find it.
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