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The story behind the #PIRANHACLAMP

This topic contains 54 replies, has 12 voices, and was last updated by  Fabrizio Forte 2 months ago.

10
Kunststoffschmiede kunststoffschmiede

The story behind the #PIRANHACLAMP

22/05/2018 at 22:37

Hey!

I (@carlf from the Kunststoffschmiede) will share with you the process of how we got to our final mould. It took us nearly 9 months and a team of mainly 4 people.

Don’t even think that we were full time on this clamp, but be sure: Product development takes some time…

So here it is:

The way from an idea to a functioning mould.

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warrior
02/08/2018 at 19:01
3

First results, the first thing I noticed is that the mould is quite hard to open and extract the part, due to the relatively long circumference of the part. I added some ‘prising slots’ to the mould. I should have done this first of all but I wanted to see what it was like without.

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warrior
02/08/2018 at 19:04
4

I’m not overly impressed with the toggle clamps. I usually use socket head set screws in each corner which provide much better clamping, only need an allen key to undo them and really only take a few more seconds to remove. I ended up with quite a lot of flashing on the part on my first attempt, as the mould was not clamped together tightly enough.

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warrior
02/08/2018 at 19:07
4

By using a spanner to tighten the wing nuts (kind of defeats the point) I was able to minimise the flashing.

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warrior
02/08/2018 at 19:09
3

The red clamps are polypropylene. I then tried HDPE. It didn’t work too well. I wasn’t able to fully fill the mould and I noticed I had to apply a lot more pressure on the handle of the injection machine. I think I made the gate too small for HDPE, even so I think this shape is better suited to polypropylene.

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warrior
02/08/2018 at 19:15
6

All in all I’m pretty happy with the results, the clamps look good and they work!

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dedicated
02/08/2018 at 20:05
0

nice job, did you use the injection and how long does it take to make one ?
g

dedicated
02/08/2018 at 20:14
0

would be awesome if you could share your fusion file, i am not sure i got it right 🙂 my CAM operations seem stupid long 10 hours or so.

starter
02/08/2018 at 21:12
3

@anne-barbier
When everythin is nice and smooth we are about 30 clamps during one hour. But  we are using a car jack to press the mould against the nozzle. That’s a lot faster then threat. and we have less waste because our sprue shorter.

@andyn
Wow! Good Work!
Do you have any daft angel? When the mould gets warm, the clamp is easy to get out.

warrior
02/08/2018 at 21:23
0

upload cad files

dedicated
02/08/2018 at 23:25
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@sharma-sagar: please, scroll up a little, she made an attachment, and i made a post to a maintained github repo & external forum post

helper
03/08/2018 at 00:59
1

They are so nice !
When will we have them on the bazar ? @andyn @kunststoffschmiede

warrior
03/08/2018 at 10:45
0

@anne-barbier oh didnt see it. thanks 🙂

warrior
03/08/2018 at 13:20
0

@kunststoffschmiede

No draft angle, just straight sides and a small radius on the corners, but I think you’re right, the part will be much easier to extract with a draft angle, I’m going to try this on the next one, I’ll have to grind a special cutter.

 

If you have the injection point on the side and are using a car jack to hold it against the nozzle then you are probably getting most of the clamping force out of the jack rather than the toggle clamps. The car jack is a good method, I think more people should use it, but I think most still just thread the moulds on, it’s simple and secure but not as fast, and you really need to split the mould along the sprue line to get the solidified plastic out.

 

@adrienluitot

When I have perfected the mould I will put it on the Bazar. I’m not 100% happy with it yet, it still needs a few small tweaks to get it just right.

helper
03/08/2018 at 13:39
0

@andyn
Cool ! I look forward to see them ! Keep me in touch !

warrior
08/08/2018 at 19:18
2

@kunststoffschmiede
@adrienluitot
Ok, here’s version 2. I made a few small changes. I went back to cap screws to close the mould, more secure and really doesn’t take much longer to open (I actually think they are less fiddly and faster to tighten as well).

 

I made this mould with a draft angle on all the edges except the actual teeth which are parallel. I made it slightly more than 3° and the part is much easier to extract from the mould. I used PP again for these tests (shredded flowerpots).

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warrior
08/08/2018 at 19:52
3

And here is the listing on the Bazar.

 

https://bazar.preciousplastic.com/en/listings/614952-number-piranhaclamp-mould

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helper
10/08/2018 at 01:40
1

Woaw  @andyn ! This is a very clean work ! And this is not expensive
Will you sell the clamps ?

warrior
10/08/2018 at 13:02
3

@adrienluitot
I’m not planning on selling the clamps themselves, just the moulds so people can make their own. I don’t think it really makes sense to sell plastic products in the Bazar, it adds a lot of unnecessary shipping when we should be focusing on tackling plastic waste at a local level. I don’t know if @kunststoffschmiede sell the clamps somewhere, perhaps they do, they would be closer to you than I am.

helper
12/08/2018 at 21:52
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@andyn You’re alright I don’t think it’s a good/intelligent idea 😉
Will you sell them locally ?

warrior
13/08/2018 at 12:51
2

I probably won’t make enough of them myself to sell, but I may give them away locally and use them as an example of a useful product that can be made from plastic waste with low-tech equipment.

dedicated
14/08/2018 at 12:39
1

@kunststoffschmiede
can you share your nozzle photos? I’m trying to figure it out how to do it in the better way.
Thank you in advance.

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starter
14/08/2018 at 23:40
0

@fabirihotmail-com
here it is. the most importand rules to design our nozzle are:
1. make sure you can heat it up nice and quickly
2. make sure you can fix the mould on a fast and save way,

we don’t use threads because it takes a long time to get the mould ready on the injection machine. that’s why we are using a car jack to press our moulds against our redesigned nozzle.

here are some pics:

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starter
14/08/2018 at 23:45
0

and another two

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dedicated
15/08/2018 at 17:35
0

So you develop your own nozzle, for sure the shorter the nozzle the faster you reach it’s temperature, I agree with you that the threaded nozzle is not good, I will try some different setup of the nozzle.
Thank you very much.

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