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V4 Sheets – Cutting methods

This topic contains 15 replies, has 5 voices, and was last updated by  Vicente Varella 3 days ago.

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Vicente Varella v-varella

V4 Sheets – Cutting methods

12/12/2018 at 12:50

Hello Community,

Here we are gonna start sharing all the tests, experiments and ideas we have around the world of cutting plastic sheets. The idea is that every time somebody tries a new cutting method or tool we post it here showing our experience and the conclusions we gather from it. Everybody is welcome to contribute with their experiences, questions or suggestions 🙂

Also, make sure to subscribe to the following threads if you are interested in the materia:

– Machine Development
– Sheets – Interesting results
– Bending
– Welding
– Thermoforming
– Finishing
– Joinery

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helper
12/12/2018 at 15:55
0

Cutting HDPE Sheets

Objective: Exploring different cutting tools and techniques.

Material: HDPE

Tools: Jigsaw, Miter Saw, Table saw<b>.</b>

Process:–  I used Jigsaw with plastic cutting blades. Continuous push and faster movement results in a smoother cut. Blades with different orientation of teeth gives different output. Because of it’s high density the blade might get stuck in the material if moved slowly. Leaves decent finish after cutting, but needs sanding for better result.

–  Using miter saw was a great success. Plastic cutting blade works perfect. Faster you run the machine smoother the result is. HDPE leaves only a bit of plastic dust due to cutting but no melted or sticky plastic on the machine. The dust can be removed easily. The finishing of the cutting edge of the plastic is already quite nice.

–   Table saw worked the best because of its speed. Using Plastic cutting blade is a must. It made very smooth cut. No fume or melted plastic on the blade. Perfect for big piece of sheets.

Conclusion:–   The result generally does not require polishing after cutting it.

–   It does not melt at the edge due to the friction with the cutting blade.

–   No bad fume while cutting.

–   Almost feels like cutting a wooden plank.

–   Leaves a little bit of plastic dust on the machine, but it is really easy to remove as it is not sticky.

–   The faster the better. Table saw and miter saw gives smoother output.

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helper
12/12/2018 at 15:58
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Test: Trying to cut PP with the Mitter saw

Objective: Cut one sheet into small beams

Material: PP

Tools: Caliper, pencil, clamps, mitter saw, sanding machine.

Process

This is a very straight forward test of how does the Jigsaw work with PP. For this test we are going to use a regular wood saw. The first thing I noticed is that you can easily tell by the side of the samples that the end result is too rough and needs to be polished. Through iteration I discovered that the smoother you make the cuts the cleaner it gets the result. But still needs to be polished because of the saw.

Conclusions

The saw will need to be cleaned after few cuts since it gets super dirty after every cut.The jigsaw is not the best for long cuts. That’s not the purpose of this machine.The smoother you make the cut the cleaner it gets. Preferably by one cut.

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helper
12/12/2018 at 16:02
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Test: Trying to cut multiple sheets at once.

Objective: Speed up the cutting process

Material: PP

Tools: Caliper, pencil, clamps, Jigsaw, sanding machine, chisel and hammer.

Process

In order to speed the process we wanted to try to make an inner cut over four sheets of PP at once. First we clamp them all together. Then we sand the sides in order to have them all equal. After that we clamp it to the table. Then we made 4 cuts with the jigsaw. And finished the cut with a chisel and a hammer.

Conclusions

– When you try to cut it with the Jigsaw the plastic melts by friction and the cut is imprecise.
– After cutting the 4 pieces just became a block and we had to separate them.
– The chisel is useful but pretty fragile when working with PP.
– After the second piece the cut is not in the right place anymore.
– Bad idea in general to cut with the jigsaw 4 plates at once. Table saw would be more ideal.

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helper
12/12/2018 at 16:33
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Test: Trying to cut PS with the Jigsaw

Objective: Trying to find the best cutting method.

Material: PS

Tools: Pencil, Jigsaw, Handsaw,

Process

PS is very interesting because it could be transparent and it’s very rigid. What makes it different from PP and HDPE. However it’s tougher to cut, and very fragile. The process itself it’s been straight forward, mark where to cut, and start cutting. Seems easy, but the reality is that was hard as F to go from one side to the other and unfortunately nothing happened. The blade melted both sides of the plate so they got welded immediately after. I used a wood blade that’s why.

Conclusions

– When you try to cut with the Jigsaw the plastic melts by friction and the cut is imprecise.
– Too much friction on the walls of the cut ended up welding the parts together again.
– When trying to use the hammer to detach both parts PS brakes.
– Best blade or machine or technique has to be found to cut PS.

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helper
12/12/2018 at 19:59
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Test: Trying to cut circles out of PP and HDPE

Objective: Apply wood hole saw to plastic

Material: PP & HDPE

Tools: Hole saw, drilling machine

Process

In order to do holes I tried a regular wood hole saw, and it was relatively easy to cut on both but unfortunately It leaves marks on the sides due to the tool. While cutting, the machine gets really messy. Also the tool gets hot really easy and little deformations could appear, some flakes got welded to the surface. And that took a while to clean afterwards.

Conclusions

– The tool is not the correct one, too many imperfections on the process.
– Will have to find a bettter one.
– HDPE worked better than PP (I think because it’s stronger)

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dedicated
13/12/2018 at 02:46
0

Coming from a CNC background I can see that your machine speed is too high to cut plastic.  You need actually a much lower speed to cut.  Possibly even 2-300rpm with that many teeth of a circular saw blade.

 

Alternately you can try a bandsaw on its slowest setting and water as a lubricant. Maybe a meat bandsaw with its more waterproof parts?

Meat bandsaws are common worldwide even here in the Philippines.

starter
03/01/2019 at 18:56
1

Hi everyone !

I dont have a lot of practice with plastic but I’ve got a lot of ideas to test. So I share it to you, hoping it will be useful for someone.

-Plastic is very soft, so I think some very sharpened blade with no many teeth and a slow cutting speed but a great pressure will avoid to melt it. Maybe a sort of paper cutter, used for thick stack of paper like books, will be usable for linear cutting.

-water-cutter is used for cutting all type of things wich cnc steel blades cant cut because of the “agressivity” of the blades. But its not very affordable.
BUT ! I’ve saw some video of people making it with pressure washer, by modifing a few pieces. And there also a lot of documentation to make cheap 2 axis base drive by computer to make things like laser engraver. So Its possible to mix the two, to make a CNC waterjet cutter for cheap if someone have the knowledge and the time to build it.

DIY water cutter with pressure washer )
A cheap 2 axis thing )

What do you think ?

Bye !

edit : And maybe its possible to create some mold by creating some stronger and sharper cookie cutter, to press it on the plastic plate and quickly cut some pieces ?

helper
10/01/2019 at 15:46
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Hi, @btmetz. Thanks for the reply, Actually right now we are trying to find the best circular saw to cut plastic plates easy and clean. Definitely the mitter saw is not the best for cutting long straight cuts so we are going to focus only on the table saw.
Having said that, later I will post what we are doing and some results.
And yes definitely, a band saw seems to be a decent option to cut plastic as well. We’ll try to dig in as well, thanks for the comment.

Hello, @benj. Thanks for the suggestion, yes definitely water cutting is cool, but not very accessible and since we have limited options to try I’m afraid we are not going to be able to explore it much. And regarding the good parameters for the blades, from my short experience I would say that something between 50 to 70 teeth (for 200cm diammeter blade) seems to be a good number. And fast cutting speed works better for HDPE and PP while medium cutting speeds works better for PS.

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warrior
10/01/2019 at 19:42
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hey @v-varella !

Have you thought of using heat to cut, like a heating string or maybe similar type of process ? (i just hate to imagine creating all the micro & nano plastic through the use of a saw .. 🙁 )

peace!

helper
10/01/2019 at 19:54
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If you want to cut plastic with a cnc (means spindle) you need singleflute endmills and a high moving speed and a relative low spindle rpm. Look on you youtube for cutting acrylic with cnc.
Concerning plasticdust while cutting, you can add a vacuum cleaner to not let it go in the nature.

helper
11/01/2019 at 18:58
1

hey @imuh, Good point, unfortunately hot wire, or hot knifes seems to give less than ideal cuts when cutting thick plates or at least that’s the theory. Would be really interesting to see it though. Indeed when cutting with circular saws it makes so much flakes but that could be fixed with a proper vacuuming system

Following the post I wrote the other day, I’ve been recommended that negative or 0º hook angles tend to work better. Also (for a given 25cm blade) configurations around 80 teeth seems to work best for thin plates up to 15mm. If the plate is around 20mm or superior the blade needs more space to retire the chips and that means less teeth, something around 60 teeth.
Talking about the family of blades, tungsten carbide chips blades are always recommended. But there are few types that seems to work best inside that family than others. Triple chip blades grind (TCG) are preffered (pic 1). But also I got recommended to try a variaton of that wich has two types of angled teeth (pic2).

Still have to find what is the difference between them and then try them out.
Soon I will update a final choose and the reasons behind it. Therefore I will jump into find the best blade for the jigsaw.

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dedicated
12/01/2019 at 01:35
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I use a ordinary circular saw to cut thick sheets of HDPE for my CNC.

 

This is a example of this tool

 

 

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helper
12/01/2019 at 11:12
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Hello @btmetz, that’s also an alternative to the table saw for straight cuts. Would you please be so kind to show me more or less which blade are you using and which are results you are getting so far?
I’ve been trying different blades this week and some works better than other but still haven’t achieved a clean clean cut. The blade “B” (mentioned few comments above) makes decent cuts for PP and HDPE but still needs to be polished after. Which I think its unavoidable even though we find the most suited blade for it.
PS it’s a little bit harder to cut and still don’t know what it’s the best way to approach it yet.
Let me know your thoughts. 🙂

helper
18/01/2019 at 13:46
1

Following the thread I’ve been testing with the hand-router to see how does it feels to use it for plastics. As always PP, HDPE and PS. And the results are kinda conclusive.
TEST A – First I tried regular router bits (ment for wood). The result on HDPE and PP are not that bad, sort of clean, very few melting spots detected. Not the perfect cut but reliable if there is nothing else around. Decent edges. But for PS seems that it just doesn’t work. Lots of melting made the process unstable and also unhealthy because of the fumes. (Very high cutting speed for the HDPE and PP around 30.000rpm)
TEST B – Then I tried a tool that would be generally used in the CNC to cut plastic and the results were much more precise. Worked very well for all the materials, including PS. No melting thanks to the polished surface that makes the chips fly away. (Medium cutting speed for HDPE and PP, around 21.500 to 25.000rpm) (Slow cutting speed for PS, 11.000rpm)

link to the tool used: https://www.sorotec.de/shop/Zerspanungswerkzeuge/sorotec-werkzeuge/1-schneider/1-schneider-sorotec-uni/

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helper
18/01/2019 at 19:38
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Okey, I have some results to share about cutting with the jigsaw. I found few interesting blades to work with that I’m sure will help somebody along the way.

– First I tried the T304H and got good results with HDPE and PP. Clean cut without melting and a sharp edge almost without scratches. But for PS got lots of melting again.

– Then I tried the T102BF and got similar results. To be honest I cannot tell you the differences between both cuts. Both really good for HDPE and PP and bad for PS.

– Finally I tested the T102D and got an interesting result. A little bit of scratches on the side but apart from that all good. Plus, is really fast, maybe good for fast jobs if the difference of quality is not that relevant. Still pretty clean cut. And I got a decent job with a 10mm PS plate. Clean cut without meltings but with quite a few scratches on the side of the cut. And on the top surface the blade is more likely to break some parts of the edge while cutting. So… not very sharp edge we could say.  Then I tried with a 18mm plate and the result was totally different. Fully melted again and no way of achieving a clean cut. I wonder if with slower cutting speed would work out. But unfortunately ours doesn’t change that much the velocity from min to max.

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