Start Roto #15 | Can I make my own mold? — Points of attention — LIVE

What you gain by watching

• You learn to assess whether it's worth manufacturing your own mold — and to recognize design mistakes that make the part unviable before the first cycle.
• You see how to turn invisible losses into numbers and how one adjustment can bring resin, box, and predictability back to the process.
• You come away with practical criteria on venting, shrinkage, corners, bridges, and qualification so you don't pay twice for the same mold.

Episode chapters

1. 1

   Rotomolding is only 3% of transformed plastic in Brazil — can you make your own mold at home?

   If you have an idea and don't know how to make your own mold, this is the starting point: episode fifteen of Start Roto enters the structuring phase to show the precautions that make a project born sustainable — and not stillborn. We reinforce that rotomolding represents only about 3% of transformed plastic in Brazil, a little-explored niche with plenty of room to grow, and that's exactly why we keep bringing the technical know-how of those who lived the factory floor firsthand.

   Only three percent, right? Of what is transformed into plastic in Brazil, folks. Of what is transformed into plastic in, in Brazil is rotomolding, right? So look at how much there still is to, to grow this industry

   ▶ Watch at approximately 5:21
2. 2

   Someone who makes gates doesn't understand rotomolding molds

   We always ran into a real difficulty: finding someone who could produce molds quickly, because market suppliers are always fully booked with lead times that reached 90, 120 days. That's how we decided to develop a partner close to us, and here's the warning we made a point of making clear — being a good welder or gate manufacturer isn't enough, you need to master mold principles, and that's exactly the knowledge we passed on to him.

   It's not just anyone, a gate maker, folks? I want to make this very clear.

   ▶ Watch at approximately 10:23
3. 3

   Why the first part at home can kill your mold

   Before risking the first mold in your own workshop, you have to respect radius, negative and positive draft — and one little mistake in the calculation already kills the mold. We told the case of the client who sent a 3D-modeled vase asking if it could be rotomolded, and the answer was yes, but with a cast mold and aluminum, not machined in carbon steel. The recommendation that remains is clear: validate and produce the first part with someone who is already established, because a mold that looks simple may not be in execution, and it's better to get on your own machine only after there's recurring capital running.

   ▶ Watch at approximately 15:43
4. 4

   When the mold looks simple, but the invisible cost eats your profit

   Have you ever stopped to think that making the mold isn't just copying the part, and that a forgotten detail like the vent can make the manufacturer himself sigh later? In this excerpt, we remember a partner who, even without structure, made impressive molds with pure know-how, and we show how geometry, shrinkage, mold outputs, and even the material lost in a part with a 450 mm opening become that invisible cost that sucks your profit without anyone noticing. The reflection that remains is clear: understanding every variable in the process is what separates the mold that makes the business viable from the mold that makes it unviable.

   It's the famous invisible cost. You don't notice, you don't see that it's sucking all your profit, no.

   ▶ Watch at approximately 20:48
5. 5

   Eight molds, five hundred grams, and a calculation nobody was doing

   We went straight to that leftover that seems small — eight molds losing five hundred grams per round — and when we put the numbers on the table, it became seven point two kilos per day going out the door, more than three thousand seven hundred reais per month that simply weren't in the calculation. That's when we showed the Portal's losses calculator: by filling in cycles, resin, and LPG, the simulation points to a potential savings of one thousand five hundred and eighty-four per month, about forty-five percent of that cost — and the material that was treated as lost can return to the process, diluted with virgin material.

   It's a heck of a waste.

   ▶ Watch at approximately 26:19
6. 6

   Rotomolding course: from Science to the Factory Floor in three regions of Brazil

   Anyone who had never seen a rotomolding machine up close and received the finished part — warped — thought that was normal until they felt their eyes burn next to an unregulated machine. That's how we showed why the Essential Rotomolding Course, from Science to the Factory Floor, goes from zero to a level and a half in two days, with one theoretical day and one practical day, teaching how to identify lost cycles, material and mold problems, and how to solve about 80% of the most common problems.

   He never saw the roto machine, he saw the part arrive ready for him, all warped, and for him that was normal

   ▶ Watch at approximately 31:36
7. 7

   From the factory floor to certification: why qualification turns into better pay

   Stop losing money due to lack of knowledge — that's what we stand for when it comes to training specialized labor, because those who qualify stop competing for minimum wage and start being sought after by companies. We also talked about how 90% of rotomolders don't have this access to knowledge, and that's why we keep distributing free material provided by Nilton Coletti, while showing that copying the part isn't enough: the mold must be born for rotomolding, with shrinkage, venting, and critical regions designed from the start.

   It's knowledge worth gold, isn't it, because sometimes the rotomolder hiring you doesn't even know how to make the mold himself, that's the starting point: episode fifteen of Start Roto enters the structuring phase to show the care that makes a project born sustainable — and not stillborn. We reinforced that rotomolding represents only about 3% of processed plastic in Brazil, a niche little explored and with plenty of room to grow, and that's exactly p

   ▶ Watch at approximately 36:55
8. 8

   Sharp corners: the design error that dooms a R$ 150,000 mold

   We went to visit a client who was about to condemn a giant three-meter mold because the part remained weak even with 50% more material than it should have — and the culprit wasn't the material, it was the sharp corner in the design, which makes the material slump and leaves the critical region thin enough to tear. We showed that, by adding a radius to that corner, the material flows and distributes uniformly, so the mold could still be saved — and the golden rule that remains is: sharp corners we abhor, especially in critical regions, whether on the outer or inner part of the mold.

   ▶ Watch at approximately 41:56
9. 9

   Mold with close walls: defect or structural reinforcement?

   When the walls of a rotomolded part get too close, the risk of warping is a concern — but that isn't always a problem, because there's the forced bridging technique, in which the material deliberately sticks in the middle of the walls to create structural reinforcement. We discussed the practical rule of two point five times the thickness for minimum distance between walls and promised to confirm the numbers in the next episode, while celebrating two hundred and fifty subscribers of an audience that, although niche, is qualified and makes a difference in the market.

   If I'm not mistaken, off the top of my head, it's, the minimum for you to do is two, two and a half times the material thickness.

   ▶ Watch at approximately 47:08
10. 10

    Forced bridging: when the thin flap becomes structural reinforcement in the mold

    A gap of two and a half centimeters can be safe, but just reduce that distance and the part starts to bridge — and that is exactly what separated a dumpster from ordinary trash, with an acceptable soft flap because it stays on the street, from a demanding part to use inside a condominium. The mold manufacturer respected the spacing and designed enough of a bend to create a forced bridge, and when we picked up the finished flap it was firm as structural reinforcement, almost solid.

    ▶ Watch at approximately 52:19
11. 11

    Accounting is an investment: the tax adjustment that returned R$ 480 thousand to the cash flow

    A transportation company invoiced R$ 2.54 million in the quarter and, under the natural regime, would pay about R$ 625 thousand in taxes — until a tax adjustment cut R$ 480 thousand and gave breathing room back to the cash flow to invest and generate more jobs. But the talk did not stop at taxes: we also showed how the shrinkage technique can work for or against you when removing a part with negative ribs from the mold — and we told the case of the water tank where the part came out loose after cooling.

    Do you still think accounting is a cost for your company or is it an investment? I will prove to you that it is a huge investment.

    ▶ Watch at approximately 57:45
12. 12

    The 3% error that jams technical parts in rotomolding

    The question that always comes back on the factory floor is: how much shrinkage should be considered for the mold? We talked about the 3% that people usually use as a reference and how that changes when the part requires fitting and precision. In the end, we showed that with conventional machines dimensional control is limited and that technical parts are territory for few, because any variation in the material already compromises functionality. We also recalled the case of the handle that got stuck in the mold because of the draft angle and explained why the geometry has to be zero or positive for the part to come out.

    Is it easy to do? No, it is not easy. Is it possible? Yes, it is possible to do.

    ▶ Watch at approximately 1:03:02
13. 13

    The clogged vent that deformed every part

    We even saw a factory where every part came out warped and deformed, without exception — and the owner didn't even know what a mold vent was. What solved it wasn't changing equipment or recipe: it was a ten-millimeter Teflon tube and the routine of unclogging it after every cycle, and we also talked about the techniques that fiberglass uses and that in rotomolding can mark the part.

    ▶ Watch at approximately 1:08:03
14. 14

    Is making a mold at home worth it? What decides is the risk of the part

    The temptation to save money by making your own mold runs into details that no one sees until something goes wrong: the vent that turns into a hole in the part, the parting line that deforms and leaks material, the flange that's too tall and insulates the heat, making the assembly even weaker. We talked about all of that and showed that the three-eighths bar, the labyrinth sealing system, and the sheets already cut and bent on the market exist precisely to reduce that risk — and what determines whether you're ready to take on the in-house job is the risk of the operation, not the price of the sheet.

    You will save money, yes, right? But from what we can guide you on in that sense, so you don't have to spend twice on the same mold.

    ▶ Watch at approximately 1:13:21
15. 15

    Whoever doesn't master the 4M may be buying a mold that only brings headaches

    We don't manufacture molds, but we know the process and we know that machine, mold, material, and labor need to work together — and that a poorly made mold becomes a problem for you and for your client. So the guidance is to seek knowledge before improvising: analyze the design, record every change, and, if needed, rely on companies specialized in carbon steel, stainless steel, cast or machined aluminum, which today already serve at common and affordable prices. And coming up: we've already invited specialists in machined aluminum molds for an in-person episode.

    A poorly made mold, you'll only have problems, only headaches.

    ▶ Watch at approximately 1:18:28
16. 16

    Five minutes, forty years of factory floor, and the hammer blow worth ten thousand

    We work on so many fronts that the workload behind the scenes is enormous, and that's how I developed tools capable of turning hours of presentation into five minutes — because in the end, what matters is the knowledge we share with you, not the presentation itself. It was in that spirit that we recalled the story of the engineer who fixed the ship with a hammer blow and charged ten thousand: it's not the ten-minute gesture that gets paid, it's the six years of study until you know exactly where to strike.

    ▶ Watch at approximately 1:24:07
17. 17

    A medical appointment and the making of that nobody forgets

    We closed the episode by adjusting the time to eleven because of a medical appointment, and we already left the invitation for the next meeting on Friday at noon. And it was between one hug and another that the name almost slipped out — but the message stuck: the making of is there on Instagram, at @portalrotomoldagem.

    I hope you all stay with God and see you Friday at noon.

    ▶ Watch at approximately 1:29:28