YOU CAN WELD THE HEATED PRESS THAT POLYMER LABS TEST PLASTIC WITH
If you can weld, you can build the gatekeeper machine of polymer research — the heated press that makes flat test sheets from plastic.
by Morgan C. Woods, Cameron K. Brooks, Joshua M. Pearce
WorkshopScience
Built withESP32Arduino3D printing
- difficulty
- ●●●●●
- time
- several weekends
- license
- GNU GPL 3.0 (designs), CERN OHL v2 (hardware)
- repo
- repo FINISHED0 stars
●●●●● · several weekends · GNU GPL 3.0 (designs), CERN OHL v2 (hardware) · 0 stars · repo FINISHED
WHAT YOU’LL NEED
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COMPAREE VERDICT
This is the machine that sits upstream of polymer testing: if you want a flat, uniform sheet or a standard test sample pressed at a known temperature and pressure, you need a heated press. This open design from Western University is built from laser-cut steel plate and welded square tubing, a bottle jack (or an existing hydraulic press), eight 125 W steel strip heaters and an Arduino Nano ESP32 running PID control from room temperature to 350 °C, with a 12 x 12 inch pressing area. The paper puts the parts at roughly 1,520 Canadian dollars, plus the optional test molds, and the documentation is unusually complete, with 81 figures covering fabrication, welding, wiring and software. The authors validated it with waste polycarbonate, pressing PC and HDPE sheets and ASTM D695 compression samples. The single thing most likely to go wrong is the welded frame: tack it square and keep it square, or the plates will not press evenly. It requires a MIG welder, a drill press, a band saw, a laser-cutting service for the plate parts, and confidence working with mains-voltage heating elements. If you have those, this is a serious piece of open scientific hardware.
IN THE REPO
GOOD TO KNOW
- —81 figures in the HardwareX paper cover the welding, drilling, wiring and software steps.
- —CAD files for all machined and fabricated parts are in the supplementary materials.
- —Full bill of materials with part numbers and costs (in CAD) is published.
- —Firmware is an Arduino script for an Arduino Nano ESP32 that runs PID control on each plate through SSRs, with an LCD menu and SD-card logging.
- —Designs under GNU GPL 3.0, hardware under CERN OHL v2 — both allow commercial use.
- —This is an academic publication, not a GitHub repository — all CAD, DXF, STL and code files are on the Open Science Framework (osf.io/wqne2).
Parts to buy
9 itemsFrom our check of the build. Exact quantities and part numbers are in the creator’s BOM.
Can I build this?
This build involves mains voltage — for adults comfortable with electrical work only.
Build at your own risk. Projects involve tools, electronics and sometimes mains voltage — follow the creator’s safety notes.
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Start here
Navigation into the creator’s own docs — we don’t rewrite the guide, we route you to the source.
- 1.Download the paper and supplementary files (The paper has the BOM and step-by-step figures; the CAD, DXF, STL and Arduino code are on OSF (osf.io/wqne2).)
- 2.Read the full build documentation(The paper itself is the build guide; work through its figures in order.)
- 3.Source the steel stock and hydraulic jack first(Send the DXF files to a laser-cutting service early, since the steel parts set the pace of the build; the paper also notes some BOM part numbers are Canadian.)
- 4.Weld the plate frames square before wiring anything(Clamp, tack and check the diagonals as the paper describes; a square frame is what gives even pressure across the plates.)
KNOWN ISSUES
- The steel plates are laser cut, so order them from a cutting service using the DXF files and deburr them carefully. Burrs or warped plates mean uneven pressure across the sheet.
- Mains-voltage wiring to heating elements is not a learn-as-you-go skill — if you have never wired an SSR or a PID controller, get help or expect a weekend lost to troubleshooting.
- The BOM lists costs in CAD and some part numbers are Canada-specific — allow time to find equivalent suppliers if you are elsewhere.
- The heating elements are 505 CAD on their own — more than a third of the total cost — and they are not something you substitute casually.
- This is a heavy steel build with a hydraulic jack under load — the frame must be square and the welds must be sound, or the press will rack and bind.
- The control box runs an Arduino Nano ESP32 with the authors' script (PID control per plate, LCD and rotary encoder, temperature logging to a microSD card). You need to be comfortable installing Arduino libraries and flashing a board.
Is this actually cheaper than buying a press?
For a scientific press with heated plates, PID control and logging, yes — the paper compares it with the open Precious Plastic sheet press, which costs about 4,260 CAD in parts and is far larger. The closest commercial analogue the authors name is a small rosin press, which is cheaper but not built for repeatable polymer testing.
Can I build this without a milling machine?
Yes. The paper lists no milling machine: the steel parts are laser cut from the supplied DXF files by a vendor, then deburred, drilled where needed and MIG welded, using a drill press, a band saw and clamps. Keeping the welded frame square is what gives even pressure.
What plastics can this press?
The authors validated it with purchased recycled polycarbonate regrind: twelve ASTM D695 compression samples pressed at 300 °C, then solid PC sheets, plus an HDPE sheet in the sheet mold. The heaters go from room temperature to 350 °C, so the design suits most thermoplastics and blends within that range and the 12 x 12 inch plate area.
Can I use this as a rosin press?
Physically it can press other things, but it is built for repeatable polymer sample making. The authors name a small rosin press as the closest commercial analogue, which is simpler if that is all you need.
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Discussion1
FROM THE COMPAREE TEAM
The paper lists the heating elements at about 505 Canadian dollars, the mechanical assembly at about 652 and the electrical components at about 364, roughly 1,520 Canadian dollars all-in. For comparison, it notes the larger Precious Plastic sheet press is quoted at about 4,260 Canadian dollars to build. If you were building this, which stage would you outsource?
Morgan C. Woods, Cameron K. Brooks, Joshua M. Pearce
Published by researchers at Western University, Ontario, as part of a broader program in open-source scientific hardware. The press was built to support polymer recycling and materials testing research where commercial instruments are cost-prohibitive.
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- Information is provided without warranty and may become outdated as projects evolve. Prices are indicative bands only — always check the creator’s parts list for current costs.
- Building and operating any project is at your own responsibility. Protective equipment, safe workshop practice and compliance with local regulations are the builder’s responsibility.
CompareeTEAM24d agoedited
Practical notes from our verification: this is an academic HardwareX publication, not a GitHub repo. The CAD, DXF, print files and the Arduino code live on the Open Science Framework (osf.io/wqne2), and the paper itself is the build guide. Its 81 figures are genuinely comprehensive, but there is no video walkthrough. The licences (GPL 3.0 for designs, CERN OHL v2 for hardware) both allow commercial use. The frame is mostly laser-cut steel plate that you have cut by a vendor from the supplied DXFs and then MIG-weld, with a drill press, band saw and clamps; no milling machine is listed. Heat comes from eight 125 W steel strip heaters, and control runs on an Arduino Nano ESP32 with K-type thermocouples that also logs temperature and PID data to a microSD card. The biggest gate is welding: if you can MIG weld or know someone who can, this is a serious piece of open scientific hardware. Correction (4 October 2026): we re-checked this page line by line against the project's own repository, documentation and videos, and fixed errors in earlier versions.