Glossary entry (derived from question below)
English term or phrase:
taper
Portuguese translation:
(alavanca) de regulação
English term
Portugal
Translating is my life
Native in: Portuguese (Variant: European/Portugal) 
Works in: Spanish to Portuguese, English to Portuguese, French to Portuguese, and 6 more.
taper
1.
Adjust lever on side of clipper for required taper.
TAPER ADJUSTMENT
Adjust taper lever so that the top of the top blade is within 0.8 mm - 1.5 mm to the top of the lower blade.
Proposed translations
Portugal
Maria Teresa Borges de Almeida 
30+ years translating EU documents
Native in: Portuguese (Variant: European/Portugal)
Works in: English to Portuguese, French to Portuguese, Spanish to Portuguese, and 1 more.
(alavanca) de regulação
Brazil
5 years of experience
Native in: Portuguese (Variant: Brazilian)
Works in: English to Portuguese
alavanca de ajuste
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Note added at 29 mins (2024-04-16 23:22:52 GMT)
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Para não repetir, sugiro "ajuste de altura".
Brazil
32 years engineering/law/contracts
Native in: English (Variant: US) , Portuguese (Variant: Brazilian) 
Works in: English to Portuguese, Portuguese to English
Ajuste de conicidade / afunilamento / redução gradual
| agree |
Paulinho Fonseca
: redução gradual
31 mins
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Obrigado, Paulinho!
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| agree |
Clauwolf
14 hrs
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Obrigado, Claus!
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Portugal
Experienced & Qualified Translator EN>PT
Native in: Portuguese (Variant: European/Portugal)
Works in: English to Portuguese, Portuguese to English, Portuguese, and 1 more.
degradê/fade
Em Portugal, usa-se o termo degradê, derivado do francês, mas o termo inglês "fade" ou "corte fade" também já se vê bastante.
No caso da alavanca da máquina em questão, penso que seria mais adequado traduzir para alavanca de ajuste (de altura), apesar de o termo "taper adjuster" ou "taper lever" se referir, obviamente, ao tipo de corte (taper) que esse ajuste de altura permite fazer.
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Note added at 10 horas (2024-04-17 09:29:46 GMT)
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Algumas referências:
https://www.saltgrooming.com/blogs/blog/mens-taper-vs-fade-h...
https://modernbarber.co.uk/how-to-cut-a-taper-with-dean-glee...
https://artisansacademy.pt/modulos-tecnicos-de-barbeiro/
Saudi Arabia
Technical and Marketing Translation
Native in: Arabic (Variants: Standard-Arabian (MSA), UAE, Saudi ) , German , English (Variants: UK, US) , Italian , Portuguese
Works in: English, Arabic to English, English to Arabic, and 3 more.
adjustment lever
Controle de graduação: This means "graduation control" and implies a more nuanced adjustment, which also fits the context.
Ajuste de comprimento: This translates to "length adjustment" and focuses on the outcome of using the taper lever.
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