Category Archives: Tech Stuff

You’re Properly Doing 3D Printing Tolerancing Wrong. Here’s a Better Way.

Do you use 3D printing to make functional parts? Do your printed parts have slight dimensional errors, such as undersized holes? It is essential to take care of this if you use your FDM 3D printer to make precise or functional parts. Here’s the easiest and most elegant fix, using nothing but your slicer and a caliper.

Because the extruded molten plastic gets squashed by the nozzle and also flows outward toward the sides, everything you print is fattened, creating overall oversized prints and undersized holes.

Fortunately, there are ways to fix this flaw. First, I would recommend against these methods, if you currently use them:

Bad methods

  • Compensating by slightly changing the values in CAD: this is cumbersome if you use different printers or have collaborators, and problematic if you work with assemblies in CAD.
  • Changing the size in the slicer: FDM 3D printers generally have undersized ID and oversized OD, so enlarging or shrinking the size is bound to reduce one problem while worsening the other.

The Elegant Way: Horizontal Expansion

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HE400i EQ Correction using Rtings Data

Introduction

I found a frequency response measurement of the HE400i that is more accurate than the ones I previously used in my equalizer settings. I discovered a way to extract the graph data from Rtings.com. Rtings.com has measurements of lots of headphones, and their methodology is one of the most accurate. So, I imported their data into Room EQ Wizard and created an equalizer profile to correct the frequency response of my HiFiMan HE400i.

Measurements and Correction

I came up with the filters manually. I’m choosing not to boost the troughs or over-correct the treble to prevent side effects that arise when any particular listener’s ears don’t exactly match this graph.

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Here’s Why MateBook X Pro Charges Slowly

Exposed charging circuit with shielding cover peeled off. Plugged in, CPU idle.

  • The charging circuit doesn’t have enough cooling and tends to overheat.
  • Since the charging circuit and the CPU use the same heatsink, heat from the CPU gets dumped onto the charging circuit, making it even hotter.
  • The charging rate is temperature-dependent, but the charging circuit doesn’t seem to have a temperature sensor, so Huawei probably went super conservative about protecting the charging circuit and modeled its temperature after the CPU temperature.

Therefore, even when the CPU is a little bit warm, the charging rate thermal-throttles.

I will discuss solutions to reduce this as part my throttling elimination project.

Also, the recent BIOS updates (especially 1.17) seem to have slightly improved the charge rate.

Simple Laptop Cooling Stand with 200mm Noctua Fan

I assembled the two sides of the stand inside-out to make room for the fan.

I hung the fan from the stand using 2 segments of string.

I angled the fan backwards to make the air flow across the bottom of the laptop.

My MateBook X Pro can sustain 2.1GHz on the desk for 5 minutes before shutting off due to VRM overheating (working on solving that right now), but this stand allows it to sustain 2.7GHz indefinitely. As a bonus, I removed the bottom lid altogether and just let the Noctua blow on the laptop's heatsink directly. No thermal throttling at all anymore. 3.7GHz on all 4 cores. I might just use that when my laptop's staying on the desk for a long time.

MateBook X Pro, CPU+GPU full load for 10 minutes, on desk.

MateBook X Pro, CPU+GPU full load for 10 minutes, on stand with fan on.

MateBook X Pro Bottom Creaking Fix

The Problem

The bottom of the Huawei MateBook X Pro makes a creaking or squeaking noise when you lift the laptop by a bottom corner.

The Cause

The noise is not caused by the laptop’s body but by the crinkling of the battery’s wrapping. You are exerting pressure on the battery area, slightly bending the bottom panel and pressing the battery.

The Solution

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