Upgrading the Genmitsu 3018-pro CNC

Thoughts around upgrading the Genmitsu 3018-pro CNC and a look at what has been upgraded to date. This is a basic CNC machine and very cheap. Let’s start by looking at the basic machine:

Sain Smart CNC Router 3018-Pro

First venture into CNC

The reason behind the purchase is primarily to make brass nameplates for some of the engines, including the boiler door engraving for the miniature traction engine project. However, the more I read about this the more I want to also use this to carve wood in 3D.

Specifications:
  • Effective Engraving Area: 300 x 180 x 45 mm(11.8 x 7.1 x 1.8”)
  • Frame Size: 400 x 330 x 240 mm(15.7 x 13.0 x 9.4″)
  • Frame Material: PF+ Aluminum – extruded aluminium and reinforced plastic panels
  • Z-Axis Component Material: Nylon – in the manual these are describe as Bakelite
  • Spindle: 775 motor, 24V, 10000 RPM
  • Rated power: 60W; Maximum power: 120W
  • Step Motor: 1.3 A, 12V, 0.25 Nm torque (2.2 in lb)
  • Drill Bits: Tip 0.1 mm, 20 degree, Diameter 3.175 mm
  • Supported OS: Windows XP, Windows 7, Windows 8, Windows 10, MAC OS
  • Software: Grbl control(Candle)
  • Power Supply: 24V/5A

Upgrades to Date

I have made a few upgrades. The first was to make a proper spindle and belt drive unit.

spindle and motor arrangement

Spindle Drive Upgrade

The reason for this was down to the play in the spindle. Not surprising really as it uses a cheap 500 series motor with an ER11 chuck mounted directly to the motor shaft. These motors are not really designed for this amount of mass on the end of the shaft. In addition the bearings are simple plain devices.

The ER11 chuck isn’t a very tight fit on the shaft and the slack is made good with a grub screw.

fitting bearings using engineers vice

Z-axis Linear Bearings

The linear bearings on this machine are of a very poor quality. I machined some plain brass bearings. This is an easy upgrade if you have a metal lathe.

My next step is to replace all of the linear bearings with solid brass bearings.

Looking further it is not really the bearings that are an issue, the z-axis rails are under size.

checking linear bearing rail diameter with a micrometer

Linear Bearing Rail Size

The z-axis has a lot of slack/play. After bearing changes I investigated further and found out the standard z-axis rails supplied with the machine are under size. Hence they are unsuitable for the bearings.

These upgrades have improved the quality of the machining on wood, but this machine still won’t engrave metal. This is not due to motor power, it is due to the overall machine stiffness. Everything is just too flexible.

Roundup of Other Upgrades

This CNC is a popular machine and so there are a lot of people upgrading the Genmitsu 3018-pro CNC. Hence I have been searching to see how others have tackled the overall stiffness issues. Ordered 1st is best to last:

  1. Richardsenior.net: Small Chinese Hobby CNC Routing Machines – this page has lots of ideas including a sprung diamond tip drag cutter, apparently perfect for cutting out vinyl. Plus lots of ideas around upgrading the stiffness of the CNC.
  2. Cosmo Channel: UPGRADE Z-AXIS CNC 3018 to improve stability at low cost – increasing the length of the z-axis bearings and adding a bottom bearing to the z-axis leadscrew improves the z-axis stiffness. Not perfect, but better.
  3. Instructables: Upgrade your CNC – this is really a spindle power upgrade to allow it to machine aluminium. OK, but first we need to tackle the stiffness.

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