CNC Pen Lift

by lingib

9.8K8813

Intro: CNC Pen Lift

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This instructable explains how to make a CNC pen-lift from an SG90 servo, two 4mm x 100mm nails, the spring from a ball-point pen, and a 3D printer.

The design accommodates pen diameters up to 14mm.

There is no pen-wobble when the pen is raised and lowered.

Construction is easy … all you need is access to a 3D printer, and basic workshop tools.

All STL and gcode files are supplied.

The estimated cost to build this pen-lift is less than $5.00 USD

Images

  • Photo 1 shows the penlift attached to an experimental plotter
  • Photo 2 shows a close-up of the assembled pen-lift
  • The video shows the penlift in operation

STEP 1: Features

This pen-lift was inspired by https://www.youtube.com/watch?v=hkwSPbMtB84&list=PL3BbZZ9thFk58og0_ueqBFIlwoCzLGlwf&index=64

Significant differences include:

  • Only requires a single bolt
  • Uses a captive nut
  • The V-shaped hole
  • prevents round pens from twisting
  • accommodates hexagonal pens
  • The use of construction nails for the guides

STEP 2: The Servo Housing

The servo housing holds the servo and the two nails that are used for guides

The pen-up servo horn position is shown photos 4, 5, and 6

STEP 3: The Pen Holder

The slot in the side of the pen-holder takes an M4 nut.

Position the nut mid-way down the slot then insert an M4 bolt through the top.

Don’t over-tighten the bolt … a finger-twist is sufficient to hold the pen.

STEP 4: Assembly

Step 1

  • Shorten the nails such that they will just protrude from the base of the servo housing (photo 1)
  • Remove any ridges with a file

Step 2

  • Rewind the ball-point spring around a nail
  • It must be a loose fit
  • Adjust its length such that it will push the pen-holder to the far end of the servo-holder.

Step 3

  • Before inserting the nails into the servo-holder ensure that each side of the pen-holder slides freely under its own weight along a nail.
  • This may require inserting a 4mm drill into the slider-holes to improve the fit.
  • Don’t get carried away with the drill… any unwanted movement here will affect your plotter accuracy.

Step 4

  • Insert one of the shortened nails through the servoholder, through the spring, through one side of the pen-holder, until it protrudes through the bottom of servo-holder (photo 3).
  • The nail is a friction fit at each end of the servo-holder but the pen-holder should move smoothly.

Step 5

  • Insert the other nail
  • The nail is a friction-fit at both ends of the pen-holder but should pass freely through the holes in the pen-holder.
  • Adjust the pen-holder hole sizes slightly if there is any tendency to stick.
  • Don’t get carried away with the drill… any unwanted movement here will affect your plotter accuracy.
  • Done

STEP 5: STL Files

All STL and gcode files are attached

The STL and gcode files were created using Ultimaker Cura 4.13.1

STEP 6: Summary

This instructable explains how to make a CNC pen-lift from an SG90 servo, two 4mm x 100mm nails, the spring from a ball-point pen, and a 3D printer.

The design accommodates pen diameters up to 14mm.

Construction is easy … all you need is access to a 3D printer and basic workshop tools.

All STL and g-code files are provided.

The estimated cost to build this pen-lift is less than $5.00 USD

  Click here   to view my other instructables.

11 Comments

anikilado 8 months ago

I have modified into a larger version for the MG995 servo.

lingib 8 months ago

Looks great :)

ghettobastler 1 year ago

That's great ! I'm actually making a CNC plotter myself, but without using 3D printed parts, and I took inspiration from your design to make a pen lift using a laser-cutter.
Thank you for sharing !

anikilado 1 year ago

can you share your lasercut model?

ghettobastler 1 year ago

There you go ! My version has a longer top part that attach directly to the bearings using zip ties, but it shouldn't be too hard to modify it. You will also need some M4 bolts to keep everything together, an M5 bolt to hold the pen, and a zip tie to attach the servo.
I used lingib's idea for the vertical guides, using two 4 mm diameter nails, and adding some brass tubing on the pen holder to reduce friction.

lingib 1 year ago

You're welcome :)
Thank you for sharing

hmk42 1 year ago

Neat! Any particular reason why you didn't make the FreeCAD files available?
(BTW, I guess you did use FreeCAD 0.20, 2.0 does not exist.)

lingib 1 year ago


Thank you for your interest in my project :)
For some reason the Instructables website refuses to upload "zip" and "FCstd" files.
Private message me with your email address and I will send you a zip file containing all files.
Thanks for the heads up on the typo ... it's now fixed