CNC Pen Lift

Intro: CNC Pen Lift

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This instructable describes a low-cost CNC pen-lift that:

• accepts different diameter pens,
• supports different pen angles,
• is precise,
• and extremely sturdy.

Only two 3mm bolts are required to attach it to the plotter described in https://www.instructables.com/id/CoreXY-CNC-Plotte...

Photo 1 shows a fibre-tipped pen attached vertically by means of two small "tool clips"

Photo 2 shows a self-inking water-color brush attached at an angle by means of a large "tool clip".

STEP 1: Design

The simple pen-lift shown in photo 1 has five disadvantages:

1. each pen diameter requires a new custom fitted bracket.
2. the pens are prone to wobble as they won't drop if there is friction.
3. a new pen-lift collar is required for each pen size
4. different pen angles are not supported.
5. pencil traces are faint.

Solution to problem 1

What we need is something that automatically adjusts to the pen diameter.

Believe it or not such a device exists in the form of spring-metal "tool clips". These clips come in a range of overlapping sizes:

• 10mm tool clips are suitable for pencils.
• 13mm tool clips are suitable for sharpies and watercolor brushes.

Solution to problem 2

Eliminate the source of wobble by attaching the pen to a friction-less sliding plate.

This is achieved by attaching a tool clip to one side of a metal plate and four V-groove pulleys to the other. The pulleys allow the plate to move up and down a vertical Z-rail attached to the plotter.

Solution to problem 3

Eliminate the need for different size pen collars by bending the top of the plate ... one size now fits all.

Solution to problem 4

The tool clips are held in place by means of a single nut and bolt ... simply angle the center tool clip.

Solution to problem 5

This problem solved itself ... the extra weight from the tool-clip(s), metal plate, and V-groove pulleys ensures that all pencil lines are clearly visible.

STEP 2: Parts List

The following parts are required:

• 4 only V624ZZ V-groove pulleys [1]
• 1 only 80mm x 40mm piece of 18 gauge aluminium sheet [2]
• 1 only 10mm x 3mm x 60mm length of aluminium extrusion [3]
• 6 only 3mm bolts
• 2 only 3mm nuts
• 2 only 9mm threaded nylon spacers
• 2 only 10mm tool clips [4]

[1]

The V-groove pulleys are available from https://aliexpress.com in packets of 20. You should have 4 pulleys left over if you built the plotter described in https://www.instructables.com/id/CoreXY-CNC-Plotte.... The remaining parts may be obtained from a hobby shop or hardware store.

[2]

Instructable https://www.instructables.com/id/How-to-Cut-Fold-S... describes how to cut and fold aluminium sheet.

[3]

18 gauge aluminium sheet is less rigid but may work as a substitute.

[4]

Large pens may require 13mm tool clips.

STEP 3: Construction ... the Z-rail

Two 3mm holes were drilled through a 60mm length of 3mm x 10mm aluminium bar using the drawing template shown in photo1 .

Two 3mm holes were then drilled into the pen-carriage assembly using the holes in the above bar as a template.

9mm threaded nylon spacers were then attached to the pen-carriage assembly using 3mm bolts.

The Z-rail was then bolted to the spacers as shown in photos 2 and 3.

STEP 4: Construction ... the Slider

Cut an 80mm x 40mm strip of aluminium sheet using the the method described in instructable https://www.instructables.com/id/How-to-Cut-Fold-S...

Drill and fold the aluminium as per the template shown in photo 1.

Mount four V-groove pulleys as shown in photo 3. If necessary elongate the 4mm holes on one side of the Z-rail to obtain a perfect fit.

Bolt a tool clip to the center hole and attach your pen. The extra tool clip shown in the opening photo isn't really required but ensures that the pen doesn't move when doing complex plots.

  Click here   to view my other instructables.

Comments

[creativerobo1602]

Tell me wire connection of stepper motor wire colour code

[lingib]

Stepping motor wire colours can vary from manufacturer to manufacturer.

Motor windings comprise two coils. Use an ohm-meter to find the coil ends.

Label one set A ... label the other set B.

My plotters use Big Easy Driver motor controllers which have four pins labelled AABB

Connect the A leads to the A terminals on the Big Easy Driver. Connect the B leads to the B terminals on the Big Easy Driver.

If the motor runs the wrong way reverse the motor connections.

[jeremy.green]

Agree with PKM that this is the only detailed pen lift that can be reproduced acurately. Made and working.

[JohnRow]

I have built this but the pen still wobbles. I've used V623ZZ and 624 pulleys and they all have too much lateral play in the bearings so the pen isn't held rigidly. Where did you get the pulleys from?

[jeremy.green]

Another observation is my z-lift hasnt now got sqaure edges more like 'v' to fit the pully. hard steel - soft aluminium

[JohnRow]

Here's a video of it working. I added the plate at the bottom to try and limit the movement of the perspex plate

[JohnRow]

Thanks for your replies. I've attached some pictures of the one I made. The sliding part is made from a piece of perspex I had lying around. I have actually done all you suggest but still can't get it wobble-free. I think next, I'll try one pulley on the adjustment side and also file the edges of the bar into a V. That sounds like a good idea!

[lingib]

Thank you for your interest in my project :)

I got my bearings from https://www.aliexpress.com/.

You should be able to eliminate the wobble if you fit two V-pulleys to one side of the L-bracket and slightly elongate the remaining holes towards the fixed pulleys.

When mounting the remaining pulleys press each towards the opposite fixed pulley when tightening the nuts.

Before mounting, finger tighten each of the pulley backing-nuts such the the pulley spins freely without any wobble.

[jeremy.green]

From Amazon (V624ZZ Carbon Steel V Groove Bearing Anti-contaminants V Groove Guide Pulley Replacement Ball Bearings For Rail Track Linear Motion System 4×13×6mm 10pcs : Amazon.co.uk: Business, Industry & Science) but individually the bearings have play. What makes it less wobbly is how you tigten them agaisnt the central aluinium bar (z-rail). Think of it more as clamping so the bearing tollerance is taken out. See CityZenToo comment as three bearings would make adjusting easier. Also the holes on my backplate are a little more like slots so i have the ability to adjust the clamping force.

[CityZenToo]

It might be a bit easier to use only 3 rollers instead of 4, with 2 on one side and 1 on the other, centered between the opposite two. This way, you only need to adjust the single roller to get the spacing right.

[lingib]

Good idea ... thank you for this suggestion :)

[jeffreywolberg]

What software of libraries do you use in order to control the cnc and where it moves?

[lingib]

Software libraries are not required for this project.

The pen-lift is attached to my CoreXY plotter described in https://www.instructables.com/id/CoreXY-CNC-Plotter/. The software for this plotter may be downloaded from step 3.

The radial test pattern shown in the video uses the built-in test menu.

[paulmat]

Keep up the posts! I've been following your builds just waiting for some free time to actually try one out (too involved with a whole house reno right now and have a Shapeoko3 to play with anyhow). Thank you for the detailed builds!

[lingib]

Now there's a thought ... a house painting robot ;)

[paulmat]

actually, I'm using the Shapeoko to custom cut cedar shingles, no need for paint!

[voxelator]

Simple and ecfective - nice one mate.

[lingib]

Thank you :)

[tittiamo68]

For my mini plotter, I used a piece of PVC pipe and two screws.

Hello

Tiziano

[lingib]

Your PVC pipe and discarded drive is a clever solution. Thank you for sharing :)

My sliders cost next-to-nothing so I have made several and simply leave the pens and brushes attached. This allows rapid pen/brush changes without the need to reset their heights/angles every time I make a change.