Advertisements

MPCNC: Modified Drag Knife Adapter Spring Constant

The bars on the original MPCNC drag knife / plotter pen adapter had a 100 g/mm spring constant:

MPCNC - Plotter pen force test

MPCNC – Plotter pen force test

Making the bars slightly thicker improved their print-ability:

MPCNC knife adapter mods - OpenSCAD model

MPCNC knife adapter mods – OpenSCAD model

The reddish tint marks the new bars, with their location carefully tweaked to be coincident with the stock STL.

Shoving the pen into the scale with 0.1 mm steps produces another unnervingly linear plot:

Modified MPCNC pen adapter - Spring Constant data

Modified MPCNC pen adapter – Spring Constant data

Real plotter pens want about 20 g of force, so this isn’t the holder you’re looking for.

A bunch of plots at Z=-1.0 mm turned out well with the ballpoint pen insert, though:

MPCNC Modifed pen adapter - first plots

MPCNC Modifed pen adapter – first plots

The globs apparently come from plotting too fast for conditions; reducing the speed to 1500 mm/min works better.

Advertisements

,

  1. #1 by Frans on 2018-10-11 - 15:00

    Tell me more about this scale with all the nice physical buttons. Does it annoyingly turn itself off or does it stay on? :-)

    • #2 by Ed on 2018-10-11 - 19:18

      Got it from Harbor Freight long ago, had to figure out the counting function on my own, and it’s worked ever since.

      It shuts down after a minute, which is surprisingly long.

      I’d probably get something similar from Amazon, if only because Harbor Freight is the Home of Single-Use Tools. In your part of the world, you’re on your own! [grin]

  1. MPCNC: Jogging Keypad for bCNC | The Smell of Molten Projects in the Morning

Spam comments vanish. Comment moderation may cause a delay.

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s