Tumbler Engraving Tips & Tricks #1: Bit Sizing

This winter we’ve been experimenting with our engraving process to lock down the best methods for different materials & cups. In this series I’ll be sharing some interesting tips we learned along the way in a small easily digestible format.

First enjoy this short teaser clip & these beauties that resulted.

How its Done

CylinDraw’s standard engraving attachment is a mount for a corded Dremel Stylo Engraver.

So chosen because the Dremel brand is the highest quality consumer grade rotary tool on the market. (The next step up IMO is dental drills!)

We use the Stylo model specifically because it is so light weight.

Tool Speed Control:

Dremel Stylo has a rolling dial to adjust speed from “1 to 5”, and the product specifications list the RPM to range from “5,000 to 22,000 RPM”. So we approximated the tool speed at each dial setting:

  • dial 1 = 5,000 rpm* (speed may reduce under load @ dial 1)
  • dial 2 = 9,250 rpm
  • dial 3 = 13,500 rpm
  • dial 4 = 17,750 rpm
  • dial 5 = 22,000 rpm

This information is helpful for estimating what the appropriate motor feeds and tool speeds should be. (More on that another time, its easy!)

Bit/Burr Sizing:

The Stylo is equipped with a spherical diamond studded engraving burr. It looks like this:

The smallest burr size we can readily get is a 0.5mm ball end, which can engrave a 0.2mm wide line. (So measured with Mitutoyo calipers & magnifying glass!)

Finer lines always look better, BUT jobs with fine lines take more time because there are simply more paths to travel through.

We tested out larger bits and interestingly found that we could predict the line width using a ratio & known info to predict unknown info.

I.e. a 0.8mm ball end burr was estimated to produce: 0.8/0.5 * 0.2 = 0.32mm line width. The actual line width was measured at 0.35mm!

Since this estimation works so well we can reasonably be sure that a 2mm ball end burr will have an 0.8mm line width (or 2.0/0.5*0.2 = 0.8mm) for example.

We used a 1.0 mm ball end burr on this Mando tumbler because it was so tall I didn’t want it to take forever. Overall I like how it turned out, but I know I can do better!

I think sticking with the smaller bit sizes & spending a bit more time in the DePixelizer software could have make his features pop more. IMO finish quality is more valuable than speed, because after a cup is made no one cares how long it took, only how good it looks! So its best to work at the finest resolutions even if the job takes an hour because of it.

Anyway that’s all for now. Here’s the full video that that short intro clip is based on. It includes the full process of preparing the imagery used on that bunny tumbler and a demo of some new Software V2 features.

Published by EngineerDog.com

Michael is a modern mad scientist. Engineer by day, aspiring entrepreneur by night, and exhausted but loving parent at all hours of the day. He is always experimenting with inventions, small business ventures, and unnecessary home improvement projects. You can follow his adventures on his blog at www.EngineerDog.com

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