How To Improve Your CNC Efficiency With HDU

We all know cutting tools play an important role when using a CNC router. The right cutting tool, speeds and feeds can cut your machining down dramatically and increase the life span of your cutting tool – and we all know finishing a project before the deadline is a great way to keep customers happy.

This is where the close relationship Coastal Enterprises shares with LMT Onsrud comes in handy. LMT Onsrud is a cutting tool manufacturer, specializing in manufacturing tools for high-speed machining of aluminum, plastics and composite materials. Over the years, many samples of Precision Board Plus have been sent to LMT Onsrud to add to the excellent database they maintain for choosing the right cutting bit for the right material.

Why is it so important to set your router to certain speeds and feeds for each bit?

The proper cutting tool, speeds and feeds let you achieve optimum chip load. Proper chip load allows the cutting tool to move in and out of the material quicker, leading to more efficient CNC machining.


Several of our customers have mentioned their machining system is not set up to handle chips and they prefer producing dust when CNC routing Precision Board Plus. According to Gary Burgus, Engineering Technician at LMT Onsrud, if dust is desired the speeds and feeds settings vary slightly.

Cuts are done using the Onsrud 52-624 1/4″ Solid Carbide Two Flute Upcut bit.

Speeds and feeds differ as shown:

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To really dispel the myths between chips and dust, two videos were recently filmed at LMT Onsrud documenting the differences between producing dust and chips when CNC routing PBLT-15. The video shows a CR Onsrud 98HD18 3-axis CNC router cutting PBLT-15 at the settings mentioned in the table above.

PBLT-15 being cut with the Onsrud 52-624 cutting tool to produce chips:

As you can see, running the CNC machine at too high of a speed has a negative impact on the surface of the HDU.

PBLT-15 being cut with the Onsrud 52-624 cutting tool to produce dust:

The cuts seen in this video are much smoother, and in the case of PBLT-15 it’s clear that the smoothest cut can be achieved by using the speeds and feeds settings to produce dust.

LMT Onsrud started in 1945 as Onsrud Cutter Manufacturing Company. They originally produced high speed steel cutting tools for the woodworking industry and were the first in the industry to produce carbide tipped high speed steel cutting tools for hand routers. The business eventually evolved into producing bits for exotic metal and composite machining. In 1998 Onsrud became LMT Onsrud, which stands for Leading Metalworking Technologies.

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LMT is a tooling organization comprised of six individual tooling companies offering a range of products including precision tools and cutting materials for the most diverse applications in cutting and forming processes, as well as tool reconditioning and tool maintenance programs. With locations in Germany, Czech Republic, United Kingdom, China, Korea, Russia, India, France and the United States of America, LMT Onsrud is an industry leader for tomorrow’s tooling technology.

Coastal Enterprises would especially like to thank Fred Phillips and Gary Burgus at LMT Onsrud for all of their filming, photography, logistics and CNC machining expertise. Working together, our goal is to make improvement of your production and machining efficiency a reality!

Achieving Optimal Performance When CNC Routing HDU

What are the benefits of having the correct cutting bit, and proper speed and feed settings on your CNC router?

  • Better Chip Load
  • Less Time Routing
  • More Chips, Less Dust
  • Increase The Life Of The Cutting Bit

We recently had some Precision Board Plus tested by our friends at LMT Onsrud, router bit manufacturers and expert CNC machinists, to find out the best speed and feed rates for specific densities of Precision Board Plus. The information was collected to add to the excellent router bit selector guide LMT Onsrud has, which recommends router bits as well as proper speed and feed based on selected density of Precision Board Plus. You can check this guide here.

We were additionally offered the opportunity to speak with Gary Burgus, one of LMT Onsrud’s expert Engineering Technicians (and the man who tested all the Precision Board) and walked away with some valuable information from someone who has tested hundreds, if not thousands of different materials with many CNC router bits.

All of the cutter bits Gary used were carbide tipped, but it is not necessary to use carbide with Precision Board Plus. Any HSS (high speed steel) cutting bits can also be used.

General Routing Tips for Precision Board Plus:

  • Cut in a conventional direction, Precision Board Plus cuts similar to a foam type material
  • Heavier cuts are generally better, specifically a full diameter or half diameter pass because the tool needs material to grab and cut away. Many customers who are familiar with cutting hard plastic or metal are accustomed to taking light radial cuts. Because Precision Board Plus is more similar to foam, the tools need more material to grab – be sure to leave a 50% radius.
  • Routing to depth is preferable over plunging to depth
  • Always maintain a constant chip flow
  • If you are cutting a large rectangle, or low detail shape, a 2 or 3 flute tool is your best choice. This will maintain a constant speed and feed rate.
  • If the shape you will be cutting is highly detailed, stick to a single flute tool, run it a little slower and keep a constant feed rate.

Gary also provided us with a great example:

Say you are going to cut a highly detailed sun, 20″ in diameter, and and set your CNC router to 10,000 RPM at 200″ a minute. ¬†Because the direction will be changing so many times, a single flute tool is preferable. Even though the settings call for 200″ a minute, realistically the most you will be seeing is 60″ – 100″ a minute. Using a single flute tool will allow for the best chip load and cut.

If you are going to be cutting letters, if they are 2″ or so, a single flute tool is preferable. If the letters are 10″ – 12″ or larger, a 2 flute tool is your best bet for the ideal chip load.

Be sure to check out this excellent guide that LMT Onsrud has for selecting the proper bit (select high density urethane and proper density) at:

This video shows PBLT-30 being routed on a Zund G3 CNC router with the proper speed and feed, talk about some fast routing!

If you have any questions, we offer free technical support and can be reached at: (800) 845-0745.