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1/8″ Precision Collet for Makita RT0701 Routers now available

Hi everyone. I’m happy to announce that we now have 1/8″ Precision Collet Adapters for Makita RT0701 Routers available on our store. These collets are specially designed for Makita RT0701 routers which are commonly used on LongMills and other hobby CNC machines.

1/8″ Precision Collet

This collet serves as an alternative to the popular 1/4″ to 1/8″ Collet Adapter that is widely used with routers that come standard with a 1/4″ collet only.

Having the ability to use 1/8″ shank bits is great as

  • It can save money from buying smaller size bits with a 1/4″ shank as 1/8″ shank bits are significantly cheaper
  • It offers a wider variety of bits you can use

In most applications, users should not see any perceivable differences between using the Precision Collet over the Collet Adapter, especially for woodworking where overall tolerances needed for runout are fairly low. However, here are some benefits of using the Precision Collet

Some bunnies to test collets. With general woodworking both types work great.

Routers rely on a certain degree of concentricity when it comes to getting accurate cuts and lower vibration. This means that the center of the bit must align with the rotational axis of the router. We refer to the distance between the center of rotation of the router and the center of rotation of the bit as runout.

Runout plays an important role in how accurately your cuts can come out. Imagine that you have a 1/4″ (0.25″) end mill. If you were to drill a hole with this end mill, you should expect to have a hole that is exactly 1/4″ (0.25″) in diameter.

Now imagine that you have a run out of 0.005″. This means that your hole would cut 0.251″ in diameter instead of 0.25″. In the real world, we should expect a certain degree of runout from any rotating tool, and in some cases, may affect the accuracy of your cutting as well.

Checking the runout on a 1/4″ end mill

I have measured and tested collets to see how they look in terms of runout.

I would preface that the measuring tools that I have aren’t great and aren’t the most precise, but they are generally good enough to get an understanding of the relationships between the different parts. I also have done some real world testing by running some projects with the collets to make comparisons.

Here are some notes:

  • All the measurements were taken on Makita RT0701 routers one was almost new, while the other one has been used for several hundred hours. Runout on both was around 0.0015″ (measured from the shank above the nut)
  • Measuring runout with the 1/4″ stock collet using a 1/4″ bit produced around 0.0015″ of runout. This was actually surprisingly accurate, as this means that there is almost no runout in the collet.
  • Measuring runout with the 1/4″ to 1/8″ Collet Adapter using the stock 1/4″ Makita collet produced around 0.0045″ to 0.006″ of runout.
  • Measuring the runout with the 1/8″ Precision Collet produced between 0.0015″ to 0.003″ of total runout.
  • The runout of both the Collet Adapter and Precision Collet was lowest with the shank seated over the complete length of the collet.

This means that the overall runout between the Collet Adapter vs the Precision Collet can have up to a 0.003″ difference.

In most situations, this difference will have no perceivable impact as 0.003″ is about the thickness of a sheet of paper. However, in some applications, the extra precision may make a difference for example with:

  • Precision metal milling
  • Small engravings and inlays
  • PCB milling
Thickness of a sheet of paper

The other factor to consider is reliability. The Precision Collet eliminates the chance for a user to install the collet adapter incorrectly or in the wrong position. With the Precision Collet, there is no adapter that can fall, and as mentioned earlier, the better the “hold” on the bit, the less runout there is.

The Precision Collet should also reduce the chance of the bit falling out during cutting or being pushed into the router with every plunge cut with its more reliable bit holding.

Fully seating the bit in the collet decreases runout


The 1/4″ to 1/8″ Collet Adapter offers an inexpensive and relatively accurate way to use 1/8″ bits with your 1/4″ router. With most users, the difference will be minor at best. On the other hand, if you want to dive into cuts that require more precision, or want the comfort and convenience of a collet that can go directly into your router without an adapter, the 1/8″ Precision Collet is a great option.

Order yours here: