UK Based Noob - Metric vs Imperial (I know how long my foot is)

Hi All,

So my Shapeoko Pro is currently flying over the Atlantic to live in the UK and I can’t wait until she gets here. I’ve run cheap CNC’s before, but it’s time to do it properly! Now over here, we’re a bit odd - I design everything in millimetres, but my car travels in MPH, I buy 6x2 timber and I drink pints of beer rather than 568 millilitres.

Already got my Makita RT0700CX4, which is the European product code for the US rt0701c version. I expected our European version would be metric so I can use ER Collets, but no, it’s a quarter inch.

I know Elaire make Makita collets for ER, but am I simply looking in the wrong direction? End Mill Suppliers look like they sell metric shanks, and it makes sense to do everything using one measurement system, but where do I start?

Can anyone tell me the way forward? Do I…

  1. Find a UK supplier for imperial collets and shanks and run designs in MM and bits in Imperial
  2. Start designing in Feet and inches
  3. Find a company that makes a converter for ER like Elaire
  4. Get a new router that accepts metric collets

Apart from this issue, I’m ready to make chips. Any help appreciated!


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You should design using the measurement system which makes sense to you and which is suited to your projects — I switch back and forth, using Imperial measure for anything which will involve thirds or sixths (breaking out a PostScript Pica rule if need be). I’ve done a number of projects in metric and just used Imperial tooling for CAM and just done those measurements in metric (mostly I use metric for CAM anyway), so no need to switch even if you use Imperial tooling.

You will be spending more for Endmills than collets in the long run, so it makes the most sense to work out what sorts/sizes of Endmills are most readily available to you, then order collets to match.

If that is metric, then the Elaire Corp. collets are excellent quality (I have the full set supplemented by the Carbide 3D 1/4" and 1/8" precision collet set) and I can recommend them w/o reservation based on my having the full set and them all working well.

One thing which you may wish to do is to try to hold out on this until the ER-11 collet version of the Carbide Compact Router is released — that should make sourcing collets much simpler. Check in w/ for availability.

One conversion option is to get a 5/16" (8mm) collet and an ER-16 adapter — you have to limit your RPMs, and it increases stickout quite a bit, but folks have been doing it:

for links and a cautionary note:


Welcome to the forum, Kris.

You’ll find quite a few of us Brits on here - some vocal, some silent - but everyone is here to help.

Personally, I use inches and decimals of inches, but it’s what you prefer to work with. In fact, Carbide Create (the design software) can switch almost effortlessly between the two, and it doesn’t really matter to Carbide Motion (the machine control software), assuming that’s what you’ll use.

My go to place for end mills is Rennie Tools, who have always been helpful and have quite a broad range of sizes, although I tend to use Carbide3D end mills for routine work. sell Makita collets and I’m pretty sure @jepho will provide details of other suppliers

Good luck with your PRO, but you didn’t tell us what size you got!

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Another brit here.

I use metric exclusively, but sometimes in designs I also use multiples of 2.54mm that I personally call inches. Mostly because 1" is such a useful size in the real world, and inches tend to come in units of 12, which is such a lovely number compared to 10.

I get most of my non-amazon-throwaways from APT and mostly metric.


@Kris-the-Big-Dog I am an American metric evangelist, and this is what I did:

Spindle Nose Alternatives - Shapeoko - Carbide 3D Community Site


I think that getting your cutting-spinning-thing on to an ER standard is liberating, no matter what you consider to be the correct way to enumerate small distances.

I have ER-11 on my Nomad and ER-20 on my G-Penny ShapeOko spindle, and the world - metric or church-of-england - is my oyster for collets and endmills.



Thanks for your fantastic advice from both sides of the pond. Apologies for not replying sooner, but I’ve had the week from hell, culminating in loosing my footing while building a decking for a friend and ending up with my elbow bone on the wrong side of my skin. I think it’s the universe’s way of telling me safety first when my Shapeoko gets here today (Hope I get a decent courier, as I can’t move my arm!)

The metric/imperial thing seems equally split and I think my big takeaway from this is that there isn’t a wrong answer. I had a good chat on the phone with @jepho for an hour who was a great help! Rennie’s looks like a great place for endmills, and Jeff mentioned them too NewToThis - still need to play with the carbide software, but again many thanks for the advice.

I love the ER conversion you mentioned @veteranbicycle and although I’ve been brought up using imperial while building houses with my Dad, I was born at the tail-end of Generation X and learnt millimetres exclusively. WillAdams is spot on by saying “You should design using the measurement system which makes sense to you and which is suited to your projects” - Jeff put it a different way on the phone, but I’m sure the automated obscenity filter on the forum would ban me if I repeated it here! :rofl:

So, the final decision I that I think is right for me is to get the thing going and cut my teeth with some imperial endmills and the standard Makita Collets, then get the metric adapter and liberate myself like Gerry said.

Again, huge thanks for everyone, and what a great community! I look forward to showing you what happens next.

Cheers! Kris

ps NewToThis … I got the Pro XXL using the American philosophy of ‘Go Big or Go Home’ :ok_hand:


I will note that the ER-16 adapter is not a supported thing — it would be best if you wish to use an ER-collet or similar to:

  • buy a “real” spindle
  • buy the ER-collet Carbide Compact Router when it becomes available
  • get a DeWalt D26200 and the ER-style collets from the Precise Bits folks

Hi Jeff

Half of it has arrived, and the other half is still at Stansted. Many thanks for your kind offer, but no major rush as I need to reorganise the garage too yet.

My injury is literally only skin deep. I fell backwards from a crouched position and put my arm back not knowing my elbow was going at high speed in to the sharp corner of a concrete fence post. Just split the skin and needed five stitches. Doesn’t half sting though! It’ll be perfect again in 7 days, so I’m going to ace the software side until then.


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Thanks @WillAdams . Out of interest, is there a list of ‘real’ ER spindles that will fit the 65mm Z sleeve?

Also, is there a release date on the carbide ER spindle or is it just in the pipeline?

Good for you, Kris!

(PS - You need to put an"@" in from of a user name (e.g. @Kris-the-Big-Dog, or they won’t get notified when you mention them, so I’m sorry for the delay in responding!)

@NewToThis - Thanks Peter, I wanted to @ you, but as it was my first post so I was limited to two at’s. Hopefully, I’m allowed a few more now! All the best…Kris

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Yes, folks have used “real” spindles.

No idea on product development (beyond the occasional bit of testing) or scheduling — that’s @Luke 's bailiwick — I just always tell folks to contact

On the subject of ‘real’ spindles, what most folks here end up with is something from China with a VFD as those are much cheaper than buying a pre-wired solution over here. eBay, AliExpress are good sources, Amazon not so much in the UK as in the US. Having dealt with some of the ‘UK’ eBay sellers I would cut out the middle man and just buy from GPenny on AliExpress.

Something like this for the 65mm mount

They do involve wiring the thing up yourself however which you may, or may not, feel you have the skills or interest to do.

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I’m UK based, I picked up the dewalt router for my Shapeoko 3 and have got a set of 1/4, 6mm and 1/8 (3.175mm) collets that are available from UK suppliers.

I keep the 1/4 for cove bits etc as even if you buy these in metric sizes they have a 1/4 shank and use the metric collets for everything else. Rennie tool supplies have a fair range of end mills in all these sizes at fair prices and they ship really quickly.


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