[How-To] Recommended DRO Scales - 2024 Edition

[ycroosh]

Hi folks,
I've updated the list of Recommended DRO Scales with more scales with links to known-good vendors. The short version is as follows:

Optical Scales (AKA Glass Scales)

• For milling machine/lathe application 5um scales are more than enough; 1um scales are an overkill in most cases.
• For a surface grinder or a jig borer - 1um scales are a good fit (although, if you run a jib borer and need to read this post - re-evaluate your life choices ).
• Unless you have serious space constraints, glass scales is the de facto choice

If money is not an object - AcuRite SENC 150. These are the "gold standard" of glass scales.
The other (more budget friendly option) are Chinese glass scales:

• Ditron - accurate scales, good quality control and good after-sales support. They have a store on Amazon and eBay. There are many fakes/QA rejects on eBay and AliExpress, so be careful.
• Aikron - accurate scales, good quality control and good after-sales support. They sell directly from their store. Shipping to the USA is pretty expensive, though.
• Sino - same exact scales as Aikron with different part numbers. Real/original Sino scales are very good. People reported decent luck with the original Sino store. most Sino scales on AliExpress and eBay are fakes/cheap rebrands. I get at least one or two emails along the lines "my Sino scale is not working right".
• ToAuto - cheap scales sold mostly on Amazon. Fit and finish is not great, but they usually work. I haven't heard any horror stories.

IMPORTANT: Most Sino scales on eBay and AliExpress are fakes, since Sino is a trademark (not a company) and anyone in China can use "Sino-something". I continue to hear horror stories about bad Sino scales. Even though real Sino scales are good, I'd get Ditron or Aikron to avoid fakes/scams.

Magnetic Scales

• Consider magnetic scales only if you know for a fact that glass scales won't work. I.e. there are space constraints on your machine, or you need to use high pressure flood coolant near the scales.
• There are no magnetic scales that provide read 1um resolution. Best one (Newall and Mitutoyo) are 10um scales at best. Different resolutions are done in the software for legacy/compatibility reasons.
• For no-Chines scales 5um models are the recommended choice for mills and lathes; do not use magnetic scales on a surface grinder unless your DRO supports error correction maps.
• For Chinese scales 1um models have better resolution, since they use finer encoder tape. Real worlds resolution is about 20um at best. 5um scales are VERY bad.

If money is not an object, Newall MicroSyn and SpheroSyn TTL scales (model numbers that end in TT) are great. They are very accurate, the error is very gradual (and easy to reduce with calibration), and support is top notch.
For the rest of us, the options are as follows:

• RLS/Renishaw - LM10/LM13 + MS10 tape is a good choice for commercial use. Price range $300-$450 per axis + shipping.
• Electronica/EMS - MagnaSlim or Magna S1/S2 are the best bang for the buck magnetic scales. 1um scales have the same accuracy as 5um models, so I recommend 5um (they cost less). Price range $250-$350 per axis. Sold by DROPros. DROPros offer great after-sales support.
• Precision Matthews MagXact - rebranded Magna S1 scales. Their 3-axis MX-100 kit is a very good value, even if you decide to upgrade to TouchDRO later. PM has very good customer support (and is a forum sponsor here).
• Machine-DRO - EH-01 or EH-05 readers with TP-05 tape are pretty decent. More cyclic error than Electronica/EMS, but much less than Ditron/Aikron. 1um and 5um scales have the same accuracy, so I recommend 5um to save money. M-DRO is in the UK, but shipping to the USA is surprisingly reasonable. Price range is $200-$350 per axis
• Ditron - (not really recommended) their 1um full size scales are serviceable. Even 1um scales have very pronounced cyclic error on the order of +/-25um every 2mm. Sold on Amazon and eBay (DO NOT buy 5um models or the miniature scales)
• Airkon - MSR2000 smaller for factor than Ditron's full size scales with comparable to full-size Ditron scales. Aikron might be using a bit better tape and slim Ditron models

There are scales from Machine-DRO and RLS that are not on this list, since I haven't had a chance to test them and haven't heard much feedback from my customers. When I get the chance, I will test the missing scales and post the results.

Important Notes

Before I get a pileup of magnetic scale fans telling me that their scales read perfect 1um over the whole lenght:
1. The manufacturers' own data sheets state the expected error. Mitutoyo's are the best in that regard, with +/- 7um over 500mm; Newall and RLS +/-10um over 1m. EMS and M-DRO state 10um over some unknown distance, and Chinse scales are "very accurate", but Ditron has a test plot in their amazon listing that shows very strong cyclic error.
2. I own most of the scales in the lists above, and have tested them on an HP/Keysight laser interferometer stand (that has nominal non-interpolated resolution of 158 nano meters. While Newall and RLS outperformed their specs over 18" of travel (maximum I can measure on my test rig), Ditron and Aikron fell on their face within a few mm of travel.
3. I don't sell scales, and don't have a horse in this race. My motivation is to provide information to help my customers (and anyone else who cares to read this) to get the right scales for their setup.

Note: Amazon and eBay are affiliate links. I don't have any explicit arrangements with any of the vendors or manufacturers, and don't get any kickbacks. I have tested most of the scales in the list (with the exception of RLS LM10; awaiting the shipment of my order).

Hope y'all find this useful.

 

[Winegrower]

Terrific information Yurily. I tried magnetic scales originally for the lathe, attracted by the small size. I could not get accurate enough readings with either a 5um or 1um cross slide setup (there was a 1um magnetic reader option). But the latest attempt is the Sino (or whomever) KA200 glass scale, because the size is now small enough I was willing to use it on the cross slide. I went to KA300 for the longer Z axis. I'm not wholly convinced yet about the KA200 accuracy, and reading your comments I'm concerned that I did indeed get it through Aliexpress. Look at the dimensions of the KA200 though...it's pretty compelling.