Recommended Scales and Touch Probes

Picture of some of the most common optical and magnetic DRO scales.

We don't sell DRO scales directly to avoid unnecessary markups and shipping costs. Instead, you can purchase the scales directly from the supplier. Based on our experience, testing, and feedback from TouchDRO customers, we have compiled a list of recommended scales and suppliers.

Please note that the ratings in each list are in relation to other scales in the same category. I.e. a 4-star capacitive scale is not the same as a 4-star optical scale.

Table of Contents

Optical/Glass Scales

Optical DRO scales (also called "Glass Scales") use a precision glass encoder strip that is read with an infrared sensor. They are commonly available with 5μm and 1μm resolution but can be specially ordered with sub-micron resolution. The effective resolution is the same as nominal resolution. Glass scales offer an excellent balance of price, accuracy, and reliability, and are virtually maintenance-free if installed correctly.

For most hobby and small commercial machine shops, optical DRO scales from well-known Chinese brands would work well. A good street price range for brand-name Chinese optical DRO scales is between $130 and $200 (including shipping), depending on the length and resolution.

Scales that sell for under $70 with included shipping (regardless of the brand name) are usually quality rejects or production overruns from larger manufacturers. Although the low price is very enticing, it's best to avoid these scales. Many TouchDRO customers reported problems ranging from incorrect pinouts to missing components or damaged encoder glass.

Recommended Optical Scales

  Models Rating Price Range Notes
Acu-Rite SENC 150 (full size)
SENC 50 (miniature)
$600-$1200 "Gold standard" of DRO scales, but expensive.
Excellent accuracy, reliability, and after-sales support.
Usually come with a single reference mark in the middle of the scale, but other options are available.

MSC Direct has good prices and availability.
Ditron All optical scale models $150-$300 Good quality control and after sales support.
Very good accuracy and reliability.
Reference marks every 50mm (Single mark available upon request).
We hear a lot of good feedback about Ditron from our customers.

There are many fakes on the market.
Best to purchase form the official Ditron store on Amazon or eBay.
Aikron AKL - full size
AKM - medium
AKS - miniature
$80-$400 Good quality control and after sales support.
Very good accuracy and reliability.
Reference marks every 50mm.
We hear a lot of good feedback about Airkon from our customers.

Purchase directly from Aikron's website.
Shipping to the USA can be expensive.
Shipping rates to the EU seem to be better.
Sino KA500 - medium
KA200 - miniature
$80-$400 Genuine Sino scales are good, but most Sino scales on AliExpress/eBay are counterfeit.
Very good accuracy and reliability.
Reference marks every 50mm.
Overall good feedback from TouchDRO customers,
but many issues with Sino scales from AliExpress.

Best to purchase from the official Sino store.
Vevor Full size glass scales $70-$150 Vevor sells rebranded scales from unknown manufacturers.
Due to poor quality control, the accuracy can range from very good to unusable.
Vevor's after-sales support is notoriously bad.
ToAuto Full size glass scales $70-$180 ToAuto sells rebranded basic optical scales on Amazon.
Quality control appears to be a bit better than Vevor, but cosmetic fit and finish is average.

Magnetic Scales

Magnetic DRO scales use a magnetic encoder tape that is read by an array of Hall effect sensors. They are usually more compact than glass scales and are very easy to cut to size. The main downside is that magnetic scales are inherently less accurate than glass scales. High-end magnetic scales (Newll, Sony, etc.) typically have declared error of ± 10μm over 1m of travel. On the other end of the spectrum, some inexpensive Chinese scale models have cyclic errors that measure in tens or even hundreds of micrometers.

IMPORTANT: After the installation, magnetic scales have to be thoroughly checked to ensure their accuracy. Instructions are provided in the TouchDRO calibration video.

Note about Magnetic Scale Resolution

Magnetic scale resolution should be taken with a grain of salt. The effective resolution of most magnetic scales (including Newall, Sony, etc.) is around 10μm; higher output resolution is often achieved by interpolation in the firmware. The exceptions are Chinese scales, which use coarser 5mm tape for 5μm scales and 2mm tape for 1μm models. Consequently, 5μm Chinese scales are much less accurate than their 1μm counterparts.

Moreover, real-world resolution and accuracy are affected by a combination of gradual/linear, cyclic, and random errors. A gradual error affects large workpieces and can be reduced by calibration. Cyclic and random errors are much harder to compensate for and have a much worse effect on overall system accuracy. As such, scales with gradual error are significantly more accurate than scales with cyclic and localized random errors.

Recommended Magnetic Scales

  Models Rating Price Range Accuracy Notes
SpheroSyn TTL
MicroSyn TTL
(models xxx-TT)
$600-$1000 ±10μm over 1m of travel.
The error is very gradual with undetectable cyclic component
Arguably the best magnetic scales on the market.
Excellent after-sales support.
Exceptional environmental protection; can work fully submerged without loss of accuracy.

Scales come without a DB-9 connector, which you will need to solder to match the DRO pinout.
Reader - LM10/LM13
Scale - MS10
$300-$450 ±10μm over 1m of trave The error is very gradual with minor cyclic component. High-end scales with a relatively affordable price.

RLS scales are configured and built to order.
Recommended configurations: Scales are made in Slovenia, but RLS ships worldwide.
Magna S1/S2
$250-$350 Stated accuracy is ± 10μm over an unspecified distance.
The scales have moderate cyclic error.
Very good value - performance close to RLS but price is about 25% lower.
Scales are made in India .
1μm and 5μm models use the same scale and reader and differ only in factory-programmed interpolation factor.
5μm scales recommended; there is no real benefit to buying a 1μm model.

In the USA, DROPros is the main supplier:
Phone: 707-452-8434 Website: Email:
They offer excellent support, but often don't have individual scales in stock.
MagXact $900
for set of 3
Same as EMS These are rebranded Electronica/EMS Magna S1 scales.

Precision Matthews has excellent after sales support.

Purchase from
Machine-DRO EH-01
TP-05 tape
Cover strip
$200-$350 Stated accuracy is ±10μm over 1m.

The scales have low cyclic and random errors.
Scales appears to be custom made for Machine DRO.
Fit and finish are good.
TouchDRO customers’ feedback about M-DOR is mostly positive.
EH-01 and EH-05 differ only by the factory-programmed interpolation factor.
5μm scales recommended; there is no benefit to buying a 1μm model.

Pinout compatible with Ditron/Sino.

Machine DRO is located in the UK, but ships worldwide.
Ditron Full Size Magnetic Scale (1um) $165-$475 Stated accuracy ±15μm over an unspecified distance
Tested accuracy for 1μm scales is closer to ± 25μm over 1m
Scales have very pronounced cyclic and random errors
The fit and finish and quality control are very good. Ditron offers reasonably good after sales support.
Readings are repeatable.
5μm scales not recommended.
Recommended to purchase the scales from Ditrons official store on Amazon or eBay
Sellers on AliExpress often use low quality magnetic tape to cut costs.
Airkon MSR2000 (1um) $135-$270 Stated accuracy is ± 25μm Scales have very pronounced cyclic and random errors Fit & finish, and quality control are very good.
Aikron provides good after sales support.
The scales are very forgiving to misalignment.
Readings are repeatable.

5μm scales not recommended.

Pinout compatible with Ditron/Sino.

Capacitive DRO Scales

Capacitive scales are sometimes used for measurement of the quill travel on many table top milling machines. They are not ideal for this application due to lower resolution and high noise sensitivity, but on some machines are the only viable option.

TouchDRO TDA-400 and TDA-420 adapters (starting with firmware version 3.2) support BIN6 (used by many Chinese calipers and scales) and Mitutoyo SPC (used by Mitutoyo, Starrett, iGaging Absolute DRO and some others).

Recommended Capacitive Scales

  Models Rating Price Range Notes
Mitutoyo 053906B $320-$350 Good:
Very repeatable
Excellent quality and reliability
5V signal level immune to noise

10 Hz refresh rate
0.0005"/0.01mm resolution
Can't be powered externally
Screen must be on to send data

Requires a custom connector and Mitutoyo 905338 connection cable.

Amazon usually has the best price, but this scale is sold by many other vendors.
iGaging Absolute DRO+ $70 Good:
Less expensive than Mitutoyo
Ground stainless steel frame
3V signal level less sensitive to noise
Can be powered externally

Inconsistent quality control
10μm resolution
10 Hz refresh rate

Requires a level shifter to connect to TDA-4xx adapters

These scales are sold by AnyTime tools on Amazon. TouchDRO customers had mostly positive feedback about this vendor.
Shahe 5403-300 $39 Good:
Very inexpensive and readily available
Can be powered externally

10 Hz refresh rate
1.5V signal level very sensitive to noise
Inconsistent quality control
Model 5403-xxx uses extruded aluminum and plastic construction
Model 5401 needs a 5 conductor Mini-USB cable (very hard to find)

Requires a level shifter to connect to TDA-4xx adapters

Sold by SHAHE on eBay.

Touch Probes and Height Setters

TouchDRO TDA-420 supports standard triggering [digital] touch probes and tool setters with NPN or Push/Pull output. This covers the vast majority of hobby grade and commercial touch probes on the market, ranging in price from $50 to many thousands of USD.

To compile the list below, we tested most of the common hobby grade touch probes and a few high-end commercial models. The main criteria we used to include the probe in the list below was repeatability.

Note on Chinese Touch Probes

The most important touch probe parameter is repeatability. Even though a kinematic triggering touch probe is a very simple device, to achieve good repeatability it must have very precisely spaced contact points and spring rate matched to the stylus length and rigidity.

There are many touch probes on eBay and AliExpress in the $50-$100 price range. This is a very appealing price, but based on our testing and feedback from our customers, these low-cost probes are very inconsistent from unit-to-unit, and overall quality control appears to be non-existent. Some had excellent repeatability, and others (some times from the same batch) were completely unusable.

Recommended Touch Probes

  Models Rating Price Range Notes
Renishaw Wired mechanical probes $$$$ Renishaw probes are the gold standard.

New, they are prohibitively expensive, but mechanical CMM-class probes (TP2, TP6, TP20) can be found on the secondary market for $400-$900.

Recommended CMM/digitizing setups; overkill for machine shop use.
Edge Finder - KT3D $$$$ TK3D is a high-end conductive edge finder.

New, it's very expensive, but can be found on the used market for $300-$500.

Drewtronics s5000LED $190 Drewtronics is a USA-based small business; probes are made in the USA.

Offer excellent performance at a very affordable price.
Build quality is very good, and after-sales support is excellent.
The probe has repeatability of ± one encoder count, and generous overtravel protection

Our top pick for USA/North American customers.
Slavtec Waterproof 3D Probe $280 Slavtec is based in Poland (EU); the probes are made in Poland.

Slavtec touch probes offer excellent repeatability of ± one encoder count.

The probes use standard 2mm threaded styli.
The company has very good support via email.

Our top pick for EU customers.


The recommendations made above are based on our own experience and testing and the feedback from the TouchDRO customers. We are not associated with any of the mentioned manufacturers or suppliers. We do not receive any compensation from them but the links to Amazon and eBay listings are affiliate links; this helps us recover some costs of purchasing and testing the scales.