i vs CNC Blue
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
i
This utility app assists machinists with CNC calculations, including cutting speed, RPM, and feed rate. It also provides databases for hole and shaft tolerances, as well as detailed thread specifications.
- Cutting speed calculation
- RPM calculation
- Feed rate calculation
- Hole and shaft tolerance database
- Thread data
- Milling, drilling, and turning operations
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iMachinist is a simple to use CNC calculator app that calculates for you the cuttings speed, RPM, feed rate and more for your milling, drilling and turning operations. iMachinist also includes a database for Hole and Shaft Tolerances and different Threads. Threads Data: - Outer Diameter (max/min) - Pitch Diameter (max/min) - Core Diameter (max/min) - Thread Height (max/min) Tolerance Data: - Zone (Shaft/Hole) - Grade (Shaft/Hole) - Diameter (Shaft/Hole) Cutting Calculator: - Tool Diameter - Cutting Speed - Spindle Speed - Number of Teeth - Feed per Tooth - Feed Rate
CNC Blue
Control your 3-axis CNC machine via Bluetooth using your iOS device. Generate G-code for various shapes and drawings, then send it directly to your Arduino CNC shield.
- 3-axis CNC control via Bluetooth
- G-code generation for shapes (circle, polygon, star, etc.)
- Custom drawing to G-code conversion
- 3D preview of generated designs
- Save and share G-code files
- Direct G-code sending to Arduino
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You can control 3 axis of your CNC milling machine which connected Arduino CNC shield with a suitable bluetooth module for iOS device at baud rate 9600. The application has G code build function modules which are circle, polygon, star, rectangle, arc, draw, gear and spiral modules. Some modules has cut inside and cut deep functions. You can select cut tool diameter. Draw module is another fantastic mode to allow to you can use on milling what you draw on the screen with selectable depth of cut function. Before use this function you have to calculate your CNC working area to fit your drawing to this area. All these modules can capable record builded G codes to a file with module name.For save G codes you have to open "save all calculations to files" switch from setting menu. You can share builded G codes. And you can send received Gcode to Arduino via bluetooth with send page, only load the received .nc file. All builded G codes automatically transfer send page, you need to touch send button to start cnc milling, application will send your Gcode to Arduino via bluetooth connection which you done from the application. You can share with airdrop, e-mail etc. all .nc files on the Files page. And polygon, star, rectangle, arc, draw, gear, spiral modes has 3D view function to show you what you build in 3D view . *IMPORTANT: The CNC Blue application has Stop button, but FOR YOUR SAFETY YOU HAVE TO USE YOUR OWN EMERGENCY STOP BUTTON WITH WIRE CONNECTED TO YOUR ARDUINO CNC SHIELD in case of needed to use.* Why I need to change baud rate to 9600: The application baud rate 9600. Because of that we need to change baud rate of Grbl from config.h file to correctly communicate with Grbl via bluetooth module. How you can set baud rate to 9600; You can find the Arduino Grbl "config.h" file from "documents/arduino/libraries/grbl/config.h" and change baud rate to #define BAUD_RATE 9600 How to connect your bluetooth module to Arduino CNC shield : Bluetooth module "TX" to Arduino CNC shield "RX", Bluetooth module "RX" to Arduino CNC shield "TX", Bluetooth module "VCC" to Arduino CNC shield "3V3", Bluetooth module "GND" to Arduino CNC shield "GND" Pins must be connected correctly to protect your Arduino-CNC shield and bluetooth module.
Screenshots
Verdict
The clearest difference is price: i at Free against CNC Blue's $2.99. CNC Blue's advantage is update cadence (every 3 days vs every 13 months) and review sentiment (50% vs 33%). On rating, ratings volume, ads and in-app purchases there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
i is free to download; CNC Blue costs $2.99 up front. Neither carries in-app purchases, so what you see is what you pay.
On the App Store both sit at effectively the same score — 2.6 for i against 2.5 for CNC Blue. Both are backed by a comparable volume of ratings — 9 and 4 respectively. Written reviews are what separate them: 33% of i's written reviews are positive against 50% of CNC Blue's.
i ships an update every 13 months, CNC Blue every 3 days. The most recent releases landed on November 2, 2026 and November 3, 2026 respectively.
| Parameter | i | CNC Blue |
|---|---|---|
| Price | Free — better | $2.99 |
| Rating | 2.6 (9 ratings) — better | 2.5 (4 ratings) |
| Positive reviews | 33.3% of reviews | 50.0% of reviews — better |
| Number of ratings | 9 — better | 4 |
| Update frequency | Every 13 months | Every 3 days — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Free — better | Paid |
| Devices | iPhone | iPhone, iPod — better |
| Requires iOS | 16.0 | 13.5 — better |
| Further details — not scored | ||
| Size | 8 MB | 1 MB |
| Age rating | 4+ | 4+ |
| Developer | ilan TETRUASHVILI | Mehmet SIMSEK |
Customer experience
i
CNC Blue
In-app purchases
i
No in-app purchases
CNC Blue
No in-app purchases









