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Guide
Paste your lathe program and watch it machine the bar in 2D and 3D: facing, G71 roughing, G70 finishing, G75 grooving, G76 threading and parting off, with cycle time and warnings before you cut. It runs in the browser, free and with nothing to install. The page opens with an M24×2 threaded shaft made with those cycles: press play to see how each one works, or replace it with your own program.
G71 and G72 rough the profile in real passes, not as a single line; G70 runs the finishing contour; G73 repeats the profile as many times as R says; G74 and G75 peck in Z and groove in X; G76 splits the thread into passes that get finer and finer. You see where stock is left and whether the profile between P and Q is closed properly.
On a lathe X is a diameter and U/W are incremental, and the simulator reads them that way. Under G96 it works out the rpm at every diameter up to the G50 limit (G92 on Fagor, LIMS on Siemens), which is what drives the time of a facing or parting-off move.
The 3D view spins the bar and removes stock pass by pass. It shows you a reversed profile, a groove in the wrong place or a parting-off move that does not reach the centre in time, before the first bad part comes off.
It warns about a G01 without a feed, cutting with the spindle stopped, impossible coordinates (a lost decimal point), text the control would not understand and a program without M30. Each warning takes you to its line.
It recognises the control when you paste the program. Fanuc and Haas G71/G70, Siemens CYCLE95 and Fagor G68/G69 are drawn as roughing cycles with their passes, each with its own syntax: on a Fagor, for instance, G71 means millimetres, not roughing.
It adds up cutting and rapid moves for each tool using the real G96 rpm and tells you which operation eats the time. Handy to quote a batch or decide what to optimise first.
It also draws on-axis drilling and tapping (G83, G84, G85 and Siemens CYCLE8x) and live-tool operations with a C axis. Under «Examples» there is a lathe part with live tools and a Citizen-style sliding-head part.
Paste the program into the editor (or drop the .nc, .txt, .mpf… file), press play and use the timeline to jump to any block. Click a segment of the drawing and the editor jumps to its line; move the cursor in the editor and the segment lights up.
Frequently asked questions
Yes, this one. It runs in the browser, free and with nothing to install: you can try it without an account, and with a free account you work full screen and save your programs. The program is not uploaded to any server: it is simulated on your computer.
Fanuc and Haas G71 and G72 roughing, G70 finishing, G73 pattern repeat, G74 peck drilling, G75 grooving and G76 threading; G83, G84 and G85 axial drilling and tapping; Siemens CYCLE95 and Fagor G68/G69. Roughing cycles are drawn with their passes and threads with their depth passes.
Look at the 2D view: the passes must stay outside the profile by the U and W allowances, and the G70 finishing pass must match the drawing. If the passes cut through the profile or fall short, check the P and Q numbers, the sign of U and W, and that the first profile block (the P block) only moves in X.
Yes. It adds up cutting and rapid moves by tool and, under G96, works out the rpm at every diameter within the G50 limit. It is an estimate: it does not count acceleration, slow tool changes or stops. To match your machine, use the cycle time calculator, which stores a time profile for each lathe.
Yes. The 3D button on the playback bar shows the bar spinning and the stock each pass removes. You can rotate and zoom the view and follow the program with the timeline.
Yes. It recognises Siemens programs (CYCLE95, LIMS…) and Fagor 8055 ISO programs (G68/G69, G92 S, P… parameters). External CYCLE95 roughing is drawn with its passes; internal roughing, not yet.
Yes. It draws axial drilling and tapping and live-tool operations with a C axis, and under «Examples» there is a live-tool lathe part and a Citizen-style sliding-head part to see how they are programmed.
A diameter, as on nearly every lathe: X50 is a 50 mm diameter. U and W are the incremental X and Z moves. The view shows the largest diameter the program reaches and the effective rpm at every moment.
On a lathe the part spins and the tool moves in the XZ plane, so diameter, constant surface speed and profile roughing cycles matter. This simulator does both: it detects on its own whether the program is for a lathe or a mill and sets the view and the stock.
Keep going
The general simulator, for mill and lathe programs from any control.
Opens with an 8055T lathe bushing: G68 roughing with the profile after M30.
Every code with its syntax and its differences by control, G71 and G76 included.
Work out the G76 or G92 for your thread and paste it here to see the passes.
Match the program's cycle time to your lathe's time profile and break it down by tool.
