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Controller Hardware

Controller HardwareThe Estlcam controller firmware can be installed on boards with with ATmega328 (e.g. Uno and Nano) or ATmega2560 (Mega) micro controllers. While an Arduino board and a simple screw shield is all that is required, there are numerous CNC specific shields and controller boards with added features (optoisolation, adjacent sig/gnd pins, etc.) that can make them more reliable. While there are only a few Estlcam specific boards, Estlcam can be installed on most? GRBL boards. The primary difference is the processor pin layout and Estlcam can be configured to use Estlcam or GRBL layouts.

The Estlcam Terminal Adapter is the only Estlcam specific control board (pictured), but it is only available in the EU (~50EUR) unless you make it yourself (complete open source documentation available)... Shipping to the US is more than the cost of the board, but it is ...once again (nov21) available from Rocketronics (~$113 shipped).

The only ready-made (or kit) Estcam specific shields, that I know of, are available from ArduinoClub.de (Germany). Tonio Grawe provides all the documentation needed to make a basic (no isolation) Estlcam Uno shield. The YRCNC UNO shield w/ isolation looks like a good Estlcam compatible GRBL shield, but it's ~$83 when shipped to the US. I'm too cheap so my latest DIY is a custom Nano shield

Controller Hardware...Slightly off topic at this point, but I noticed that at the end of the Estlcam controller page Christian mentions increasing the responsiveness of the controller by having Windows check for new data from the controller more often than the default 16ms. This appears to only be an option with the FTDI USB2serial driver, i.e. the Estlcam FT230XS and Nano (and old Mega) FT232R (right) chips. The Uno and Mega 2650 use the Atmega16U2 (older = 8U2) and most of the cheap Arduino clones use a cheap CH340 chip (left) which has no latency option.

While a common recommendation is to set the FTDI USB2serial chip driver to 1ms intervals (e.g. Digi), FTDI themselves do not recommend 1ms because it "is the same as the USB frame length"*. SeaLevel does "not recommend setting the latency timer below 4 msec" and 4ms is apparently the latency of the Uno Atmega8u2 (no hits on the 16u2) so 4ms sounds like a good starting point... Somehow I missed that Christian suggests 2ms. I have no idea when/if the extra I/O might be an issue.
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Nano Shield

ShieldsWith no relatively inexpensive Estcam (or GRBL) pinout shields available to the US I've been making my own. The pictured Nano shield (w/o Nano) is the latest and currently supports drivers, probe, DC-AC relay/VFD run and VFD speed - all but the probe are isolated via external optocouplers (e.g. spindle run and PWM). While I have no need for them, I may add a daughter board for isolated limit switches (via 6 pin stacked header).

While I had been using pins and plugs and was planning on upgrading to latching plugs, the layout seemed to work better with screw terminals (the driver gnd pins/plugs were an as-built change). Especially on the crowded top row, using crimp ferrules makes it much easier to (re)hook things up reliably. The primary purpose of the design was having the signal and ground terminals next to each other to maximize shielding and minimize mess (not possible w/ a basic screw shield).

Estlcam USB errors* motivated me to rewire everything with shielded cables. I used two shielded pair 22awg sound/security cable for everything not in the drag chain. The cable allowed shielded signal/ground pairs from all external components (e.g. driver step/gnd and dir/gnd) all the way to the adjacent signal/ground terminals on the shield. The cable was also convenient for shielded 24v and ground pairs between the power supply and drivers - 2 x 22awg = 19awg.

*I used to have rare random days when I would get multiple USB errors. All were triggered when the spindle was under load and the repeats would all happen after a relatively small period of load on the spindle. After trying a lot of things (all shielded wires, VFD signaling optoisolation, etc.), I have reasonable confidence in it having been a grounding issue... It's now been some months of zero USB errors since running wires from power supply earth to the previously isolated X carriages/beam/stepper and the Z plate/stepper.
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Axis Calibration

Axis CalibrationThe calibration distance should be as big as possible, the closer to the axis limits the better. I used what I hope is an accurate steel rule and fixed one end (clamp just before 100mm/axis 0) securely to the spoilboard. Eyeball measurements aren't very accurate so I used a 20 degree engraving bit, a flashlight and a magnifier. Getting the flashlight centered behind the bit, getting the bit as low as possible and rotating the bit (because of the flutes, the tip appears to move from side to side and centering it in the grove can be tricky) all helped.

Estlcam storing the X/Y origin/coordinates makes adjustments to the distance per revolution (DPR) setting easy. My example distance was 650mm (axis zeroed @ 100 and moved to 750 on the ruler) and the controller coordinate read 649.91, i.e. .09mm shy. My 650 distance / my 8 DPR = 81.25 revolutions and 81.25 / .09 shy = .001 so I bumped my DPR from 8mm to 8.001 and after reprogramming the controller the coordinate read 649.99. In reality it was not that simple and the new coordinate may not match the math perfectly due to the changed revolutions (81.24@8.001 VS 81.25@81.25), but you can see how longer distances are more accurate (.09 @ 650 is only .014 @ 100mm).

Ruler distance / DPR = revolutions, (ruler +/- coordinate distance) / revolutions = DPR +/- distance
e.g. 650 / 8 = 81.25, (650 - 649.91) .09 / 81.25 = .001, 8 + .001 = 8.001 DPR
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