Yeti – Electrical Design Part 3

There comes a time in every project when you have to just get a grip and get on with it and damn the consequences and I think I’ve got to that stage with the electrical part of this build. I’m still reading everything I can get my hands on but it seems to just be stopping at my eye balls now.

The plan was to build the control system into the computer case that I have as it is in a full server case. Unfortunately that doesn’t look like it will be possible or at least it might be a very bad idea. The PMDX board provides two different grounds: a PC ground and a board ground. As the manual states, these two grounds may not be at the same potential. The board ground should be the same as the case the board is in – in fact it recommends joining them to help with interference – but that would be difficult to achieve if the case is at PC ground which it almost certainly is. I should probably point out that not only the board but all the other components should be at case ground as well so they would all need to be isolated from the computer case.


The lists below are my shopping list of parts for the electrical system in Yeti. This is a work in progress (as of 2013-12-10) so don’t go rushing out and copying this just yet.

Supplier Part Description Price (ex VAT) Total (inc VAT)
Airlink Transformers Toroidal Transformer – Part No CM1000224 1000VA 230V to 2x24V, £60. Since this is inside same case as the rest of the electronics an electrostatic screen was added at £13. For 70V power supply.  73.00
Airlink Transformers Shipping 10.00
RS Bridge Rectifier – Part No. 629-6320 GBPC3504-E4/51, 35A, 400V, 4-Pin. For 70V power supply. 2.18
E-Bay Smoothing Capacitor (listing) 4 of 100V, 10000μF electrolytic capacitors, 35mm dia, 51mm height. For 70V power supply. 18.56 18.56
RS Bleed Resistors – Part No 485-2243 4 of 10k 2.5W resistor (as a pack of 5). For 70V power supply. 2.16
RS Capacitor Clamp – Part No 203-5698 Nylon 35mm (as a pack of 5). For 70V power supply.  1.80
Chalon Components Fuse Carrier – Part No RT18-1P 4 of DIN mountable fuse carrier one for each of: main system (20A), 70V supply (8A), PMDX (<1A)and VFD (10A). Requires slo-blo fuses. Requires Cartridge 10×38 RT19 Fuses 5.00
Chalon Components Fuse – Part No RT19-8 5 of 8A fuse for 70 V power supply. 2.00
Chalon Components Fuse – Part No RT19-20 5 of 20A fuse for main system. 2.00
Chalon Components Fuse – Part No RT19-2 5 of 2A fuse for BOB. Note smaller value RT19 fuses can be bought in e-bay. 2.00
Chalon Components Fuse – Part No RT19-10 5 of 10A fuse for VFD. Note, also bought 5 of 16A RT19-16 for the VFD as 10A is right at the edge of what the spindle can draw. 2.00
Chalon Components DIN rail – Part No DIN-35 2 of 1m length 35mm Top Hat profile. General mounting. 4.00
Chalon Components DIN Terminals – Part No JXB2.5 40 of 2.5mm cable, 6mm thick, 25p each. 10.00
Chalon Components DIN Earth Terminals – Part No EK2.5 10 of 2.5mm cable, 6mm thich, 75p each. 7.50
Chalon Components DIN Terminal Jumper Bar – Part No J10JB2.5 5 of 10 way jumper bar for JXB2.5 terminals, 88p each. 4.40
Chalon Components DIN Terminal End Cover – Part No JEC2.5 5 of terminal end cover for JXB2.5, 12p each. 0.60
Chalon Components Trunking – Part No DEN2540 3 of 1m length 25mm wide by 40mm high  cable trunking. General cable routing. 6.00
Chalon Components Main Contactor – Part No NC1-2501Z 25A contactor with 3 NO and 1 Aux NC contacts, 24V coil. 32.27
Chalon Components 24VDC Safety Power Supply – Part No BAE0005 24V, 2.5A, 60W. Full Details. 27.50
Chalon Components Relay – Part No FIN-4031-24V DC 3 of 1 Pole SPDT relay, 24V DC coil, 10A rating @ 240V. For 24V latching, limits and faults circuits. 5.85
Chalon Components Relay Holder – Part No FIN-4031-BASE 3 of Base for FIN-4031 relays. DIN mountable. 8.52
Chalon Components E-Stop Button Case – Part No CB4-BS
40mm mushroom twist lock e-stop button. 3.95
Chalon Components E-Stop Button Housing Case – Part No CB4-BZ102 Normally closed contact block for case e-stop button. 1.95
Chalon Components E-Stop Button Machine – Part No NP2-J174 Yellow / Red e-stop button for the front of the machine. Normally closed. 5.95
Chalon Components Start Button – Part No CB2-BA/G Green start button. 0.79
Chalon Components Start Button Housing – Part No CB2-BZ101 Normally open contact block for start button. 1.74
Chalon Components Stop Button – Part No CB2-BA/R Red stop button. 0.79
Chalon Components Stop Button Housing – Part No CB2-BZ102 Normally closed contact block for stop button. 1.74
Chalon Components Power Lamp – Part No BA9LED-230R Power on lamp. 1.68
Chalon Components Running Lamp – Part No BA9LED-230G Running lamp. 1.68
Chalon Components Lamp Holder – Part No CB2-BW06 2 of lamp holders for power and ready lights. 2.70
Chalon Components Fuse Terminals – Part No JXB-RD 5 of. 6.3A Fuse, 20x5mm. For drivers (plus spare for future additional axis). 4.75
Chalon Components Fuse – Part No MCF5 15 of 5A miniature fuse for drivers. Also bought 15 of MCF6.3 as 5A is close to the dirver draw. 2.25
Chalon Components Boot Lace Ferrules – Part No BF250 2.5mm, pack of 100. For cable ends. 1.25
Chalon Components Boot Lace Ferrules – Part No TCEF250 2.5mm, pack of 100, twin entry. For cable ends. 2.75
Chalon Components Spiral Wrap – Part No CAB-06 6mm spiral wire wrap, 10m. 1.35
Chalon Components Case – Part No EKO050520 500x500x200mm steel case. Should fit five drivers and the VFD across the width of the case (full spec).  63.10
RS Door Interlock – Part No 466-176
32A, 3P, 282mm adjustable shaft. 19.87
E-Bay NPN Home Sensor – Part No LJ12A3-4-Z/BX (listing) 4 of NPN NO induction proximity sensors. 4mm detection distance. £1.83 each 7.32
E-Bay Limit Switch – Part No LJ12A3-4-Z/AX (listing) 6 of NON NC induction proximity sensors. 4mm detection range. £1.93 each 11.58
RS 24V Fan – Part No 668-8833 2 of 24VDC fan, 68m^3/h. 12.32
RS Fan Filters – Part No 713-4396 4 of (2 input, 2 output). It’s possible to get these a lot cheaper but RS were out of stock of the cheaper parts. 21.88
RS Standoffs – Part No 222-402 12mm x M3 standoffs 7.00
E-Bay Volt Meter 0-30VDC Caes bling 2.72
E-Bay Volt Meter 0-150VDC Case bling 3.82
Wire – Part No 2.5mm black sheathed wire.
Wire – Part No 2.5mm red sheathed wire.
RS Shipping 0.00
Chalon Components Shipping 0.00
E-Bay (CCS-UK) 2.5mm^2 Cable 5m of each of red, black and green / yellow cable. 11.97
Cromwell Machine Screws Assorted M3, M4 and M5 machine screws for mounting items (far more than required). 13.03
Screwfix Nuts and Washers Assorted M3, M4 and M5 nuts and washers (far more than required). 15.26