illeboc-r's first cnc build in pics and diagrams

[neurofen]

thanks arizonavideo for the offer,i want to use 2 caps in parallel:


if i was to use one cap it would need to be rated at 17280uF and 40V(just under x1.5 the required voltage)

if my maths are correct for capacitors in parallel Ct=c1+c2

I'd need 2 caps rated at 40v and 8640uF

the rectifier needs to be approx 55v-60v at around 20A

sorry , just noticed youre in the usa... lol, im the other side of the atlantic. thanks anyway dude

[neurofen]

ok so after a lot of hunting around and a lot of help i think i'm ready to order the parts for my psu. i've been given a lot of conflicting formulas and am wandering if this is correct:-

i have 3x 1.1v 4a stepper motors so:-

Required VDC 1.1x23 (i've gone for 23x the motors rating) = 25.3VDC [ its been recommended to aim for between 10 and 25x the motors voltage, but no more than 25x ]
Toroid secondary voltage AC should then be 25.3/1.4 = 18.1VAC
Toroid power rating is (4amps x3) x 0.66 x 18.1 = 143.4VA
Toroid output current = 3 x 4amps x 0.66 = 7.92A [gecko recommend no more than 66% the rated motors current rating ]


Capacitors:-

C=(80000xI)/V = (80000x7.92)/25.3 = 25043 uF
I'll be using 2 in parallel so each one should be 25043/2= 12521.5uF


So if the maths is right i've found the following components closest matching:-

Toroid transformer coil = 160VA, 18VAC (secondary), 8.88A
2 x stud moutned capacitors = 40v, 15000uF a piece
1 x bridge rectifer = 25A, 50v


I was a little worried that the transformers output current is .88A more than required. The capaicators are slightly higher capacitance and about 58% greater voltage than required, i hope i havent overdone it.

also when working out the capacitance value wot is the 80000 value? someone else said 60000??

[Boomslang]

That looks good. Now start building so we can see if the smoke comes out.

[neurofen]

lol, im waiting for it BOOM oh ****

[neurofen]

ok so its early days but thats one of the y axis beams with rail, ballscrew and a gantry suppport plate(which isn't finished yet). i'm still a bit worried about using ally box section but as long as i fill it with kiln sand (thanks hemsworth lad ) it reccon it should be ok..

[neurofen]

got a bag of 100 rivetnuts through the post today which was nice and mean while think ive nailed the motor mounts which have been giving me a headache. i can slip them into the support beams over the tops of the rivetnuts and secure them with the top ends of the bolts that run through with a thick rect. washer and nut... and then another couple of nuts further down just to make sure. (the motor mounts not supposed to be through the beam as it shows int he render, i didnt position it properly)

theyre heavy 34nema motors so some thickish 15mm ally with a fairly long 200mm base length ..

ive given myself a bit of room for motor adjustment - length ways along the beam, and vertically, unfortunatley not to the left and right: with any luck the couplings will do the job in that direction

[neurofen]

after a bit of worry about using 4"x4" box section for the gantry decided to go for some 90x90L retrofit extrusion. done some redesigns, ordered some parts. the toroid's arrived and once the other parts trickle in i can actulaly make a start on the psu.

[neurofen]

114mm clearance from the bottom of gantry to the top of the bottom support trusses. should be enough room to get a vise under there just(and whatever its holding)

[neurofen]

why have i never got the right drill bit,. ..


right one psu, which wire goes where then ?

i know the rectifier needs heatsinking (so its strapped to the aluiminum plate with thermal paste), the toroid has a non electrically conducting rubber under pad, but should i put an insulating layer between the bottoms of the capcitors and the aluminium plate they're sitting on?

[hemsworthlad]

Originally Posted by neurofen 114mm clearance from the bottom of gantry to the top of the bottom support trusses. should be enough room to get a vise under there just(and whatever its holding)

If your planning on using a vise You'll struggle to get a vise, material and cutter under there.? Most vise's are nearly this height.!

[neurofen]

i saw a couple of low profile clamp jaws which may fit but doesnt matter if i cant for the time being,. i could make some at a later date, for a start bolt/clamping things to mdf or a metal top will do.

otherwise i can get another 100mm clearance by clamping inside the botom supprt beams , though i might have to reinforce them, and add a bottom plate.. this should be ok . there's about 400mm betwenn the middle and end trusses.



hows the laptop? i'll buzz you later, still in trouble with the girlfriend though

[neurofen]

thought i'd post a couple of gratuitous shots of the power supply as it stands , ive run out of bits. needs a switch, some fuse holders and fuses, a surge limiter, some clips and screws for the caps and more wire. its coming along though, im particulary liking the earth plate block