taig and sherline mills to the UK

Milgo, what's the value of the capacitor? I might be wrong but it looks like a motor start/run type.

Looks like I was wrong, just had a look in the RS catalogue :-O

the guys at simply cnc put it down on the circuit diagram. It seeme

like really high values to me, but i got it anyway. It is rated a

-- milg

----------------------------------------------------------------------- milgo's Profile:

A rule of thumb I was given years ago was " a least a mufti per milliamp" (ie microFarad per mA).

So that looks alright

I also seem to remember that the voltage rating shouldn't be more 10x the working voltage for an electrolytic to work effectively. So that seems OK too.

Have you got some resistance across that cap to bleed off the charge when the unit is switched off? I bet that bugger will still bite a day or two later...

Oh and if you wire up that cap the wrong way round it will do a reasonably good impression of a landmine, blowing chemically impregnated crap all over the show. I've only done that once, fortunately I had the lid on the PSU when it went off.

Steve

Just a quick follow-up to let you know that the software works a treat. Thanks John GeoffH Norfolk - UK

lol, what way is the wrong way? How should it be wired? What do yo

suggest I use to "bleed" it off

-- milg

----------------------------------------------------------------------- milgo's Profile:

Yup, I had motor start capacitors on the brain from reading another thread :-/

That will work very well with the board. I put a 10000uF/63V in mine and getting very little kickback from the 1.75A motors (it's one of those low inductance / low ESR audio types). There's a pic etc:

Nice :) Well seeing as I have earth coming into the PSU I am just goin

to wire everything in to that for grounding. What holding torque ar your motors? I was reading up about stepper cables, and came across something abou grounding the shielding, would that be correct? Thanks for all the help :

-- milg

----------------------------------------------------------------------- milgo's Profile:

Not high, about 116 oz/in. I got four of them off ebay for £20 the lot and had them surface shipped from the US for shillings...

To be honest, I don't think they will be man enough for the job but I'll have to try them out on the mill and see. I won't have lost a lot if they're a total flop.

wow good deal :) Yeah that one you got is quite heavy I should think. A

least they are a start, you can easily upgrade the motors later. I hav been quite busy today progressing my conversion, going for the slow bu steady approach. Here we have all the stepper wire joins. I decided to try those crimp and they seem to have done the job nicely. I used the opening end of m wire strippers to make the 3 large dents. [image:

-- milg

----------------------------------------------------------------------- milgo's Profile:

No, that's wrong.

Usually the capacitor+ goes to the supply+, the capacitor- goes to the supply- (which is probably also ground).

eh? So what would be the point in that? Surely it isnt doing anything i

you just have it on its own closed loop? Or do you mean to have the on the supply to the + on the capacitor, then another cable from the on capacitor going into the + on the driver board and then the - on th psu wired to the - on the capacitor and then a wire going from there t gnd on the board

-- milg

----------------------------------------------------------------------- milgo's Profile:

What's the point of what? It would be *a lot* easier to follow your posts if you quoted enough of the previous message in your reply to establish the context!

Regards, Tony

The theoretical connection is +Ve supply terminal to +Ve capacitor terminal and -Ve supply terminal to -Ve terminal on the capacitor. If I understand the layout discussed in this thread so far the practical connection is to wire to a common earthing stud (forming the centre of a star wired config), which in a simple power supply scheme would be connected to the -Ve supply rail, the -Ve on the Cap etc.

As for a bleed resistor, I think 3.3k 1/2 Watt across the capacitor terminals would be good practice, though not essential and you should take the views of others. I still don't have a delivery date for my mill so you are way ahead of me!

Steve

I must admit to having lost the plot as far as this thread goes, Milgo never seems to post any of the thread he is replying to, which makes for a disjointed read unless the previous posts are familiar enough to recall what was said.

Presumably, Milgo has a newsreader that allows quoting of the post he is replying to??

Peter

-- Peter & Rita Forbes snipped-for-privacy@easynet.co.uk Engine pages for preservation info:

It seems I havnt made myself clear. I am using a enclosed psu (not hom

made) and connecting the capacitor between the psu and the drive board. I understand that I have to connect the positives and negatives but I am unsure where I have to go from there. Here is a close up of the wiring. Brown positive and blue negativ (obviously). [image:

-- milg

----------------------------------------------------------------------- milgo's Profile:

That looks right to me. The capacitor is connected in parallel with the supply lines as it should be. I can't see the + and - on the capacitor, but you've already been warned about the potentially dire consequences of getting that one wrong.

Use the blue "quote" button.

Tim

Cheers for the confirmation. I checked with the bloke from xylotex b email and he said the wiring was correct as well.

Peter I do not use a news reader no, I did try google but it wa painfully slow at updating and the threads made no sense because th posts were in the wrong order

-- milg

----------------------------------------------------------------------- milgo's Profile: