[Mike F]

Today, I have been tidying up all the unwanted wires from the toroidal transformer and working out where everything is going to fit. Mike, my electronics friend has a question concerning the grounding of things on the low voltage side of the transformer, including the Geckos.

Are the Geckos and other, low voltage boards such as the 12v and 5v supply, interface board, relay board etc., assumed to be tied to ground via the chassis or should there be a physical connection? Supposing the Geckos are mounted on insulating material - how are they then grounded? Without a physical tie to ground, my electronics friend says they are floating and this is not a good idea.

Mains voltage is tied to ground by the chassis, should everything else do the same?

Don't ask me, I haven't a clue but I hope someone out there can help.

Mike

[Apples]

I too had the same questions when I did mine. I ended up using a wooden box so that nothing would be conductive and cause any sparks. But now I want to put it all in a nice fancy box.

They are a direct connection, as in I have run the -ve to the ground terminal of the gecko. Not as in bolt the wire to the chassis.

Because my box is wood (MDF) I don't have any grounds, even my earth wire from the mains isn't attatched to anything.

Peter
Australia

[Mike F]

Thanks for the reply Peter, I was really expecting quite a few others to chip in but maybe it was too stupid a question. I emailed Mariss, Gecko supremo, and got this reply: It won't make any difference if you: (1) Use a seperate ground and +supply wire from your supply to each drive and (2) connect a single wire from your power supply ground to your chassis. Mariss However, being the electronics dunderhead that I am, it still does not make much sense and I cannot figure out what Mariss is actually saying here. Failing any replies to this, I will just have to plough on regardless.

A bit more progress today. Cutting the eight 'D' holes for the servo and encoder outlets was not a job I was looking forward to as the chassis back is 1.5mm steel. I started by carefully marking the centre of each hole and centre punching it, then drilled a 6mm hole through each. It then struck me that I could make an accurate template from 1.6mm ply using my small Isel CNC machine (it's not man enough to machine steel). The template was stuck over the pilot holes with double sided tape and the holes filed to shape.

All connectors fitted perfectly and a job I was not looking forward to only took just under one hour to complete. Moral is to stop prevaricating and get on with it Photos attached.

Mike

[epineh]

Hi Mike, just read through the ENTIRE thread...Phew!!! Amazing that you started two years ago and haven't given up the project at all, congrats on that alone!

As for your wiring question, personally I would take a positive and negative cable from the power supply to the drives, I don't like relying on the framework for a current carrying function, just the thought of eddy currents, electrolysis (got any different metals touching?) etc.

For a grounding function only then no problem, but for the sake of another wire to the drives, you are covered.

Nice work so far, hope to see motion soon...

Russell.

[fanie]

It won't make any difference if you

Probably because the PSU smoothing sits inside the Gecho's and the maybe 1V drop over wires won't make any difference.

One usually ground the negative supply in an attempt to help minimising static that may (and still will) build up especially when working with plastics.
Static has a tendency to jump where it shouldn't and could abruptly end or disrupt a current process...

Funny how you need the CNC to make CNC stuff... it's like you need the soldering iron to fix the soldering iron eh !

Don't give up.

[Mike F]

Fanie,

I have found the small machine invaluable during the build so far and don't know how some of the zone guys can make such superb machines with just hand tools - there is an incredible amount of talent out there.

I appreciate the comment about static and will do everything possible to minimise the risk. On my small machine, with the extractor working, drawing air through a plastic pipe, there is a huge amount of static build up yet the machine has never missed a beat - must be well insulated.

Mike

[epineh]

Yeah a cnc machine would have been handy while building, either that or a time machine, go ahead in time, cut some parts on the finished machine, then travel back and fit them.

Guess its plan C...

Russell.

[Mike F]

A little progress.

Six out of the seven doors are now finished and I am just waiting for the weals on my back to improve before getting stuck into the machine :violin: (I hope she doesn't read this)

Got the mains side ot the power supply all rigged up and ready for testing - switched on and ----- nothing, not a dickie bird, zilch. Mains indicator light came on and the E stop turned it off so that part was OK but nothing from the transformer. A quick call to my electronics friend had him scurrying down the road.

It turned out that when I joined the windings, from the secondary side of the transformer, I had not removed the shellac lacquer insulation (chair) I told you that electrics was not my forte. You cannot see anything moving - so how can anything be working??? However, it was not that obvious a mistake as my friend did not spot it for some time and the lacquer used was crystal clear so it looked like good, clean copper, unlike some of the other windings that had a red lacquer on them.

Oh well, nothing broken, just a little dented pride and a red face. All sorted now so on with the rest of the wiring. Didn't make my objective of getting the control finished by the end of the week though.

Mike

[epineh]

Lol, fault finding is always best when you actually FIND the fault. Just think, you will be prepared for that on the next machine....

Russell.

[Mike F]

Well, at last some progress on the mechanics. The pictures probably tell the story better than words so just a short explanation.

The X axis ballscrew is mounted directly onto the wall, not the frame, and the first photo shows the fixed, motor end of the ballscrew. Second photo shows the supported end, mounted in a similar fashion. All mountings are temporary, at the moment, and once the nut has been positioned and mounted to the gantry, final adjustments can be made.

The third photo shows that the X axis and Y axis are mounted in the same, horizontal plane. This should help negate any extreme twisting moments when taking heavy cuts. The final photo is an overview of the gantry showing the relative positions of the X and Y axes ballscrews in relation to the whole machine.

Mike

[traviscs2k]

Mike,
Brilliant! I just read the whole thread. Very impressive. I am currently in the process of gathering parts to build a 6' X 3' X 8" machine. Your experience will help me with my build. I believe I'll start a thread of my own.
Regards,
Travis

[Mike F]

Travis,

Yes, please do start your own thread, you won't regret it as the advice you get here is fantastic. Sometimes you have to decide between opinions but generally, someone, somewhere will have the answer to any of you questions or concerns. There is no doubt that had I not found this site, I would not have attempted to build my own machine. It remains to be seen whether my radical design idea works as well as I hope.

A small amount of progress today. I got the motor mounts made for X and Y and a little more done on the control box. The electrics are still causing me some restless nights.

Mike

[fanie]

Yeah a cnc machine would have been handy while building, either that or a time machine, go ahead in time, cut some parts on the finished machine, then travel back and fit them.

This would be very handy... time travel...you'd also know where you'd end up eh ! It's the getting back that worries me !

To add a comment on static, it's not so hard to get rid of, you get static removers, works on the principle of blowing the static air over a high voltage and the high voltage removes the static from the air. Ideally you'd have the 'same' air circulate over the cutter / workpiece but it's easier said than done.

The shellac lacquer insulation is nothing new, but it does help to break down self confidence a bit ! Keeps one humble...

[Mike F]

Progress is in dribs and drabs - managed to get the X axis motor mounted in temporary fashion. The brass straps work well but a slight mis-judgement on the positioning of the aluminium saddles has meant the two pulleys do not quite line up as they should. I will probably re-machine the slots and move them about 20mm to the right. Unfortunately I cannot just move the motor through the straps as the motor terminals get in the way.

Question - How tight should the belt be? If I were to squeeze the belt together, between the pulleys, how much movement should I expect? I appreciate that too much slack introduces quite a bit of backlash so I would expect the answer to be as tight as possible.

It's almost getting to the stage where I can apply some power to the motor and watch the ballscrew revolving - doesn't achieve much but it's fun to do and all helps with the feel good factor.

Oh well, back to the workshop and the bowl of spaghetti that is the control box!

Mike

[epineh]

Nice, dunno 'bout your belt question, but good to see more progress.

Russell.

[bp092]

Fanie,

I have found the small machine invaluable during the build so far and don't know how some of the zone guys can make such superb machines with just hand tools - there is an incredible amount of talent out there.

I appreciate the comment about static and will do everything possible to minimise the risk. On my small machine, with the extractor working, drawing air through a plastic pipe, there is a huge amount of static build up yet the machine has never missed a beat - must be well insulated.

Mike

Static? What are you doing, using pvc/plastic for dust collection? If so I had the same problem hooking up my entire shop with dust ports and floor sweeps with PVC. It's cheap, lightweight but unlike metal it draws tons of static. I ended up getting a kit from woodcraft, wiring the copper wire and then grounding it to the dust collector. Works great, 0 static now

[Mike F]

bp092 ( a bit impersonal! Brian, Barry, Boris???)

Static? What are you doing, using pvc/plastic for dust collection?

Just like you, it was cheap. Lol.!!! Thanks for the tip. Do I assume you are still using the PVC pipe but have grounded the dust collector or have you replaced everything? Do you have a url for 'Woodcraft'?

Mike

[fyffe555]

www.woodcraft.com but a piece of regular copper wire run through the tube with an earth and suitable attachments works fine..

great to see you back on the case again.. I've been looking to see how you've been progressing.

Congrats on the 3rd place too.. any photos of the glider? Presumably the cnc machine is to build those rocket things?

Andrew

[bp092]

bp092 ( a bit impersonal! Brian, Barry, Boris???)



Just like you, it was cheap. Lol.!!! Thanks for the tip. Do I assume you are still using the PVC pipe but have grounded the dust collector or have you replaced everything? Do you have a url for 'Woodcraft'?

Mike

Brian, yes, impersonal. http://www.woodcraft.com/family.aspx?familyid=3536


Surely you can just buy the stuff sep. but for $10 you can't go wrong, especially if you're always on the run like me, just grab it, no hunting around home depot! I'm still using PVC, I'm going to switch to metal when I move into my own commercial space and also plumb an all copper air system.

[Mike F]

Brian,

Just found the same kit in the UK, with slightly less copper wire but was virtually the same image, at http://www.axminster.co.uk/user_sear...Kit-365542.htm Look at the price!!!! £18.35 is about $35 yet 'Woodcraft' sell it for $9.99 - no wonder it's called rip-off Britain

Andrew,

Yes, it's good to get back into the build - it will still be a long haul but at least things are moving in the right direction. Your bit of copper wire down the tube is looking good

Kazakhstan was brilliant - photos of gliders are attached. First is me with my model and the next three are a sequence of one of my models being launched by a team mate. In the last one, you can just begin to see the rocket motor's thrust.

The idea of the machine is to enable me to manufacture the wing moulds for myself without having to rely on expensive, third parties.

Mike