Meddings MF4 drill electrics

[TobyParticipant @toby]

One thing I haven't worked out yet with this design is how to easily make and fasten a window on the front. ideally it will be openable so I can get to the inverter buttons.

[Alan Waddington 2Participant @alanwaddington2]

I listen to DAB radio through an ipod linked to a stereo in my workshop…….took a while to figure out why it kept turning itself off when I used the lathe or mill, then I twigged both are running from inverters……..

Guess I need to invest in an EMC Filter

[Michael GilliganParticipant @michaelgilligan61133]

Nice work with the SketchUp model, Toby

First thought for your 'window' was to insert magnets … but swarf & cast iron dust may be a problem.

… I would probably just let it slide in a couple of grooves [a bit like a portcullis]

MichaelG.

.

https://en.m.wikipedia.org/wiki/Portcullis

Edited By Michael Gilligan on 15/01/2017 10:26:15

[MWParticipant @mw27036]

Posted by Alan Waddington 2 on 15/01/2017 10:21:53:

I listen to DAB radio through an ipod linked to a stereo in my workshop…….took a while to figure out why it kept turning itself off when I used the lathe or mill, then I twigged both are running from inverters……..

Guess I need to invest in an EMC Filter

It does sound like typical EM interference. It's funny you should mention that because I've got a radio that keeps turning on, rather than off, whenever my neighbour puts the central heating on.

Michael W

[MWParticipant @mw27036]

I can see why Toby wants this pillar drill so badly, because it's a very nice example, you only have to look at the quality of the drilling table to know it's a good one and you'd struggle to get something just as good brand new without spending a huge amount of money on it.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Alan Waddington 2 on 15/01/2017 10:21:53:

I listen to DAB radio through an ipod linked to a stereo in my workshop…….took a while to figure out why it kept turning itself off when I used the lathe or mill, then I twigged both are running from inverters……..

Guess I need to invest in an EMC Filter

.

… Having recently had that PaceMaker implanted …

I need to investigate this quite carefully !!

MichaelG.

[TobyParticipant @toby]

MichaelG: Thanks, I think you are right, magnets and swarf will become a problem. I did think of velcro but that might have similar problems. I like the idea of the portcullis but wasn't sure how to easily stop it dropping on my fingers.

Anyway, after a bit more playing I have come up with this:

So it will lift up and rotate over the top, resting upside down on top of the fan. I need to double check my pivot points and arm lengths etc but I think it is roughly right as shown.

Michael W: Yes, so far it looks like a good one. It is certainly better cosmetically than anything else I have seen 2nd hand and way more solid than anything new in my price range.(ie up to £500). The real test will be when I get it running though……

[Mark CParticipant @markc]

Thanks for the compliment on my installation, there are a number of shortcomings in it but it is OK for my own purposes (it would not be acceptable for an industrial application).

I know you are only using the line in filter but I thought I would put the picture up to show what is needed for a fully filtered setup. The two large filters are the drive side chokes (drive reactors). They take out all the horrible digital synthesised waveform and turn it into a close approximation to a sine wave. I imagine that my installation would be significantly safer for Michael than an unfiltered arrangement! There are a lot of armature electronic engineers on here (and a few professionals I suspect from reading some posts), any of them with access to a oscilloscope can see for them self what the output looks like without a choke and then they can see the improvement if they buy one.

You might also notice I am using the cheap Hungyang inverters – I like them!

Mark

[AjohnwParticipant @ajohnw51620]

What are Huanyang inverters like on the range they will cover Mark. In other words min power on an inverter of a given rating?

I went for Mitsubishi as I have had it for a long time and it was early days for chinese inverters. People seemed to be happy with the cheapest they could lay their hands on not long after a changed my lathe over.

Also thought they would produce a decent manual. Worth while for if there are problems. Mine wasn't expensive. It was slightly used. Not an uncommon problem. Motor not up to what turned out to be needed so both changed. I took care of that by doubling it on my M10. x2 as they fitted lower power motor to the ME's. I didn't 'alf have some problems getting it to fit.

John

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[Steven VineParticipant @stevenvine79904]

If the vfd control panel is very close to the cut out (or in line with it) then a soft clear plastic cover should do the job. Something like the flexible plastic on a see through umbrella, or fold up map cover etc.

Steve

[TobyParticipant @toby]

Mark: You are right about the noise generated on the motor side. When measuring phase voltage and noise on the system we are currently developing I need to put the signals through an R-C filter just to make something meaningful from them.

Just to give people an idea how things work, this is a trace I took of the pwm switching signals to the output transistors on a VFD. If you squint you might just work out there is a sine wave in there somewhere

put through an RC filter you something more meaningful……

Steve: I like the soft plastic idea although it might challenge my metal bending skills trying to get the panel close enough to the front of the VFD

[Alan Waddington 2Participant @alanwaddington2]

Interesting……never realised it might be beneficial to filter the output of the VFD's

Are the chokes commercially available items Mark ?

[Mark CParticipant @markc]

Toby, the my output is better than that after a choke (I realise you are measuring the transistor drive voltage so it may well be different). I don't have any traces from the scope but the biggest error I saw was the shape of the wave (it was a little "stepped" and there was some offset or dwell at zero crossing).

Alan, I get them from Lamond Automation, I have not been able to get them cheaper anywhere else. The make is not important, you just need the correct amperage. These are recommended when using a non-inverter duty motor (as in the motors on our machines) and the justification is that the choke removes the damaging transients that might cause insulation breakdown on older windings and probably helps with the issue of arcing across bearings – not that I have ever seen that but I have been assured it can happen. There does seem to be an improvement in audible noise but that may be imagination.

Using soft plastic to cover the inverter panel might be OK if there are no hot chips flying about but in my workshop it would be ruined in no time!

Mark

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Toby on 15/01/2017 12:01:40:

Anyway, after a bit more playing I have come up with this:

…

So it will lift up and rotate over the top, resting upside down on top of the fan. I need to double check my pivot points and arm lengths etc but I think it is roughly right as shown.

.

Looks good to me, Toby

MichaelG.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Mark C on 15/01/2017 12:28:28:

… to show what is needed for a fully filtered setup. The two large filters are the drive side chokes (drive reactors). They take out all the horrible digital synthesised waveform and turn it into a close approximation to a sine wave. I imagine that my installation would be significantly safer for Michael than an unfiltered arrangement!

.

Thanks, Mark

… It does seem that I need to take this quite seriously.

Chatting to the PaceMaker Nurse, when she checked the settings on 05-Jan, she was quite emphatic that I shouldn't use the Induction Hobs … apparently, now that my Heart is under PaceMaker control, that magical 33bpm that my ventricles had 'on standby' has probably been lost.

Perhaps I could get 3-phase power to the workshop, on prescription

MichaelG.

[Mark CParticipant @markc]

You might want to stay out of our kitchen Michael, the hob draws 10 kW at full tilt… I don't know how far away from it you would need to be but I expect safe distance might be outside the house!

Mark

[TobyParticipant @toby]

Posted by Mark C on 15/01/2017 19:10:58:

Toby, the my output is better than that after a choke (I realise you are measuring the transistor drive voltage so it may well be different). I don't have any traces from the scope but the biggest error I saw was the shape of the wave (it was a little "stepped" and there was some offset or dwell at zero crossing).

A good point. Yes, to avoid confusing others, that top trace I posted is the input to the final drive stage of the inverter. The output will be filtered, either internally or effectively by the motor, so will not be anywhere near as bad as that. I just posted it to show how much electrical noise there is internal to the inverter. How much of that gets out (either to the motor or back through the supply) depends on how good the filtering is – both internal to the inverter and external in the form of EMC and output filters.

Toby

[TobyParticipant @toby]

I realised I had not updated this with the latest progress – the inverter is temporarily on a bit of ply so I test everything out but wired into the original start/stop switches.

Yes, I know the wiring is not exactly to the regs but it will get done properly when I put it all in a box, honest!

After a bit of playing with the inverter settings I was ready for some drilling. First a 10mm drill through 10mm of steel, then follow that up with a very cheap 20mm blacksmith drill. The drill was visibly blunt but it didn't even break a sweat, even when leaning on the star handle I could only get the current indication on the inverter up to 1.85A (no load is 1.7A). IIRC this was on 300rpm.

I do think I need a bigger drill vice though….

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