|Thread: Tingling from Myford Super 7|
Posted by Colin Wilks on 07/10/2019 20:42:32
As stated the lathe is unplugged and will not be used until properly checked. However, to clarify, the tingling I felt occurred some thirty minutes after the lathe had been switched off at the 13 amp socket, although the plug was still in. Prior to this the switch had been operating correctly. Slightly foxed.
It would depend on what sort of distribution board is your house/workshop; RCCD, ELCB, MCBs, wired fuses etc.
As regards the lathe, if the Green/Yellow earth isn't actually earthed to ground (on the machine or the socket) and the neutral is in contact with the metal body of the machine, then I'd expect there to be an ac voltage to ground on the chassis. Probably enough for you to feel it. This would be coming from the 13A socket, so would be the case, regardless of when you last used the lathe.
It would be the case even with your arrangement of turning off the motor at the 13A switch, as very few are double pole switches, so mains neutral is still connected to the machine. (obviously the earth should be too, as that shouldn't be switched)
If somewhere someone has managed to wire an earth neutral reversal, or maybe an earth neutral contact, but with broken earth continuity, the machine would still work live to earth when you turned it on at the wall, rather than live to neutral, as it should.
An early house distribution board might not sense this and trip the circuit.
I should probably ask, are you in the UK?
Edited By peak4 on 07/10/2019 22:01:19
Edited By peak4 on 07/10/2019 22:08:08
Posted by Simon Williams 3 on 07/10/2019 17:08:01
Well, I'm not saying it can't happen, but it would be a strange and significant fault in the supplier's PME system to allow sufficient potential difference between neutral and earth to be detectable by the "tingle test".
The point of PME (parallel multiple earth) is that there are many paths of cross connection between neutral and earth; all of them within a zone would have to fail simultaneously to get a "tingle" as described. Not to mention a few house fires....
No. Go looking for a failed or broken earth connection. The last one I did was caused by the earth pin socket pin not making contact in the socket outlet (13amp socket at the wall).. The machine earth bonding was all connected together but the whole lot was floating from the house earth because the earth pin didn't connect. In that instance the motor was connected to a VSD so that was the cause of the leakage current. If I've understood correctly there is only switchery in this application, so there is no excuse for enough leakage current to cause the symptoms as described.
But that's not the whole problem in this case, you've got a second fault (earth leakage current) as well. Come what may you need an adequate earth connection and this is absolutely a text book example of why.
HTH, do let us know how you manage to resolve this.
Good luck Simon
Yes, been there, which is what I was alluding to in my previous post about checking the wall socket.
When I first bought my previous house, back in '84, I was aware that something in the downstairs ring main wasn't quite right.
It turned out that whilst the walls were apparently dry(ish) on the inside, they had been plastered on top of a corrugated bituminous cardboard like stuff.
There was enough dampness behind it, that the bare earth wire in the grey twin and earth had completely corroded away; I don't mean a bad connection to the 13A socket, the wire had vanished completely.
Edited By peak4 on 07/10/2019 17:51:28
If indeed the motor, Dewhurst switch, and lathe itself are well earthed and commoned together, you might need to get the earthing in the 13A wall socket checked out.
|Thread: Saw doctor|
You could try East Midland Saw Services, in Sheffield, who I used to sharpen several saws for me last year; dovetail, tenon,and hand saws. With the back saws, he even enquired whether I wanted them crosscut or rip; the hand saws were obvious.
The sharpening was fine, but he's not as sympathetic with the handles as I'd like. I think I'd take the handles off at home before posting the blades, always assuming he offers a mail order service.
He should by now have got his Foley tooth cutting machine up and running again, so aught to be able to guillotine old teeth off and re-cut at a different pitch.
|Thread: Sharpening Machine Drills / Clarkson T&C Grinder|
Here you go, I found the bits lurking behind the grinder.
Crude but it works; if I needed to buy the parts to make another, rather than raiding the scrap box, I'd use a single leading shoe slave cylinder, which has two opposed pistons. That way, one would have a through hole to accommodate longer items for sharpening.
I was house/workshop bound at the time, with one leg in a pot.
The individual end mill holder were cut from a length of hex bar I had in stock and then turned and bored to suit, with a pair of grub screws to hold the cutter in place.
For drill sharpening on my Clarkson, I use a cup wheel and a Reliance Drill Sharpening jig.
I'm sure its not as good as the proper Clarkson attachment, but these can be had for about £15-20, rather than £400-600, and I'm a skinflint.
Mine didn't come with a universal head either, though I've since found some old J&S bits and cobbled one together.
In the short term to sharpen the cutters to make something more exotic, essentially all you need is a tubular hole which you can orient and lock in two planes.
For several years, I used a rear brake slave cylinder, bolted to a piece of substantial angle iron. The face that would go on the brake backplate already had a round register, so all it needed was a hole in the angle iron to suit and a couple of curved slots for the fixing bolts. A separate holder was made for each size of cutter to drop in the brake slave, indexing being carried out in the normal manner with a pointed finger on each flute.
Yes it was crude, but worked fine and allowed me to get the machine up and running quickly.
Have a look at TheBedroomWorkshop for information on more official methods.
It's the second time I've mentioned a slave cylinder recently, I'll see if I've still got it and add a couple of photos further down this thread.
|Thread: Dore Westbury Boring/ Facing Head instructions?|
I picked one up a while ago, but without the advancing bracket; it did however come with instructions etc.
Never got round to using it yet as I've a more conventional head, but will get round to fabricating the missing bit eventually, ready for the facing jobs.
It took a while, but I think I've got a reasonable set of scans of the construction manual and blueprint (cobbled from 4 scans + Microsoft ICE)
PM me with a full email address and I'll send it over.
|Thread: Universal Joint Alignment|
Here's quite a good video on the subject; A some Landrover/Rangerover owners will know, depending on the model, the two flanges are sometimes not parallel. This is particularly true on the front prop only on a 110 or rangerover as the front diff is angled upwards.
|Thread: Battery charger problem|
Posted by Andrew Johnston on 03/10/2019 11:06:12
I'm not sure why the batteries in the OP's case are phut. One of the quickest ways to kill a lithium cell is to over-voltage it, but as I understand it the hack charger was a lower voltage than required?
Indeed, so effectively it may have sunk even more current from the cells, taking them below the minimum voltage threshold for the correct, higher voltage, charger.
As mentioned above, a cell with too low a voltage might not even be recognised by a good charger.
I'm guessing that this is part of the protection to prevent a lower voltage battery pack being overcharged in a higher voltage charger with disastrous results.
When I've had one go below this voltage, and I know I'm using the correct charger, I've used either a stabilised bench power supply, with current limiting, or an IMAX B6 charger for a brief period.
I do mean brief, and not left unattended; just long enough to raise the cells voltage sufficiently so the correct charger will recognise it.
|Thread: Collet sticking in chuck|
Posted by Sandgrounder on 03/10/2019 11:17:51
Thank you all for your very helpful advice which has resulted in me finding the problem, the collet does lock into the nut with a click however it doesn't withdraw the collet, but I found another chuck, a MT3 one, and this nut fits the MT2 one as well, this was assembled the same way and works, I've just tried both a couple of times more and the results the same, the MT2 nut must have a fault, it was just a cheap one but it will suffice now I have a nut that fits.
Thanks for pointing me in the right direction, the Arc Euro page is very good.
John Ketan also sells Ball Bearing Nuts to replace your damaged plain one; as soon as I tried mine, I realised it was money well spent.
|Thread: Slotter identification|
Posted by Rainbows on 02/10/2019 16:37:19
It seems like facebook avoids a lot of the price inflation of ebay, maybe not taking 15% commision helps among other things. But yeah made a lot of recent purchases from it including this one
I saw the photo somewhere on FB, but couldn't remember where.
Just tried a Google reverse image search out of curiosity; it identified it as "rust"
I've no doubt you will get it up and running fine, good luck
|Thread: What is it|
Re, the first one, the table on my Meddings high speed drill sits on a similar boss
This could replace the table, depending on size, and allow a circle of holes at a fixed pcd, adjustable via the dovetail slide.
Is there a sensible number of slots, say 36 to give 10º spacing, or 24 to give a 15º spacing?
Alternatively for holding cutters or saws on a tool and cutter grinder, either for sharpening, or making in the first place.
|Thread: Slotter identification|
I'm sure I've seen that photo before; Facebook?
|Thread: 3 Phase|
Davey, I'm not formally electrically qualified, my electrical engineering skills/qualifications are related to telephone exchanges, but one thing jumps out at me.
It may well be that I'm missing something on the photo(s) of your inverter.
It looks like it's mains fed from two core cable, with no earthing back to the supply side. I'd be inclined to use 3 core, of appropriate size and fusing.
Similarly when you get to the motor end, I'd add another length of Green/Yellow from the motor frame termination back to the main drilling machine itself.
The motor side connections in the inverter look OK at U-V-W + Earth
Personally I prefer to leave the earth tail longer than the phase wires; that way should the cable get heavily snagged, the earth is the last one to become disconnected.
Have a look in my album on here for a way of making a compact ring terminal for the motor end of the 3 phase cable; they are just leatherworkers eyelets.
The inverter end is designed to accept either bare wires or a pin termination; just make sure there's no straggly bits if you use bare wires.
p.s. NDIY beat me to it with less typing.
Edited By peak4 on 29/09/2019 14:50:09
Posted by Michael Briggs on 29/09/2019 13:20:06
Sorry, hadn't looked at Bill's link, Michael
Pleased you did post your photo directly on this forum. I don't like stealing other peoples photos from their web site(s).
Davey, From your earlier posts, I gather you have a "3 phase 240v supply"
I and others have made the assumption that its a 240v single phase in, 3 phase out inverter.
Is this correct and what model and ratings are displayed? What country do you live in?
I understand that some folks may not want to visit another forum, such as MadModder, buy may I refer you to the website of the contributor to that forum who shows a photo of the wiring plate on a similar motor to that which you own.
I'll not deep link to his photo for copyright reasons, but I'm sure you could print it out at reduced size and stick it inside your motor's cover plate for future reference.
Edited By peak4 on 29/09/2019 12:11:51
Old Mart, there's a little bit more to it in that each of the three windings need to be in the correct orientation, but the colours linked to in my earlier post should avoid Davey having any problems.
The motor will run rough and overheat otherwise, as one coil will be working against the other two.
Yes, you should be able to run it off one of the 240v inverters.
There is normally a label on the inside of the cover you removed to expose the wiring.
If it's not there, may I suggest you visit this Mad Modder thread where you will be able to write down the colours of the wires and re-terminate your motor.
Essentially you take Brown White Black off "N" and double them up on Red Yellow Blue, in that order, leaving the "N" terminal spare.
Mesh and Delta, are one and the same in this case.
Edited By peak4 on 28/09/2019 21:16:33
|Thread: Thread Size Help|
Posted by Michael Gilligan on 27/09/2019 20:17:29:
If I recall correctly, the ‘error’ was first made by Canon and has persisted.
The matter under debate is simply what thread Leitz used when the screw-mount Leica was launched. … and as an interesting rider to that; whether Leitz ever succumbed.
Everything I've read thus far, and it's quite extensive since the weather's been lousy, points to Barnack's use of a 39mm 26TPI thread on the Leica II through to the IIIc, and most sources point to it being chosen as Leitz were geared up to that pitch for microscope lenses.
Whilst there are claims it was patented, I've failed to find the original Reichspatentamt which ran from from 1931 to 1940. Since the LTM 39mm lenses were released in 1931, it was about the changeover period from the previous patent office. Post war of course, all German patents were voided as part of the war reparations, hence Leica patenting the M bayonet mount.
I've also tried several other worldwide patent searches, and found several by Leitz/Barnack, but not the relevant one specifying the pitch.
Schneider used to produce lenses, both for Leitz and in their own right; Google searches quote text from their web site referring to 39mm x 26TPI; see first link.
Unfortunately, Schneider have re-vamped the web site since this Google indexing, so the text is now missing. I've even tried using Wayback machine on their old site(s), but there isn't a snapshot at the relevant time. I think I narrowed it down to FAQ-10, but can't find it anywhere.
I'm not trying to force a point against anyone here, but pursuing it for my own interest now.
p.s. Leitz also made various lens adaptors to enable the use of LTM lenses on M mount, such as IRZ00 Part No. 14097, but I've failed to find the spec thus far.
Edited By peak4 on 27/09/2019 23:15:35
|Thread: Album pictures|
Just swapped browser from Opera to Chrome, and still don't seem to get any options to rotate, either on screen directly or with a right click. Am I missing something somewhere?
I can edit an album, but not an individual photo within it, (i think anyway).