Member postings for Simon Williams 3

I'm a bit late to the party, but FWIW I'd imagine something like this:

The loop of wire carries a small current of about 2 mA until it is broken, whereupon the RON sounds. At the very least it advertises to the stewards they they need to look over their stall carefully. You can't sit there all day long concentrating on everything, you'd go barmy. You do need to test it periodically say twice a day as it's not failsafe.

If anyone wants the bits to make something like this PM me, I've got only one RON so first come first served. Alternatively if it helps I can point to suitable components on ebay if that's OK with the mod's.

Note there are two basic types of piezo squawkers, one makes a continuous noise, the edgier the better, the other needs an oscillating signal to drive it as it is intended as a low cost speaker. Only the first type is compatible with this simple cct.

I've seen something along these lines with the loop made of sections of coax TV connectors. That way you can have as many sections as you wish. The lengths of cable sold for ear phone extensions with 3.5 mm jack connectors would also suffice. You need something that shouts to the scum bags that there ain't no way you're going to =get away with anything while not becoming the focus of the exhibit.

Is this a hang-over from the days of stove enamel, which, without a baking process, wouldn't reach its potential performance in terms of chip resistance and durability. My recollection is that they needed a short spell at 150 - 200C after initial air drying. Modern car finishing systems appear to often involve cookery.

Cooking modern coach enamel paints (polyurethane or alkyd resin based, i.e. air drying) will tend to soften them, even at fairly moderate temperatures.

Two pack epoxy or cyano-acrylate paints are hardened chemically, and set more expeditiously at an elevated room temperature. Not sure I want to put figures against the permissible limits of this, it depends on too many other factors.

What sort of "paint" are we dealing with?

edited for typo

Edited By Simon Williams 3 on 01/10/2023 10:37:03

Try 1/2 BSP

Rgds Simon

edit Jason types faster n' me

Edited By Simon Williams 3 on 17/09/2023 13:56:16

Machinery skates with a Bridgeport on top loading up a ramp onto a trailer. I hate to be the party pooper but you are right to think this is a mite iffy.

Know any farmers? With a nice chunky front loader on a big green tractor? One each end of your journey maybe?Much more re-assuring.

Otherwise there are specialist machinery movers - if you would like to indicate approx locations for start and finish of this adventure perhaps the combined knowledge of the forum can identify suitable alternatives to Mr LandyLift.

Solution of the circuit for Vc depends on the upstream resistance of the supply as well as all the other stuff. Inrush current of a single phase motor on start-up is about 9 times the Full Load Current, which is why single phase motors are a beast to start on a generator. With an upstream source resistance of typically a few ohms you can very soon see a significant voltage droop at the motor L-N terminals.

So the answer is always going to be an approximation. To a first guess, the squirrel cage rotor is a short circuit when stationary. This is magnetically coupled to the start and run windings, so they also look like a near short circuit until the rotor starts to turn. IF you've got enough oomph in the supply to get the rotor rolling.

If the start winding is effectively short circuited something approaching the full supply voltage appears at the terminals of the start capacitor, which is why it should be rated for the full supply voltage,

Incoming supply is nominally 230 volts RMS, so peak instantaneous supply voltage as experienced by the capacitor is 1.414 times 230 volts = 325 volts as near as the model needs.

However, as a related train of thought I found myself repairing a tumble drier recently, which resolved itself into replacing the series capacitor in a little pcb which controlled the power button latch function. Essentially the capacitor (0.22uF) was in series with the 24volts DC coil of a miniature relay and a bridge rectifier (no smoothing) with 230 volt mains applied to the circuit. So the capacitor was the dropper resistor. Measuring the capacitor revealed it was no longer a 0.22 uF one it had become 0.1 uF and the coil of the latch relay now had about 8 volts dc on it. I can't remember the RMS to Peak conversion factor for a full wave rectified waveform but any which way this wasn't enough to pull in the relay. The capacitor was marked 250 V and one would expect this to be the peak dc voltage rating. I tried a higher voltage capacitor, but it wouldn't fit the pcb, so against my better judgement I fitted an exact replacement. It's famous last words but it hasn't gone bang yet.

Which I offer as anecdotal evidence that the voltage ratings on these capacitors are conservative, though I guess one ought to consider the effects of the circulating currents the capacitor sees, and therefore the effects of heat generated by these currents and the internal resistance of the capacitor, So any old capacitor won't do, it needs to be a motor start capacitor designed for the duty.

Rgds to all

Simon

My bad, but I ought to not let it pass into archive.

My last post (para 3) refers to the reversible gear pair of the "normal" drive train as a 51/17 pair. Afficionados of the art t will know this wrong, and the tooth count is 57:19.

My apologies.

Simon

OK, and congratulations for figuring out the niceties of the routine for uploading photos.

The last but one of your photo's shows the cover plate of the older Mk1 gearbox. The newer Mk 2 gearbox also has a cover, but it has a 2:1 step down gear pair hidden behind it. The import of this is that Myford decided to run the internals of the gearbox at twice the speed of the original design. I would imagine this was a ruse to reduce the torque transmitted by the gears as at that stage of its development the internal gears of the QCGB weren't hardened. Eventually Myford built these gearboxes with hardened gears inside, but that's another story.

Further evidence of this being the old Mk1 slow speed gearbox is in photo 3, which shows that the mandrel gear is 12 teeth. This gear is 24 teeth when driving the Mk2 g'box. I'm assuming that the set-up with the two 51/17 gears between the mandrel and the broad 72 T g'box input gear cuts TPI's as detailed on the g'box top label - i.e. the imperial settings all work out, it's just the metric conversion kit which has screwed things up.

Unfortunately it seems that Myford only ever made a metric kit for the Mk2 g'box, though there were undoubtedly two versions of this kit and so there are two different label diagrams with the accompanying table of gears to use. This appears to have been a cost cutting exercise - that later kit has one less gear in it. AFAIK you can use the banjo with either selection of gears.

If you can fathom out a way of reducing the input speed of the g'box by half I think you will have solved the problem you have encountered with cutting threads of twice the pitch expected. A 120T gear on the leadscrew would do it, but I'm not sure it'll fit in the space available.

There is another solution, for which you don't need the metric kit at all, just a different gear mounted on the mandrel. This is the subject of a whole slew of correspondence on the forum, and if you would like to read up on it this is a good place to start. There is some more related stuff here where the OP was trying to cut imperial threads and finding he was cutting an apparently arbitrary TPI.

If you decide you want to experiment with the idea of changing the tooth count of the mandrel gear let me know, but DON'T buy the 33T and a 34T gears mentioned in the posts I have tagged, they are no use to you and will give you the same problem you presently have. I will explain further in due course though the details are in the threads referenced above.

Hope this helps, in due course do please let us know how you get on.

Best rgds Simon

P.S. This is also relevant, more of the same.

edited for post script

Edited By Simon Williams 3 on 09/09/2023 14:26:05

Can we have a picture of the right hand end of the QCGB please. Also a second pic' of the gear train between the spindle and the broad 72 T input gear to the gearbox.

There is a possibility that you have the old Mk1 gearbox which runs at half the speed of the Mk2. This would give you the fault (double the pitch) you describe. It is recognisable by the shape of the die cast cover over the right hand end of the g'box where the leadscrew comes out.

If it is the case that the old gearbox is confusing things there is plenty of previous to help herein, but to save starting that hare running unnecessarily let's check what we've got first. We can catalogue some links to the relevant info once we know which g'box you've got.

You'll need the instructions to put pic's as jpg's up. Essentially you initialise an album, then upload pic's to the album. Now you can call them into your post on the forum. There is a sticky post with detailed instructions, somebody please add a link cos' I can't find it just now.

More anon Simon

If it's any help I bought exactly the same machine, albeit with an Alpine badge on it, and still have it in my shed, used regularly. It's got its shortcomings as a mill, but it makes an excellent drilling machine.

If you want photo's of how the pulley idler is arranged, also the crank and lifting rack let me know and I can add some photo's to my existing album. This album presently shows a simple mod' I carried out to improve the belt tensioning arrangement.

I'm in West Gloucestershire - nearly South Wales - if you want to visit and take measurements etc you're welcome.

I've changed the motor to 3 phase with VSD which avoids a lot of belt changes, but I wouldn't like to forfeit the low speed/high torque capability of a two stage belt driven reduction.

Is this perhaps served by reference to this thread ongoing?

If you need more info' do please let us know.

And just to finish off, here's the answer to the "S" or "T" prefix riddle:

Snip from Cutwel (Bison) Catalogue

A quick blip on the googlenet revealed we've been here before:

Dickson Tool holders

and also that Dickson were part of the same group as Colchester so it would be pretty natural for a simple re-badge exercise.

Rgds Simon

I don't think the tool post holder height is the deciding factor, it's the centre distance of the vee slots and the height of the tool post itself that determines what to call it. As ever, Tony at lathes.co.uk has the definitive chart here but they seem to be an "S" number not a "T" number.

If the overall length of the holder is 73 mm, then that makes the vee centres credibly 63 mm, which in turn identifies the variant as a T63, previously known as a T1. I have several, all are 43 mm high though they have a variety of tool slots mostly 19 mm though some will accept 22 mm.

That's a re-badged Dickson quick change tool holder sold as an alternative to the four way tool post Colchester also offered. I fancy the business about there having been an alternative tool post is a choice between a four way and the Dickson style. Whether Colchester badged Dickson or made their own others may know, but I can say that I have tool holders which have the original Colchester part number, also genuine Dickson ones and I've bought no-name equivalents including the relatively cheap Indian ones and they all fit the toolpost without any debate about the accuracy of the vee spacing. No wobble.

As for Zoro's suggestion that their tool holders only fit their tool post, I think that's probably them being cautious. I have at least one of their holders, fits my tool post perfectly fine. I believe my tool post is as originally supplied by Colchester, though the badge has worn off long since. But the lathe came from AEA Harwell, so I doubt if they bought anything other than the manufacturer's recommendation.

HTH Rgds Simon

edited see strikethrough first paragraph

Edited By Simon Williams 3 on 06/09/2023 14:11:52

Sorry, but I can't let that one past.

If you reverse a bench grinder there is a good chance the fastening nuts each end will come unscrewed, and let go of one or both wheels.

Exciting, but bad for the nerves.

By the way an old motor such as this needs a proper insulation test at at least 500 volts DC before it can be considered safe to apply mains voltage to it.

RGds Simon

... and for opening your pay packet!

#Michael Horley

Re-reading my earlier post I need to warn you that the function of the Kraus and Naimer switch is achieved by wiring contacts in series and parallel, as well as having a cam internally that moves the individual contacts. They can be a bit of a mind bender to understand. But knowing that the original scheme had:

two contacts (i.e. four terminals) closed in forward, otherwise open

two contacts (again, this will be four terminals) closed in reverse, otherwise open

one circuit closed in off, otherwise open

one circuit closed in forward or reverse and open in off

gives you a fighting chance.

I'm imagining that the last two functions may be contacts wired in series or parallel to give the overall function.

HTH Simon

Edited By Simon Williams 3 on 19/08/2023 00:25:24

#Michael Horley

According to the circuit diagram there is indeed a pole of the Kraus and Naimer cam switch the apron lever operates that is an open circuit when the lever is in the middle position, and closes when the lever is moved down or up for forward and reverse. In the original Colchester control circuit this energises the main contactor. There is another circuit which makes only when the lever is in the centre neutral position. This is wired into the emergency stop/no volt release circuit so it can only be reset when the apron lever is in the centre "off" position so the motor can't restart without a second confirming action.

There are also two poles which close circuits when the lever is moved to the "forward" position, and another two poles which close for the "reverse" position. These switch the motor connections directly, hence these four circuits are wired as a two pole changeover switch.

The High/Off/Low switch under the front of the machine is a different animal, but it also switched the motor connections directly.

I converted mine to VSD operation, so I used one pole forward to tell the VSD to run forward, and another pole to tell the VSD to run reverse, i.e. a single pole changeover switch. The other changeover pole is spare. The pole of the cam switch which was closed in the off position is wired into the E Stop circuit as per the original and gives a "only reset in Off" function as per the original scheme. This forces the user to select "Off" before pressing the reset button, and (with an associated control relay) gives an emergency stop function with a second action to achieve a reset, also a no volt release function. Note that this means the switch carries mixed voltages but these switches are designed for this duty and this is OK.

I used the original speed selection switch to tell the VSD to run at either 50Hz (= Low) or 100 Hz (= High). These were simple contact closures into the VSD digital inputs. Overall I tried to stick to the function of the original controls even if the wiring was different.

By the sound of your description you've only found the circuit which closes when the apron switch is in either run position. This is only part of the story, and either there are more wires to discover or the switch is faulty, or maybe the previous owner had OAWS (Over Active Wirecutter Syndrome) and ripped out some wires he didn't orter.

Unfortunately the wire colours mean nothing as they are not specified on the circuit schematic and I wouldn't have bothered to keep to them anyway. I did this stuff for a living and just followed my own star.

Understanding the Kraus and Naimer cam switch is a bit of a dark art, If someone has been ripping wiring out and not keeping a record of which terminal did what then you're struggling somewhat. However I notice Tony at lathes,co,uk in his notes on the Mk1 Bantam not only identifies the K&N switch part number but also an alternative. That might be worth pursuing. Alternatively Google Kraus and Naimer in your area and find a distributor, they should be able to give you a circuit diagram for the switch function of the particular part number of the switch you have to hand. Otherwise if you want me to diagnose the switch function for you I can (probably) do that (they're a bit of a beast to decode!) but you'll have to remove the switch and post it to me, I'm sure I've seen a function diagram for this switch in the K&N catalogue but I don't have a copy to hand.

Good luck and do keep us posted.

Rgds Simon

Hammerite Kurust Rust Converter or it's equivalent. This is a surface treatments for steel based on Tannic acid, so leaves the base metal a deep navy blue.

Other maker's equivalent preparations give much the same results. Jenolite make one, also Vactan, and Aquasteel.

Loctite also make one but it's expensive though a little goes a long way. I've recently used one called Neutrarust 661 which seems to work. I thought the resulting colour was more dark brown than blue or blue-black, but the part (a wheel rim) was pretty rusty!

Getting an even coating is going to be about cleanliness - try caustic soda rinse first. Maybe an uneven coating can add to the character of the piece.

Do do a show and tell afterwards, please!

Dunno nuffing about the rules in Slovenia, but in the UK one of the fundamental requirements under the Pressure System Regulations is to have a calibrated and reliable means of indicating the pressure in a pressure vessel at all times. I don't believe (though I'm ready to be corrected) that this requirement is relaxed for a vessel below the relevant bar-volume exemption for low pressure/low volume systems. A simple risk assessment indicates that a pressure gauge is necessary.

If I was the insurer I'd want to see such a safety critical feature of the system present and demonstrably correct.

<Edited for minor typo>

Edited By Simon Williams 3 on 10/08/2023 21:27:38

Roger -

If I can offer use of a lathe to make a fresh one or whatever repair you think is appropriate let me know. I'm in Ruardean, less than 10 miles from you. I have sent you a PM with contact details.

Rgds Simon