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Member postings for Martin W

Here is a list of all the postings Martin W has made in our forums. Click on a thread name to jump to the thread.

Thread: Bottom of the beginners heap
02/04/2020 00:11:17

Jeffery

You have only got to ask and there are plenty of members of this forum who will be only to willing to help you with any questions you might have. Remember we all started knowing precious little about things but by asking questions and talking to others is how most of us learnt. Also if you don't know the answer then there it is never a stupid question. As Hopper has said post some pictures of your kit and accessories with your questions and you will get answers.

Welcome aboard this crazy ship and good luck.

Martin

Thread: Now is a good time
21/03/2020 10:42:08

Wise words Hopper, no need to say more. I'm lucky to still have my better half after 50 years together but it won't last forever.

Martin

Thread: A very elegant mechanism
21/03/2020 10:33:59

Michael

I must admit that I had never considered why I had not seen a slack spider' web. I expect like many others I had just thought that the silk had enough stretch built in to accommodate movement. This is a brilliant and as you say quite astonishing revelation. Thanks for posting it and I shall definitely look at this type of spider's web in a new light from now on.

Martin

Thread: Sanitizer
19/03/2020 02:16:14

Here is an extract from the World Health Org site.

"It is not certain how long the virus that causes COVID-19 survives on surfaces, but it seems to behave like other coronaviruses. Studies suggest that coronaviruses (including preliminary information on the COVID-19 virus) may persist on surfaces for a few hours or up to several days. This may vary under different conditions (e.g. type of surface, temperature or humidity of the environment).

If you think a surface may be infected, clean it with simple disinfectant to kill the virus and protect yourself and others. Clean your hands with an alcohol-based hand rub or wash them with soap and water. Avoid touching your eyes, mouth, or nose."

The inference is that touching a contaminated surface carries minimum risk, however if you then touch receptive areas on your face this gives the virus the opportunity to enter the body and cause an infection.

The strange thing about any virus is that it is not, apparently, classified as a living organism as it doesn't consume any form of food and can not reproduce on its own. To reproduce it needs to hijack a compatible living cell by injecting its DNA into it. This DNA then takes over the cell function and forces it to just make copies of the virus. Once the cell can no longer function it then ruptures releasing a vast number of replica viruses, think of the scene from Alien but on an epic scale.

From then on it's up to your immune system to identify the virus and attempt to eradicate it, if it fails then you just become another statistic on the news. The good news is that if you survive the infection the immune system remembers the viral fingerprint and is ready to attack the same virus, the bad news is that virus's of this family can and do change their signatures leaving the immune system in the dark when they infect again. The common cold and flu are typical examples and this is why it is virtually impossible to make an effective vaccine for them.

Cheers

Martin

Thread: Internet crash
17/03/2020 19:27:42

In view of the above comments regarding potential internet speed problems I decided to run a speed test. I don't think my connection speed had varied much as it is still running at it's normal pedestrian rates of 216 Mbps download and a miserly upload speed 20 Mbpsdisgust. I will keep a close eye on it and flag up any significant changes regarding the speed thereof. wink 2

Martin

Thread: Printers
09/03/2020 09:34:11

Larry

PM sent re roller cleaning for the MG3200 series printer/scanners.

Hope it helps

Martin

Thread: Coronavirus
06/03/2020 16:03:42

And every sheet of that 50,000 tons of Izal paper will have GOVERNMENT PROPERTY printed on it in a precisely specified place and font. One side rough and t'other smooth, rumour had it that it like that to accommodate both male and female use.! Long gone are the five hole planks in the garden privy with the various types of paper hung on a nail driven into the wood. Mind you were never alone with all the insect life that decided this was a good place to call home. Ah those were the good old days.

Thread: Tooling Choices, identification & WM290 Feed Question
03/03/2020 00:09:25

Dave

Kevlar body armour, hard hat, several pairs of safety goggles and you will be fine.

Thread: Rocket
02/03/2020 18:27:03

Michael

Whereabouts are you, nearest town will be fine, as there might well be somebody local that who could have a look at it and even repair it.

Martin

Thread: WM18 - Broken it again :(
23/02/2020 10:02:22

Duncan

The fans on these motor are standard bladed fans that are pressed onto the motor shaft and are internally mounted. Change motor direction and this changes air flow direction unlike some of the fans that can be seen on power hand tools etc. which are centrifugal and can shift a lot of air through the motor when running at a reasonable speed

Martin

Edited By Martin W on 23/02/2020 10:04:30

22/02/2020 19:27:59

If you use a 12V fan similar to those found in computers then a relatively small wall wart psu will be adequate and they are only a few quid each from the likes of CPC or Ebay etc.

Fitting one directly to the motor could be problematical if there is a motor reverse function as then it would be opposing the air flow from the motor. However being aware of this and not running it for extended periods in this mode would mitigate this problem.

Have fun

Martin

18/02/2020 11:17:20

Dave H

While the use of a power meter might give some indication of the instantaneous power and total power being consumed it is far from ideal and can lead to a very false sense of security. Primarily this type of digital power meter is designed to measure sine waveforms, as one would theoretically expect to be supplied by the energy company, and usually makes a good stab at it plus or minus a few percent.

However when the measured waveform deviates from a a near sine wave then the readings can be grossly inaccurate. This can happen when these meters are used to measure the power being absorbed by a phase switched load as the load current is now a chopped up part of a sine wave. Even what are supposed to be 'True RMS' digital meters have a limited form factor for which they are accurate.

The main problem with these and similarly cooled motors is that when run slowly the cooling becomes very inefficient couple that to being fairly heavily loaded and it spells problems. The current is going to be high, as are the I2R (I squared R) heating effects with limited cooling. I suppose a fairly good analogy would be using a car with the cooling system blocked off and towing a heavy trailer up a long and steep hill. Frequent stops to let it cool down and all would be fine but try it in one go and the engine would soon emit a different type of magic smoke irrespective of build quality.

The use of a Power Meter could be a good idea if they were anywhere near accurate when used under these conditions at least one could monitor the total power being used and set a safe maximum time v power limit.

Cheers

Martin

Edit as post crossed with S.O.D. Dave's post

Edited By Martin W on 18/02/2020 11:19:10

Edited By Martin W on 18/02/2020 11:20:13

18/02/2020 09:56:24

If these motors are run within their specified limits and duty cycles then there doesn't seem to be a problem with overheating. Again it comes down to price and what people are prepared to pay for a machine. Like most products the features and to some extent quality will be set to meet the minimum standard that customers will accept at a given price.

There are many examples of same problem manifesting itself even on tools supplied by respected manufacturers, a classic example was using mains powered variable speed hand drills at low speed and high loads for extended period of time. Result the same problem damaged motors or hot hands plus magic smoke. I don't whether it is the same now but in the past welding sets used to be issued with duty cycle information to restrict self heating and prevent damage to the machine.

Martin

18/02/2020 01:24:37

The problem with DC brushed motors is that if they are not turning at a reasonable speed then the cooling fan is ineffective and they can overheat. To stop the Asian kit critics trotting out their usual mantra this is a problem with any motor that is dependant on cooling from a shaft mounted fan when it is run slowly and heavily loaded or as in this case looking as if it was overloaded.

Marttin

Thread: Chester DB7 speed control board? NVR switch doesn't lock
22/01/2020 00:26:34

Ian

Good news and I hope that they will replace the defective switch without too much faffing about.

Cheers

Thread: Fradley Canal Crane Progress
21/01/2020 17:36:42

For them that's interested pictures can be seen here, if moderators think this infringes on IP then please delete.

Martin

Thread: Chester DB7 speed control board? NVR switch doesn't lock
21/01/2020 17:10:26

Ian

Going back to your first post you said that if the NVR was physically held in then the motor would run and that the fault was that the switch was not latching. Is this the case still? If it is and the motor responds to the speed control then there is nothing wrong with the drive electronics or the motor.

If the switch has the A1 contact then to activate the latching mechanism this must be taken either directly or via normally closed interlocks to contact 24. The other version of the KJD 17 NVR doesn't have the A1 contact and the coil is internally wired between contacts 14 and 24. In both cases the mains live and neutral can be connected either way round to contacts 13 and 23 without affecting the function of the switch or latching operation.

If I am teaching my granny how to suck eggs then I apologise.

I agree with you that they are cracking little lathes and seem to be nearly bomb proof; famous last words.

Martin

 

PS. With regard to that circuit from Chester, when they had a forum it was shown there until I suggested that it wasn't correct. They removed it from the site but evidently they didn't follow through to check where else it might raise it's ugly head. Unfortunately they closed the forum probably as it was not used a great deal however it was a good source of information regarding some of their machines especially some of the smaller lathes.

Edited By Martin W on 21/01/2020 17:21:48

21/01/2020 14:39:25

Ian

Had another look at your wiring diagram and it looks as if the 'Hold On' coil has been wired incorrectly. Your diagram shows contact A1 wired to contact 14 and therefore the hold in coil will have no voltage across it as it is effectively connecting mains neutral IN to mains neutral OUT across the hold in coil. This assumes mains neutral is applied to contact 13 and mains live to contact 24 that said connecting the mains the other way round will make no difference to the operation of the NVR. If you move the link so that A1 is connected to terminal 24 then it should function as intended as the mains will applied across the hold in coil when the switch is active/on.

Martin

20/01/2020 13:12:51

Ian

If you activate the chuck guard interlock by having the guard in the up position and then press and hold the NVR switch and the lathe starts then the interlocks are not in series with the mains feed to the NVR.

Martin

20/01/2020 11:50:00

Ian

I can, on my DB7, replicate the fault that you described above. With the chuck guard 'open' the NVR will not latch but if I hold the NVR down then the lathe will work. Your schematic shows the interlock in series with the mains feed to the NVR if this was the case then it would not be possible, certainly on my incarnation of the DB7, get the lathe to run by holding the NVR on with an interlock open.

The safety interlocks are normally wired in series with the 'Hold On' coil of the NVR and not as part of the mains power feed circuit to prevent overloading the interlock circuits and potentially leaving them live when the NVR has reset to OFF, a certain washing machine manufacturer put the full mains load through their interlock system and the result was a potential fire hazard.

The connections to the NVR in your schematic show terminals A1 and 14 to be linked, I would expect these terminals to be connected to any safety interlock circuits. It might be worth checking again how the wiring your machine is configured with regard to this. If I recall correctly the reversing switch does interrupt the mains feed circuit and is intended to stop the lathe from being switched directly from forward to reverse instantly.

Martin

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