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Member postings for Martin Connelly

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

Thread: VFD Question
09/01/2020 11:21:59

The star point at the alternator supplying the grid is connected to earth through an NER (neutral earth resiztor). If the load is un-balanced then the voltage across the NER rises and if it exceeds a given value or rises above a set rate then the system assumes a fault and trips the alternator off the grid to avoid damage.

Martin C

08/01/2020 14:41:47

3 phase voltages csn be given as phase to phase or phase to neutral. UK mains is 230v phase to neutral and 398v phase to phase. The output of a vfd connected to 230v phase to neutral is 230v phase to phase. As there is not usually a neutral from the vfd they do not give the phase to neutral voltage but it would be 133v if it was measurable. If you really want to measure it connect it to a motor wired as star and measure the star point to phase voltage. It should be 133v. Voltages are approximate.

Martin C

Thread: Keyway Broaching
05/01/2020 14:47:57

Crude but effective.


I made a bush with 3 different depths to guide the broach. With the broach in position a piece of copper was placed on top and tapped with a hammer to drive it through. Material was aluminium alloy. The workbench helped avoid excess shock to the set up.

Martin C

Thread: Collet identification
04/01/2020 15:52:21

Model L with PDH headstock. According to website this was a collet only headstock so it is probably quite rare and owners will already have the required collets.

Martin C

03/01/2020 23:09:34

Found the original scan and clipped a bit for you.

smart and brown collet clip.jpg

Martin C

03/01/2020 18:08:48

Look through this album. Page 13


Martin C


Edited By Martin Connelly on 03/01/2020 18:15:39

Thread: No wonder my swarf bucket is full
03/01/2020 18:02:52

I have some rotabroach type cutters. Where possible I use these to remove most of the metal from large holes as the waste slug out of the centre is useful raw material. I have just done some parts where some aluminium alloy slugs provided the material to make some cylindrical spacers.

Martin C

Thread: Correct use of slitting saw for deep cut.
01/01/2020 20:34:27

Do not let the blade get hot. The blade will warp or dish if the tooth area gets hot and the centre remains cool (the arbor is a good heat sink). A spray bottle of water based cutting oil is useful for this if there is no flood coolant.

Martin C

Thread: Satellites going over Kent Sussex
29/12/2019 19:43:51

I saw a recent news report about mini internet satellites causing problems for astronomers as they caused streaks of light across the sky.


Martin C

Thread: Mystery change wheels
29/12/2019 19:35:56

Smart and Brown model M, possibly other models as well.

Martin C

Thread: Imperial Fasteners
26/12/2019 22:29:19

Old Mart and Michael G. Smart and Brown Model M Yahoo group has moved to Groups IO.

Howard, as I am not trying to maintain a museum piece lathe I have put 5/16 UNC hex grub screws into the tail stock adjustment positions to replace the original slotted screws that were worn and annoying to adjust. They may have been Whitworth form to start with but the UNC screws fitted without any issues so that's what I used. Proves your point I believe.

Martin C

20/12/2019 19:20:16

A tpi thread gauge in your Christmas stocking would be useful. I have sourced screws like this on Ebay.

Martin C

Thread: Heatshrink tubing
20/12/2019 19:16:10

Farnell have a large selection and should suit your needs.

Martin C

Thread: Non tilting; tilting head.....tilt
18/12/2019 17:57:38

Looks like Grey got it right. The top right tee bolt looks like it is pulled up into the hole for fitting and removing the tee bolts. This will prevent the head rotating until it is pushed back into the slot.

Martin C

Thread: Old Lathe Lubrication - oil through a grease nippled?
08/12/2019 17:55:33

There are two oil topping up points behind the spindle bearings. One of these leads to a sump under the bull gear to lubricate it and a wick from the oil gallery also takes oil up to the spindle bearings. Grease will obviously not work here so make sure they are not clogged up with mistakenly used grease. There is also an oil point on the spindle pulley with a screw in it. It should say oil but may be worn away. I take the nipple off vertical oiling points to add oil then put the nipples back. It should not be hard to make an extender for any awkward oiling points if you have trouble finding a suitable oil can.

I have a PDF user manual. If you want a copy email me with a suitable contact email.

Martin C

Thread: Why mostly manual cars in UK
05/12/2019 13:18:31

For information purposes, driver's manual instructions for a DSG Tiptronic gearbox car.

With selector lever in any position (except P) the vehicle must always be held with the foot brake when the engine is running. This is because an automatic gearbox still transmits power even at idling speed, and the vehicle tends to "creep" . The accelerator pedal must on no account be pressed inadvertently when a gear is engaged with the vehicle stationary. The vehicle could otherwise start moving immediately (in some cases even if the parking brake is engaged) resulting in the risk of an accident.

Unless you select P every time you stop in traffic you should be using the foot brake, makes no difference then if the engine stops or not or if you select neutral. If you select P then you have to press the brake pedal to allow the selector lever to move away from P. The result is a lot of brake light dazzle to following drivers whatever you do.

The law for lights used to be based on lamp wattage but that doesn't work for LED lights. A 5W incandescent lamp is nowhere near as bright a 5W led. This is why modern car lights can be brighter than the older types. I don't know what limits are applied now but I'm sure the manufacturers work as close as possible to the maximum.

Martin C

05/12/2019 11:30:02

Foot on the brake auto drivers do it in modern cars because it stops the engine and restarts it when you ease off the brake. Putting it into neutral or park does not do this, it may stop the engine and then you have to restart it using the key for which you have to press the brake pedal anyway. This delays starting and results in brain dead drivers behind you blasting their horns and putting their main beam on because you haven't moved the instant the lights change and because your brake lights come on when they think you should have just driven off. There is also a delay moving from a fresh start as opposed to an automatic restart as the systems check and set themselves up. With an auto box without a torque converter holding still with the hand brake and the engine running may not trigger the clutch to go completely into neutral resulting in rapid wear of the clutch.

On the subject of engine braking-

If you have a front wheel drive car and use engine braking then as well as not activating the brake lights to let following traffic know you are slowing, differences in torque from the gearbox and steering inputs can result in reduced grip on one wheel and unbalance braking. In slippery conditions this is dangerous. Brakes are balanced to give the correct braking force on all four wheels and should be what you habitually use to slow down. Under used brakes are also at risk of seizing due to lack of the movement they would get if used correctly.

Martin C

Forgot to mention ABS. This does not work with engine braking.

Edited By Martin Connelly on 05/12/2019 11:31:50

04/12/2019 15:19:20

I have an auto box (7 ratio double clutch) and have had auto boxes for the previous 3 cars (Borg Warner with torque converter and lock out in 4th gear so no slip) so that is about 20 years. Most of my driving was commuting 17.5 miles each way on a rural A road with about 15 miles of no stopping for lights, junctions etc. but I still started to get a sore left knee so went for the auto option (which fixed the problem).

I think the auto versus manual came down to cost. The manual was cheaper and more reliable for a long time so that's what people bought and were used to. It becomes a case of avoid those new fangled, expensive, fragile and unknown experience autos even when it is no longer true.

I always go for an auto when hiring a car because they are usually in a much better state than manuals that have been used/misused by lots of people.

Another thing to point out is that there is no manual gearbox on a fully electric car so people will have to change if they get one.

It is my belief that learning to drive in an automatic would be a lot easier than a manual car. Since there are so many small autos becoming available now I would suggest it as the way to go. Pass the test, drive for a while to learn roadcraft then take further lessons and pass the manual test at some point in the future if you want to drive a manual car.

Martin C

Thread: Nuts
04/12/2019 14:58:36

Steve, no idea but I hope there was insurance and happy to not get involved. This was not in the UK and probably not UK drivers. The item was being transported from ship to site and weighed over 35 tonnes plus the vehicle which is why it didn't stop when the collision occurred.

Martin C

04/12/2019 13:24:47

If there is a likelihood of the stud not being normal to the face of the metal being bolted over it then the nut may have a skewed load on it. This may require spherical washer and seat set underneath the nut to even the loads on the thread or alternatively a longer nut which is likely to be a cheaper option.

Martin C

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