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Member postings for John Paton 1

Here is a list of all the postings John Paton 1 has made in our forums. Click on a thread name to jump to the thread.

Thread: Mystery forging
24/02/2020 17:17:47
Posted by pgk pgk on 24/02/2020 16:10:05:

door knocker?

Only if they are bad at spelling - it is marked DN not DK

(I'm now hiding behind the settee!)

Thread: Electric welder at Lidl
15/02/2020 17:47:37

FWIW my plasma welder is a Jasic and the chap that runs the welding courses I attended chooses to use Jasic kit and says he finds them durable and reliable.

I think the combo unit was just over £300 new when I last lookd, so not exactly 'budget' but certainly not in the £700 arena.

Thread: What would I use a Plasma Cutter For
15/02/2020 17:33:37
Posted by Andy Fryer on 10/02/2020 20:24:20:

I notice from the spec it states the compressed air pressure in kg/mm but does anybody what volume capacity is required (CFM, litre/min) ?

Hi Andy, in the absence of specific replies, I would just say that mine runs happily on a 'normal' domestic sized compressor (1/2 hp) running through a pressure regulator. You might need something stronger for thick material but i wonder if more air might just chill the 'flame'.

These small plasma cutters are really for sheet material and box sections.

Thread: Did i make the right choice buying an old banger Myford lathe.
14/02/2020 08:56:19
Posted by Steviegtr on 14/02/2020 00:45:44:

A couple of months ago now. I bought an old, 1977 vintage Myford super 7B lathe. The lathe came with the quick change gearbox & the powered cross feed. It also came with a box of bits which I assume the previous owners had accumulated over the many years.

Before I purchased the present lathe. I looked at many other brands. I once had a Boxford which did not come with much in the way of change gears etc. It was pretty badly worn too, it had been a college lathe.

A few friends have the Asian models, of which I did consider. They would have worked out much cheaper to purchase & I would have had the advantage of being the 1st owner.

Anyway after much ado, I opted to stay with a British old banger. I could not have purchased a large lathe of which there are many for sale for scrap metal money. I just do not have the room for one of those wonderful old lathes. Colchester, Harrison & many more. What prompted me to create this thread is that tonight I came to a steadfast , yes I am glad I bought my Myford.

I know they are probably mediocre in quality & do not have every mod con on them. Also to date I have probably around £3000 invested in it's present state with the 3ph inverter mod & tool post + many other bits I have purchased. I love the choice I made & have no regrets whatsoever. It's like an old car, it leaks oil all over the place. Has a stupid plain bronze front bearing with an old wick out of an oil lamp. Needs adjusting regularly. Anyway what made me glad I did not go down the Asian route is this. I know a lot of people have gone down this route & are very happy with them. It was just not for me.

Blondihacks

Edited By Steviegtr on 14/02/2020 00:46:56

I know just how you feel- I once bought what I thought was a basket case Super 7' every bit was loose almost to the point of falling apart and the bed badly worn, the motor burnt out too.

I really enjoyed putting it back into shape - including correcting the wear by grinding and the scraping the bed and underside of the saddle by hand. Much use of a precision level and engineers blue as I worked on the bed and final checks by turning test pieces.

In fact this took rather less time than I had anticipated and the end result far exceeded my expectations as it produced accurate, chatter free, work.

They share the virtues of early cars, they may not be highly advanced in design and engineering but their simplicity is such that you can actually repair and maintain them in the home workshop.

Thread: Fast bit of engineering work.
13/02/2020 08:48:49
Posted by Bill Pudney on 13/02/2020 04:21:43:

I had a knee replacement in 2001...the twin towers disaster happened whilst I was in hospital. At the time I used to fly free flight model aeroplanes for an obsession, which entailed A LOT of walking. Prior to the knee replacement I had difficulties completing competitions; frequent early retirements were common. After the op. no worries!! I was in hospital for 3 days, the exit criteria were, 1/ Being able to bend knee more than 90 degrees, and hyperextend to "straight", 2/ Being able to walk with the use of a stick, 3/ Being able to negotiate stairs. There followed about 6 weeks of physio, with bucket loads of painkillers. It was well worth all the physio and pain...which was considerable!!

cheers

Bill

Bill

Did you ever come across a free flighter called Alan (aka Bob) Wells? (used to fly Wakefield mainly to extremely high standard and good frind of Jessica Nash who I think was National Champ in same class)

Topical story associated from the late 1970s, Alan and Jess were gently walking across the Army Flying airfield at Middle Wallop retrieving their rubber powered models from a competition flight (lowest risk activity that I can think of) when Alan was mown down from behind by an out of control land yacht. Smashed his leg horribly to the point it was to be amputated. Fortunately his friend was an ex nurse and intervened insisting that his leg could be rebuilt and saved. It was - it took an awfully long time but was very successful.

I visited him in hospital and have to say it was not a pretty sight with stainless rods sticking out all over the place and wide open wound giving access to the bone!

A mark of Alan as a principled devotee of the sport was that he absolutely refused to raise a claim as he feared that might result in loss of the site to aeromodelling. I have heard recently that the airfield is indeed not now available for this use but Alan's sacrifice must have prevented earlier loss to aeromodellers.

As well as all this he was a talented whittler of balsa with a wicked sense of humour! I was privileged to both work and fly with Alan in those days.

Thread: 3D Scanning, Anyone?
09/02/2020 23:24:34

I got an ISense to go on my IPad but resolution was so poor I haven't even tried printing from the images.

Thread: Effect of Tensioning a Boring Bar
09/02/2020 23:08:21
Posted by DrDave on 09/02/2020 21:32:12:

Is that still the case with something having a preload? I thought general black steel stretched more for a given force than it compressed (thinking back to materials lab days) but you may well be right and I will stand corrected.

Yes, unless you exceed the elastic limit (in tension or compression) for the boring bar material. But if you do, chatter is the least of your worries!

Got it - thanks DrD!

09/02/2020 21:27:24
Posted by DrDave on 09/02/2020 21:20:32:
Posted by John Paton 1 on 09/02/2020 21:09:36:

maybe I am getting the wrong end of the stick, but ....... we have a tube to which we exert a lateral force at one end, resisted by compression of the steel on one side of it's neutral axis and stretching of the steel on the other side.

steel stretches more than it compresses so by introducing some pretension the net effect will be to reduce bending.

yes the increased stiffness wiLl alter the harmonic frequency but it is the reduction in deflection that we are really after.

To me the logic of tension is sound but the margin of improvement is probably quite small.

 

Edited By John Paton 1 on 09/02/2020 21:11:20

For a round bar, Engineer’s Theory of Bending tells us that the tensile and compressive stresses are the same. Preloading does not change the stiffness of the assembly. We need to look elsewhere for the reason that it can reduce chatter in a boring bar.

Is that still the case with something having a preload? I thought general black steel stretched more for a given force than it compressed (thinking back to materials lab days) but you may well be right and I will stand corrected.

I confess that my experience with pretensioned components has always been with composite assemblies of dissimilar materials

Deflection results from strain, does Young's modulus assume that the neutral axis is exactly central to a round bar? I had always assumed from work in the lab that under bending conditions the neutral axis wa slightly offset allowing compression and tensile forces to be equal despite the steel being stronger in compression than in tension.

 I am ready to learn on this as it is an aspect of materials science that is fascinating.

Edited By John Paton 1 on 09/02/2020 21:34:30

09/02/2020 21:21:33

Thinking again' were the boring bar to be drilled along its length slightly to the rear of its centre and perhaps a shade below centre also a similar result may arise ( essentially trying to equalise compression on one side of the bar and extension on the other under given cutting forces) although this might not assist with torsional forces as well as preloading would.

i am sure there are materials scientists in the group who can use real figures to quantify what I am trying (poorly) to get at. Doubtless the effect will vary greatly with different grades and temper of steel.

09/02/2020 21:09:36

maybe I am getting the wrong end of the stick, but ....... we have a tube to which we exert a lateral force at one end, resisted by compression of the steel on one side of it's neutral axis and stretching of the steel on the other side.

steel stretches more than it compresses so by introducing some pretension the net effect will be to reduce bending.

yes the increased stiffness wiLl alter the harmonic frequency but it is the reduction in deflection that we are really after.

To me the logic of tension is sound but the margin of improvement is probably quite small.

 

Edited By John Paton 1 on 09/02/2020 21:11:20

Thread: What would I use a Plasma Cutter For
09/02/2020 20:54:12

FWIW I have a combined Stick/Tig/Plasma unit (inverter technology) which I bought second hand principally for the Tig function.

I have found plasma to be a dream - cut a profile from off the of sterlingboard and run the nozzle round it, no broken teeth on the bandsaw cutting stainless sheet and no deafening ringing cutting sheet with an angle grinder. Leg is only about 1mm wide so very neat too.

I was pleasantly surprised but even so I am not sure if I would buy a dedicated plasma cutter as storage space is at a premium.

The caveat with all of these 'cheapies' is to expect the diodes and capacitors to fail at quite a young age. If you know what you are doing these can normally be replaced quite satisfactorily but I would hope a better unit would last longer.

Thread: My (bad) carbide grinding setup
06/02/2020 00:03:54

The back end of the lathe spindle is rarely used unless one uses a collet drawbar or hand crank for low speed.

that being so, and recognising low volumes of abrasive dust from diamond wheels, how about having a semi permanent grinding wheel set there, it would be a little bit away from the lathe bed? It would need a reasonably accurate expanding mandrel to mount it on and a decent catch on the change wheel cover to keep the rest in position.

On the other issue of abrasives and the lathe, does anyone know if all abrasive particles settle in the suds tank or does some of it get recycled in the coolant flow? The splash tray must attract lots of filth given its perpetually sticky state and on my lathe that gets rinsed over when using the coolant liberally.

( I might run some of the suds through a filter paper to see exactly what comes back up from the tank.)

Thread: What bench drill
04/02/2020 17:53:47

Plus 1 for Meddings second hand.

i bought mine second hand nearly 40 years ago, use it pretty well daily iincluding some heavy work and in its time light milling and routing.

Still no different to the day I bought it and it owes me nothing now.

Try and get one with rack and pinion to raise the table, not too many about but that feature is a godsend as you get older!

Thread: Bench grinder troubleshooting
03/02/2020 22:30:34

Modern fittings with risk of high temperatures use glass braid sleeves. You can salvage these from all manner of items especially light fittings. I would be tempted to put lengths over the heatshrink just to make sure if you think the joint may come in contact with a bit that matters. The sleeping is normally white in colour or creamy coloured if it has got warm in service. Especially common on halogen light fittings.

01/02/2020 23:11:13

Sorry again - just re -read and see that you have eliminated capacitor - ignore my post unless you fancy my 'seat of the pants' diagnostic methods ( they might be crude but work for me as a first ' non destructive' exploration)

01/02/2020 23:06:23

Sorry for typos in the above but I hope it still makes sense!

01/02/2020 23:03:30

Don't give up just yet!

Did you manage to ascertain if the switch was actually working? If it appeared to be ok then be ready to suspect the capacitor itself.

They often fail after 10 years ( depending upon the make) and actually dislike being left discharged.

some capacitors 'reform' over a relatively short period of use and recover some of their capacitance ( but will still be suspect) others may show signs of seepage around the join of their 'end plate) to the aluminium can. Disconnect one lead of the capacitor and take an ohmmeter reading across the terminals ( in both polarity directions). If you get zero ohms both ways it has gone short circuit.if one polarity or the other it starts almost short circuit but the meter reading then rises over few seconds it suggests that the capacitor is functioning to some degree. If the latter it would seem that there is another problem.

I would start by looking at the capacitor with the symptoms you describe because it is easy and then move onto the centrifugal switch can also be the problem. I suspect we all go by our own experiences and for me I have had more failures due to capacitors and then cooked windings from poor ventilation or overloading of the motor. I have only experienced switch faults on hard worked motors which have done lots of stop start work.

i wou.d hazard that switch is more likely to be proble,attic with damp storage and capacitor mor likely if stored somewhere hot - perhaps an unventilated roofspace which gets hot in summer.

you can test the switch by shorting out the capacitor terminals with a bit of wire,putting the meter across the line and neutral wires to the motor and then spinning up the motor using something like a rubber bung on the end of an electric drill pressing obtuse the end of the grinder shaft (spinning it in the correct direction)

watch the meter to see if the reading varies as you get up to, or slow down from, speed.

obviously don't have the machine connected to the mains while doing this!! You ,at find that the motor creates its own voltage while doing this in which case test with volts scale, if not use the ohms. You aren't looking for a particular reading, just a step change in the reading as the centrifugal switch cuts in and out.

Thread: What a sad day for the British motorcycle industry.
01/02/2020 18:26:56

I wonder if Tata might take on Norton - they seem to have pretty effective with Jag so can do things other than far eastern lorries and seem to be able to get the best out of UK engineers and designers. The brand has similar appeal.

If the engine's the bit that lets down Norton how about a Jag (electric) engined one, batteries low down to keep C of G where it should be?

Thread: Digital readout
01/02/2020 18:07:44

I am risk averse on such things but an issue for me was the postage cost if I had to return the item to China under warranty. Something to bear in mind if (like me) the cost of one unit was at the very limits of my hobby budget.

My mantra with tools tends to be 'buy right, buy once' - so I often end up buying high quality tools second hand and look after them (treating them as investments). Not easy to do with DROs though!

Thread: Where are tool fairs/swap-meets advertised?
15/01/2020 22:26:56
Posted by choochoo_baloo on 15/01/2020 00:07:32:

Ok thanks chaps. I'm in Somerset, so the only one of those mentioned events that is close-ish is the Great Dorset!

I will now have a look out for "auto jumbles" and the like.

Maybe don't get too excited over GD Steam Fair.

two years ago they changed things to increase camping are so there is now a shuttle bus from the main car park, but the bus stops the far side of the campsite. So carrying heavy items, and disabled acesss also is hopeless. At the same time they stopped the time honoured 'courier' service on site so I don't know how they expect sellers and buyers to cope. I spoke to their comms team but they seem unrepentant, just saying there is more money to be made from camping. I had taken a friend with arthritis and he was totallyjiggered just getting to the turnstile, so unable to see any stands.

last year there were very few 'workshop goodies' stalls as a result of the revised arrangements. The organisers seem hell bent on killing that aspect of the fair

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