Member postings for martyn nutland

Brian

If this is your first lathe and experience of latheing don't, please don't, land yourself with a four jaw independent as your only chuck.

Whatever you're told, whatever you see on internet videos and YouTube, setting it up will drive you absolutely stark raving bonkers and most likely put you off your hobby for life. Centring an independent is hell, unless you're a trained, operator, and have been doing it since you were an apprentice. It takes me, someone, I guess like yourself, for ever and is still slightly off.

Also, a dial indicator is absolutely essential. My humble suggestion, as a relative beginner myself, is get a three-jaw self centring chuck and you will be latheing away virtually from the moment you get your Sherline. Learn to use the dial indicator on work in the self centring type, then get your independent chuck. But then be prepared to be very, very patient.

Good luck.

Martyn

Howard et al

Thank you for that interesting train of thought for which I am very grateful. I do think we must not now apply rocket science to this! It did occur to me that a collar might be the answer which is a sort of variation on your theme. It leaves the fundamental problem of determining the thread, that as far as I can calculate is about 19/20 tpi on a diameter of about 6/10’’. But once the type is established one could insert the collar and then fit a new plug to it threaded to a size of one’s choice. The snag is, there has to be enough room for the king pin to be extracted upwards and there’s not going to be much metal to carry a male (for the boss) and female (for the new plug) thread. Your idea is simpler (i.e. better) and more elegant.

Another advantage with your recess scheme is one could easily get the plug flush with the top of the boss. This is important, because the nut securing the pivot for the brake shoes (the pivot passes through the back of the stub axle base) is directly above the plug and close to it which, I guess, is why the cap is so thin in the first place.

To be honest, I don’t think special tools or hand crafted screw-drivers are necessary here. The plug’s slot is very shallow with no practical means (remember, it’s flush with the top of the boss) of deepening it. Also it’s usually so brutally butchered that if it is at all tight a device created by Sir Henry Royce himself would be unlikely to shift it. Drilling, drifting and/or a chisel are, in my experience, the unfortunate but only way of extracting something that is already ruined.

So…how about this? Pop the cap in the post to Tracey Tools (or equivalent) and ask them to categorically identify the thread and send it back with a die. Then, with a lathe and piece of brass bar one could make as many as one liked and give them to the similarly afflicted. Simples?

Thanks again Howard for a bit of ‘out of the box’ thinking.

Martyn

Alan,

Right on all counts!

And Russell, he also said four wheel brakes weren't dangerous (not his uncoupled variety at any rate) because people would be so busy trying to steer as not to have a hand free to put the front ones on at the same time as the back!

Martyn

Alan

Enjoyed your posting and although this is not the place to talk 'Austin Sevens', identified with what you say.

The swerving (loss of steering) I think emanates from a change in castor angle from positive to negative when a badly designed steering/suspension system is subjected to very heavy braking forces (can you get very heavy braking forces with an Austin Seven!?). I have had this on an Austin Ten; and it's scarey.

I have a 'chamber of horrors' in my workshop that includes a bent and broken king pin I removed from a spare Seven axle that had been damaged in some unknown violent mishap. But damage like this is not confined to Austin Seven's of course. I had a friend who drove his Speed Six Bentley into the back of a fellow Bentley club member's Three Litre model. The Speed Six appeared to suffer little more than a buckled registration plate, it was only much later that a king pin was found to be broken in half. Salutary lesson: potentially lethal damage can go undetected. Moral, perhaps: if you bend the number plate check the king pins!

Thanks again for the sound advice.

Martyn

John

Your illustration shows exactly the part I was talking about. It blanks off the bushed top boss for the king pin on the stub axle. The trouble in the Austin Seven context is that ham-fisted owners/mechanics put them in as if they were securing a girder on the Forth Bridge. The screwdriver they use to try and get them out again then buggers the slot and helped by dirt and age the blanking plug won't come out so you have to drill, drift, or use some other butchery to remove it.That's why I need some!

Martyn

I think I'll be able to do this now. So many thanks everybody

Yes, it is the plug with the screwdriver slot across the top. The cap is the male part, the stub axle boss carries the female. And yes Phil, absolutely right, these things were built down to a price. Earlier cars have a blind bush at the bottom which presents it's own problems for extraction! Some Austins also close the holes with a welch plug which is not as elegant as the brass cap but simpler and, of course, cheaper.

As the company needed thousands of these caps I suspect they were produced on a dedicated machine. Probably stamped out like coins then thread-cut with an automatic die and had the slot milled at more or less the same time.

Thank you again everyone.

Martyn

Wow. John, how long did you spend explaining this to me? I rely do appreciate it and hope I am a better educated soul as a consequence. Thank you for your trouble, many times over.

And Bob, from the kingdom of Austin Sevens. Helps. I really do feel ashamed and belittled and inadequate when I have to bin a job. Do you think Herbert Austin or Henry Royce ever made a bollocks of a part and had to bin it? It would make me feel better if they did. I doubt it though.

Martyn

Thanks Phil. Sounds sensible, fairly straightforward and satisfying if I pull it off.

Martyn

I'm afraid this is a very open ended kind of question but I really would appreciate an experienced practitioner's view to help me think sensibly.

I restore vintage Austin Seven motor cars as a hobby. One of the many, many, many machining jobs I am undertaking (or contemplating) is making the rather sexy little brass cap that closes off the eye for the king pin boss in the stub axle. (You unscrew it to fit an extractor for the king pin and/or pump in grease).

It's brass. About half an inch in diameter. About a quarter inch thick and threaded, I think, but am not yet sure, to a Cycle Engineer's Institute 'spec' but possibly its BSP.

Would you try and buy one - simplest, but I learn nothing and gain no satisfaction?

Buy a die - extremely expensive solution at this largish size for something I will use once or twice in a life time?

Or could I chase it by hand on brass bar and would the skill to do that be very hard for a rank amateur to learn?

I really would appreciate a sensible view to help me 'wise up'.

(Might be a case of life's too short to shell a prawn, eh?)

Martyn

Just as a silly little aside, David, I have the rather pretty little oilers you describe on my lathe and 'mill' and I use the oil can that came in the tool kit of my great uncle George's World War l era Sunbeam motor cycle.

It's all that remains of the machine, but has found a new life 100 years on in my workshop and it does work a treat!

Good luck.

Martyn

Hello Peter

I wonder, if you are going to do a lot of work of this kind, and you are clearly a fastidious sort of chap, if it might be worth sending to the chuck maker for a set of soft jaws. I think they would help.

I find that the serrated jaws on the chucks we buy these days cut through masking tape when I use it. I find a strip of emery cloth around the work is quite effective as the abrasive surface grips well. Personally, I'm a bit nervous of strips of metal for the same reason as shim is bad news.

Good Luck.

Martyn

Yes...now I think I see, or I will when I re-read with a piece of paper and pencil.

Many, many thanks for elucidating; and in advance to anyone else who explains.

And yes, I do think we learn useful things at school, although it's a pity no one tells us at the time why that might be so. However, I doubt whether my aging maths mistress knew this theory was applicable to lathes!

Thanks again.

Martyn

I wonder if someone could explain in very very simple arithmetical terms how this works.

I wanted to take some very light cuts on my lathe to get a male and female spigot to mate fairly snugly.

I looked up such icons of knowledgeability on the internet as Tubal Cain and they tell you to incline the compound to the bed axis by x degrees - 30 or 60 in some cases 5.75 - 6.00 says one guru.

This then reduces (by half?) the amount the tool is advanced by the handle and as measured on the vernier.

I've puzzled endlessly how this calculation works mathematically and am at a total loss!

Martyn

I'm repeating my sincere thank you to everybody. Some of this I'm doing, some is a revelation. It's all extremely valuable and I'm studying it and taking it on board. Thank you.

Martyn

Many, many thanks to everyone for the comments and extensive advice.I shall be studying this closely and then implementing. Thank you again.

Martyn

Could someone please give me advice on using a dial test indicator (or what I think is a dti !)?

I bought my Mercer instrument on e-bay. It reads in 0001’’ increments. When it’s at rest in its case it has the needle poised at about 13 gradations anti-clockwise of zero, that, I assume, is to allow pre-load back to nought. In the box is a flat rectangular bar about two-and-a-half-inches long with an attachment at one end to take the stalk of the instrument. I assume (again) this can be used somehow to increase the ‘sweep’ but I don’t know where you would hold the bar.

I’m trying to use my instrument to sweep a 23mm hole in the centre of a lathe chuck adaptor plate I’m making. I have the work held in a self-centring chuck on a rotary table on a milling machine and I want to centre the quill over the workpiece hole.

I begin by putting a 22 mm drill bit in a Jacob’s chuck (nearest I have to 23) and with everything unlocked on the mill (head – it’s a Warco Economy – X/Y axis) trying to centre the drill in the hole. Thinking is, this will roughly position the quill.

I now put the Mercer in the Jacob’s chuck (I know I should use a collet but at the moment I don’t have one that will fit its stalk. I use Posilock collets in a Vertex collet chuck for endmills etc.) I push the Mercer’s stylus into contact with the interior of the hole with the tip of a scriber (nothing clever intended, just seems convenient way to touch it). Then, mill belts slack, Mercer zeroed, I rotate the quill by hand. But the stylus loses contact with the hole by a huge amount (i.e. so much I can clearly see it with the naked eye) I just don’t understand why.

If I do manage continuous contact of the stylus I have wild swings of the needle (easily more than one revolution of the dial). I try to proceed in the same way as I use my dial gauge (‘clock&rsquo. I half the value by manipulating the axis (X or Y) from the highest reading, zero again and proceed until I’m getting a zero to modest (5-10 Mercer gradations) discrepancy on each rotation, but that’s almost always because the stylus is losing contact!

How do you correct the discrepancy on a dti – even if you are doing it right !?

Do you measure in one plane only? Say the stylus is pointing along the X axis of the mill table, and showing an eccentricity, is that when you half the value, zero, and take a reading 90 degrees on, when it’s lying on the Y axis and so on until (hopefully) you have zero all round (with, of course, continuous stylus contact !)

Wow! This is a really long question for which I profusely apologise. If someone says s-d o-f you fool, I won’t be the least bit offended! If someone says, ‘there’s an easier way to do this’, and I suspect there is, I’ll accept that unreservedly. It’s just they make using a dti look so easy on the internet and I do feel a fool! Very many thanks in advance.

Martyn N

Nick_G

Absolutely right. Polish. Sorry about that.

Martyn

Not my best buy, Peter, but if you want a bit of exotica in your early days you might try a tailstock scroll chuck from Chronos. It's hard to find on their website by describing it, so use the reference number 154032.

I'd been looking for one of these for a tong time, in preference to the rotating Jacob's variety. A firm in America called Bison make them and I'm sure they're a splendid engineering job, but they cost mega-bucks. The Chronos job is cheap and cheerful (about 70 quid) and, I think, as the Americans would say, it's quite 'neat'!

Enjoy your machining and good luck.

Martyn

All this electrical expertise is enormously erudite and impressive, but isn't the golden, irrevocable rule NEVER EVER buy old electrical equipment from e-Bay, car boot sales, flea markets, auto jumbles etc etc whether it be an electric fire, a hair-dryer or a drill.

This is quite obviously a 'dud', probably dangerous, and most definitely for the scrap bin now!

Might be worth saving the plug.

Martyn

Chester Machine Tools who produce a lathe and a range of chucks but can't supply an adaptor plate to fit their own expensive chuck to their own b----y lathe and kid you that making the plate is a simple machining exercise when it is a very complex job, especially if you are fairly inexperienced.