Member postings for Martyn Nutland 1

We have them as well - electricians!

I know...key in your credit card co-ordinates and you have one by return (or something) of post from the usual suspects. Or most other Austin Seven parts for that matter..

I just wanted to make one, which is what I thought we were about. And I wanted to learn.

Best

Many, many thanks everyone. An education in itself!

I'll pursue PG29; maybe ask our plumber, who, resident on the Somme, may not often deal with Austin Seven radiator caps,

Thanks again

Martyn

Jason - the cross-piece (referred to in my parts list as 'the beam' and attached to the plunger in the main body of the instrument and clearly shown in your photo. The arm that holds the probes is attached to it by the set screw, also clearly visible in your picture. I can't get any tension at all on the arm, and thus the probe, so it just dangles vertically. Surely, and all the internet explanations confirm this, when centring over an internal bore, you need to set the probe over to slightly beyond the bore's diameter. Obviously it then needs to stay there, not flop limply back to vertical. Once it is set to just beyond the diameter you then gently insert the probe in the bore - the pre-load - and away to go.

Martyn

Michael...good ideas, but for less than 2mm enlargement of the hole, half round files are probably simpler, and let the bezel hide any discrepency.

Jason...mine is exactly like yours and I understand the points you make.

Clive...an excellent resumé if I may say so and I'll look up the references.

Meanwhile, I've looked up all the 'internet' I can find and am left in no doubt that you must - but must - be able to initially tension the probe by way of the screw that connects its arm to the beam. This is what Jason correctly maintains. On mine you can't. So as someone said at the beginning - it's a dud!

I will try, as an exercise, to make a new arm to replace the one I broke and will then introduce some frictional resistance between it and the beam. Then I'll put it all away and fork out for a Blake!

Best to everyone, as ever.

Martyn

I think it's a very good idea, as 'old mart' suggests, to turn the spindle by hand to start, and I would always do that. But to be fair to Tubal Cain, I have watched other videos where they advocate running at what I would consider too high a speed.

However...this does not solve the fundamental poser of what to do about a probe that just dangles vertically without any resistance in one direction! Take, for example, the situation where you were using a dial test indicator to centre the spindle, you would gently push the stylus over to an angle where it contacted the side of the bore and it would stay there while you turned the spindle by hand and manipulated the X and Y axes until the zero reading was consistent round the circumference.But with a stylus/probe that dangles, limply at the vertical it's not possible to do that.

By the way, in response to Dave's most helpful suggestion - I did cut the holes with hole saws, but, by sod's law, the ones for the magneto switch and oil pressure gauge need to be about 1.8mm larger than the 50mm saw!

Once again thank you everybody for your patience and guidance.

Martyn

Thanks for that folks.

My plastic ring, they call it the 'guard ring' in the brochure, came off without much bother.

I didn't use the spanner that came with it, but good fitting BAs, but can't get any tension at all on the arm/probe, it just dangles and flops around. There's tension in the other direction but then the arm has a face that pushes on the beam and thus the main spring loaded plunger.

Mine doesn't have a knob on the back to set the direction of the probe - I guess that might be a Centro feature?

I'm a bit confused about speed. I too use a Warco mill. Tubal Cain on his instructional video, using a Bridgeport says to run at 600rpm with a 100-buck indicator like mine. Must confess I don't now fancy anything over about 100!

Thanks again everyone.

Hello

I wonder if someone could advise me on the use of a co-axial indicator on a milling machine. I've just bust my new one first time out of the box!

Let's start from the premise that the instructions that come with it are total gibberish and that I do know basically how they work. I wanted to centre holes in aluminium plate so I could enlarge them with a boring head to make a dashboard.

I fitted the short straight probe but was mystified why I couldn't get any resistance on it in one direction - I was expecting it to be like a dial test indicator where you push the stylus over to contact the workpiece. In this case the probe just hung limply down flopping about and no amount of tightening of the nut at the connection between the arm and beam would tension it. (Pushing it in the opposite - non-dangly direction - did produce tension against the beam and a reading on the dial).

I then, very foolishly, put it in the mill, wound it across to get tension on the probe on the side where it wasn't dangling (the instrument was now of course about 25mm off-centre). I started up at 170 rpm, the probe hit a step block holding the work and snapped off the arm.

I can probably make a new arm, and I would still like a co-axial indicator. I can't afford a Blake, that apparently is the Rolls-Royce, but any thoughts on a decent one in, say, the 200 Euro ball-park.

Many thanks in advance for any guidance on both use and purchase.

Best Martyn

Many thanks all. My understanding much improved. Didn't get on with the form tool. Obviously lathe too small.

Thanks again. Keep Safe.

Martyn

Hello

In the days when showman's engines drove electric generators to drive the gallopers and traction engines drove threshing machines in the fields, I'm told by the wise that the belt didn't come off the pulley because the circumference of the pulley is convex. I know this to be true but I've never really understood the physics.

I need to make Austin Seven crankshaft pulleys that carry the fan belt. The originals do have flanges about 3-4mm deep on each side but the belt track is also convex. Do I need to make a convex track, given, I would have thought (probably in ignorance) the flanges will keep the belt on?

If I do need to make a convex track, how is the best way? I tried a 'form tool' but it wasn't a great success, someone suggested using a wood-turner's gouge, but I strongly object to that approach! How do you do it, please?

Keep safe in these difficult times.

Martyn

I cut a lot of BSF 5/16 threads as I restore Austin Sevens (e.g. new cylinder head studs).

I use button dies but have difficulty starting the thread. I turn the blank to the specified external diameter and chamfer it. But still have problems. I've improved my technique by coming under the nominal by about 0.10 mm - but it's still not great.

I have tail-stock die holders for my lathe ( Chester Super B - sorry!) but I can't run under 160 rpm which I feel is at least eight times too fast to die cut a thread, and to tackle it manually - blank in chuck, die in tail-stock etcetera - you need at least three paws.

Any thoughts?

Needless to say, I need to clean threads in the block, sometimes where I've removed broken studs. I don't have any real problem hand tapping, but wondered if my very wise and experienced colleagues on the forum would recommend one of those (very expensive) reversible tapping chucks for the drill press/mill.

Many thanks in advance and do keep well.

Martyn

Thank you very much all. I'm now much wiser. Had I been relying on eight, I like the simple expedient of adjusting the tappets to reduce the load around the bearing - of course, you would always have smart a---s telling you you had a loose tappet! I don't think a roller could get diagonal as, width-wise, they are pretty tight in the track on the camshaft.

Thanks again.

Martyn

I hope you'll forgive this question because I've already solved the problem, but would like to be a wiser Easter bunny.

Does it matter (strictly speaking), in an originally designed roller race with nine roller if you have eight?

I'm sure you've guessed! Austin Seven camshaft. The centre bearing is a nine roller roller race that is an absolute design abortion of assembly technique. The stuff that unending nightmares and perpetual damnation to Hades are made of.

When I originally assembled my engine I became so desperate and frustrated I put the camshaft in with eight rollers. The great and the good said 'oh no! No way! Conscience got the better of me, I pulled it all aoart again, and after a day and a half of workshop misery my wonderful wife intervened, dextrously managed to get an elastic band around the nine rollers I had stuck in their track with Dum Dum compound and we entered the camshaft with all nine rollers.

To cut a long, tedious story short, would eight have been catastrophic?

A happy and peaceful Easter to you all.

Martyn