Here is a list of all the postings martyn nutland has made in our forums. Click on a thread name to jump to the thread.
|Thread: French model Engineers|
Not a modeliste, but build vintage Austin Sevens from boxes of bits in what used to be Picardie, now Hauts de France. Lathe and mill a bit in a very modest sort of way to make small parts for them. Like others here find vintage engineering outfits hard to find but buy materials and tools from the most excellent company RC Machines in Luxembourg who will deal in English and have no silly automated credit card insistence.
I'm in Gueschart which no one's ever heard of, nor can find on the map. But it does exist and lies between Auxi-le-Chateau et Crecy-en-Ponthieu, or, if you prefer Abbeville et Hesdin!
4, Place de l'Eglise, 80150 GUESCHART (don't you just love succinct French addresses), website email@example.com
Best and many thanks for the opportunity to reveal this.
|Thread: Quality Finish|
Many thanks again for all the good advice.
I didn't know about shear tools which seem essential to the process.
Strangely enough, Tubal Cain has a whole video on making them and I'm now studying this.
Many thanks all. HSS, fast, light, lubricant, stone. Got it.
I wonder if the experts could give me some advice on obtaining a high quality finish on a part.
I'm making track rod ends for a vintage Austin Seven. As many, many of you will know; on an Austin Seven a fork on the end of the track rod clenches a steel pin by means of the ubiquitous cotter pin, then the steering arm/track rod arm has a bronze bush to pivot on said pin.
I'm using EN16T at diameter +/- 9.5mm and for mechanical rather than purely cosmetic reasons I'd like to achieve as near to a glass-like finish as I can. Recently I used some steel described as 'polished' from my supplier here in continental Europe (the excellent RC Machines in Luxembourg) but found the tool tended to tear the surface and leave it rough how ever sharp the insert or light the cut. I don't want that to happen again.
I won't be tryng to harden the pin in any way - the mileage doesn't warrant it.
Any advice and many thanks in advance. Keep well.
|Thread: drillling bronze|
Like Philip, I've had trouble drilling bronze which I do when I make bushes. I have to confess that I have found that blunting the drill lips is of absolutely no help whatsoever! Maybe I do it wrong. As I understand it, what are termed the 'lips' are the parts of the tip that look like hooks and you are supposed to take the 'points' off said 'hooks'. I've bought and spoiled drills doing this and got no where.
That said, I find a brand new (or very sharp) unmolested drill will cut bronze as if it were cheese; no problem.
Just my experience.
|Thread: Wot No Teeth?|
In the end I began by setting the flywheel vertically on the milling machine and, using a slitting saw (4" x 1" x 1/32), I undercut the teeth at the root in tangential increments. This is a laborious process as there are 80 teeth and the saw would only span 5 or 6 teeth at a time.
The tedium was relieved somewhat by the fact that, as we know, Bendix pinions of the pre-engagement era, are brutal devices. They bash their way into the ring gear usually in about the same place each time. In my case this meant that over about a third of the circumference of the flywheel the Bendix had destroyed around threequarters of the width of the tooth and I figured that could be removed by means other than the tangential cut process.
Having treated the teeth from the root end I chucked (three jaw self centring front fixing) the flywheel. horizontally on a rotary table. I then repeated the previous process but at the bottom side of the tooth. This isn't quite so tedious as I calculated I only needed a cut about 2mm deep on an undamaged tooth to reach the first cut. The theory was to end up with an 'L' shaped incision that 'voila' would part the teeth from the flywheel. This time I used a 1/16" thick slitting saw but the diameter was the same so I could still only treat 5 or 6 teeth at a time. I used 18° increments on the rotary table. There was no clever math about that, I just guessed that was the most I could rotate each time if the two cuts were to meet.
Naturally, the two cuts didn't meet! But I found it relatively easy to break away the teeth in short sections with a cold chisel after joining the slitting saw cuts with an ordinary hack saw.
I have a strong aversion to, and fear of, angle grinders but I used my Makita to take off the remains of the teeth that had been virtually destroyed by the brutality of the Bendix. I then gritted my teeth and used the grinder again to restore some degree of roundness to the denuded wheel.
Next I put the fmywheel in the lathe held on the tooth side in a four jaw independent chuck. This is the only side that has a decent boss on which to grip. I supported the opposite side on a rotating tube centre fitted to the tailstock. One has to work from the 'backside' of the job and I used left hand and right hand cutting tools to clean up and 'round-up' the wheel where the teeth had been. I got to 0.02mm run out on a dial indicator
The photos show the toothless wheel and the set-up on the lathe. The good news, apart from the wheel, looking 'half-decent' is that it has lost about 9 oz from its original 12 pounds.
The bad news is that I cut slightly too deeply on the tooth sides with the slitting saw leaving visible saw cuts around the periphery of the flywheel. You could revove these by continuing to machine away the area where the teeth had been, and although this would lighten the flywheel further, it might impinge on the bolt holes forthe clutch cover (see photo). Also I'm wary of heavily lightened flywheels as I've known them burst with nasty consequences!
Thanks again to everyone who suggested and advised. It really set me on a successful track.
Edited By JasonB on 09/02/2020 16:23:09
|Thread: Apologies for raising this again|
Many thanks all. I will have a go and report back.
The question as to 'why bother' is sensible. It's just that, although it will be out of sight, it looks and is a mess and offends the eye.
I apologise to everyone for revisiting this but I'm having a lot of difficulty trying to remove chronically bashed up ring gear teeth from an Austin Seven flywheel. To be clear, these are teeth, milled directly onto the flywheel (not shrunk on ring gear) and not on the clutch cover, and I do not want to cut them away with a view to fitting new ring gear. The flywheel will go on a vehicle that will always be started on the handle or with a push. Thus, in a sense, this is a cosmetic exercise.
I am very adverse to putting the flywheel on the lathe because although my Chester Super B has plenty of swing, I'm afraid that the tool running over dozens of teeth is going to hammer the machine to pieces. Even if I did resort to attempting this on the lathe I can't see any realistic way of holding the piece securely. There's no boss worth speaking of that a chuck could get a grip on and fixing the thing to a face plate is going to cause the clamps to obstruct the cut. A mandrel through the centre hole might be a possibility, but I'm not sure one could get it tight enough to resist the pressure of the cutting.,
Is this an idea....there are two blind 1/2" BSF holes on the face of the flywheel (to attach a puller). Could I drill the holes all the way through and use them to bolt the 'wheel to a face plate?
The plan to date has been to mill the teeth off with a roughing mill or slot drill. To that end I've tried to do a set up on the mill with a rotary table and its dedicated three jaw self-centring chuck. I've adapted an Austin Seven flywheel puller (mentioned above) to try and grip the job. (Cross-piece of puller bolted tightly across the flywheel and the forcing bolt gripped in the chuck on top of the rotary table. However, when the job is tight it's horrendously out of true axially and side to side and when it's true it's loose in the chuck. NBG.
Could I...get rid of the rotary table/chuck set-up but retain the bolted on cross-piece and lock that in a milling vice mounted on its rotating base on the mill table. Then, rotate the vice under the cutter in increments?
Sorry to 'go on' about this. It's becoming a 'give up for good' moment.
Many many thanks in advance for any views/suggestions.
Bonne 2020 to one and all.
|Thread: Opening a Port|
Again, very many thanks for all the advice and practical guidance. This accords with everything I have read and studied on the subject of enlarging/profiling ports and I will be printing this off and keeping it close as I work. Congratulations to everyone who has already made such a splendid job of the procedure and, above all, thank you for sharing the expertise with me.
Many thanks everyone.
Especial thanks to Grindstone Cowboy. You seem to understand exactly what I want.
By the way Brian...I'm not into 'messing' with pre-War components. That is normally anethema to me. I'm just using conventional (pre-War if you like) engineering methods to try to improve an extremely poor aspiration system as thousands of Austin Seven Special builders have done since pre-War days!
Thanks again everyone. Bonne année from warm and sunny Paris.
A Peaceful and Healthy 2020 to All
A very simple question...I need to enlarge the inlet ports on my Austin Seven exhaust manifold. It's cast iron of course. Would you recommend doing this with an end mill, slot drill or with a stone (perhaps even with a Dremel attachment).
Many thanks in advance.
|Thread: Bronze bushing|
Many thanks everyone.
Yes...they were Oilite originally. I bought the Oilite replacements from the site Colin mentions of whom I am also a satisfied customer. But on this occasion the bushes were a mile too big. I baulked at making a tapered mandrel to hold them to try to turn them down largely because I'm not good with tapers. Hence I decided to make new ones.
Yes also...they were Imperial originally, but I always work in metric because I find it 100(!) times easier and logical.
Finally, the 'Oilite' bushes I got from the supplier had a lubrication hole halfway along! Struck me as a bit odd as there's no provision on the back plate for an oil/grease nipple and my understanding was Oilite bearings were permanently pre-lubricated?
Thanks again and a tres bonne weekend from la belle France!
I'm needing to make bronze bushing for the brake camshafts on my Austin Seven project. For those not familiar, the bush carries the stem of the shaft through the brake backplate from the brake actuating cam itself to the operating lever.
The bushing needs to be about 26mm long, 13-ish mm O/D for a push fit in the back plate with a bore of 11mm.
I've got the stock set up in the lathe with a 10.5mm drill in the tailstock drill chuck. (The plan is to reamer to 11mm when the axle is attached to the chassis).
However, the drill is making painfully slow headway and repeatedly snatching in the bore.
I think this is because I haven't 'backed-off' or blunted the lips on the drill (didn't want to spoil a drill!). Would that be the likely cause of the problem?
As always many thanks in advance for a view/advice.
|Thread: RENAULT DAUPHINE|
Remember them well, and a school mate who was very miffed if anyone raised the issue of instability.
Think it was a myth. As someone says, you had to accustom yourself to the characteristic of the car in those days, and the Dauphine layout was helping to break new ground, particularly in the UK.
Rust? Everything rusted to billy-o then, even R-Rs and cars like the Vauxhall Viva and Hillman Avengers were catastrophies.
Suspect the disparagers of the Dauphine may be displaying a touch of Europhobia....lot of it about.
Martyn in Paris
|Thread: Automotive starter ring (ring gear)|
Very many thanks everyone. That helps.
I wonder if anyone could advise on this?
I have an Austin Seven flywheel from which I want to remove the ring gear. This is the early type where the teeth were milled(?) onto the solid. I.e. not the type where you heat a gear ring and shrink it onto the flywheel.
Most people would probably do this on the lathe and I have sufficient swing to do that. However I am worried such a heavy interrupted cut will bash the hell out of the lathe headstock.
I'm thinking a gentler approach would be to mount the flywheel on a rotary table and cut down just behind the teeth with an end mill or slot drill.
Is this a sound tactic?
Thanks in advance for any help. Martyn
PS Not an angle grinder please! They terrify me.
|Thread: Tab Washers|
Good advice and tips I shall employ.
Does anyone make tab washers in their workshop, and know an easy way to do so that's not like taking a steam hammer, the size of Big Geordie, to crack a very small walnut? I know your going to say: ' tab washers cost buttons, so why bother'. True; but my supplier makes them from far too hard a steel and when they are close behind a nut and tight against a ball race (my context) they are nigh on impossible to bend neatly without damaging the nut and/or bearing.
Soften them by heating. Yes? But to what colour and quench?
Or, could you do it like this? The Big Geordie and nut method! The principal difficulty as I see it is the internal tab. What if you took a piece of aluminium bar, turned to the desired outside diameter of the washer and bored to the inside diameter less the width of the tab. Now set up the workpiece on a rotary table and mill round with an endmill for, say, 350° of the bore - or any circumference that left the appropriate tab width. Could you now slice off as many washers as required, as thinly as practicable, with a slitting saw and grind them down to an appropriate, bendable thickness.
|Thread: Milling that slot|
A few weeks ago forum correspondents were good enough to advise me on milling a slot in a round bar and I thought it would be an appreciative gesture if I let you know the denouement.
We explored a number of possible causes for difficulty. Unknown specification of the metal - I was using a surplus Austin Seven gearbox shaft; lack of centricity and/or rigidity of the workpiece, suitability of, and working procedures in using the slot drills I was 'hell-bent' on employing, and so on.
So, I threw away the bit of A7 gearbox and ordered virgin, free-machining steel from that most excellent supplier, R C Machines in Luxembourg. I took the precaution of buying both 15mm and 20mm diameter lengths as the finished part was barely 14mm in diameter and break out either side when machining was an issue, particularly if I let the tool deviate to one side or t'other.
To that end I trammed the vice to within 0.02/0.05 mm parallelism which, in spite of watching numerous 'how to You Tubes' from the great and the good, is about the best I can manage. I also decided to use about half the 300mm long bar although the finished part needed to be no more than 30mm long, the thinking being it would give me plenty of material to 'hold on to'.
To do so I set up twin precision ground V-blocks held as far apart as practicable in the vice jaws. I found the jaws would only grip one block. This could be because there is slop in the newish Vertex vice, although none is perceptible, or the identical V blocks (Chester) aren't in reality .
I have to confess to not taking the advice on centring, largely because I didn't really understand. I guess I could have touched on one side of the bar with an edge finder, done the math, touched from the other side, calculated again and divided, but given my level of competency and the back-lash on the Warco I stuck with my dangly inverted V gadget, that I do happen to like, in the mill spindle. But I did double check with the old machinists' trick of touching down with a centre drill on a steel rule placed across the circumference and eye-balling it for levelness.
I then drilled into the top of the bar at each end to seat the clamp of each V block and I overcame the fact that one was not gripped by the vice by building up with parallels a step block pressed across the end of the recalcitrant block. I also packed with spacers the gap in the vice jaws between the V-blocks.
I found I could get away with an 8mm wide (as opposed to 9mm) slot, so I amended the 'spec' accordingly. I felt the rigidity and centricity(?) I now had was the 'answer to a maiden's prayer' so applied the previous technique. Drill holes on the ends of the required length; cut through with an end mill and widen accordingly. M-I-S-T-A-K-E! Worse mess than before.
Thus I decided to 'bite the bullet' and experiment with a brand new 8mm slot drill. In a test slot on the material I found the slot drill would plunge 0.75mm static then
happily slot at that depth over a test length (12-ish mm -18/20 required). 'Perfick'!
Try it for real. Problem. Slot drill is pushing the bar along the V blocks. This problem was identified in the forum when I was holding with a collet block in the vice. Paper stuck to the ground surfaces was suggested. Because I didn't want to disturb the workpiece I didn't do that but instead pressed step blocks against both ends of it. Slot drill now plunges and advances with no problem and makes a perfect slot on the axis of the bar. I finished to diameter with an interrupted cut on the lathe. I ran the mill at 360 rpm and plunged the slot drill by 0.5mm increments.
Delighted with the result so thanks again.
10 avenue de la Porte de Ménilmontant
|Thread: Cut a slot in round stock|
Thanks everybody, I think we can make progress here!
Rigidity, rigidity, rigidity is a good axiom I feel.
Maybe turn down the centre of the stock shy of diameter first. Clamp the collet block vertically certainly, but with a long piece of stock there's also the opportunity to hold the other end rigidly.
Not working to the finished diameter would strengthen the sides of the slot during the cutting process and once it was done an interrupted cut on the lathe would take it down to size before finally cutting off the part at each end.
Take the point about the material. That's the trouble with non-virginal material isn't it? You don't know the composition. I'll buy new steel.
I'll forget slot drills. Cut a flat with an end mill I think. Use twist drills at each extremity then gently take out the balance with end mills of increasing size.
I appreciated the drawing. That's not quite it. The bar, 27mm long at the finish remains intact at 14mm diameter. The slot - 9mm wide x 19mm long - goes through it. Thus you can't take out a complete portion as in the drawing but are leaving about 2.5mm on each side which is what makes it tricky. The slot needs to be straight, consistent and in the middle so as not to weaken one side or the other. Nice artwork though!
Thanks again everybody
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