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Member postings for John MC

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

Thread: 15/64x48 tap
14/02/2020 16:23:39

Metric? M6 x 0.5 possibly.

John

Thread: What a sad day for the British motorcycle industry.
12/02/2020 15:25:59

It is a sad but inevitable that Norton should be finishing again. I think it was the most successful (long lasting?) attempt at resurrecting the name.

I say inevitable because what did the bikes have to offer at the selling price? Plenty of other bikes as good as and often better are available at considerably less cost.

No doubt the Administrators will sell the Norton name. Who will buy it? Seems to me that the name has become tainted by repeated and unsuccessful attempts to resurrect the brand.

I can see the new Brough Superior going the same way, if it does I hope its in an honest way.

Best wishes for the future to employees and customers who have been affected by this sad business.

John

Thread: Noisy Lathe Gearbox
09/02/2020 07:58:08
Posted by Samsaranda on 08/02/2020 21:09:43:

John, the product you referred to was Wynns Friction Proofing, an oil additive that used to be on sale years ago, I never used it and I have no idea if it’s still available, I think modern lubricants negate the need for additives nowadays.
Dave W

No, its an oil rather than an additive. Just had a look at the Lucas Lube website, I see they no longer use the term "climbing oil", plenty more do, Plusco for instance.

John

Edited By John MC on 09/02/2020 08:00:05

08/02/2020 15:55:24

Don't know if its been mentioned, try some "climbing gear oil" (google Lucas climbing gear oil, other brands available).

I first heard about this type of oil in relation to the new version of the not very good Morgan three wheeler. They have a gear box that turns the drive through 90 degrees. Its often very noisy, climbing oil turns down the volume, a bit, apparently.

John

Thread: milling crankshaft on cnc mill using A axis
05/02/2020 16:16:55

During the early 2000's when I was involved in various aspects of engine design I visited a a crankshaft manufacturer in the UK midlands. They specialised in one off and very low volumes, the shafts were typically "car" size. I was surprised to see the method of machining.

The cranks were roughed out from a suitable diameter piece of steel on very heavily built lathes. No top slide, tool post mounted directly on the cross slide in the "front" position. The tool looked like a very substantial parting tool with a screw jack arrangement supporting the tip of the tool. Even with one machine in operation the building seemed to shudder every time the lathe took a cut. I found this very wearing, frankly glad to get out of the building after a few hours of constant noise and vibration!

The roughed out cranks were then transferred to 4 axis CNC machines that finished the cranks prior to heat treatment, grinding, radius rolling and peening/polishing. Watching the speed and ease at which the CNC's worked I asked why not rough out on the CNC as well? Apparently quicker to do it as they were, was the reply. I wonder if they still do.

John

Thread: Nalon Viper
27/01/2020 18:16:13

Graham, never bothered with a tapered bore, I've always taken great care to get the bore (and piston) parallel in these small sizes. I think that the amount of taper required in these small cylinders with piston and cylinder made from the same (or very similar) metal is so small that it would be difficult to measure and I don't like the idea of guessing! I've always tried to arrange effective cooling of the cylinder to try and keep it parallel and round. Screwed on or "slip fit" fins doesn't do that.

Tug, I don't understand your point about preloading. Preloading of the bearings is to be avoided in this type of use, your design will, most definitely, preload the bearings when the engine warms up, assuming they are not when cold.

John

27/01/2020 11:46:57

I hone both cylinder and piston using Delapena equipment, one photo show a small cylinder being honed while the other two photos show the external honing equipment, one is with the hone on a truing mandrel. To fit a piston (and contra piston) I turn a length of suitable bar to ~0,002" then hone to size, I make the contra piston quite tight compared with the piston. I've "rebored" many more cylinders for others than I've finished cylinders for myself!

Earlier on in this thread I commented the mounting of the crankshaft bearings being poor so I thought I would have a go at doing the job properly with the Nalon Viper, I've modified the "cooling system as well, the cylinder in the photo is for the Viper. Thats one of the engines I'm building, the other is another diesel of my own design, more or less, again with rolling element crankshaft bearing but with a different arrangement from what I have seen in many years.

John

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img_20200127_110359_4.jpg

26/01/2020 17:08:09

Great to see the engine running Graham. I'm presently building two engines, close to completion now. One of them has had two pistons already, I use an external hone to finish a piston and neglected to true the hone before sizing the piston!

24/01/2020 14:25:52
Posted by JasonB on 24/01/2020 13:04:59:

As John MC has hinted they do nor run on diesel that you get at the petrol station

I do hope the OP is not thinking I'm suggesting that he is using pump diesel!

The reason I ask is that I'm wondering what the preferred fuel is, its been a while since I bought any. What with the demise of my local model shop, I'm not sure what to buy. to get my latest engine running.

John

24/01/2020 12:42:28

What fuel are you using?

John

Thread: Torx Grub Screws?
22/01/2020 17:26:10

The problem I have found with Torx is that the next size down (to the correct size) key almost fits, without care it can easily be mistaken for the correct size key. If the fastener isn't too tight it will undo. If its tight then rounds out the socket nicely. My local BMW motorcycle dealer hates them because of this, they are frequently asked to remove a damaged Torx fastener by owners who are unfamiliar with them.

John

Thread: What Did You Do Today 2020
13/01/2020 10:46:28
Posted by Steviegtr on 13/01/2020 01:09:50:

An interesting analysis. Car bodies do not rust anymore because they are zinc bath dipped. They used to say the best cast iron was from Detroit

Not quite true, car bodies are pressed from Zinc plated steel, "Zinctec" being one name for it. Along with much better joint sealants, better design and very much better paint systems car body corrosion is no where near as bad as it was.

Having said that Porsche, some years ago, hot dipped (galvanized) the bottom 6 inches of complete body shells to stop the appalling corrosion they suffered from. The last 100 (150?) Reliant Scimitars also had galvanised chassis.

What Detroit did with cast iron was to develop techniques to enable casting in very thin sections, they probably used good quality iron but the skill was in their casting techniques.

John

Thread: The cultural status of engineers in the UK
11/01/2020 11:40:56
Posted by old mart on 10/01/2020 16:42:43:

In my book, an engineer is someone who has completed at least to university degree level.

I agree. After completing an engineering course, gain experience, join the relevant professional institution, then register as an engineer with the Engineering council. Either Technician Engineer, Incorporated or Chartered Engineer. Then, possibly as a Eur Ing. Then, in the UK, you can call yourself an engineer.

There are other routes to achieving engineer status, based on experience, rather than focusing too much on academic achievement. I've been involved in peer reviewing work from people attempting to gain engineer status through this route and have come across some extremely competent individuals, and a few complete idiots!

None of this is easy, to achieve engineer status takes a good few years and to belittle it seems very wrong to me. I suspect that the cultural status of engineers has diminished due to whats involved is not understood.

A good analogy could be the term "GT", grand tourer, as applied to cars. At one time it it was an expensive car capable of covering large distances quickly and, for the driver and passengers, comfortably. The term was held in awe by motoring enthusiasts. Then Ford stuck a GT badge on the Cortina, then the Transit.....

John

Thread: Have a look at this, view from the chuck
09/01/2020 08:17:41

Probably just trying to justify spending a small fortune on a Go-Pro.

Thread: 3 in 1
30/12/2019 12:02:37

I've had one for some 15+ years. Assuming its used within its specification (or even a little beyond) I find the folder is good, the shear works well but suffers somewhat from deflection. There's is a stiffener to stop the deflection but doesn't seem to work too well, I've thought of a fix for that but yet to do anything about it. The rolls are it's poorest feature, not too good. I certainly wouldn't be without it now.

John

Thread: A Question on Bench Blocks
26/12/2019 08:10:47

I'm guessing the answer to the OP's question is "poorly made".

I've had a Starrett bench block on my bench(es) for longer than I can remember, a useful thing to have. if you don't then its a couple of productive hours to make one.

Not sure what makes the block precision, other than the parallelism of the top and bottom surfaces, thats been useful on the mill a good few times.

As for using it as a drill and tapping guide, the Sparber article, surely using it inverted would be better?

John

Thread: Merry Christmas Everybody!
25/12/2019 09:05:29

Merry Christmas!!!!

Just enjoying the peace of this Christmas morning before the family invade.......

Thread: Nalon Viper
24/12/2019 09:44:31

Old School, as you say, design of the bearing housing doesn't seem to have changed much in a long time. I cannot help but think that some of that is due to a lack of understanding of the principles of rolling element mounting.

I would like to know why wide clearance (hybrid?) bearings are being used?

Please don't call it my design, I claim no originality for the design, its good bearing mounting practice and I've seen it used on several engines.

My current project is using a bearing arrangement copied from an engine that was designed and built some 40+ years ago. If memory serves the aim was to get 1bhp from 5cc's, (may have been 10cc's), I think the aim was achieved. I'm no longer interested in sharing this design. I may incorporate it in to a Nalon Viper in the future as there are some aspects of the engine that seem to be good.

The pleasure I derive from occasionally dipping in to the world of small I/C engines comes from the design, manufacture and getting it to run aspects. My aero modeler friends mount them in aircraft to see if they make the power to fly. My present project is going to be tried in a tether car. The engine is not a high performance job, never the less it will be satisfying to see it do a few laps.

John

24/12/2019 08:00:39
Posted by Roy Vaughn on 23/12/2019 11:02:23:

John, you seem to be suggesting that the rear outer race should be free to move in the housing. This is exactly the condition that must be avoided at all costs with this type of motor. As Rob M says in his article, the hammering the rear bearing gets will eventually loosen the outer race if it not securely fitted, friction will build up and performance will be lost. High performance motors which use standard ball races often use a nut to secure the inner to the shaft. The philosophy nowadays is to clamp everything up so it can't move. The expense of shimming is the price to be paid.

So, the recommendation is to impose a preload on the bearing to try and stop them moving in the case? Looking at the lengths these guys go to extract the last few watts of power from these engines it seems to me to be counter productive.

Frankly, it looks like some engine designers have gone down a non-productive alley with design. While some of what they do is impressive in terms of power to weight ratio, the designs are not so good. Time for a rethink perhaps.

23/12/2019 08:15:48

I've just read through the service sheet for the MB engine. Like the idea of incorporating one of the inner races in to the crankshaft, a simple solution to the vexing problem of clamping one of the inner races to the shaft.

Why, I wonder, is there any need to use shims to control end float of the shaft? In the area I have circled in the (copied) sketch, if there is a small amount clearance between the case and the bearing the need to him would be eliminated. As a bonus the tolerances on the various linear dimensions associated with the components could be eased somewhat.

As Emgee has pointed out the heat required to disassemble the engine suggest the bearing won't move in use. What will happen is that the bearing will be able to find its own position during running, therefore not imposing any axial load on its self. The other bearing is doing all the axial location, just as it should be.

mb engine3.jpg

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