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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: Velocette
16/08/2019 16:32:20
Posted by Graham Williams 11 on 16/08/2019 11:31:37:

What's the consensus on the use of a 0.8mod cutter using 32dp specs i.e. depth of tooth and outside diameter on a magneto drive gear for a Velo MAC, alloy engine, 92 teeth?


Graham W

Sorry to say no good at all, assuming you are forming rather than generating the gear. These gears need hobbing (generating the tooth form), although not transmitting any great load the formed tooth will probably be quite noisy, defeating Veloce's use of helicals to keep thing quiet.

Why not buy a gear (£59 from the VOC) intended for the manual advance/retard and modify that?


Thread: What 3 Words
16/08/2019 07:48:26

Recently I had first hand experience of the app working. Out mountain biking we came across a group of walkers, one of them in very obvious distress. Fortunately they had the app on a phone and luckily the local emergency services had just started using it. The emergency services were able to get to the location quickly. These walkers were not local so, would by their own admission would struggle to give an accurate location. Us MTBers being local may also have struggled using local rather than the "official" names for the area and features that the services need.

Needless to say I've installed the app!


Thread: Chosing a drill grinding attachment or machine
15/08/2019 16:51:17

This drill sharpener was a pleasant surprise! I bought it from Aldi (under a fiver, I think, complete with a spare grinding wheel) several years ago as a means of sharpening drills "off site". It works very well. Power is provided from an electric drill, I used a drill with a top speed of about 3000rpm, not really enough but I suspect running any faster would shorten it's life significantly .

Copes well with both HSS and tipped masonry drills.



10/08/2019 16:45:12

The last two posts, should we ignore or follow the instructions! I (and others) have taken both approaches, still doesn't work. My 20 year old (I think) version of the Drill doctor was notorious for variable results, newer versions seem better. It was the second one I had, first one returned to the supplier, really should have sent second back but never got around to it. Anyone want it, free to a good home......


Edited By John MC on 10/08/2019 16:51:50

10/08/2019 11:52:54

I would recommend one of these,

Not cheap, I shopped around and found the same machine for ~£200 less.

In the past I've used a Draper attachment, looks cheap and nasty but works remarkably well. Also a Martek and a Drill Doctor, both hopeless. Ok for getting an even point but both failed to give any clearance, needed to do that off hand.

There was a recent thread about drill sharpening that encouraged me to have another go with the Drill Doctor, same result, even length cutting edges, no clearance!

Perhaps somebody out there wants it, they might have more luck with it than me.


Thread: What Did You Do Today 2019
09/08/2019 07:53:15
Posted by John Hinkley on 03/08/2019 15:39:52:

Meantime back at the ranch ............

I've done a bit more with the gearbox internals:

Input and output shafts

The reverse gear idler is missing from this shot. I need to find out how to insert a new offset axis in Alibre Atom. And the shaft ends aren't complete, yet, either. But it's progress.


Interesting, what's the gearbox for?

John MC

Thread: Shot peening for metal improvement
05/08/2019 17:55:23

I have used Oselli engines, when they were based in Oxford, to shot peen connecting rods. I was pleased to see they used Almen Strips to gauge the intensity (is that the correct word?) of the peening. Oddly enough, it made the rods very fragile until engine assembly was completed! The slightest mark on the rod completely nullified the advantageous effect, extreme care was needed on assembly.

I have considered using my blasting equipment for shot peening. I occasionally change the blast media from something aggressive to a more gentle media but have been advised by a supplier of peening media that A dedicated cabinet is vital so as to avoid contamination and therefore negating the advantages of shot peening.


Thread: Tolerance for needle bearings?
02/08/2019 15:34:52
Posted by Howard Lewis on 02/08/2019 14:43:15:

Sounds like a proper roller bearing, with a hardened outer race is what is needed.

Drawn cup needle rollers are intended to be supported by the housing. Assymmetrically loaded, and unsupported, the thin housing will distort and be liable to fail in fatigue.


Thinking the same, Gary W. (OP) do you have an ID/part number for the bearing you intend using?


01/08/2019 16:47:08

Have you fitted the bearing in to its housing yet. If not the shaft, at the correct diameter, will be "slack".

Drawn cup bearings needed to be fitted in to a housing of precisely the correct size and shape, this will bring the bearing to the correct size and geometry.


01/08/2019 07:41:29

Well known for their ability to rust! I think it was an American journalist wrote that the corrosion problem was so bad you could almost hear them rusting!


Thread: Using a brake cylinder
25/07/2019 12:33:09

Was there a design for a Robinson type hot air engine using a car brake cylinder described in ME some years ago?

May have used a beer can for the displacer, (I could be wrong about that).


Thread: Remembering Apollo 11
17/07/2019 07:59:40
Posted by Neil Wyatt on 16/07/2019 15:10:31:

I was six at teh time of the Apollo 11 mission, but I remember many of the events in that week - and standing on the doorstep staring up at the moon.

I just watched the launch in 'real time' (+50 years) at

What's your normal heart rate? And what does it go to when you are under stress...?

" This is Apollo Control at 36 minutes. That's the end of the tape. We have a report on the launch heart rates now from the Flight Surgeon. Commander, Neil Armstrong's heart rate 110, Command Module Pilot, Mike Collins 99, Lunar Module Pilot, Buzz Aldrin 88. These compare with their first Gemini flights, their first liftoff back in the Gemini program. Armstrong's heart rate was 146 at that time, Collins was 125, Aldrin was 110. "

Apparently when Armstrong was piloting the lander down to the surface his heartbeat reached 160, mission control were worried! This got me thinking, is this bad for you if the elevated rate is caused by stress, as it was piloting the lander (I guess) rather than physical exertion?

I agree with the comments on "The Dish", a wonderful film, I'm hoping one of the TV networks will broadcast it as part of the moon landing celebrations.


Thread: Barrier Cream
16/07/2019 08:28:56

I started to suffer from dermatitis, the Doctor said it was an accumulative thing, many years of working with oily things had just caught up with m. Using aggressive hand cleaners also added to the problem.

I tried various barrier creams, these made no difference. Having said that it was 20 years ago so time will have, no doubt, improved these products.

I then tried latex gloves, end of the problem. A useful "by product" of wearing gloves was that my hands stayed relatively clean, a wash with a mild soap is all that is needed even after a long oily session in the workshop.

There was a period of getting used to them but worth the effort!


Thread: V-Twin 100cc Design & Build
10/07/2019 15:24:32

Craig, the bearings need to be constrained correctly. Its a rotating shaft so the inner races need to be clamped to the shaft. As drawn, when the engine gets hot axial load from the expansion of the bearing housing (al/alloy?) will put extra power absorbing axial load on the bearings

One of the outer races needs to be fully constrained so an interference fit in it's housing and one side against an abutment in the housing and, in this application, a circlip (space/weight considerations) for the other side, that is to say the bearing cannot move axially and therefore provides the axial location for the crankshaft.

The other outer race needs to be able to move so a transition fit in it's housing but not against any abutment. This is so the bearing can move (a very small amount) as the engine gets hot. This will stop the bearings taking unnecessary axial loads.

The SKF catalogue has all the information on tolerances.

You could consider a fully constrained ball race for axial location at the drive (propellor) end of the crank, that would locate the shaft and a drawn cup needle roller (hard steel sleeve pressed on to shaft) at the other end, absolutely no risk of excess axial loading.

I see the incorrect mounting of rolling element bearings in the model engineering world all too often, has there never been an article in ME to show the right way?


10/07/2019 11:41:51
Posted by Craig Booth 1 on 09/07/2019 22:21:06:


You need to sort out the crankshaft bearing arrangement, I assume they are ball races.


Thread: Motorcycle General Discussion
09/07/2019 07:46:15
Posted by Windy on 06/07/2019 16:24:39:

If you are feeling fit a simple way to align single cylinder cranks.


The guy has the right idea but IMO executes the procedure poorly. Even though it looks brutal a surprising amount of "feel" is needed to do the job properly. He wont get that with his lump of lead dancing around. He also seems to be using excessive force to shift the wheels, something wrong there. Or is it that he cannot get a clean "bump"?

Also the DTI is too close to the main bearing location, he needs to make a close fitting sleeve that "extends" the crank shaft (both ends) so the DTI sits over the ends of the shafts. This is the way to get the accuracy required.


Thread: Best instructions
06/07/2019 10:11:07
Posted by Douglas Johnston on 06/07/2019 08:49:36:

I was using my Haynes manual recently and tried to follow the instructions for removing the rear bumper of my Fiesta. Try as I might I could not complete the task, the last instruction just did not work. I must have spent an hour trying to complete that final instruction and then went for a break. On the off chance there might be something on youtube I fired up the computer and had a look. Bingo, there it was in great detail showing the subtle move needed for that final instruction. Back to the car and I had the bumper off in two minutes.


I too have found Youtube useful for filling in the gaps that the written instructions have missed. This made me think of "Wheeler dealers" on the TV. I'm sure that program has been responsible for many failed rebuilds of classic cars. They make it look so easy, never a rusty bolt that shears off and a seemingly limitless budget for equipment!


Thread: Cast iron - 160mm dia
05/07/2019 07:37:52

Seems that from the above posts cast iron is the preferred material for chuck back plates, why is that?

Thread: Satnav
25/06/2019 07:59:12

Clive F. I do hope you are joking! I suppose competing in a 3 wheeler with a co-pilot is cheating, Sitting behind a fairing could be considered the same, riding a diesel engined bike that did not need a refuel for the (540miles) duration of the rally is unfair! An ubundance of power is an unfair advantage! A real rider would achieve the top award on a Honda 50!

The rally now runs from 12.00 untill 10.00am the next day, 2 hours longer than a few years ago! And only 540 miles maximum, in the good old days it was 700 miles in 2 hours less.

My favoured method of route finding was a map in a tank bag. The thing is scooters don't have anywhere to put a tank bag so its a satnav for me. But, I'll only be listening to it so I'm only half cheating!

John (with tongue firmly in cheek).

24/06/2019 15:10:32

Thanks all for the replies. The device (Tomtom) is quite old so no Bluetooth. I've cleared out some memory on the phone and downloaded Waze. Pleasantly surprised with how well it works! The reason I want satnav on the bike is because I have entered this years ACU National Rally for the first time in a few years. When I was a regular competitor I could remember where the location of the controls, mostly. I'm staying local (ish), trouble is some controls have gone and been replaced with controls in different places, I'm hoping the satnav will help ne find them.

As for buying a motorcycle specific device, they seem to be quite expensive, especially for something that will get very occaional use. The last to new cars I bought have built in satnav. The old Tomtom still gets used in my classic car.


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