Member postings for John MC

I would recommend one of these,

https://www.warco.co.uk/metal-grinders/303225-dg-20-drill-sharpener-grinding-machine.html?search_query=drill+grinder&results=9

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.

John

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.

John

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

John

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.

John

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!

John

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).

John

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.

John

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!

John

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?

John

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

John

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.

John

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

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).

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.

John

Nothing to do with model engineering and I apologise for that but with the depth of knowledge around here I might get an answer!

I have a Tomtom car satnav that I want to use on a motorcycle and will need to mostly hear rather than see the instructions. Problem is there is no headphone socket, only the USB connection for charging and upgrading.

Is there some way I can get the voice commands in to an earpiece?

I suppose the alternative would be to use my smart phone, problem there is that it doesn't have much memory......

Thanks in anticipation of some wondrous solution!

John

I've no idea if the piston rod is guided by the extension on the cover! It may have been the "chucking boss" on the casting that I decided to machine in that way.

John

This is my attempt at the Reeves popular engine. I acquired two sets of castings some 30+ years ago from the estate of a deceased model engineer. This is one of them, the other is in a small steam launch.

Could be distortion of the worktable? I have seen, on these lightly constructed machines, work clamped to the table causing the movement to become somewhat stiffer due to distortion.

What to do about it I don't know.

John