Here is a list of all the postings Jeff Dayman has made in our forums. Click on a thread name to jump to the thread.
|Thread: Suffolk Colt 'Restored'|
Nice job Neil!
|Thread: Back to the Workshop|
Re: the house - Not sure in the UK, but here in Ontario the home owner is fully responsible for a property until the sale is closed and keys change hands. Most house insurance states that someone must check a property every two days maximum while occupants are away for any reason, or the insurance is void.
I agree that if agents were there after a break in and did not report the damage, that is awful, but the owner is probably responsible for the property unless papers designating responsibility to the agents have been signed.
Between the boiler and the property, not a good year so far, eh?
|Thread: 2-stroke timing|
Glad you got it sorted Keith.
There were several Briggs and Stratton engine models on mowers a few years ago that liked to shear their flywheel keys when they first came out with the flywheel safety brake band. When these engaged, the heavy blade inertia kept the crank turning while the flywheel on top of the engine was braked. This overstressed the key, and the flywheel would shift on the shaft, throwing the timing off. I was given several mowers that people said were "blown up" or "scrap - take it away" and after just a few minutes work and a new key they ran great.
I have seen a few trimmer engines and chainsaws with the key cast into the soft zinc alloy flywheel. It's a poor design but it is cheap to do for the makers.
Lots of fun for us.
Forgot to say that the starting problem could be crank seals as Ian suggests, heaven knows what quality they are. Also it could be a bad coil. A coil test would also be on my troubleshooting list after the items I already mentioned. If you don't have one Keith, a mower service shop will.
Agreed Ian and Hansrudolf, most engines of this type that I have seen have a conical taper and a key. However Keith is saying he has not found a key. I've asked if there is a keyway for one, however, as he doesn't say if there is or not.
I've never seen such a trimmer engine without cone, key and keyway, and I have serviced many, but that doesn't mean there isn't someone making them that has taken out the key and keyway to save costs. In the past few years I've noticed a lot of makers taking off good features to save a few pennies. A couple of examples - fuel shutoff valves under the tanks, and carburetor bowl drain valves - these both save a lot of headaches on mowers snowblowers and tillers. Another good example is grease fittings on blower and tiller low speed high torque shafts being discontinued. If they aren't present, a simple greasing job becomes a major disassembly and if not greased, life of the unit is short. But I digress...
Good luck to Keith in any case. Jeff
quote -"However, As I noted, there is no sign of a key for the magneto flywheel - even after I removed the securing nut"
Keith, I understand there was no key, but were there keyway slots for one in the flywheel and crankshaft? If not, that is the first time I've heard of an engine without them. If so, find and fit a new key. If a manufacturer makes an engine without key/keyway features they are flying in the face of fate for service, or it is a "disposable" unit ie not meant to be serviced. I have seen this approach on small snowblowers where they even rivet the carburetor to the crankcase!
(Not my cup of tea though, such a waste of an otherwise serviceable unit)
Back to your issue - I think if there is no key or keyways you will need to go trial and error positioning the flywheel to time it if the flywheel has slipped.
As a first guess you might try positioning the flywheel so the magnets LEAD the points or coil position by about 20 to 30 degrees. Logic for saying this is that the magnets must fully pass the coil poles to generate the primary voltage and it takes a little time (milliseconds) after that for either the points to open/secondary current to flow to plug or in electronic ignition for the trigger coil to induce the secondary current.
Edited By Jeff Dayman on 07/05/2010 12:02:03
If the flywheel shaft key is intact and the magneto plate bolts are tight, the problem is not likely the magnet/ignition timing. You can NOT set the spark timing of weed trimmer engines using the flywheel magnets. You need to time it with the freshly cleaned points, or if electronic ignition, change the module. If there is an ignition "off" switch on the trimmer check that to make sure it is in the "on " position while cranking, and that its wire is not shorted anywhere. Check that the plug wire is intact, and put a new plug in. Check for spark by using a gap type tester with .080-.090 gap and pulling the engine over with the recoil starter, with the plug out of the engine. If there is not a healthy blue spark in the gap the points or ignition module likely need work. Before doing anything radical on the ignition, I would check several other things to deal with the water in the fuel situation.
--disassemble the carburetor and blow out all fuel lines and the fuel tank with compressed air, and wash all parts with ethanol or methanol.
-inject raw gasoline into the crankcase down the inlet hole, slosh around and drain it. Discard this gas. Inject an ounce or so of 2 stroke oil into the crankcase and slosh it also, and then drain. This will get rid of any water in the crankcase waiting to enter the engine.
-reassemble carb and fuel system and try starting.
If it still won't go, the engine can be mechanically timed. This is done by physically holding the piston at the manufacturer's specified distance BTDC and setting the ignition plate to open the points (or position the ignition module at the specified location in the manual). Distance BTDC for firing will be in the service manual.
Good luck Jeff
|Thread: A beginners locomotive|
One thing I will say about Doug Hewson's designs/plans is that the drawings are clear and very complete, at least the ones I have been seeing for years in ME and EIM. When the occasional error happens (very infrequently) he publishes corrections very soon afterward. Same with Neville Evans. I give these guys a LOT of credit for that - embarrasing as errors are, publishing corrections is best for the hobby.
There has been a lot of talk about errors on this forum and others and some designs by other designers have errors that have been on the drawings for years.
If you go the Sweet Pea route you might want to look up an alternate die block design for the valvegear, published a few years ago in ME. The idea was to use a roller bearing setup to reduce block wear, which in some Sweet Peas has been an issue. It's a great engine in any case.
Looking at Reeves website, Dougal looks very simple, but might be nose-heavy and a bad rider due to front tanks over the cyls. However on Dougal it would be easy to reach the controls (no cab) and with outside cyls it would be relatively easy to make as long as boiler is simple (it should be). You could always revise the tanks to be centred over the axles as well.
Ajax would also be a candidate, although slightly harder to reach the controls inside the cab, compared to Dougal, it has tanks over the axles which should make it fairly evenly loaded on the axles.
Seems to me it was Harold Pearson and his daughter that wrote recently in ME about his own Ajax, which as I recall has given excellent service over many years.
Good luck whatever you choose.
Bear in mind Caribou is nowhere near a true scale model of a CNR 0-8-0 switcher. If you don't care about that, by all means go ahead, it sure will pull, regardless. It is too bad that Evans didn't make it closer to scale though.
For simplicity and pulling ability, a Sweet Pea would be good I think, but they are big.
|Thread: M E W articles on truespace|
Yes professionally, there's "CAD jockeys" and then there's 'designers'. The CAD jockeys run every branch of the CAD program like virtuosos, customize every user setting, automate menu picks and repetitive functions, etc. but when you ask them to design a simple part that fits between 'here and here', weighs less than X, and will not exceed 20% of yield point of the chosen material, they look at you oddly and say they're leaving early today. The best one I've seen in action designed an entire library of standard fasteners - but all the hex head bolts and hex sockets were five sided. He said he didn;t think it mattered, and could easily be changed.
|Thread: Vertical Finger Engine|
I like the engine - no valvegear!
|Thread: M E W articles on truespace|
Have I missed something in the series on Truespace, or am I correct in saying is it not possible to make 2D drawings from the 3D models made in Truespace?
I hope folks realize they can't make a drawing at the end of all their modeling work, unlike most CAD programs. Otherwise somebody could put a lot of effort into a model or models and be shocked to find they can't make a back of envelope sketch of them!
I concede that the program can do beautiful models and rendering though, better than the stock rendering module in many expensive CAD systems.
However I think page space would be better spent on a CAD program that can do 3D models AND make 2D drawings from them later, to be of max use to model engineers.
|Thread: ZA12 - a new option for model engineers?|
ZA-12 ahould not be used where the temp is higher than 100 deg C, because it has a low melting point, and its properties degrade rapidly above room temperature. It has low creep resistance as well, so if you use it for a cylinder head the bolts holding it will seem to loosen over time. This is actually not the bolts loosening, it is the alloy relaxing and squeezing out under the bolts! ZA-8 has better creep performance but is also not a high temp material. I would not recommend any ZA or zinc alloy for cylinder heads or other model IC engine parts. High silicon aluminum would be far more suitable, as used in mower engines and trimmer engines.
For manufactured goods the ZA family of metals are used because they have good properties for this class of work but the main reason is they are relatively cheap compared to steel, aluminum alloys or copper alloys. They are better in strength and bearing properties than even high grade engineering plastics, but can be moulded (die cast) so are cheap to make per part, and often no machining or little machining is needed after casting. This is why you see them in cars and consumer goods. I have designed and had made many parts in these alloys over 25 years professionally. For consumer products with a limited life they perform well.
Personally I would not use any zinc or ZA alloy on any heirloom ME project because they all corrode to some extent, some rapidly in wet or salty / soapy enviroments, and rapidly lose their properties as they do so. Also they creep far more than any other class of metal. They are not suitable for use near high heat (like near a boiler). Getting paint to stick to them can be difficult.
In short I wouldn't go near the stuff unless it is a quickie throwaway project. If you're planning to eventually have your project sit on your great grandkids' mantel use cast iron, steel, bronzes and copper.
Edited By Jeff Dayman on 10/04/2010 20:26:54
|Thread: Drive belt tensioning dolly wheel|
How about shortening a tubular roller from a conveyor belt? good bearings already in those...
or a wheel from a commercial paint roller?
or a wallpaper roller tool?
Hope one of these works. Failing that , you could make a solid aluminum one with a pressed in ball bearing quite easily. A 2" offcut of 2" dia alloy would not be too expensive.
|Thread: Making the Hand Crane|
Looks great so far Neil, nice job.
|Thread: Newest EU legislation|
I heard a rumour today that the EU in Brussels is tabling some new legislation about some commonly used materials.
Rumour has it they want to ban the use of iron and steel because they contain carbon, and carbon is flammable.
This has serious implications for model engineers. Personally I am worried about the safety risk of wearing a fire blanket in case my lathe bed bursts into flame. The fire blanket could get caught up in the chuck jaws.
|Thread: MEW 162 - Phoenix Battery Drills|
in my opinion low voltage devices should never be fitted with mains plugs or receptacles, to prevent the risk of them getting plugged into mains. If it can be it will be.
There are so many low voltage connectors around, and some really cheap ones for cars, I would encourage people to use those instead.
The "weatherpack" style are reliable even in wet weather, and have no exposed male metal terminals. They are recessed in the plastic shells to resist shorting when disconnected. Spade connectors are also available now with nylon shells around male and female terminations, are very cheap and can be crimped without special tools. Panduit and Faston are two brands.
I believe a statement should be made that the mains plug arrangement in the article was for experiment only and that low volt connectors are recommended for anyone making drill mods as described.
|Thread: Thread dial indicator|
Your dial gear does not have to be helical if you angle the shaft at the appropriate helix angle for best mesh. Rather than try and measure/do the math/set it up it may be easier to just make the mount bearing adjustable with a pivot and clamp screw and set the angle for best mesh.
The gear does need to be a close mesh on the leadscrew, with least possible backlash, for good thread start accuracy. The adjustment above may actually enable this on its own, by permitting backlash to be taken up helically rather than axially as usual. (Easy to make as well.)
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