Webster Build

[simister]

Ok, that explains a lot. This engine has stopped after 10 or so minutes of running. It may be that there is not enough lubrication in the fuel mix. I will give that a try and post the result.

I am also using Viton-O-rings. I took them out today for inspection and there was no noticeable wear in comparison with a new one I have on hand. So, they seem to be coping very well.

John

 

[gus]

Viton o-rings are rated for applications around 400F and there would be a significant safety factor as well, so the chances of one melting or catching fire in a small engine would be very slim I imagine.

However, when they do melt or catch fire they decompose into hydrogen fluoride. On contact with moisture or skin this becomes hydrofluoric acid - which boils at room temperature, dissolves corneas! and burns really badly. Check the picture of burnt fingers at the bottom of this link.

So it looks like everyone is right, they do work in engines and they will cause you severe injuries if they fail catastrophically.

Hi Al,

Thanks for warning and advice. I have no idea that Viton when subjected to prolonged hi temperature can be so hazardous. Will stick with C.I. Rings.Have no desire to worsen my eye sight with ''Glaucoma Right Eye''.. No worry. Permanent eye drops kept Glaucoma at bay.

 

[Mechanicboy]

Hi Al,

Thanks for warning and advice. I have no idea that Viton when subjected to prolonged hi temperature can be so hazardous. Will stick with C.I. Rings.Have no desire to worsen my eye sight with ''Glaucoma Right Eye''.. No worry. Permanent eye drops kept Glaucoma at bay.

Same here i prefer cast iron piston ring due hi temperature. Never tried Viton ring in combustion engine, steam engine only.

 

[simister]

I found that the spring on the intake valve was not strong enough. I replaced it with one that has two extra coils and it runs fine. I recognized the problem because I noticed small puffs of blue smoke coming out of the carby intake on the exhaust stroke. With the longer and stronger spring that has now stopped.

What is the most efficient way of setting up the ignition? I am currently using a motorbike battery with a car coil. Has anyone found another or better way of setting this up?

John

 

[Longboy]

I see this listed in EBAY/AU. Seems to be a new product will little Ebay sales now. I use a 3V vintage model engine coil with a pair of "C" batteries. They come up on Ebay every month. Coils from small gas engines like Briggs & Stratton or a gas string trimmer are small and convenient sized too.
http://www.ebay.com.au/itm/Spark-pl...056900?hash=item43e738a0c4:g:9pgAAOSwys5WVxNT

 

[simister]

That unit off Ebay looks quite good. I wasn't sure if you could use a coil out of a brush-cutter or motor mower that was run by a magneto. I have seen a lot of Briggs & Stratton coils but they look like they require a magneto to run.

John

 

[Cogsy]

The switch that unit uses to actuate is a simple microswitch commonly used for limit switches. I bought a bunch of similar switches and was going to use one on the ignition of my Rupnow Hit and Miss instead of a hall sensor but I wasn't sure how fast such a switch could cycle and how many cycles it would perform before failing. I still have doubts about how durable the switch would be, and how may RPM it could sustain so I hope whoever developed this ignition has tested it and they are up to the task.

 

[Longboy]

That unit off Ebay looks quite good. I wasn't sure if you could use a coil out of a brush-cutter or motor mower that was run by a magneto. I have seen a lot of Briggs & Stratton coils but they look like they require a magneto to run.

John

Ya, I guess thats true ..... with their coils wrapped around the flywheels. Motor bike coils next best bet.

 

[kquiggle]

This discussion about ignition systems is much appreciated - there is a lot of info around on Webster building, but very little detail on the ignition system(s) used.

I have seen at least one other build which used an electronic (Hall sensor) system. Nothing wrong with that, but my own goal in building my own Webster is to keep things as "mechanical" as possible - so points, coil, etc.

 

[Brian Rupnow]

I have used both the auto ignition points and coil and battery, and the "modern" hall effect sensor and ignition pack with 4 small dry cell batteries. If you already have some kind of battery, either car or motorcycle, then the points/coil/condenser costs about $80.00 and is great for home use but not very portable because of the large battery required. That system is virtually "foolproof". The electronic ignition with Hall sensor , switch, and battery pack is over $100, is very compact and portable and is rather fragile. If you should test a sparkplug without having it properly grounded, then it blows the Hall sensor which is the heart of the system and quite expensive to replace. I have many engines, so I built a "power box" which is basically an automotive coil with wire leads and a ground strap mounted in a box. Each of my engines have their own points and condenser, with plug in wire leads (about a $30 cost). That way I only have to buy one of the 12 volt coils (at over $50 each.) Of course, it means I can only run one engine at a time.----Brian

 

[10K Pete]

Here is some interesting info on ignitions:

http://www.oldengineshed.com/ignitor.html

http://www.homemodelenginemachinist.com/showthread.php?t=17198

http://www.eldensengines.com/Otherstuff/LT Scope Pictures/LT Scope Pictures.html

http://www.old-engine.com/magign.htm

Pete

 

[simister]

Thanks Brian for the info. I figured that the simple car battery and coil is probably the way to go. I already have that set up. I will now fit it up in a box with terminals, switches etc.

Also, Thanks Pete for those links. I will have a look through those before I finally decide, but, I think at this stage I will keep the method I am already using - nice and simple.

Regards John

 

[simister]

Can anyone suggest another i/c engine to build? Brian originally suggested I build the Webster, and this was good advice for a beginner.

I would like to build another engine as a step progression from the Webster.

Regards John.

 

[Cogsy]

My first I.C. was an Upshur farm engine, which I think is about the same complexity as a Webster, then I built the Rupnow Hit and Miss. It's a little more difficult but runs well and has a cool set of flyballs swinging around. Brian's design and build thread is http://www.homemodelenginemachinist.com/showthread.php?t=21176

My finished version is here http://www.homemodelenginemachinist.com/showthread.php?t=23431 - although I had it running a lot nicer after that video was taken (I don't know why the pictures won't display, I haven't moved them).

 

[simister]

The hit and miss looks really interesting. Did you have any problem getting parts?

I am not that familiar with the operation of the "hit & miss" so it would be a big learning curve.

Your video looks great.

John

 

[Brian Rupnow]

Simister--Although my engine was fun to build, it did require some special mitre gears and was a badly balanced engine. The next logical progression after the Webster would be the Kerzel hit and miss engine. It too is an engine built totally from bar stock, and the plans are (or at least were) a free download from the internet. The "hit and miss" mechnism that controls the exhaust valve opening/closing is a bit complex, but if you can build the Webster, then you can definitely build the Kerzel.----The engine itself is a quite simple water cooled single cylinder engine.---Brian (I have a build thread on it as well.)
http://www.homemodelenginemachinist.com/showthread.php?t=10091

 

[Cogsy]

The engine is a bit out of balance, I would like to get it back and try my hand at drilling a few well placed holes in the flywheels to see if I could make a difference.

As for the parts, the bearings are off the shelf and cheap to buy, the valve springs I used came in a $8 200 part assortment from a hardware store and the only things I had to think about for a while was the mitre gears. In the end I pulled apart a $10 right angle drill attachment and the gears in that were almost spot on the correct size.

For another option, the Upshur farm engine plans give you 4 options to build for $10 + $3 postage - 2 horizontal and 2 vertical. They can all be built hit and miss as well and the plans are very easy to follow. The website is http://upshurengineworks.com/ .

 

[simister]

Thanks Brian and Cogsy,

I will have a look at the Kerzel and the Upshur.

Do either of these days engines involve building your own gears or carby? With the Webster I purchased the gears and carby as I was not confident enough at this stage to build my own.

John

 

[Brian Rupnow]

Just about all i.c. engines I know of have some form of carburetor. All but the Philip Duclos gearless have gears, unless they are a two cycle with no cam shaft. As a generalization, most of these engines will run with a purchased model airplane carburetor if you don't want to build your own carburetor. If you are going to seriously get involved with i.c. engines, then you should buy a set of gearcutters.

 

[Cogsy]

The carby isn't something to be too concerned about, especially with a hit and miss model that doesn't have a throttle. I felt the same as you but both my engines ran better with my home built carbies than my RC carbies.

For both the Rupnow and Upshur engines I used a simple home made 'hob' to cut the gears. If you've got a rotary table / dividing head acceptable gears are fairly simple to make. Full info on making your own hobs is at this link.