Webster IC Engine build log.

[raynerd]

Jack - thanks for the info - very informative stuff!


Firstly, I`d like to apologise for this next post! I`m so sad that I made a little video because I was so pleased with the piston seal! This is the longest bore I`ve done and I can safely say that turning it between centres was a great suggestion, it is true all the way through. I`m sorry, you`ll have to wait for photos of the piston as I put it together before taking any. But here is the video....

My finger is over the end of the cylinder bottom and I`m getting such good compression that is blows my finger away or in the reverse direction, sucks the crank back around! I`m very please with this as you can tell. All my other piston/cylinder seels on my other engines have been pretty poor! This is the first to give me a satisfying pop when removed!

[NickG]

That looks superb Chris  , presume that is with the o ring in place? What is the friction like? Don't think it will matter as much on an engine like this but I'd still aim to get it quite low if I were you.

[raynerd]

No !! No O-ring or it wouldn't be as impressive!!

The groove is cut ready for the o-ring but it is not in place yet. I tried it with out and got this great seal !! It is just cast on cast so turns very very smooth yet excellent seal.

[NickG]

Excellent - told you, you don't need an o ring! You'll probably find the friction is quite high with an o ring, mainly the starting friction but the dynamic friction shouldn't be too bad, depending on how much you make it compress. The seal will obviously be even better but it might make it more difficult to start etc. With a hit & miss type engine you'd want to reduce the friction to as low as possible, but with this you should be able to live with the trade off of friction vs best possible seal.

Nick

[raynerd]

Yes, I`m going to try without. The groove is in place ready for the o-ring and the orings have arrived. I`m just thinking that after a bit of running the cylinder bore and piston might lap/smooth out (what is the right word?) and make a poorer seal. That being said, I lapped the bore to a good finish and also have highly polished the piston to get such a good fit so hopefully it might not.

Chris

[NickG]

Yeah you could always try it without first, it should polish it nicely, although after a very long time it would wear oval. As long as the bore is very smooth, the using the o ring should make things wear less as it will sort of centralise the piston in the bore won't it.

Nick

[raynerd]

I thought I`d give the flywheel a go this weekend. To be honest, I`ve had several hours on it but I`m a bit off completion yet although hope to get it finished over the next few days. I really really liked how this turned out considering it is made from a dumbell 2kg weight as suggested in the plans. I was warned that the casting could be very bad but it was perfect, not a single flaw!

Here is the weight on a stub I made. I was turning it very very slowly. This was to simply turn the edge so that I could grip it in the outside jaws.


Once gripped securely in the outside jaws, I faced one side. I then flipped it around so it sat flush on the back of the chuck and faced the other side until I had a nice slab. This required removing a lot of metal at slow speed so there was a good few hours of work just in this.




I removed it out of the chuck but marked its position so it could be returned. I then turned up a kernal for the centre out of brass and drilled and tapped the big end so that a grub screw can be used to tighten it onto the crank shaft.




I then silver soldered the kernal to the cast blank, cleaned it up and put it back in the jaws at the marked position. I then centre drilled and this will now go on an arbour throught the centre bore to clean up and finish to size so that everything is concentric.




Hopefully I`ll get it done in the next few days. I was just more impressed that these lovely disks of cast iron are available for very little and quite easily. I`ve just taken a load from my parents loft that I purchased when I was younger... they were going to find there way to the skip, now they are set to the swarf gods!

[saw]

Looking good 

[dbvandy]

It will be spinnin on its own before you know it!!!

Good job!

Doug

[Stilldrillin]

Those castings are a nice handy size, and quality, and price...... 

Looking good/ progressing nicely Chris! 

David D

[NickG]

Nice 1 Chris, looks really good quality.

Nick

[raynerd]

  My flywheel failed. I soldered the kernal into the centre. Drilled it and mounted on an arbour to take the outside to size and the wheel started spinning on the kernal, the solder had failed. I tried for a second time with the same results so clearly my soldering isn`t up to scratch! I`m going to have to read up more on brazing and buy some correct sticks - I`m using some I got from BQ and clearly it isn`t the right stuff. I`m guessing it need to be a good join as well as the weight of the cast spinning when trying to cut the outside rim is just too much and ripping it off the kernal!! I take it there should be no reason why I don`t get a good joint between brass and cast iron??

Anyway, not to be deterred, I didn`t really have any materials for a fly wheel and then looked through a box a kind madmodder gave me over a year ago (please shout out if you wish  ) and in there was a ready cut fly wheel inside hub and outside, just not mounted together. So after a bit of measuring and take a little cut from the outside, I plugged the predrilled inside hole with a 15mm bar of aluminium cut to a taper and used loctite. I then loctited in the hub into the flywheel rim. The next day I drilled a new 8mm bore through the centre gripping the outside of the flywheel so the hole was concentric and tapped it to hold the flywheel to the crank shaft. Flywheel complete -well nearly, just needs a good polish! - OK I cheated a bit, but I figure the 5-6 hours work on the  failed dumbell made up for it.... BUT I will complete that, I`m not just going to leave it and give up.

I also had to made an adapter for the small 24 tooth spur gear so that it could be also held to the crank. The plans call for the spur gear to be attached to the flywheen but I figured I`d have no problems just using grub screws to fasten each to the crank independently.  



Here is the con rod and piston.







So it is looking quite good now and turns nicely with a push on the flywheel yet has a great piston seal. I have a few questions if anyone can answer:

1. Obviously any advice regarding the soldering of the brass kernal to the cast iron surround would be useful even thought my flwheel is now made.

2. I now have to fit my 48 tooth spur wheel to the frame to mate with the 24 tooth gear. The plans just call for accurate measurement and drilling the frame to mount the stub on which the spur gear will sit. I`m just worried about the accuracy of this method. Because I made the gears they are not perfect and consequently they need to be as close as possible without binding. This method doesn`t allow any adjustment. I was thinking it might be worth mounting a stub on a bracket and then attaching the bracket to the frame on slotted holes to allow a few mm of adjustment. Do you think this is necessary?  Also, if the axle is actually attached to the spur gear and spins with it, going through the frame, you could actually run the hall effect sensor off this and just get the required 1 fire per 2 cycles rather than running it off the crank shaft and getting 2 fires of the spark plug per action of which one is wasted. Then again, I guess this is more hastle when it isn`t needed and it also forces the hall effect sensor to be mounted under the cylinder which is more ackward.


Thanks for any advice and your comments so far. I`ve got another week in work and then I`m off for a few weeks for Easter so I`d like to try and finish it in this next month! The next part to make after mounting the second spur gear and making the little valve leaver will be the valve itself....which looks horrible! Truth is, I don`t really understand how it works and is built, so lots of fun and games to come!!!

Chris

[Bernd]

Solder won't work to good on cast iron, also there is a lot of mass to heat. I'd LoctiteŠ  the kernal, or what ever you call, it in place.

Bernd

[dbvandy]

I also had to made an adapter for the small 24 tooth spur gear so that it could be also held to the crank. The plans call for the spur gear to be attached to the flywheel but I figured I`d have no problems just using grub screws to fasten each to the crank independently.  

1. Obviously any advice regarding the soldering of the brass kernal to the cast iron surround would be useful even thought my flwheel is now made.

2. I now have to fit my 48 tooth spur wheel to the frame to mate with the 24 tooth gear. The plans just call for accurate measurement and drilling the frame to mount the stub on which the spur gear will sit. I`m just worried about the accuracy of this method.

I attached mine to the crank with 2 screws 90 deg apart.  worked good

Brazing with brass brazing rod and an oxy acy torch will work, but you have to get it real hot...

With the crank installed, but no flywheel, lay the central upright on its side and place the large gear up to the smaller one just above where it would clear the base plate.  mark the hole with a transfer punch and mount the gear.  You might find that the crank throw would hit anything that went through the upright to the other side.

When you are turning the valves you have to do both surfaces in on setup and put your compound at 45 degrees.  I made my block a bit thicker than the plans so that I could use bigger bolts and have more surface to seal the valve guides to the block.

Doug

[sbwhart]

I've seen that flywheel someware before 

As Bernd and the guys said not s good idea to solder the cast iron it will take a lot of heat to get it up to temperature, even more heat is required for brazing unless you've got the Kit to get the temperature real high stay clear of brazing.

Stew

[raynerd]

I've seen that flywheel someware before 

Stew

  It has come in very useful !! 

Thanks for the advice regarding the cast iron brazing - I`ll stick with Stews flywheel, I`m just not sure if it has enough weight.

Chris

[NickG]

I didn't think it'd be easy to solder cast iron and was going to say something - but then I remember my dad brazing some cast iron (with sif bronze and oxy acetylene) so thought it could be done and was being stood corrected. I'd loctite it too, alternatively, how big is the hole in the dumbell? You could make a taper collet like Stews?

Current flywheel looks the part though 

Nick

[srm_92000]

Hi Chris,

I am just starting to get some bits together to attempt a Webster-ish build.
I planned on putting adjustment on the gears by boring a hole in the side plate for the second gear larger than required and use a bronze bush with a slightly eccentric hole for the gear.
The bush is then rotated to adjust the mesh and locked in place with a screw in the edge of the plate.

As to the flywheel, maybe drill a hole on the joint of the two parts and loctite in a pin as a sort of key.

Steve.

[BlueRock]

Hi Chris

Re the flywheel, you could cut a keyway into the flywheel and the kernal and key them together as well as using some locktight to make sure nothing is going to move. Your build is looking good!

[Rob.Wilson]

Nice going Chris 

 making good progress    by the looks of things should be a runner soon 


Rob

[Bogstandard]

I have shown this before in my other posts Chris.

Stick the bush in with a dab of loctite or superglue, as long as the bush doesn't move when doing the second operation.

Drill three, say 2.5 holes equispaced around the flush join, and then tap them out to say 3mm. Stick a grub screw down into each threaded hole, and the hub will then be a permanent fixture. Or if you don't want to use grub screws, normal screws will do, and then when in tight, cut them flush and machine them to a nice finish.

That is the method I used for fitting the flange on the tube when I did my RT mod.


Bogs

[raynerd]

Guys, thanks for all the suggestions and words of encouragement! John, yes that is a really great idea - I`ll go for that method for sure! Although Stews flywheel looks amazing and the hub is nicer than anything I could do, I don`t think it is weighty enough. I`ll let you know how I get on!

Chris

[madjackghengis]

Hi Chris,  silver solder is about the only way to get a good solder joint with cast iron, and you need pretty much the same kit for it as you do for brazing, so if you're not set up for brazing, you've got to go with what you've got.  John's suggestion is about as solid as they come, that's what I'd do.  With regard to the gears, if you run a cigarette paper between the gears and use it to make space, you can use a transfer punch and get your hole right where you want it, and the paper will make sure you've got enough backlash as long as your gears are close to round and even.  Aluminum foil will work, but it makes for more space, and maybe some noise from the gears being too loose.  Cigarette papers are almost all universally one thousandth thick, and can be very useful in finding zero with a cutter, without touching the work and for bits like this, spacing out gears with minimum working backlash.  Looking good, and coming to a point it's getting close to fire. cheers, Jack

[raynerd]

Madjack - yea, I don`t have an equipment for brazing. The truth is, I don`t really know the difference between soft soldering, silver soldering and brazing - or if they are the same thing - or certainly the latter two. It is something I need to do more research on and get equipt for later on when I have more understanding in general machining. I`ll go with three threaded screws machined flush and see how it goes, it seems like a sound method

I`m looking into the future a bit and planning ahead for the time when I`ll need to sort out a carb. Apparently the one in the plans is not so good and my plan was to build the one designed for the NE15s. However, I was doing some googling last night and came across this very very simple looking vapour carb:

http://www.homemodelenginemachinist.com/index.php?topic=9587.0

Look down the page to the post by Chuck. There were some concerns regarding the safety of this system with the webster - I can't see it being valid but I was curious as to others thoughts. I expect that the fuel concentration in the tank is far too high for any explosion if the spark in the cylinder some-how comes back down the line. Any thoughts?

EDIT:
Just to add another quick question - I`ve been confused about this for a while. What is the best way to cut a cam? It is just cut it free hand and file it?  I`m guessing any machining method would be complex for a one of cam?

Chris

[lordedmond]

this site should give you the low down as to silver soldering ect http://www.cupalloys.co.uk/



Stuart