startin' on a Webster

[dgjessing]

Nothing major today. Lots of pesky software customers have been calling for tech support, plus it's my birthday and people keep stopping by to do nice things for me :

I epoxied the main bearings into the frame and made a bronze spacer to hold the crankshaft in the right spot in relation to the rod. I trimmed the thickness of the big end of the rod down to be a few thou less than the length of the crank pin, so now the screw holding it together can be tightened. Still need to replace the nylon washer with a brass or bronze one. I drilled 1/16" oil holes in the big end of the rod and the main bearings (then counter bored 1/8" a little ways to form tiny funnels). Made a permanent wrist pin from steel to replace the brass tubing one I was using to fit things.

I've been running it in a little with a drill - compression seems good enough to run to me ;D

Started on the timing gears; made a 5/16" sleeve to fit over my existing 1/4" dia. arbor which I use to cut gears, and made the blank for the small one (18 tooth). I'm going to depart from the plans and make this little gear on the crankshaft independent of the flywheel. Just seems like it will be easier to me ...

I don't anticipate any progress this weekend as my darling wife and my mom have both got out of town, birthday-related activities planned for me

 

[vcutajar]

Happy birthday Dave.

Vince

 

[dgjessing]

Happy birthday Dave.

Vince

Thanks!

OK, the timing gear blanks ready to get teeth:

Note that I've got them marked so I can put them back on the mandrel in the same location. The mandrel is also marked so it goes in the lathe chuck the same way each time.

Fly cutter in action:

And we have gears:

Mine are of 6061 aluminum instead of the steel the plans call for. I expect them to hold up just fine.

On to the exhaust cam, and locating the cam shaft on the side frame. ;D

 

[dgjessing]

Turned a suitable piece of mystery steel to the over-all outside diameter of the cam, drilled and reamed to fit the hub of the gear, and turned down the middle to the smallest diameter:

Used an end mill and the rotary table to form the lobe:

Cut it off and cleaned it up w/ belt sander and my hand:

And epoxied it to the gear:

The hub on the gear is a little short - I'll have to make a spacer to go in there to keep the cam from rubbing on the frame.

Almost time for a flywheel - I'm going to run out and see if I can find a 4" CI dumbbell weight

 

[Blogwitch]

Very nice job you are doing there Dave. :bow:

I do like the way you are using what you have got about you rather than worrying over the materials shown on the plans.

Most things are grossly over engineered and so don't need expensive materials to make a running engine with the amount of use they get, making buying expensive materials absolutely silly.

Use what you've got in the scrap box, I do for about 99% of the bits on engines I build.


John

 

[dgjessing]

Thanks, John! I agree - I mean, if all goes well and this thing works flawlessly, it may be asked to run perhaps 5 or 6 hours at 1000 rpm in five minute increments over the course of the rest of my life. It doesn't need to be MIL-SPEC or anything...

Made the shaft for the cam gear from brass, and pressed/epoxied it into the frame:

And here's the entire thing so far:

I wish I could say that the gears meshed perfectly right off the bat, but... I got them a bit too close together and there was some binding. They aren't perfectly concentric, so I spent quite a while trying them in one place then the other to get the best mesh. I then made some center punch marks so I can put them back together where they fit best. Then I ran them in with a drill motor and a little valve grinding paste and oil on the teeth. A few minutes of this and they fit pretty well.

I did go out flywheel shopping earlier and eventually found the mother lode at a used sports equipment place called "Play it Again Sports" - all the cast iron disks you could want at fifty cents a pound. This seventy-five cent one is even milled already:

Shouldn't take much work to make a hub and turn it into a nice flywheel ;D

 

[dgjessing]

Trued up the weight... although it was machined, the center bore was not exactly concentric with the outer diameter, and of course the cast hub and rim weren't either. The original plan was to get rid of all the text, but once I got into it a ways I decided to keep it

I heated up the weight to 500 f in the old toaster oven and measured the diameter of the bore:

(it grew about 1.5 thou...) then turned an aluminum hub blank to about half a thou larger then that:

Pressed those together and let them cool, resulting in a nice tight fit. Turned both ends down to about 7/8", drilled and reamed for the crankshaft, and drilled and tapped for a set screw. So here we have it to date:

I think having the timing gear independent of the flywheel will be an improvement; there isn't any weight to speak of in the gear train, unlike in the flywheel. The chance of the gear being knocked out of place (by a back fire, etc.) should therefore be less. Dunno if that's an issue or not, but I feel better about it. :

 

[Blogwitch]

Dave,

Dunno if that's an issue or not, but I feel better about it.

That is definitely the correct attitude to take. Make engines how you feel you should, not what everyone else expects.

You'll make some real blunders over your learning time (and they will get less), but if you accept them as facts of machining life, you will also gain that independence that a lot of home machinists never achieve.

Still looking very good.

John

 

[cfellows]

Just a note that these cast iron weights show up at Goodwill stores a lot and the prices are usually dirt cheap.

Chuck

 

[dgjessing]

Ignition cam and points mounting exactly according to the plans:

So you know I'm going to have to go to a junk yard and get a coil and try to make a spark this afternoon ;D (Been meaning to go there and get a spare wheel for my daughter's car anyway...)

Then on to the valve block, which I'm thinking is going to be the most difficult part

 

[rhitee93]

I am still along for the ride with you on this one. I am excited to see it run!

 

[dgjessing]

We have ignition! ;D

 

[rhitee93]

Oh, now that requires a video!
Congrats

 

[dgjessing]

Oh, now that requires a video!
Congrats

[ame]http://www.youtube.com/watch?v=e0yFxH3r4QM[/ame]

 

[rhitee93]

Very cool Thm:

 

[dgjessing]

So onto that valve block! Cut the three pieces and glued them together so I could mill them all to exactly the same size at the same time:

I learned that you do NOT want to inhale any of the fumes when you heat super glued parts to separate them. Nasty...

And here are the three parts of the block more or less complete:

I'm not going to bother with the little counter bores for valve seats. My valve guides will just be straight shafts epoxied into the blocks. The glue is rated for 600 degrees f - they won't go anywhere.

 

[dgjessing]

Valves and valve guides today:

Yes, those are 2" common nails I got to looking at them and found that they have perfectly round shanks a consistent .100" in diameter, and heads a bit more than 1/4". Not all the heads are concentric, but I spent some time selecting the best ones and used a dremel tool set up as a tool post grinder to shape them. Made about half a dozen then selected the best two. Used a number 38 drill (.101") to do the guides and they fit very well. I think they are going to work just fine ;D

I glued the guides into the blocks with JB Weld. Once that's cured up tomorrow I'll fit the valves to the seats with valve grinding paste.

 

[Smithers]

Great idea leaving the text on the flywheel, adds heaps of character. I like it!

Andrew

 

[ShedBoy]

Good score on nails
Brock

 

[cfellows]

I don't want to second guess you on using the nails for valves, but if you have trouble with compression when you are trying to start the engine the first time, these valves would be the first place I'd look for problems. Not to say you shouldn't use the nails, just be aware that they may cause you problems.

Another problem you may have is sucking air in around the valve stem on the intake valve. These will cause your engine to run lean and it will be hard to make it run smoothly.

I only mention this because I've had an extraordinarily hard time getting valves to seat and for the seal between the stems and the guides to be relatively airtight. Valves seem to be one of the common problem areas with IC engines.

Chuck