Trigger wheel pt.1.

In the last post, I wrote that I needed to attach the trigger wheel to the crank somehow in order for it to be able to be used to fire the ignition system. The logical place to attach this to is the crankshaft damper. This is a big lump of nodular iron that is attached to the front of the crank with the aim of contributing to (1) the balance of the engine, (2) the flywheel effect and (3) damping the effects of the crank's turning the up-and-down motion of the pistons into rotational motion.

The 'easy' option is to bolt it to the front of the damper, but the problem here is that the bottom pulley attaches to the damper. That's OK, but anything the belts touch (alternator, water pump, power steering) would need spacing forward 5mm (the thickness of the steel of the trigger wheel), which is a pain. My solution to this is to turn a register in the damper and attach the trigger wheel that way. I am aiming for an interference fit, so I'll have to cut the register pretty accurately (within a thou or so) I think. I reckon to be having to put the damper in the freezer and the timing ring in the oven to get the two things to mate together.

Probably some of you are thinking about the consequences of attaching the timing wheel now on the timing. So basically the question is "how do you know where TDC on pot one is without the engine together?" Well, I don't. I could build the engine up and do this prior to balancing (and I may yet do), but with the software the Emerald ECU runs, you can supply an offset. So perhaps I position the timing wheel 90Deg from where it should be, I can correct this out in the software.

So, in terms of pics, here we are - the damper mounted in the four jaw on the lathe:

On the four jaw chuck, the jaws move independently of one another.This means you can set jobs up in the lathe with great accuracy. You can see the dial gauge mounted on the cross slide here. It took a while, but the damper spins in the chuck with less than 1 thou run out. That's pretty true.

Unfortunately my digital vernier let me down. It was a cheapie, and it was a bit old, so I got what I deserved - cheap tools always let you down when you want them. This meant I couldn't complete the cutting of the register because I can't measure with anything like enough accuracy how much to take off.

Here's the cut so far:

Lots to go. Here's a pic with the trigger wheel:

There's a slight risk in the way I'm doing this. That ring you can see outside the bolt holes on the crank damper is a ring of rubber that's bonded to either half of the damper. Obviously the wheel will be able to move fractionally. However, I'm betting that in real life, this makes sod all difference.

Got some more inspiration for the Enfield: http://vimeo.com/30586946. Cheers Jim.

I'm back? Excuses and more lathe stuff

I logged into my own blog the other day. It's a useful resource (at least for me). I was looking for something about the camshaft I'd bought for the V8, and noticed that the last blog post was 7 months ago! That's what having another ankle biter does. Anyway, I did say (way, way back) that I wouldn't say when I'd just been accumulating parts, but I would blog when I'd actually done something with them. Well, rest assured the parts accumulation is ongoing. The aim right now is to get the bottom end built. However, that means balancing it. There's a load of bits to get in order to get this done. Basically, anything that hangs off the crankshaft  needs to be balanced, so although I had the entire bottom end of the engine bought, I still needed to get the crankshaft damper, bottom pulley, flywheel, clutch and all associated nuts and bolts in a state where they could be balanced.

As I want to run a proper ECU controlled injection and ignition system (I already have an Emerald ECU bought), I need a trigger wheel. These are basically a toothed wheel which has tooth missing. A magnetic sensor detects each tooth as it passes, and through the missing tooth, the ECU can tell where the engine is on its firing cycle.

This is the one I have:

It's a laser cut ring-gear style 7.5" job from www.triggerwheels.com, who have this base covered pretty well.

Basically though, you need to attach it to the crank somehow, and this is where I've shown great forward planning in investing in a lathe. 

A small digression:

Last time I used the three jaw chuck that came with the lathe, I noticed a bit of run-out (basically whatever's in the chuck wobbles ever so slightly). With a three jaw this is going to happen, and run out of a about about a thousandth of an inch in each inch you move away from the chuck is about what you get. Which is about what I have. Still, I have a decent quality chuck, and didn't see a reason why I shouldn't give it a clean and see if this makes is a little more accurate.

Here's the chuck off the machine:

And the machine chuckless:

That bit of wood on the ways is because the collar you can see in the pic (which is what holds the chuck on the taper) can eventually force the chuck off the taper as it's spun. Chucks are heavy - you don't want one landing on the ways of the lathe.

I took the chuck to bits and gave it a clean and regrease.

It really wasn't at all filthy, so I'm expecting zero as a result of my efforts!

Unfortunately the phone ran out of battery at this point, so the rest of the process will not be documented, but overall I took it to bits, cleaned the scrolls and put everything back exactly how I found it.

Just for fun, I mounted the faceplate in the lathe:

Earlier this week, I found a 10" four jaw chuck locally to me (same guy who sold me the lathe), so snapped it up. I didn't quite appreciate how big it would be - it's a big lump and no mistake. Here it is next to the cleaned and reassembled 3 jaw:

Big beastie!

On the lathe, it looks like this: