Opposed Twin I.C.

[10K Pete]

Hi Brian

just wondering :hDe: you don't believe in the x3 rule
in a lathe

cheers

What's the x3 rule? Never heard of it.

Pete

 

[Cogsy]

I think he means you're only supposed to have a maximum of 3 x the diameter out from the chuck unsupported. I must admit I stretch this rule regularly, but then I don't take production depth cuts at production feed rates so I figure I can get away with it.

 

[10K Pete]

I think he means you're only supposed to have a maximum of 3 x the diameter out from the chuck unsupported. I must admit I stretch this rule regularly, but then I don't take production depth cuts at production feed rates so I figure I can get away with it.

Ahhh, never heard of that before but I guess there is a ROT for most
anything. My rule is that if it's rigid enough to make a cut, I do it! Actually I do
have a rule: The part must never come out of the chuck on it's own.



Pete

 

[gus]

I think he means you're only supposed to have a maximum of 3 x the diameter out from the chuck unsupported. I must admit I stretch this rule regularly, but then I don't take production depth cuts at production feed rates so I figure I can get away with it.

Hi Cogsy. Thanks for the thumb rule. Been taking risks with longer extensions but when I have the gut feeling , I shorten extension or take like cuts or end up with centre supports.

 

[Brian Rupnow]

Since I distinctly remember making a beautiful one piece crankshaft a few years ago between centers, and then discovering to my horror that the lathe tailstock was way out of alignment, I thought some checking was in order. The lathe tailstock "as delivered" from the factory was out---not much, but not dead nuts either. I did a google search last night and discovered a Youtube video of aligning the tailstock with a co-axial indicator. This morning I set things up as shown in the video, and adjusted my tailstock side to side as close to zero indicator reading as I could get it. Now before anybody jumps on me with both feet, I know this doesn't truly align the spindles. However it does align the rotating centerline of the chuck with the centerline of the tailstock spindle. The TIR of the chuck is very little.--It will be close enough to accomplish what I am planning to do.

 

[Brian Rupnow]

Today I removed the chuck and mounted the faceplate on my new lathe, put the dead center in the headstock spindle, and made a couple of discoveries. First discovery was that the two lathe dogs I bought 6 years ago with my first lathe and never actually used, won't work with my new faceplate. Second discovery was that although I bought a "live center" when I bought the lathe a few months ago, it has dissapeared. In fact I don't ever remember seeing it since I bought the lathe. Of course, this raises the question, ---Did I ever actually get one and bring it home? (It is on the invoice which I still have.) ---or---Did I pay for it but it was temporarily out of stock and they were going to order it in from Toronto for me. I will talk to the Barrie store tomorrow and see what they know. I've had so much machinery coming and going around here in the past six months that almost anything is possible. I still haven't totally sussed out my tailstock alignment, but have decided that if I am going to do this right, I might as well do it between centers, and since I plan on machining the crankshaft between centers anyways now was a good time to get the faceplate mounted and to take the four jaw chuck out of the packing box and make sure it was okay. I keep my shop and garage fairly well organized---It is very unusual for me to misplace a piece of tooling. It is especially suspicious when I never remember even seeing the live center. I will build a couple of "custom fit" lathe dogs this week to work with the crankshaft.

 

[Brian Rupnow]

Hi Brian

just wondering :hDe: you don't believe in the x3 rule
in a lathe

cheers

Luc--I don't think I ever heard of that rule before. If it means that you mustn't have the part stuck out from the jaws more than 3 x the diameter, then I was probably okay. The total length of stock is 6 1/2" and the diameter is 1.5" to start with. I machined half the length down to 1.3" diameter, then flipped the part "end for end" and machined the other half. There was never more than 4" of material stuck out past the jaws.---Brian

 

[Jasonb]

3x rule does not apply here as Brian had Tailstock support.

If the rule was for when using tailstock support you would never turn anything long.

 

[Cogsy]

3x rule does not apply here as Brian had Tailstock support.

He only used the tailstock on the mill, I think Luc was talking about the lathe where he wasn't.

 

[Brian Rupnow]

It looks like the first order of the day will be to make up a couple of "custom" lathe dogs to use when making the crankshaft between centers. These will be welded up from some scraps out of my steel "odds and ends" pile and saved as "future tooling".

 

[raven007]

The engine looks great. You will however need to implement a distributor of some sort. One single ended coil feeding two plugs wont work as the electricity will follow the path of least resistance and only fire the plug not under compression. Alternately look into a motorcycle coil with two high tension leads. One from an older Harley or Honda CB (twin or four cylinder, you would only need one from a four) should work fine.

 

[canadianhorsepower]

One single ended coil feeding two plugs wont work as the electricity will follow the path of least resistance and only fire the plug not under compression. .

Your quote is half wrong:wall: you are wright about the path following
the least resistance, BUT the lest resistance is the one with a gas mix.
It's called Lost Ignition and this is how all distributor-less cars truck>>>>>> are working
cheers

 

[raven007]

Suit yourself, no matter how wrong you may be.

But wasted (lost as you say) spark systems use a coil without one end of the high voltage grounded. Rather, both plugs complete the circuit. Feel free to google it. Cheers.

 

[johnny1320]

waste spark on a two cylinder with one coil uses the two plugs at each end of the secondary windings one plug is ground one is pos.

 

[canadianhorsepower]

But wasted (lost as you say) spark systems use a coil without one end of the high voltage grounded. Rather, both plugs complete the circuit. Feel free to google it. Cheers.

I'm not trying to have an argument here but simply give information
that was explain to us at GM training plant, "I'm a Grand Master Gm certified"
have a look at this enjoy

https://en.wikipedia.org/wiki/Wasted_spark

 

[johnny1320]

Been drag racing motorcycles for 28 years and we use waste spark setup and with one coil doing two cylinders. I run two coils for 4 cylinders and secondary windings are as raven007 stated.
Have a look at the diagram on your link. It illustrates exactly what we are saying

 

[canadianhorsepower]

.
Have a look at the diagram on your link. It illustrates exactly what we are saying

I guess it's lots in translation Rof}Rof}
we both agree on the same pictures but explain it differently
Maybe being a freshmen and explaining thing in English is not a good IDEA
cheers

*beer**beer*

 

[johnny1320]

Your talking about two different things, a coil sharing two leads is not the same as a coil with dual outlets, the spark plugs on a dual outlet coil with spark at the same time, not so with a siamese connection which only the plug with the least resistance will fire which most likely will be the cylinder on exhaust due to the cylinder under pressure makes it harder to jump the gap. I don't know why you have to be insulting when someone disagrees with you canadianhorsepower?

 

[canadianhorsepower]

Sorry Johnny1320,
not trying to insult anyone, as I said we both agree on the diagram but could not explain it properly in English

 

[raven007]

Its cool on my end. No worries.