Headlight switch problem- 1978 280z

[Mark Maras]

I'd look into UHMW plastic for the button. It's tough, durable and abrasion resistant. Curbell Plastics sells 5' of 1/4 rod for $10.09. That small investment would build well over 200 buttons and put you in the button business.

[SteveJ]

51 minutes ago, Zed Head said:

I see a brass tube with a plastic knob inserted.  That is an injection molded part.  Those thin walls will be difficult to replicate.

The cost of machining is in the tolerances, not the dimensions.  

That's what I was thinking when I looked at the 4mm rod I received today.

[Captain Obvious]

6 hours ago, Zed Head said:

I see a brass tube with a plastic knob inserted.  That is an injection molded part.  Those thin walls will be difficult to replicate.

Yeah, the original part was injection molded. That's what you do when your making hundreds of thousands of them. Or you're @SteveJ

And I'm not sure what you meant about a brass tube with a plastic knob inserted... Are you suggesting the possibility of making the finished item out of two parts pressed together? If that's the case, I'd be wary of that. Remember, the bottom of the hole is the spring seat. And it's pressing in a direction to separate the two parts.

Yes, in theory, all the force would be on the spring seat (and not on the thin wall tube around it), but there's the transition positions when the spring extends and all that inertia. I don't know how many G's that part sees when it snaps from one position to another, but I bet it's not trivial.

Remember the same lubricity the plastic provides to the tip (to let it slide smooth across the switch contacts) will be allowing the two parts to come apart.

[Zed Head]

23 minutes ago, Captain Obvious said:

Are you suggesting the possibility of making the finished item out of two parts pressed together? If that's the case, I'd be wary of that. Remember, the bottom of the hole is the spring seat. And it's pressing in a direction to separate the two parts.

Yes.  I consider the brass tube to be the locater of the spring, just holding it under the contact point.  The forces aren't really trying to separate the parts.  At worst they have to resist a side-load, mostly resulting from friction as the switch is actuated.  You can look at the pictures of the parts and see that there is little (no?) sign of distortion of the tube even though there was, apparently, enough heat to melt the tip. 

Actually, the flatness of that melted part in the picture is kind of surprising.  That takes a lot of heat to cause that.

 

[Captain Obvious]

Well I'm no ME, but I have concerns about using two dissimilar parts for that assembly. It's really not a big deal and I'm not going to throw my body in front of anyone who wants to try it, but I've just got concerns. Things like this:

If you make the tip out of some slippy plastic and press it into a tube... How deep of an engagement do you get? The whole thing is 5mm long. With the spring seat being maybe 3mm deep? So you get .078 inches of some slippy plastic into the end of a brass tube?

You make the press fit mild and there's less force to hold it together.

You make the press fit aggressive and that slippy plastic squeezes itself out of the hole just sitting static on the desk like toothpaste extruding out of the tube.

Change the temperature and who knows what's gonna happen.

And then you put that assy into an un-damped spring snapping application? When that thing changes position, what's the frequency of the bounce? That brass isn't going to change direction instantaneously. Newton's laws and all that say there will be forces trying to pull that thing apart.

Like I said, not a big deal... A lot of discussion and analysis of such a small simple part. 

[gotham22]

The machine shop made me a sample.  Going to pick it up today!  Stupid question?  How do you keep the washer button from falling out?  I cant see how it connects in other than that little tab.

 

 

 

[gotham22]

never mind on the washer button.  I forgot to put a piece back.  Could not get the brass nubbin today.  Most likely friday

 

[ensys]

 

Hello Folks:

I do appreciatively applaud the effort to provide the switching bits that time has forgetten; rest assured that I'll be in the line to obtain those parts that make the combo switches work at their peak again.

That being said, I hope I will be forgiven for taking a sharp left at Mr.Head's post #14, regarding the concept of Relay Options that minimize the high-amp effects on the stock combo switch configuration of the equipment (old or new).

I have studied the issue of electrical stress on the Combo switch, and while I make no claim to Electrical Engineering proficiency, I have come up with a diagram that would, in my ignorance, seem to be a workable integration of 30amp relays as a workaround for the effects of routing amp-heavy loads thru the two Combo switches.

Thus, I would humbly offer this potential solution that seeks to provide all the stock switch functions, without running big-amp loads thru the actual combos. I would note that with but a couple exceptions, the current version does not require substantial alterations to the stock harness (the exceptions are centered around connections to a couple plug bodies).

I proffer this proposal with the express purpose of soliciting critical feedback from any and all among this august body of readers, hoping they can show me the errors of my construction, thus enhancing a better solution for all.  

I whole-heartedly encourage corrections/alterations/thoughtful crits to the following diagram (which depends on my ability to insert a jpg (and no, I can make no promises here either}) ....

If you please, look this over and share your improvements for our mutual benefit.

I thank you for your attention.

P.S.: Wouldn't cha know it: I've just noted a connector graphic error at the interception of the incoming red/white hot line. Very embarrassing.

 

Edited August 29, 2022 by ensys

[SteveJ]

5 hours ago, ensys said:

 

Hello Folks:

I do appreciatively applaud the effort to provide the switching bits that time has forgetten; rest assured that I'll be in the line to obtain those parts that make the combo switches work at their peak again.

That being said, I hope I will be forgiven for taking a sharp left at Mr.Head'st #14, regarding the concept of Relay Options that minimize the high-amp effects on the stock combo switch configuration of the equipment (old or new).

I have studied the issue of electrical stress on the Combo switch, and while I make no claim to Electrical Engineering proficiency, I have come up with a diagram that would, in my ignorance, seem to be a workable integration of 30amp relays as a workaround for the effects of routing amp-heavy loads thru the two Combo switches.

Thus, I would humbly offer this potential solution that seeks to provide all the stock switch functions, without running big-amp loads thru the actual combos. I would note that with but a couple exceptions, the current version does not require substantial alterations to the stock harness (the exceptions are centered around connections to a couple plug bodies).

I proffer this proposal with the express purpose of soliciting critical feedback from any and all among this august body of readers, hoping they can show me the errors of my construction, thus enhancing a better solution for all.  

I whole-heartedly encourage corrections/alterations/thoughtful crits to the following diagram (which depends on my ability to insert a jpg (and no, I can make no promises here either}) ....

If you please, look this over and share your improvements for our mutual benefit.

I thank you for your attention.

P.S.: Wouldn't cha know it: I've just noted a connector graphic error at the interception of the incoming red/white hot line. Very embarrassing.

 

And I have already demonstrated that your flawed design won't work and should be consigned to the trash heap.

But what would I know? I only work with these kinds of circuits for a living.

Edited August 29, 2022 by SteveJ

[gotham22]

I am picking up the part this week. If it works are there a lot of people who could use them

 

 

Edited August 29, 2022 by gotham22

[ensys]

Mr.J:

Well, then.

I wonder; when you were introduced to Calculus, did you ever diligently struggle with a difficult problem solution unsuccessfully several times, just to have your Teacher advise disrespectfully, that you should burn your math book? Somehow, I don't believe you would have quit, and nor will I.

However, I will continue my education on a new thread; I apologize to the Forum for the interruption of the original discussion focus of this thread.

 

[Zed Head]

My post about the relay was meant only about taking the load off of the power supply switch, which has the plastic nubbin melting problem, and the solder joint breaking problem (which the new brass piece won't fix.  It will still get hot).  I haven't seen any overheating problems described at the dimmer switch, which is where high and low are separated.

Zs-ondabrains setup had relays on both ends, I thought.  Might be worthwhile to go back and look at his work.