A Side Thought Regarding The "Lubrication" Question.

[richard37066]

To one and all -

We've had a spirited and informative thread concerning the use of a couple of very good lubricants to be used, for the most part, in changers. It occurs to me that we've assumed something which should not, necessarily, be assumed. (How's THAT for sentence structure?)

I'm thinking of the state of the surfaces which are to be mated and lubricated. Is it possible that this was a contributing cause for the "wear" that Bent experienced and posted about? His judgement should answer that question.

We all would rebel at the thought of hogging out a hole with a worn drill bit and slapping any old rod through it and accepting a sloppy fit. In regards the typical changer with its' axle and drilled out fingers I should think that one would pay particular attention to the surfaces which will find themselves in a mating position when assembled.

We all know that three points, in space, define a plane. In a changer - and even though those three points might be in close proximity to one another - those three points could act somewhat like a raggedy old end mill and start gouging the adjacent part. What if there were thousands of little "mountains" or "points" just waiting to scrape and scratch the opposing surface? No lubricant in the world will be effective under such circumstances. Yes, I know - microscopically, a surface has a jillion such mountains and points. MACROscopically, however, they're akin to the teeth of an ore grinder.

I recall, not long ago, where a member wanted to ream a hole to fit and it was questioned by another member. If the act does not fit this discussion then the concept certainly does. I, for one, advocate a close sliding fit with surfaces as blemish-free as is practicable. If one assumes a dead-straight and polished axle and if the process of reaming holes in the fingers for a proper fit is a means to excellent surfaces then so be it.

I recall a friend - some many, many years ago - using a precision expansion reamer in some oilite bearings on his Porsche. Neat little tool.

I know just enough to be dangerous in regards to being an accomplished machinist thus I can offer no concrete direction towards achieving the above stated goal. I would welcome the input of those who have the experience and are willing to give us their thoughts and practices when building the most "precision" part of the instrument.

My many thanks and understanding.

Richard

[Ross Shafer]

Reaming or boring is pretty much a necessity if one wants to insure a precise hole size. Assuming sharp edges and reasonably appropriate feeds and speeds are used, reamers will net a fine surface for the use being talked about here. Boring can offer a good surface too though not nearly as easily or conveniently as a reaming.

Reamers are wonderful and not really that expensive. They're available in tons of sizes and can be ground (not usually cheaply though) to any size or taper angle you could ever want. Unless you need the ability to creep up on a hole size, stay way from the adjustable ones for anything involved in the type of work being discussed here.

I generally prefer a spiral fluted reamer as it offers better chip clearance and this helps insure the best surface finish.

[louckswayne]

Yes
I agree with you guys that the changer is the heart of the PSG. I have not yet built
a changer but i do plan to ream the fingers for a nice fit on the axle. A little more
work and expense but worth it in the long run!
Wayne

[LushPyle]

I will through out a theory here regarding the wear on Bent's axle:
Steel and aluminum have different electrical potentials and the aluminum in this case is somewhat "sacrificial". Their close proximity causes the aluminum to oxidize even in the presence of a lubricant. Aluminum oxide is highly abrasive thus the galling seen on the axle. All it would take for this to happen is a very small amount of oxidation over an extended period of time. This used to happen to the axles on Emmons PP guitars on which I used light machine oil as a lubricant. If my theory holds water then we are barking up the wrong tree thinking a better lube might prevent this. Then again I have been known to come up with some theories that are really out there where the buses don't run so to speak. I only really know that I only know enough to be dangerous hence the term "theory".
Gary

[louckswayne]

Gary
Yes, this brings me back to Ed Fulawka and he puts in a oilite bushing. There is now
no direct contact between aluminum and the steel axle! This provides less friction
and separates the two metals. It is odd though that he is the only builder
( that i know of!) who does this.
Wayne

[Pat Comeau]

I've been reading all those post about tight fit for the changer ect..., i have to say that if you make the holes to tight for the shaft it will wear faster in my opinion, and in my opinion and experience i really think the shaft needs to turn freely and have space for the lube, otherwise... you wont be able to keep the lube on the shaft if it's to tight fit

Pat C.

[richard37066]

Pat -

That's why I favor a light slip fit. Any lubricant applied will migrate between the two surfaces. It doesn't take but a thin film to do the job. However, if the surfaces are really raggedy then even axle grease won't help.

Richard

[Bent]

Pat, The holes were not too tight in this case. They have to be loose by nature, so that the finger can turn on the shaft with no resistance.
Richard, The surfaces were not "really raggedy". The axle was brought to correct diameter by honing with #400 sandpaper as I remember. The fingers slipped over the shaft and almost fell onto the shaft and would turn by the lightest touching. It was loose enough for the oil to migrate UP through.
I believe that the cause for this is what Gary suggested regarding the incompatibility between the two metals, brought on by the wrong type of oil.

I have hopes for the next lube I am trying out. I installed my new changer the other day and oiled it with the jet turbine oil. The fingers are un-plated brass, running on the same st.st. axle and laying up against the galv. changer plate on one side and a zinc plated washer on the other side. We shall see....

[richard37066]

Bent -

Unless your pickup winding machine is truly dedicated, could you rig up an "eccentric" on it with a rod to one finger and axle and then excercise the heck out of it?

Wouldn't want you to get bored with all of that milling stuff, now would I?

Richard

[Bent]

Richard, I would sooner do it with a geared motor and rig it all up on my 4x4 that I have for this purpose. I take it you are looking for a test rig for a changer?
More details please