Large Scale Central

Aluminum track questions

Track and Trestles
#61

Correction Greg,

Aluminum is quite conductive, just not as conductive as copper or brass (but far cheaper). It is the OXIDES that are not conductive. And considering that aluminum begins oxidizing almost immediately when in contact with air (more specifically the oxygen in air), therein lies the rub of aluminum as an electrical conductor, ie. rail. When one finds a method to keep aluminum from oxidizing that is as conductive as the base aluminum, and is economically viable all this hoop la about aluminum rail and conductivity will go away.

Anodizing is a process to hasten the oxidization process, so of course it will not be conductive. Scrape the oxidized layer off the anodized part and see how well it conduct electricity.

As for coefficient of friction, I should hope that it oxidized aluminum rail would have the best tractive adhesion. Oxides of aluminum are very hard and coarse. For those interested, go you your local Harbor Freight and look at their ‘air eraser’ (an air brush sized blasting outfit). The material provided as a blasting medium is ‘aluminum oxide’.

I pose a question to you Greg. IF aluminum is such a poor conductor, why then is it the preferred conductor for our power utilities on all the long distance high voltage power transmission lines?

#62

Aluminum is more conductive than brass.

Silver, copper and gold are the only metals more conductive than aluminum.

http://www.eddy-current.com/condres.htm

Aluminum oxide is non-conductive.

The oxidation that occurs on brass is also non-conductive.

The problem with aluminum is it oxidizes faster than brass.

If you want to run dirty track, get nickle silver. The oxidaton is conductive :wink:

Ralph

#63

Bob,

You are quite right.

Back in the 1970’s aluminum wire was approved for use in residential/light commercial construction in the state of California. Within a few years trouble started to develop at the terminations because of the oxidation, even at aluminum to aluminum connections. After review the wire was still approved for use but all terminations had to be coated with the anti-oxident paste. Well the extra labor and possible liability issues soon ate up any economic gain to be had by using aluminum wire and soon everybody went back to copper. Architects and PE’s soon began specing the use of copper conductors only and not long after aluminum was removed from the approved conductors list for construction. As for as I know it is still not code approved for residential/commercial wiring.

Different amalgamations/purities of aluminum oxidize at different rates. The full soft used for house wiring oxidized at a very fast rate. The wire used in high voltage/tension lines is a harder material and I don’t have any information as to the use of paste in those installations.

Aluminum rail,

Years back the aluminum rail you could buy seemed to all be 6061T alloy, which is a very hard mix containing magnesium and works super good for track powered systems. Most all the rail available today seems to be made from a softer(less expensive) material.

Just my personal opinion but I think the raise in popularity of on board power, battery and live steam, as well as the introduction of alternate rail material IE. stainless steel have left the producers feeling there is no market for the more expensive hard aluminum alloy rail.

Just my opinion.

Rick

#64

I tend to agree, Rick (and not because of your name)! I live in one of those houses built in 1975. The additions and electrical upgrades were all done with CU wire, but the original house (probably 60% of the wiring) is AL. I’ve never had serious trouble with the AL. Once I had a loose connection in an outlet that caused all the downstream lighting to receive about 90 V. Sure took a long time to charge my shaver, and the lights were visibly dim.

I use Llagas Creek code 250 AL, primarily because it was much cheaper than code 332 brass at the time I bought it. Plus, I liked the smaller size. It’s still 150 lb rail in 1:32, but that’s better than that REALLY BIG stuff!

The only rail I’ve bought since I “finished” my trackwork has been small amounts of used Llagas Creek code 250 rail to keep it compatible with what I’ve already got. The color seems slightly different so even LC may have changed their formula.

I don’'t have too much problem with the rail as such, but the joiners are brass, and I’ve been fighting that for years. Now I wrap the AL rail with AL foil. I put a dollop of “No-On” on the rail to hold the foil on, then tighten it all up. Eventually the grease washes or melts out, but the foil seems to keep continuity. I may move to small gauge AL wire squeezed between the joiner and the rail, but haven’t found any that is small enough.

#65

Wow…this has tuned into a wealth of info on the subject …most I knew already but a lot of KEY info(as to values or why this happens) I did not …

Thanks guys now I need to add another memory card to my brain

#66

Ralph,

Thanks for that link. I could find data, but it never seemed to be in the same format, and metric conversion was never my strong suit. Not referencing specific values but relativity with in that page, I viewed the page source for the link and found it interesting that aluminum 6061-t6 (a very common alloy) is in line 77, and stainless steel alloy 304 (also a very common alloy) is listed on line 291. The lower the line number the higher the conductivity.

Bookmarked that page, I see more usage in my future.

Rick,

On the contrary, the harder alloys are still very much in use. Alloy 6061 in a T6 temper is very readily available in almost any shape configuration you wish to purchase. Whether the producers of aluminum rail for the hobby utilize that alloy is of course another question. It would be most interesting to see if those selling aluminum rail know or are willing to divulge the alloy of the rail they are selling. My dealings with Bruce at Switchcrafters tells me he might.

Another factor in aluminum extrusion cost is the amount produced in a run by the manufacturer. Rail is rather small cross section and therefore requires a fairly large run to get a given price point. Shorter runs, higher cost per pound to produce. Most aluminum extruders have a minimum weight (usually about 2,000 pounds) to load the die and run the material. Some smaller extruders may be less, but that has been my experience. The alloy produced may also be affected by the remaining billets the extruder has on hand when the order is placed. He may have a small quantity of an alloy that is close, and considering we are not building bridges, small changes in the alloy may make significant changes in the price of the material.

This information on the extrusion process and cost effects are from another forum after looking into extruding my own rail cross section, along with several years in my profession working with aluminum and aluminum extrusions.

Bob C.

PS - The aluminum flats and angles you buy at Lowes or HD are usually 6061-T6or 6063-T6.

#67

You can tell how hard AL is by trying to bend it. With rail it should be easy. Put it in a vise and bend it to a tight 90 deg bend, if it breaks or cracks before you get there it is pretty hard. If it bends to 90 and then bends back in one piece it is really soft. You can also tell by the finish, the chip and how gooey or stingy it is by machining it. I just bought some micro engineering rail, I will see if I can figure out how hard it is.

#68

A quick scan of the LLgas Creek site, they state their rail is 6061-T6. I will be checking with the others to see if they will reveal their alloy.

#69

I was curious. I took a piece of micro engineering .250 AL rail and put it in a vise. Bent it over 90 deg. A nice smooth bend, about 1/4" radius. No cracking. This should have broke off. This stuff is not very hard. It acts like any typical Al extrusion. I have some 6061-T651 1/4" plate that will break off if you try to bend more than 30 deg. Maybe someone here knows what substance Al is alloyed with to make it hard and brittle. What ever that is, it isn’t in the rail I have.

#70

David,

6061 is the alloy. It defines the chemical composition of the aluminum. T6 or T651 or whatever is the temper of the material. Generally speaking T0 is no temper and is structurally the weakest, and easiest to bend. T6 is one of the hardest tempers and generally the most difficult to bend. Keep in mind that the shape and thickness of the material will have a lot to do with how difficult it is to bend. As I said earlier, If I get a little time I will inquire of the manufacturers what alloy and temper they are using. Work seems to always get in the way of the hobby thing. i will do my best over the next couple of days.

The 1/4" plate you are trying to bend requires a 1/2" minimum inside bend radius to avoid stress cracking on the back side of the bend. If you anneal the bend area you can get almost a 0 inside bend.

I have a chart of alloys and bend radii at work. I will see if I can post it for reference.

Bob C

#71

Used to make gyrocopters of the stuff. It’s REALLY hard, as aluminum goes.

You can’t handle it without getting your hands dirty. I’d expect it makes good rail, especially if you’re not trying to pick up power from it.

#72

Bob, I understand what your saying. The rail material just doesn’t act like it has much of a temper. Maybe t3. I can fold it over to a sharp inside corner with no stress fractures. I spent 20 years machining various types of AL and not paying any attention to the metallurgy. All I wanted to do was make the parts to print and get paid then go home. Now I wish I would have paid more attention. Oh well thanks for reminding me. Hopefully I’m not to old to learn.

#73

David,

I think we are all ‘Old enough to know better and young enough to learn’. I am also thinking that the cross section might be small enough to allow what in larger pieces can’t happen. The post I made above was about LLgas Creek product. I am sure the other mfgrs are similar, but not necessarily. More research to be done.

Bob C.

#74

Old enough to know better. Childish enough not to care.

#75

Dick Friedman said:

I use code 250 Al track from Llagas Creek. I run track power, and have no intention to change to batteries … Ah, brass joiners. That’s the rub. If you can find them, I suggest using something else.

SwitchCrafters offer aluminum joiners

Charley

#76

I read all this and have learned nothing about “which track is better”

#77

There is no one simple answer … It depends on your application and budget.

Best electrical conductivity?
Best for not oxidizing?
Best material hardness?
Best durability?
Best price?
Best availability?
Best prototype look?

It’s great to have options.

Below is a chart of electrical conductivity which may help with one aspect.

Andrew

#78

Matt, what’s better for you may not be better for someone else…

My layout will both be inside and outside… Outside is ground level, so the track has the possibilty of being walked on, byt people and critters… So, outside, I want a track that will hold up to being stepped on and having the least amount of damage done to the track… For this purpose, Brass or stainless steel are my choices for outside track…

Conductivity of the track doesn’t equate into consideration, as all the outside track is for battery power, and/or Live steam…

For inside, I got aluminum track, mainy because it’s cheaper than brass or stainless steel track, and it won’t be walked on… I do paint the track to get rid of the aluminum color…

What type of track you use, is best determined by you, for whatt you are planning to do/use with your railroad…

#79

I think Brass is ideal no matter how you run trains, track power, battery, or steam,

because brass is softer than stainless steel yet harder than aluminum. Steel can cause wear to brass or pot metal wheels, while AL rail could wear out from steel wheels. Everytime it rains you’ll likely get an abrasive coating of sand or dirt on your rails which the train wheels will gently grind into the rails.

I plan to use AL for my long bridges and storage tracks. The bridges reinforce the track and protect them from damage. Everywhere else I will be using brass.

#80

There is a fellow on this site that I know that has a large layout in Gig Harbor, Washington. ALL aluminum, code 250, battery power AND it is on the ground. I’m guessing around 1500-2000 feet of track. Has been there for about ten years. Extremes of temperature and weather conditions. But like Andy says, you have to decide on power, time spent in maintaining track. Everybody is different in how they approach this. No “set” answers.