Cleaning Magnesium Spools

[kyreels]

There is currently not much information in ORCA on the subject of cleaning of magnesium spools and reel parts. A search of this site turned up very little, and our new Third Edition of Reel Restoration (available on the ORCA store) does not have any information on this topic. So I am opening this topic for your review and comment. I hope that some of the engineering specialists may have more information.

I edited this post on June 24, 2022 to included updated experience and information. For a complete detailed reference to magnesium parts maintenance and cleaning, refer to Handbook: Aircraft Maintenance Cleaning - United States. Navy Department. Bureau of Aeronautics · 1956 - available on google books.

Magnesium spools began to appear in special casting tournament events in the 1950's, and were de rigueur in winning a tournament in the late 60s and into the current period. ABU 2100 made factory magnesium spools, but most spools were made by smaller machine shops for use in the unrestricted events. The magnesium spools will corrode readily if left exposed and uncoated. The oxide crystals will appear, and the thin spools may become easily pitted if left untreated.

Spools with moderate to heavy corrosion:



The steps I concluded with consisted of combining material from the cited aircraft maintenance and information from some tournament casters.

1. Preclean with mineral spirits to remove any white oxide crystals and any oils. Use a toothbrush to scrub if needed.
2. The part will likely still have a dark grey coat of oxide as well as small bumps of oxide. This is best removed by mechanical means, but can also be carefully treated with Chromic Acid for very short periods of time. I also was successful with using Acetic Acid at 10% dilution.
3. Mask up with N-95 or equivalent because the Magnesium dust can be toxic and harmful if inhaled.
4. Use 000 steel wool to remove some of the remaining surface grit that is oxidized magnesium. When the oxide is removed, the part will turn light gray, about the color of aluminum.
5. If you have a media blaster that can be regulated carefully so as not to damage the small parts, you can use glass, plastic or walnut bead polishers, but caution is in order here.
6. Clean in denatured alcohol to remove any of your cleaning solutions or dust.
7. Finally, you have to coat with something to prevent oxidation. Aircraft engineers and slot car hobbyists recommend Boeshield T-9 spray which will provide a thin wax coating when dry that will protect the spool surface. Boeshield was invented at Boeing for use on aircraft parts including magnesium alloys. Alternatively, you can use a shellac or paint or other coating. It seems to me you should be careful to not impact the performance of the spool here.

Here is one spool cleaned with mineral spirits and a 15% acetic acid bath of 1 min. I did not have the recommended chromic acid solution, it may have turned out better.


Here is a spool I tried to clean with steel wool for around 45 mins. I could not get it uniform. I think that to be practical, I need some kind of media cleaner machine.


Here is the spool on a Lew Perkins unrestricted tournament reel (model 2):



If you have other tips or technical info to add, please reply. Your comments will help me and others, and may be added to our next handbook addition.

[john elder]

Thanks, Matt, I have no experience with cleaning this type of spool. It sure sounds like the best course there is prevention rather than recovery.

I would be interested to know how much advantage such a spool would really give you in a tournament situation. It would be interesting to take one of those magnesium spools and compare weights with aluminum and just see what you’re gaining in using that material. There should also be a way to compare the rate at which a line will come off that spool as compared to an aluminum spool of the same size and diameter. A Graphite spool would be a nice add to that experiment and just compare the three to see what’s up. I’m betting that at the end of the day, one would bail on those magnesium spools!

[Midway Tommy D]

You need to mask up and get rid of the fine dust. Magnesium sanding dust plays havoc on the lungs, it's toxic! I learned that when I restored the tiered spools on my ABU GARCIA Tournament spinner. The original ABU tiered spools were sealed with a candy-apple red paint. Nowadays a lot of the slot car guys recommend candy-apple red with a clear coat to help prevent oxidation.

[Mike N]

Great topic, Matthew. The ironic thing is that the magnesium casting reels I’ve posted about all had wooden spools. Why did the machinists not make the spools magnesium, too, for these reels?

LINK:

viewtopic.php?p=107517&hilit=Magnesium#p107517

[kyreels]

The evolution of unrestricted reels and their bodies and spools is not well-covered in our literature. Colby Sorrells is collecting information on that, and I am contributing what I know. I have 8 different unrestricted reels, and have been cleaning them up for photographs. I have also photographed another dozen I don't own.

Unrestricted revolving spool tournament casting started with wooden spools on steel shafts. The reels were strung with tiny nylon line that came to be known as spider line due to the tiny diameter. As the line got smaller and the reels evolved, the distances rapidly increased. A major advancement would be the shift to aluminum and magnesium spools. Graphite spools were attempted, but according to casters I have talked to, did not hold up well to the tremendous stress involved in a cast. However, I do have at least 2 graphite spools for Lew Perkins Reels.

Edited 2/24/22 to include a Lew Perkins Graphite Spool.
Graphite spools weigh around the same as magnesium spools, at least to the gram. I don't have anything to measure micrograms. A 1 and 3/16" diameter mag and graphite spool both weigh around 1 gram. An aluminum spool weighs around 3 grams. So you can see that the mag and graphite should have been very competitive. But who knows about the other factors.



It is interesting that there were schools of thought pertaining to 1) what material to make the spool with (aluminum or magnesium) and 2) what diameter was optimum for the longest cast. These schools of thought were tested at the regional and national casting tournaments and fed by the few machinists that made these specialized reels. I have several models with larger diameter magnesium spools, but these did not prove out and the smaller spools down to 1/2 inch became the most frequently used.

Magnesium spools seemed to predominate in the 1950's and 60's as the machinists that made them began to understand how to best do that. However, it appears that starting the in the mid 60s to present, aluminum alloys became better and magnesium spools were no longer winning tournaments, and the aluminum spools dominated. Magnesium on CNC routers require special caution https://www.3erp.com/blog/safety-tips-f ... e-metals/# (the part is easy to machine, but the shavings are flammable), so maybe that had something to do with it. The corrosive issues also were a factor in the use of the spools.

To answer Mike's question, it would appear that making a reel body from magnesium may have been easier than making a narrow spool that held up to the casting stress. I think the wooden spools just kind of became a standard and probably worked very well in practice. I think it just boiled down to who was winning tournaments with what configuration, not what was theoretically best.

One more thing that is not well-covered was the subject of the shaft used in unrestricted events. The shafts carried the spool and spun on the pivots, and were built to very close tolerances. They carried the oil and may have determined whether the cast was 10 feet further in a tournament event. I have heard anecdotally that on the Green Abu unrestricted reel, that only the European casters got the polished and precision shafts. That was an important factor in performance of the reel.

Another factor in unrestricted reels were the use of ball bearings to replace the pivots used to support the rotation of the shaft. It would seem that was the final evolution of the unrestricted reel. We are trying to track the national and world records to the type of reel and spool. That work remains to be done.

[kyreels]

Here is a photo that shows the transition and experimentation from wooden spools to aluminum in the early 1950's (estimated). This would be in the style of Walter Willman who set the world record on a similar reel with a wooden spool. Jay Klenck reel:

[kyreels]

I edited the above posts today to better reflect the cleaning recommendations and work to date. Of particular note, it turns out I did have various graphite spools for the later model 2 Lew Perkins Reels. I am going to do more work in sorting those out.

Magnesium is harder to clean well than I hoped.

[kyreels]

I updated the list of cleaning tips to include the use of acetic acid at 10%, which is what I have and have tested. The Air Force recommendation is for chromic acid may be more effective and is used in leather tanning and other industrial processes, but is more toxic to humans. As a hobbyist, I think the increased effectiveness is not worth the increased risk and hazards and disposal issues.

[Reelman2]

I have a B F Meek #25 that has a magnesium spool with a wood arbor. When I got it, the edges of the spool were pretty much white. So I took warm water and a toothbrush and removed all the white. When it was completely dry, I squirted some fine oil onto my finger and rubbed it on the the spool and then dried it off with a soft cloth. It has remained black ever since.

[kyreels]

Well, magnesium is not black, that is the oxidized color. Yes, some lightly exposed magnesium just needs a light coat of oil to clean a bit and prevent further oxidation. The recommended product is Boeshield, which leaves a very light wax coating. But almost any surface oil is good.

For spools where the line rides on wood or for cases where you are not going to cast the reel, cleaning the magnesium may not be necessary. It sure is a lot of trouble. I would agree with most collector reels that don't worry about it if it does not cause issues. But I see a lot of powdery oxidized magnesium that has pitted the spools and makes them less functional and eventually hurts the purpose and value.