OTHER: Parts Tumblering knowledge & How-to.

I didn’t invent it, but im probably one of a few using a parts-tumbler to clean small car parts. But what is it?
I often get asked how to use the procedure properly, so here’s a little description.

1. ABOUT
I first came across this procedure when i was looking for a procedure to clean all those special-bolts on the Z, that cannot just be easy replaced with a standard screw. I found Mr. Maurers Ford Model A Restauration website, describing the procedure (german). see here:
https://www.maurer-markus.ch/ford_a/tipps_vibrations_tumbler.html

The Case tumbler aka Stone tumbler, Spirator, Vibrator, Deburr, etc., can be used for various things, but the main reason i know is to polish and or clean things. You for e.g. put stones with some abrasives into the tumbler, and the abrasives will polish the stones.

With some slight modifications you can use it to remove surface rust, grease, dirt and other stuff from small parts.

2. MATERIALS
2.1 TUMBLER
The tumblers are available in various sizes. from Small hobby-stone tumblers (like i use), up to industrial scale Tumblers. Here’s an example of an industrial sized version:

I found mine cheap on ebay, but next time i probably would buy it one size bigger because bigger parts won’t fit that good.

It’s a simple assembly and so far it has worked many hours without problem.

2.2 ABRASIVES
Depending on how agressive the Abrasives should be, you can use a huge range of abrasives. The tumbler i bought initially came with a bag of schredded walnuts, but they didn’t work at all and it was way to soft. I guess it’s definitely more for polishing.

The website above mentioned to use Delfir chips, which are basically small Ceramic pyramids. So far they have lasted quite a few weeks of non-stop tumblering.
Those are quite soft and will remove dirt, grease, slight surface rust etc. but i have figoured out they won’t remove any old car- or industrial grade paint. But the advantage is, they’re soft enough to not remove any metal either. So the threads will stay intact. More agressive abrasives will attack the metal and therefore can reduce the quality of threads on bolts.
For my tumbler size, i use 2kg Delfir chips PL-M (10x10x10mm):
In switzerland you can get them here. but i’m pretty sure you can get them anywhere. Also i’m pretty sure your can guide you to get the right abrasives for your needs.

3. Mixture
I have figoured out that a mix of Abrasives to water in a 4:1 ratio works best.

The water is there to wash and collect the dust from abrasives and dirt (you’ll see how dirty the water gets!)
Too much water will soften the effect of the abrasives. no water will not clean stuff as effective. Also i’d like to add the water hot first (not cooking), which will soften the old grease and support the initial cleaning proces.
If you add a few drops of dish-washing soap, this will additionally improve the removal of old dirt and grease and help to clean stuff. If you add too much soap, it just end’s up in a huge foam-bath 🙂
In the Past i mentioned that you can add some grease to give the surface a rust-protective layer. However i meanwhile think this is nonsense, since the dish-washing soap and the whole procedure would remove the fat again

4. PROCEDURE
1) Put above mix and a bunch of parts (not too much, they should be able to move freely into the tumbler.

2) Close the lock and let it run.

The vibrations will create a rotation of parts and abrasives and make them rub on each other, removing dirt, grease and weak surface materials during the process:

4) Check every 6 hours or so. Replace dirty water and soap if needed (usually every 24 hours or so).
Depending of how dirty the parts are, you may have to run it for up to 36 hours.
Some party can be removed after a few hours already. Some parts may need additional cleaning with a dremel tool or so. During the wait, have a beer:

3) Once parts are finnished, remove them, clean the parts and the abrasives and the tumbler separately with lots of water. let everything dry. Here’s an example of parts that have been tumblered. they should now have a smootn and clean surface.

5. OTHER
As mentioned above, the delfir chips will not remove old paint, but at the same time not remove any metal. Also they’re too big to get into the threads and clean it there. but so far that’ hasn’t proved to be a problem, because the zinc plating company will but it in a cleaning bath anyway and usually there is no rust inside the threads.
I think you can quite improve the process by trying different abrasives and methods. If you’ve figoured out something better, please let me know 🙂

I recommand to run the procedure just before you get the parts further processed (like zinc plated), to protect it from building surface rust again, etc..

Pro-tip: Don’t let the tumbler run in your unheated garage during winter time. in my case the water froze during the night:

6) CONCLUSION:
Me for myself think the procedure is not perfect, but overall was very worth the money, just just throw a bunch of Bolts and small bits and pieces in there, let it run for a while and you have the parts ready for the next process like replating, etc. Compared to other processes (like a dremel tool) it will not leave any marks or so, so for me it’s perfect and proved, while i’m pretty sure the abrasives and the overall process can be improved further.

Here’s above inspection lamp housing after beeing tumblered and replated: