Polishing a magnesium transmission

[Shaun @ Tru6]

I got this transmission in a few weeks ago to polish the case and plate everything else, powder coat the crossmember mount. This was mostly an aesthetic job for a restoration but it turns out the polishing via 3mm porcelain beads have a micro-peening and micro-burnishing action to seal the very porous surface of magnesium 915s. This prohibits any further, significant oxidation. Also, a clean transmission is a cooler transmission which has it's own benefits. Easy to do on an early engine case as well.

Started with a hot tanked but very oxidized and still crusty case.

[Shaun @ Tru6]

Started making sealing plates and got rubber stoppers and first tumbled the tail and mid-section using a small pyramid, low abrasive ceramic media which did a decent job of cleaning up the sections. Still some caked on crud which I removed by hand. The challenge was going to be cleaning up decades of deep oxidation.

[Matt Monson]

Cool stuff.

[Shaun @ Tru6]

Progress was slow but sure using the low abrasive media and adding some burnishing compound.

[Shaun @ Tru6]

I then switched to the 3mm porcelain polishing beads with no abrasive and added some burnishing compound. The tail section came alive pretty fast but the center section oxidation was deep.

[Shaun @ Tru6]

Soda blasting worked well on the mid section and it turned out well with some extra tumbling.

[frankc]

Very nice. I'll have to keep you in mind if the Mg 915 I recently purchased needs to come apart to be rebuilt.

[Shaun @ Tru6]

Crossmember mount was in fair shape with typical scars but cleaned up nicely with an aggressive ceramic abrasive. Look at all the grease that oozed out from between the plates when heating up for powder coating.

[Shaun @ Tru6]

Originally Posted by frankc

Very nice. I'll have to keep you in mind if the Mg 915 I recently purchased needs to come apart to be rebuilt.

Sounds good Frank, sorry I couldn't help on the idlers.

[canamfan]

Beautiful! Are you going to seal it with anything like Zoop, Shark Skin etc. or? It's way too pretty now (with such invested labour) to let oxidization to degrade it again sooner than later. I really like it polished up like that

[Shaun @ Tru6]

Plating turned out well with a little extra tumbling and care.

[Shaun @ Tru6]

Originally Posted by canamfan

Beautiful! Are you going to seal it with anything like Zoop, Shark Skin etc. or? It's way too pretty now (with such invested labour) to let oxidization to degrade it again sooner than later. I really like it polished up like that

Thanks! Talking with my media supplier, they said the surface has been micro-peened and micro-burnished essentially sealing the surface which will slow oxidation way down, if at all. Running your fingers over it, it's super smooth. No open or rough pores in the Mg.

To keep it this way forever, I think a Cerakote Clear would be best. But rubbing it down with Gibbs may be all it needs to stay like this for years.

[TheSt|G]

Mmmm I love everything in this thread.

[KTL]

Nice!

[cgarr]

Ahhhh good ole Gibbs!

[Bergo]

seeing all your recent posts makes me want to buy one of those vibratory tumblers, would be a great addition to the shop. What would you say you've invested in media? is it pretty expensive? last a while, or is it consumed pretty quickly?

[Discseven]

Originally Posted by Shaun @ Tru6

I then switched to the 3mm porcelain polishing beads with no abrasive and added some burnishing compound.

Nice thinking Shaun.

[Shaun @ Tru6]

Originally Posted by Bergo

seeing all your recent posts makes me want to buy one of those vibratory tumblers, would be a great addition to the shop. What would you say you've invested in media? is it pretty expensive? last a while, or is it consumed pretty quickly?

If you had a kid who had great attention to detail qualities and his sole job was tumbling/blasting/brushing, this would be a good addition to any shop, especially a restoration shop. Like anything, the quality of what you get out of tumbling is directly proportional to the time and work put into it. Most of my customers are shops who have had bad experiences sending things out to be plated with poor results due principally to poor prep and lousy platers and honestly, they just don't have time to deal with stuff like this, hence the kid.

The investment in media is a good one. It's expensive, about $600 delivered for each type. But it lasts forever. I have 3 different types and will be getting one more next week. Then I should be set. Other consumables include acid, soap, burnishing compounds and most importantly, a corrosion inhibitor to throw parts into after being washed off out of tumbler. It's amazing how fast stuff flashes with nothing protecting it.

Hope this helps. Send me an email at shaun@tru-6.com if you have any questions.

[Bergo]

Originally Posted by Shaun @ Tru6

If you had a kid who had great attention to detail qualities and his sole job was tumbling/blasting/brushing, this would be a good addition to any shop, especially a restoration shop. Like anything, the quality of what you get out of tumbling is directly proportional to the time and work put into it. Most of my customers are shops who have had bad experiences sending things out to be plated with poor results due principally to poor prep and lousy platers and honestly, they just don't have time to deal with stuff like this, hence the kid.

The investment in media is a good one. It's expensive, about $600 delivered for each type. But it lasts forever. I have 3 different types and will be getting one more next week. Then I should be set. Other consumables include acid, soap, burnishing compounds and most importantly, a corrosion inhibitor to throw parts into after being washed off out of tumbler. It's amazing how fast stuff flashes with nothing protecting it.

Hope this helps. Send me an email at shaun@tru-6.com if you have any questions.

I should have specified, I just meant my "personal" shop/garage. If the cost of media is less than the cost to send all my parts away to have done professionally (shipping heavy metal stuff all over the place gets expensive) I'd consider picking something up for personal use!
I enjoy buying/owning tools. having a desk job, working on vehicles is my pass time, so I'd rather buy tools and enjoy wrenching on something than pay a shop to do it, plus, at the end of the project, I get to keep all the new tools!

[Shaun @ Tru6]

Tough call for home use. If you did a few cars over the years, I think it could be worth it, and it is nice knowing exactly what you have and being able to correct flaws better before sending things out to be plated.