What material for PM25V column lift?

Agreed, and thought provoking on a number of different levels. Not just about materials and how we design for particular characteristics, but also how and when we decide to be satisfied with “good enough”.

Most interesting indeed.

-frank
 
Nice thread here. I think the saying goes, "Experience is the best teacher", but it's tough to argue with the math. I tend to be on the conservative side. If I was going through the work to make a riser, I'd use steel. Then you don't have that nagging question in the back of your head gnawing at you every day you use the mill, "should I have used steel or is the aluminum good enough?". Take a little more time to hog it out of steel and you won't question yourself. Reminds me of another old saying, "no one ever got fired for buying IBM".

Bruce
 
Nice thread here. I think the saying goes, "Experience is the best teacher", but it's tough to argue with the math. I tend to be on the conservative side. If I was going through the work to make a riser, I'd use steel. Then you don't have that nagging question in the back of your head gnawing at you every day you use the mill, "should I have used steel or is the aluminum good enough?". Take a little more time to hog it out of steel and you won't question yourself. Reminds me of another old saying, "no one ever got fired for buying IBM".

Bruce

+1
There are a number of threads on this forum where members have expended a fair amount
of effort trying to improve stiffness in their machines. Folks with round column mills fill the columns or create bracing, lathes
get solid plinths to replace the compounds and so forth. The light weight machines that hobbyists use often need all the help
they can get, and folks that make these improvements report noticeable results. Small improvements
frequently matter.
 
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Other the the dielectric/galvanic corrosion issue (which i consider to be a Major Sticking point that would Absolutely need to be addressed before proceeding down the aluminum path) what would you be loosing besides some of your time and some scrap material to try it for yourself? You will be able to actually verify if the Aluminum would be strong enough to handle the job YOU need to complete. If it works for Your Specific needs leaving you satisfied by its performance then what does it matter if its not as stiff as steel? If theres a problem then either adjust to accommodate, change paths or revert to the previous setup without the riser/spacer.
 
I really wouldn't worry about galvanic potential. Aluminum needs hydroxide ion to make an electric cell. In a dry system, it's not much of a concern. If it was something to be concerned with, the quarters and dimes would be cooking off in our pockets, because copper and nickel have a difference in standard electrical potential of 0.5 volt. If you put a clad coin in water, it will corrode, but on your workbench there ain't much going on. Now when you bolt your aluminum heads on an iron block, that's different because the coolant is working as the electrolyte. Even so, it wasn't a big deal for the Big 3 auto makers, who mixed metals with impunity for decades. The 200,000 mile motors end up with some corrosion, but by the time they get there they're already spent and rotting in a junk yard, past their service life before galvanic corrosion became a problem.
 
I really wouldn't worry about galvanic potential. Aluminum needs hydroxide ion to make an electric cell. In a dry system, it's not much of a concern. If it was something to be concerned with, the quarters and dimes would be cooking off in our pockets, because copper and nickel have a difference in standard electrical potential of 0.5 volt. If you put a clad coin in water, it will corrode, but on your workbench there ain't much going on. Now when you bolt your aluminum heads on an iron block, that's different because the coolant is working as the electrolyte. Even so, it wasn't a big deal for the Big 3 auto makers, who mixed metals with impunity for decades. The 200,000 mile motors end up with some corrosion, but by the time they get there they're already spent and rotting in a junk yard, past their service life before galvanic corrosion became a problem.

Being new to this, I am rather unfamiliar with the common cutting fluids used.
Do you think that water based cutting fluids used on the mill would provide such a hydroxide ion? And if it splashed onto and wicked into the joint could that raise the risk?
Still probably a low risk, but I'm curious about the forums experience with corrosion due to cutting fluids.
Also, my personal shop is also the family garage, so my humidity goes way up when wet and snowy cars are parked in the garage/shop.
 
Yes, water based fluids will provide a hydroxide ion, and the wetting agents added to them will help with wetting, but the reduction in surface tension will inhibit capillary flow. But sure, water based cutting fluids can help corrosion along (pretty sure Kool Mist has some corrosion inhibitors, the stuff is similar to antifreeze in every other way). When I drip water-based fluids on my stuff, it leaves a mark on cast iron if I don't wipe it up right away. There's so much oil on all of my stuff that it's not likely for real rust to form (flash rust that wipes off with an oily rag does not count). With known sources of humidity in your garage, it would be wise to keep everything oiled or coated with lanolin. Small increases in humidity compound rust's insidious desire to get on tools. If your machine's all buttered up with petroleum, water-based cutting fluids just roll off.
 
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