Cast iron/steel vs. aluminum vs. brass

[Janderso]

Yes, brass/bronze are like apples and oranges, it seems that many hobbyists are unaware! of the difference and or uses of each of the two. Bronze is the choice for wear uses, and bear in mind that there are many alloys of bronze for different applications.

Boy howdy.

I went to Online metals to shop for bronze.
In the section they had these options for just bronze!!

510
544
623
630
632
642
651
655
673
863
932
937
954
C87850
C89835
SAE841
SAE863

And, they are all expensive!!

 

[matthewsx]

So what would be the preferred material for a new carriage for a small lathe with a dovetailed likely steel (but cast) bed? Once I get my small mill running I figured I could make whatever I want. (The rusty part is the ways if it weten't obvious. The photo makes it look considerably worse then it is. It's all surface rust).

I would just clean it up and use it. While it's possible that you can improve what you have it's a pretty small machine and the design probably has many other limiting features.

Just work within it's envelope and keep your eye out for a larger, more capable machine.

JMHO,

John

 

[skogkatt007]

I have other machines. Didn't want this one to die a lonely death. The carriage is really flimsy. The rest of the machine is comparable to a Taig I guess. Parts are not interchangeable though.

 

[skogkatt007]

Bronze is beautiful stuff. I just don't like cutting it on a lathe. Long thick shafts anyway. Everything tends to explode. I got hit in the chest with a chunk of it once. I suppose it could have knocked my teeth out.

 

[matthewsx]

Understand.

I have a bunch of bronze but nothing that I would make a lathe bed out of. Post up some more pictures once you get it cleaned up. There may be a way to stiffen it up without replacing the bed. Otherwise steel is probably your best bet.

John

 

[Geswearf]

Brass comes in many flavors (alloys). Yellow brass is commonly used for casting plumbing parts, it is 70% copper, 30% zinc. Red brass is red tinted, and usually 85-5-5-5 (copper, tin, lead, zinc). Other brass alloys will fall in between these two. Bronze is primarily copper/tin (90/10% +/- a few percent) but silicon and other elements may be added to change its properties.

In addition to wear properties, you have to figure in the cost of the metal. Iron/steel for heavy machines costs in the pennies per pound while brass and bronze alloys will cost dollars per pound. Sure, it might be affordable for a one off machine, but if you factor in the metals' wear properties cast iron (or steel alloys) wins out. Other important properties are an alloy's physical characteristics - thermal stability, etc. While you can probably make a machine out of any material there are good reasons besides cost why ferrous alloys are almost universally used.

 

[matthewsx]

One thought is if you can find an old cast iron tablesaw top that is big enough to cut your part from. I’d be worried about internal stresses though making it move after you thought it was done.

Steel should be more stable. Ground aluminum plate can be had pretty cheap on eBay too. I made a mill table from that.

John

 

[Flyinfool]

This has been brought up before but Howard Precision sells drops of many sizes and alloys for very reasonable prices.
It has been a while now but every once in a while when their supply of drops gets to big they run a special at $1.00 per pound. Otherwise the price varies depending on supply. I just recently picked up a chunk of tooling AL plate for a project 1 x 10 x 20 for $33 all I needed was 10 x 10 but the $33 was cheaper than what I could get new for in just the size needed and I get to add another chunk to the stock essentially for free.

Random Aluminum Pieces & Parts | Aluminum Flat Bar & Tooling Plate Suppliers - Howard Precision Metals Inc

Howard Precision Metals has a variety of random metals in stock and ready to cut your specifications. Call our sales department to lock in your random piece at 800-444-0311.

www.howardprecision.com

 

[skogkatt007]

Thanks. I'll check them out. Also eyeing some surprisingly good prices on poopBay.

If I were to make something out of steel, whatbwould be the best type? Something as soft as possible that won't unduly wear on the bed.

 

[Flyinfool]

Cast iron. There are reasons cast iron is used by almost everyone to make machines bigger than the smallest of the hobby machines. It wears well with out abusing the mating surface, is slightly porous to help hold oil, once it is done it is very stable, although very messy, it is not hard to machine.