Making lathe from scratch and using mild steel plate? Why use cast iron?

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TSutrina

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The design use to be on www.makeprojects.com concretelathe Which is founded on lathes built during WWI when cast iron was not available. Machinery June 1916 page 877 - 879. Patent 1154155 Yoemans, the stiffness of the design is lowered since the concrete is at the ends supporting the ways which are pipe.

I suggest looking at the lathes others have built. https://www.vintageprojects.com/lathe-milling-plans.html
The Turret and Hobby lathe are good choices for starting point. Another site with a concrete Milling machine on the list is:
http://packratworkshop.com/lib13.htm
 

threesixesinarow

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Hi everyone maybe not the right post here,but need some to give me a quick help regarding about grey cast iron 250 grade or ductile cast iron 500-7(sg).
My intention to build my own milling machine and I'm in stage to build the head for it but not sure what of the top cast iron to use. Any help? THANKS
What kind of machine?

On my little, non-model, bed-type mill (and sometimes-lathe) the major parts are just gray cast iron, but it’s really little! Like 4” x 3” x 2” travels, so forces and overhanging distances are very small, and more weight from extra material at weak points isn’t really a problem. That is, I guess, until I want to move it.

- Clark
 
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john_k

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Good day,

I understand that both cast iron and concrete have the desirable attribute of damping out vibration. In the 1970's George Fischer - a Swiss company making state of the art CNC production lathes were using concrete beds to exploit this characteristic. As far as strength vis a vis steel - just make it a bit thicker.
 

TSutrina

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I actually covered lathes from hundred Horsepower to down to jeweler's lathes with the web site and patents provided above.

"I suggest looking at the lathes others have built. https://www.vintageprojects.com/lathe-milling-plans.html
The Turret and Hobby lathe are good choices for starting point. Another site with a concrete Milling machine on the list is:
http://packratworkshop.com/lib13.htm "

I suspect no one looked at the options provided. I opened those sites today. The both the sites list designs of lathes, and milling machine that are bench top and smaller sizes. Concrete is used for a lathe (6 inch turret lathe) on the vintage site and a mill on the packrat site. V. J. Romig design one of each and many others including a 6 inch powered all metal shaper Nov. 1928 Popular Mechanics where Walters turned it into a horizontal mill, and turn the concrete horizontal mill into a shaper. All steel lathes are provided on the vintageproject site. These all come from magazines like Popular Science and Mechanics. I have found that these magazines published shapers also, both hand and powered. April 1959 Popular Mechanics has a small bolt together lathe from bar stock. "A metal turning lathe for Model makers" by W. R. Bell is from an earlier article, all metal, article is yellowed. "Hand shaper for your shop" by S. S. Miller in Oct 1955 didn't have the magazine at the bottom.
 

SmithDoor

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I have used concrete in round Mill tube .
It works great for milling steel on lite weight Mill.

I have posted in photos in the down section

Dave

Good day,

I understand that both cast iron and concrete have the desirable attribute of damping out vibration. In the 1970's George Fischer - a Swiss company making state of the art CNC production lathes were using concrete beds to exploit this characteristic. As far as strength vis a vis steel - just make it a bit thicker.
 

Wizard69

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For DIY with simple tools I really think the way to go is with cast composites. That is epoxy granites. The material still requires the use of steel for thread inserts, exoskeletons or in other areas where the qualities of steel can be leveraged. There is a massive thread over on CNCZone that goes into the “mix”.

why consider epoxy granites? The primary reasons are to avoid foundry work or the cycle of heat treating and machining steel weldments. Plus done right you put a bit of mass in the lathe bed right where it is needed. Produce a decent bed and you could even put a commercial head stock on it like a Sherline.

by the way the mention of Sherline is important here as feasibility goes down as lathe size increases. Consider a large lathe build requires proper shop equipment just to handle it. That means cranes or other material handling equipment. So in the context of a DIY project in a home shop the size of the lathe is a big factor considering such a build.

this is an old thread and I can’t remember if it was mentioned previously but Dave Gingery publisher what is perhaps the best series of books on building shop machinery. The problem is it is from the ground up using cast aluminum. It is worth considering but for a lathe bed I would expect that one could do epoxy granites far faster especially if optimized for epoxy granites. Of course you would still need to fab everything else that goes on top of the bed. In any event Gingery’s books are a must read for a DIY machine tool builder.
 

TSutrina

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Epoxy or Portland cement are both great binders for the filler and reinforcement steel. Epoxy is expensive which is why the concrete lathe is made of cement. Prof. Tyler Lay (www.tylerlay.com) and on youtube provides information on making good concrete. I suggest you see his youtube on curing that is recent and on post tensioning since concrete is an order of magnitude stronger in compression then tension. Both curing and tensioning will keep the concrete from cracking. I would consider the fiber filled concrete for making such things as the head of the lathe and the other smaller parts. Lot stiffer then aluminum and can be bigger.

Gingery and every cast metal machine I know are made up of pieces bolted together. Need to make the lathe bigger yet manageable them make it out of multiple parts. You can use the methods use to make plaster casting to insure alignment The first half is cast with dimples manually put into the mating face. The next half creates the mate. I would use some of those tensioning steel cables or rods to clamp the two parts together. Even a long lathe bed can be made with multiple segments that are stacked like you would bricks. The key to stiffness is lots of tensioning with many also clamping the segments together.

Tensioning fasteners should even be use in the smaller components with fiber as part of the fill. It will be harder to cover all the load directions with tension rods which is why fiber is used. At least the primary load points can be covered. Some steel mounting surface will be needed since concentrated loads can not be avoided. Each tension rod should have a steel load spreader.

Your worried that the accuracy of the lathe bed will be compromised by segmenting it? Once the concrete is properly cured which from Tyler the majority is achieved in 3 days so if your in a rush wait a week to get more then 90% of the compression strength. Then tension up the steel. Creep should only drop the tension in the bars a little, both the steel and concrete will creep but if your well away from the yield strength this should not be a problem. And I assume your design will not even come close to loads causing the assembly to get close to the yield strength. Thus nothing should move more then the bending deflections that you have set at well below the tolerance you designed. Add a sealer to the concrete and you home. Epoxy is a good choice.
 

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