Introduction: Concrete Metal Lathe

I've wanted a large CNC lathe for a long time...key ingredient to that being a large lathe. Unfortunately most places that sell these lathes want a large sum of money in exchange. After some searching on the internet it turns out one could build a lathe from scratch using concrete and scraps of steel. This is the process of me building such a machine. This lathe is designed to be built in the most rustic conditions using minimal tools, however I have access to some better fabrication tools so I used them to my advantage. With the said I'm confident that if I had to build this beast with a hacksaw and a hand drill it would certainly be possible!

The final result is a machine that is far more precise then I initially imagined and a great machine to upgrade into my full fledged CNC metal turning monster!

It seems the Make Magazine link online was the best repository for information on this lathe but it can be hard to find. I've downloaded the complete article (which was free online to begin with) and posted it here to make life easier. I've based my machine largely on the size and scale of these plans (my lathe shrinking in length to 42" overall).

Step 1: The Concrete Form

The first thing to do was cut a mold and pour the lathe's main form. The form is a simple shape that could easily be cut with a table saw, or a skill saw for that manner but as I have access to a large format CNC machine I decided to design the mold in CAD and cut all the required parts (IGES file attached).

With the metal parts embedded into the concrete I installed the main bearing mount as well as the CNC cut pipe holders. Once again this is a part that was going to be simple off cuts of angle iron but access to my little CNC let me get fancy. This is the modification that will allow for continuous adjustment as the concrete slowly shrinks over time.

I've also attached a rough BOM which as approximate costs of things I purchased. I had quite a bit of scrap metal and plastic on hand so I worked the design around what I had.

Step 2: Moving the Beast

I started casting the lathe when the weather in the garage was still dropping below freezing the odd night. I decided to cast the concrete in the basement and then figure out how to move it after...which was silly.

Moving a 500lbs of concrete up a flight of stairs is NOT easy. However people build spaceships and go to space so I figured I should be able to make this happen. After a few hours, copious use of ropes and pulleys and a few extra nicks in the walls I had the lathe up into the garage.

I added some extra bracing to my work bench in the garage and once again used a combination of bricks, jacks, and car tires to eventually lift the beast up onto its new home.

Step 3: Casting the Carriage

With the weather warmer I was able to finish the carriage casting in the garage. This time I made the forms using the table saw and some scraps of wood. The metal elements were placed into the concrete while everything was still setting up.

Brass was bent into crude angles to function as wear strips for the bottom of the (heavy) carriage. At this point I could dial in a more accurate alignment of everything and start actual work on making the lathe function.

Step 4: Cross Slide Addition

Picture of Cross Slide Addition

After installing the lead screw for the carriage I moved onto building the cross slide. I have a milling machine so I was able to make a cross slide out of blocks of aluminum, this could easily have been made with a hacksaw, file and drill as I mention in the video...after this machine my hack sawing skills have definitely leveled up.

I used UHMW for lead screw nuts. I have used this plastic in the past on an old CNC machine and find they maintain a very low backlash drive for a long long time.

Step 5: Pulleys for Turning

Picture of Pulleys for Turning

Now this would be a pretty poor functioning lathe if it didn't spin. In this step I took an off the shelf shaft, err....the big black thing in the picture. I took that black thing and drilled and tapped a couple holes corresponding to the holes in the pulley. From there I could bolt everything together and have a reliable way to transmit power to the chuck.

I used fancy link belt as I figured I wouldn't be able to bolt a pulley onto a shaft by eye all that accurately but it turns out that I hit the mark perfectly and the pulley runs extremely true. None the less link belt is wonderful stuff if you can tolerate the cost.

The motor is nothing more then a 1/2HP furnace motor which works surprisingly well! The pulley ratio gives me 300-400 RPM at the spindle which suits me well for the screw pitch of this machine.

Step 6: Tool Post and 3 Jaw

Once the spindle was able to run under its own power I decided to tackle the tool post. With this built I could now start using the lathe to help built itself. First I found center on the main shaft, made note of that height and milled up a solid block of aluminum to hold a tool at that height. Once again there is 1000's of ways to do this, I built it this way to suits my needs with the material and tools I had on hand.

A backing plate was cut, trued up on the spindle and shaped to attach the 3 jaw chuck. I goofed slightly on this part and ended up over cutting the alignment plate for the spindle. I will remake this part in the future from thicker aluminum plate as it seems the 1/4" is a little small for holding the chuck perfectly true (can be seen in the video while turning the brass).

Step 7: Final Thoughts

Picture of Final Thoughts

I am very very impressed with the results this machine has been cranking out! I still have to go thru the process of perfectly aligning the ways (over the entire length) lapping the slides, rebuilding the chuck plate, casting/turning hand wheels and possibly building some way covers to protect the exposed lead screws but already its a great machine to use!

The standard threaded rods I have used on this machine mean the hand wheels feed in and out exactly opposite to what I am used to...but that will only be a factor while this machine sits in full manual mode, as I mentioned earlier the next step is to convert this creature over to full CNC control, stay tuned and thanks for watching!

-Curt

Comments

overblast (author)2017-10-16

Awesome instructable!

I was just doing some research today and found this technique was created by Lucien Yeomans in WW1 to make millions of artillery shells. It only took 7 hours to create a 10-ton lathe vs. 6 months for a traditional lathe. After WW1 ended, they scrapped all the lathes.

JohnD833 (author)2017-08-19

Would it not be possible to take the same concrete base, turn it 90 degree's, and X-Y-Z table on it then mount a chuck and motor on it to have yourself a mill?

Indeed it would be. Some people even mount a vertical slide on the mill cross slide table and use lathes as sideways mills...limitless options.

France41 (author)2017-07-20

Gracias .eres el mejor

Drake six six six (author)2016-10-23

Hi, first of all I want to say thank you for putting up your awesome project!
I'm so keen to build my own, I have been trying to open the files you have added for the MDF cuts. Unfortunately all that it displays is a whole bunch of numbers, that's all each file shows me is numbers that make no sense. Any Help accessing these files would be much appreciated. Thank You

podarok (author)2016-10-17

Thank you for the proof of concept. man
I have similar plans for surface grinder made from lathe...

So you work so excited me to start with those plans...

Mr.Brownstone (author)2016-09-11

Thank you so much dude.. I needed this to finish my own engine brand. I'm making my own engines from sand cast aluminum and junkyard pieces.

Saved my life. I was gonna have to buy a lathe. Out of thanks, I donate you this immunity cat. The immunity cat saves you from stupid facebook chain letters.

Yonatan24 (author)2016-08-11

Hi, I've added your project to "The Ultimate Collection of DIY Workshop Tools" Collection

Here is the link If you are interested:

https://www.instructables.com/id/The-Ultimate-Colle...

Fat-One (author)2016-06-09

The best diy made (by one man only) machine I've ever seen, definitely most needed in the workshop as well, be proud of yourself man, enjoy.

ajod (author)2016-05-18

Where did you get the three jaw chuck?

twheeler4 (author)2016-04-23

Pretty brave mounting a lathe in front of a window. ;)

Haha, the taig lived infront of that window for a few years so I'll take another gamble...cant beat the light!

dapiguy (author)2016-04-26

Do you think you could post the DXF files for the form?

So sorry friend, I have not forgot about you. They reside on my work computer and I constantly forget to upload when I'm sitting at it. I'll do my best to get it up before the weekend.

dapiguy (author)2016-04-13

That's awesome that you've posted the IGES form file and the BOM. I really appreciate it as it will certainly help me get started making this. Do you think you could post the form broken down into pieces (either in DXF or PDF or similar format, instead of as a solid model) for easier loading into CAM software for milling?

How important do you think the rebar is? Would this project work if you didn't embed rebar, or is it critical for structural integrity? Thanks!

Thanks! I'll be sure to upload the dxf files of the cut sheets, its fairly specific to my build but would be a nice starting point for others.

I'd say the rebar is important, it would probably still work but the chances of it fracturing under a shock load are higher (probably only something you would encouter moving it around). Even dropping in some wire mesh, or fiberglass fill would probably work just as well if not better then rebar.

I appreciate how open you are about this project. I'm looking forward to seeing the DXF's.

I plan on building a machine like yours, pretty much exactly as you built yours. I don't see any reason why that wouldn't work, although I'll probably use styrofoam instead of MDF to make the form. Your build seems to have worked out so great, and I've already found suppliers for almost all the important parts. I'll build it right on the workbench where I plan on leaving it for years to come so moving won't be an issue (although I was looking forward to spending a whole day attempting to move it, just as you did). Where did you get your motor? Can you provide the model/wattage/size/any other identifying information you can find for it? I'm trying to find one from the appliance recycling centre from a dryer or something (hopefully get it for free). I need a lathe in the next couple months or so, and this looks like the best option by far, so I'm quite excited to begin toying with the plans (I was going to try to aluminum cast a much smaller version, but this appeared out of nowhere right before I was going to get started designing the basic aluminum version I had in mind). Thanks!

bougakov (author)dapiguy2016-04-22

Don't underestimate the weight of the concrete - it can break your styrofoam. Plywood is a smarter choice.

Thanks! I am open about the design because its based on an open source machine: https://concretelathe.wikispaces.com/00+-+Introduc... . Just remember that if your making your forms from foam you might have an issue with pressures inside the mold, 500lbs of concrete can exert a decent amount of sideways force, I was worried about my mdf mold breaching during the final tamping.

The motor I used was a cheap 1/2 HP furnace motor that I picked up from a local buy/sell site. If your going to use the lathe for big turnings 1/2HP is a little anemic but workable with light cuts. Be sure you have room to mount the motor in both directions, or are able to reverse the direction it runs (I electrically switch the direction of rotation to suit my mounting position).

Thanks for the comment!



Just noticed you haven't uploaded the dxf files yet...do you know when you'll have a chance to do so? Thanks!

bougakov (author)2016-04-22

Your build could have looked so much better if you have invested just about $2 in a cheap mixer for a hand drill (or, better, stronger mixer with SDS+ tip for power drill). It is almost impossible to mix concrete with a stick in large amounts - it is damn hard and takes too much labor. If you had used that, all surfaces would be so much smoother and concrete would be stronger.

Skilltagz (author)2016-04-12

I'd suggest using Portland cement instead of concrete containing larger aggregate bits, it would look a little cleaner on the end

Thanks for the comment, they actually had some proper portland cement right beside the el cheapo concrete I bought...but the cost pushed me away. I've tossed around the idea of epoxy coating it to make it pretty but its uglyness is growing on me.

Really? The cement I found was cheaper than the quickcrete ready mix we have here. I guess it depends on where you are

dapiguy (author)2016-04-09

Can you post the files used to create the wood cast using the CNC? I'm very interested in making one of these! Thanks!

Sure! I'll have the files uploaded Monday as an attachment in the "Forms" step.

Can you also upload the design you used for making the carriage (I'm assuming you milled those parts before you poured them). Also could you upload the plate designs (the ones milled out of aluminum for holding the ways). What bearings and bearing blocks did you use? Do you have a parts list available anywhere, and if not, could you make one with the key parts? I'm incredibly excited to try making one of these, but I'd like to ensure I'm prepared and am not going to get too far ahead of myself.

Why did you use brass underneath the angle iron on top of the ways? Would linear bearings work instead?

Thanks, I'll do my best to get everything uploaded. I am currently working on a parts list as well as costs to give people an idea what I spent. I used brass under the slides to give a proper wear surface (brass is normally used in dovetail ways on the adjustment side as it slides/wears nicely with steel). You could use linear bearings but I was trying to keep the parts cost low and use readily avaiable materials.

Shiseiji (author)2016-04-07

Just super to see one being built! I know you are on some of these other sites, but for those who are looking to learn more . . .

More Information Sources:

https://groups.yahoo.com/neo/groups/Multimachine-Concrete-Machine-Tools/info

From https://groups.yahoo.com/neo/groups/multimachine/info


http://opensourcemachinetools.org/ (see the resource page for 150 carefully selected plans, files, books)

http://makezine.com/projects/the-multimachine-150-12-swing-metal-lathemilldrill/
http://makezine.com/2014/02/10/patdelany/

See a 75 minute long (but very amateurish!) video of the machine at http://opensourcemachine.org/the-multimachine/multimachine-video

http://concretelathe.wikispaces.com/Current+Design+Drawings (Yeomans files)

https://groups.yahoo.com/neo/groups/romig_designs/info (VITAL THAT YOU LEARN ALL ABOUT "BOX" WAYS AND OTHER JOE ROMIG TECHNIQUES)

Thanks for all the links! All these are great sources of information.

colormix2 (author)2016-04-08

Hello Confounded Machine

I agree with the others on the need for way rigidity.

You need a neutral rake tool (flat on top) to cut brass, bronze or copper. That is why it sucked your insert tool in that has a positive rake on top.

Cool and creative project, good for you.

HoppyH1 (author)2016-04-07

Looks kinda cool and very functional. I heard that in WWI or WWII they made a bunch of these for the war effort; but in much larger size

GregoryM31 (author)2016-04-07

Very nice. I have been talking about building one of these for years. You may have motivated me to get off the couch.

Please keep the videos on this project coming!

Many thanks, will do!

watahyahknow (author)2016-04-07

vibrating the mould or pricking a piece of rebar in and out of the freshly poored cement wouldve helped getting the air out and have the cement flow in between the gravel a little better making the body of the lathe look better , you can still kindah stucko it with some thick mixed cement to get the outside smooth

not quite convinced on this method , might try sumtin simulair and use resin epoxy , reason being is that you can machine epoxy to fit parts ontoo it perfectly flat and level basicly treat it like a rough metalcast

I think my problem with the top of the headstock may have been overdoing it with mixing (causing the aggregate to rise up and the cement to settle out)...once again I'm no concrete expert.
I thought about coating the whole thing (once fully cured) in thick epoxy sealer but thats just one more thing for oil to get under and flake away...I'll probably leave it ragged...its growing on me.

tdisney (author)2016-04-07

I made the sketchup drawings you see in the old original plans... and it is so, SO gratifying to see someone build this at long last. Super nice work, and the writeup and the videos are so valuable for the rest of the community obviously. Thank you.

I know I already said thanks on youtube but thanks again here. Those drawings were so nicely put together, something I took reference to many times in the build to make sure modifications I was introducing wouldn't complicate another element of the design.

balisticsquirel (author)2016-04-07

Epic.

minitehnicus (author)2016-04-07

Great work!

Thank-you!

bongodrummer (author)2016-04-07

Nice work and documentation. Thanks for taking the time to share it. Really interesting stuff!

One of the many thoughts I had swirling about while watching your cool vids was that the lathe's ways could be better supported. Cutting will induce a lot of sideways forces, and it appears that the gas pipe rails are only supported at the ends and from underneath (which would only give downwards bracing along the length, but not sideways or upwards). This seems a shame, as by having 'semi-floating' ways you don't take full advantage of the damping and rigidity of your large mass of concrete.

I'm not that sure how else to go about supporting the ways now your cast is all done... I guess to do anything permanent you will need to be quite sure you have the ways adjusted nice and parallel and coplanar with the spindle (though with your system I guess you could adjust the spindle after the event). I am imagining something a bit more heavy duty than angle iron, extending almost completely up to the gas pipe rails (maybe concrete filled steel box?) and then a cupping layer of grout or epoxy granite (something solid and non-shrink) cast in situ to lock the bottom half of the gas pipe in place.

Having said that, it looks like your getting nice cuts from it as is :) And if you go the CNC rout, that will take a lot of the tedium out of multiple shallower cuts. Thanks again for sharing.

Thanks and great suggestions! The flat iron rails contact the pipe slightly to the outside to try and help with side loads...nothing amazingly strong but once I have the chuck re-done I can try some beefy cuts in steel and see where the problems exist. I also may end up casting the rails in place with non-shrinking grout in 6months time or so....once I'm sure the concrete isn't going to move. I do really like the 1/2 cup idea you write about...may need to revisit that in time.

Oh, also put a coolant tank and pump on your to do-list. My experience has been that a good flow of coolant makes a really big difference to surface finish and tool life (esp. for those carbide insert tools).

rgeelen (author)2016-04-05

did you know that concrete has less thermal expansion then steel! so basically this structure could be less reactive to heat then a steel lathe! depends on the the concrete though. but i'm talking about the one used in construction so you should be fine :)

Interesting, I wasn't aware of that. If I get it dialed in enough where I have to worry about temperature swings I'm doing something very right ;-). Thanks for the comment.

Nobody is aware of that..... Because it is not true...

Concrete and steel have the same rate of thermal expansion! That is why steel reinforced concrete is so popular as building material.....

darrenhall (author)2016-04-04

Welll - she ain't pretty - - but she is AAAAWWWWWSSSOOOMMEEEEEE!! - - - great build, straight onto my F/B group.

Haha, its pretty to me in its own way. Thanks for the share!

if you really wanted to, you could just mix up a little bondo and fill in all the gaps. it wouldnt add anything to the structure but would smooth it out, then paint it

or just leave it rustic and wild, with the cnc as a nice hi tech counterpoint

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Bio: I'm a electronic engineering tech with massive love for DIY building, and tools that make tools.
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