Building lathe/mill in cast of concrete?

[Steve WanParticipant @stevewan33894]

Hi guys,

 

I read that this invention of mass production for lathes in WW1 were possible. Concrete was used then as cast iron was in short supply. With this in mind, has anyone tried making his lathe/mill in concrete cast? Though concrete is good for making the machine stable from vibration, what about the thin walls and cracks will occur in due course. If anyone has done this approach, please share your exciting moments as I would like to give it a go one day.

 

Steve

[Steve WanParticipant @stevewan33894]

[Clive HartlandParticipant @clivehartland94829]

A composite material might be very good for vibration damping in a job like this!

Some concrete mixes have fibres mixed in to make them lighter and stronger.

They would have to be cast in a jig and any bedways would need to be attached during this process.

I would think they may be very large machines and not bench type machines where cast iron and steel would be far better.

An interesting project if you want to machine something like an aircraft spar about 60′ plus.

 

Clive

[Gordon WParticipant @gordonw]

I can remember seeing huge lathes in shipyards, for m/cing prop shafts ,I guess. These had big mass concrete head and tail stock, with steel bedway for the cutting tools, but I think to big for you.

[PekkaNFParticipant @pekkanf]

Hello,

 

I bet you are thinkking of casting normal rebar reinforced concrete structure.

 

Concrete can take a lof of compression and it is good in dampping among other properties. Although It shrinks much with the time. You could age it naturally before milling pads, you could try to find more stable concrete or you could make provisions for shrinkage.

 

Because of shrinkage it would be a bad idea to pour concrete inside of the metal “tube”, far better idea would be to have iron structure outside and have concrete body on compression. Concrete really is pretty bad to machine, you need metal pads and plates that you can skim and level after curing and agigng the structure. In the industry often machine base plates are jacked straight over concrete sructure and then voids are filled with injection “epoxy”. I’m pretty sure it has some filler.

 

I chekked some injection concretes that are available at the hardware stores, they expand first to counteract shrinkage. I’m not sure if this leads to more stable body.

 

See here some good info about frames and concrete core damping.

http://tinyurl.com/3dcwa4o

 

Then there is polymer concrete. This is rather different animal. If you think of a minimum possible amont of epoxy and maximum amount of rock in differet particle sizes – you are close.

 

This approach needs better process control and also materials tend to be more expensive. For a professional builder benefits are clear: More stable and fast production i.e. no concrete type of shrinkage.

 

CNC Zone

 

Have fun. I have been toying with an idea of trying this to a small grinding machine.

 

PekkaNF

Edited By David Clark 1 on 06/04/2011 17:14:13

[Ian S CParticipant @iansc]

Some one (it may have been Tubal Cain), wrote of concrete lathe benches as being ideal for a good foundation for any bench type lathe (or Mill) think it was in ME. The bench would be easy to level, before mounting the machine. Ian S C

[GoCreateParticipant @gocreate]

Just a bit off topic but this thread reminded me of the remains of WW1 or WW2 concrete boats laying in a horbour near where I lived as a child. My grandmother assured me they did float. So concrete has more uses than you would think.

 

Nigel

[Richard ParsonsParticipant @richardparsons61721]

Steve

Yes you can make almost anything out of concrete. The moulds for the Mosquito fuselages were made of it. The Mulberries were, some yachts still are and all of the tracks in the Paris underground –the Metro- still are. The trains have rubber tires which run on steel plates bolted to the concrete track way. The stations stink of hot rubber.

I once worked in a factory which built machines. Each time a new machine was started its concrete building base was ground dead flat before the machine was started.

The real problems with concrete are the mix and the ‘green’ period. That is the time before the concrete develops its full strength which in some cases can be months. There can also be a problem with heat which can affect crystal growth.

Yes you have got ‘advert incurtion’ again!

Edits 1 & 2

Interesting I have just posted and the ‘advert incurtion’ has disaeared.

If you are getting it try pressing PF12 in Edit mode it gives you the message as a full page no ads.  To return to ‘normal’ press PF 12 again. 

Edited By Richard Parsons on 06/04/2011 17:34:18

Edited By Richard Parsons on 06/04/2011 17:35:34

[wheeltapperParticipant @wheeltapper]

I see David has edited the offending links, so advert incursion go away now

 

I wish posters would learn how to shorten their links.

 

Roy

[Dave TointonParticipant @davetointon92281]

Many years ago I worked in a sugar mill where we had a home-made lathe for machining the cane crushing rollers. They were about a metre in diameter, 3 metres long, in some sort of cast steel. Th lathe was made of concrete with welded steel frame. It worked a treat, albeit slowly.

Regards

Dave Tointon

[Ian S CParticipant @iansc]

I don’t know if its still done very much here now, but 20-30yrs agoconcrete was being used to build fishing boats and yatchs, now glass or carbon fiber over a sandwich of foam or balsa wood is common, while the fishing boats are aluminium, and often jet powered. Ian S C

[WeldsolParticipant @weldsol]

All the big column and booms 7m high x 9 m reach for welding, we used to supply for the wind turbine towers for offshore had concrete bases and all the attachment points for the slew ring 20 off 16mm and rail mount bogies were cast in.

We never had a problem and they all seemed very stable on dimensions

I think with some fore thought you could acheive a good base for a lathe. The main problem would be machining all the mounting point to get them level (depending on the size of lathe)

One last point we were not allowed to drill and and use expanding fixings i,e, rawlplug as it could be a stress point that had not been calculated for

 

Paul

[adyParticipant @ady]

Yes you can make almost anything out of concrete. The moulds for the
Mosquito fuselages were made of it. The Mulberries were, some yachts
still are…

 

The mulberries used up so much concrete they stripped Britain of concrete for other war uses.

http://en.wikipedia.org/wiki/Mulberry_harbour

The Hoover dam was built in rectangular blocks because a single pour would have taken 125 years to harden.

Edited By ady on 08/04/2011 00:39:45

[Richard ParsonsParticipant @richardparsons61721]

Yes they used much concrete as we built two. These were full sized harbours each able to support and supply armies.

One was for the Brits and the other was for the U.S. of A. Unfortunately one of them was a total loss after the first really good Atlantic storm, so the second one had to carry the whole load. This ‘bottle neck’ which led to supply shortages, and caused a slowing down of the war in Western Europe. as it gave the enemy time to consolidate. The remains of the second one are still there to this day (nearly 70 years later)

Which one was lost and why? A few clues, which lot did not bother to train the builders? Who placed a senior officer, who could not read engineering drawings, in charge and who threw away the instruction manuals? If the designers/builders give you 24 anchors each with two wires attached do they mean you to use them all? And finally who just took the bits and pieces higgledy-piggeldy (for speed) and not in the order they were laid out. You guess who.

[Bill PudneyParticipant @billpudney37759]

We seem to have wandered off the thread a bit.

Rather than concrete I would have thought that an epoxy based polymer would be the way to go. Hardinges use has already been mentioned, but there are several others.

There has even been a couple of articles in MEW about using an epoxy based vibration damper in Chinese mills. This would be a start in reading.

 

About the Mulberry harbour stuff up, I gave up guessing when I got married 36 years ago, so come on who was it????

cheers

Bill Pudney

[Gray62Participant @gray62]

Pure cast concrete will not withstand the stresses and vibration induced by normal rotary machining processes.

I believe the structural materiel you are aluding to is more akin to an epoxy granite based compound.

This is often used in industry to produce high strength, highly stable machine bases and superstructures.

 

There is a great deal of science in selecting the correct grade of epoxy resin and granite,silicon and quartz fillers that make up a suitable tructural compound for the intended purpose.

 

I have used some fairly crude epoxy granite based fillers to fill out the voids in the cast base and column of a low cost mini mill which has made significant improvements to the rigidity of the machine.

 

I suggest googling epoxy granite fillers and also take a look at http://www.cnccookbook.com/CCMillEpoxyFill.htm , there is some useful info there. I based my mix on the info on this site and it has worked very well.

One thing to bear in mind when building anything purely from an epoxy granite based compound, is that you will need to build a rigid mould and be able to vibrate the entire mould in order to compact the fillers so that teh epoxy is purely a bonding agent. The epoxy has little structural strength, it is the varying grades of filler that provide the strength and rigidity, in much the same way as traditional concrete does however, epoxy has greater long term stability properties than cast concrete.

[Steve WanParticipant @stevewan33894]

Hi Guys,

 

Thank you so much for the vast information and also generated so much interest here

I have learnt alot and will be prepared to experiment filling cast voids with epoxy granite instead of purely concrete.

 

First will look out any supplier here, I guess the epoxy granite is widely used for housing the washing basin in the kitchen nowadays…so should be easy to find.

 

Steve

[Sub MandrelParticipant @submandrel]

Back in the 70’s I knew someone who was researching ‘light concrete’ at UWIST. They made a concrete canoe and he demonstrated a 6″ cube of ncrete that floated.

 

Neil

[BazParticipant @baz89810]

If my memory serves me correctly, the Hardinge CNC lathe using concrete was the Talent range. These were slant bed machines as opposed to their CHNC range which were similar to the HLVH series.

[Richard ParsonsParticipant @richardparsons61721]

The Mulberry ‘A’ Off Omaha beach.

[Douglas JohnstonParticipant @douglasjohnston98463]

one of the best ways to mount a lathe or mill on a wooden bench is to place a concrete slab on top of the bench using a bonding agent between the concrete and wooden top. The concrete should be a decent thickness, made from a thick paving slab or cast in place.

By this means you ensure there is no distortion in the machine if the wooden structure moves slightly over time. There is probably some damping benefit as well when the machine is solidly bolted to the concrete.

[jomacParticipant @jomac]

Hi. This topic is not much to do with lathes and mills, but it will work the same, because I started to build a 3/4 size snooker table, the ” slate” bed was formed from 3 sections, using 3×2 outer frame and the base was 3/4 thick formwork ply, which is waterproof, and each side is varnished, as you only need one former, altering the “pockets” with poly foam, the fixings were Ramset expandable fixings, screwed these to the side frames, but filled the inside with a melted candle to stop the concrete from intruding on to the threads. The inside was layered with strong chicken wire, tied to the bolts with tie wire, (its too thin to weld). and then filled with a strong concrete mix, ie more cement than normal concrete.

I vibrated this with a large industrial Ramset drill, ( using a small workshop hammer drill is not big enough) using a block of wood drilled to take a bolt, made it loose enough to allow it to spin on the bolt, and locked the bolt in the chuck. BUT !!! DONT vibrate too much as the agregate will settle to the bottom and the base and the top and bottom will have only a weak slurry, which will crack, So I pushed the drill and block from below, hitting it it in 10-12 postitions for only a maximum of 10 seconds. You can make a vibrater probe out of plastic pipe fixed to the wooden block and sealed at the end, If you are careful you can hold the pipe from turning, but still vibrate enough the settle the concrete mix to the bottom without air bubbles and voids. As an after thought what if you use a watered down contact adhesive that will run down the inside of a Mill columb and then set, or won”t it go off ???.

Some of the cheap Chinese pool table had so called slate beds, but these were only concrete, coloured grey. and only 3/4 to 1″ thick so were very fragile if handled wrongly.

Hope this is some help !!!

PS. its getting cold down here now. Although Autumn is a very pretty time of the year.

John Holloway.

[ViKARLLParticipant @vikarll]

Hi Steve,

Interested to find out whether you made any progress?

To mention a bit ‘out of topic’ experience, some time back, I have used a concrete mould to turn out a small classic car part from 22 gauge brass sheet. This was done by making the male and female parts of the sample with concrete and pressing the sheet metal sandwiched between them on a 1-ton arbour press. I made about a 2 dozen pieces but the mould held fine.

I used common Portland cement, granite dust, sand; about 10% epoxy (JB Weld-USA) to reduce the brittleness of concrete. But I think the secret of strength lies in the reinforcement I used. Which is none other than plenty of fine grade steel wool. You have to make a little effort to not let tiny strands of steel wool stick out of the surface.

If you make something like a headstock of a lathe for instance, which can afford thick sections and is not a moving part, the chances are that it should hold.

Hope this helps.

 

[Michael Cox 1Participant @michaelcox1]

Hi Steve,

If you join the Yahoo Gingery Machines group there are some articles in the files section about making machines from concrete.

Mike

[Richard ParsonsParticipant @richardparsons61721]

Steve

I think you will fnd it all on this thread. You have to read down a bit but it is worth it. John McNamara makes a tool grinder out of Mineral aggrigate.

look here http://www.model-engineer.co.uk/forums/postings.asp?th=51617&p=2

 

Rgds

Dick

 

Edited By Richard Parsons on 27/09/2011 11:00:46

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