[jdholbrook]

I've been looking to either build or retro-fit a lathe for CNC.
Looking at something like cnc'ing a Hardinge is very appealing but the stumbling block of almost 2000 pounds is hard to get over.
During my quest I ran across a lathe made by a group member using what looks like Thompson rails.
If a person were thinking of going that route.. what is a good material for the bed of the lathe?
At my disposal I've got various metals such as a large I beam of 100+ pounds and around 24" length, I'm guessing over 1/2" thick. Some steel plate in various thicknesses from 1/2" to 1 1/2".

I envision having it decked to make it flat and having the mounting holes bored at the same time.

Any suggestions? Other ideas?

What is the ideal solution?

Thanks
James

[lakeside]

bed weight is very imporant in a lathe consider your forces of a part spining and a tool cutting a lite weight lathe will transfer vibration from bed ,tool and part to each other that why hardinge's bed are one piece casting

[NEATman]

There are other tricks that you can do to "deaden" a welded or tube steel frame. The best is to start with thick walled steel tube, finish a side to mount your rails, and fill it with lead shot or sand (make sure there is no salt in the sand!). The loose material inside acts to absorb vibration, and also makes for a firm base. Plus, by adding the weight later, you can position your machine where you like, then add the mass. Of course solid cast iron, composite granite, or real granite are still the best, but this approach is probbably the second best.

NEATman

[lakeside]

neatman those are neat tricks good post

[Ken_Shea]

James,
The stress on a lathe bed I would expect to be quite low for general use, you could use some mild steel plate then have it ground flat and parallel. On a conversion I am working on I purchased a 1x12x36 plate of 1018, cost was about $175 and you can expect about another $175 to grind it reasonably true, it looks good but does have some twist in it so using is as is won't work.

To me NEATmans suggestion of good quality cast iron would be the best bet but in trying hard to keep cost down I chose another route. Even now the use of the 1018 is on hold for another product that a friend showed me which is a type of epoxy, it is heavy, stone hard, strong, good specs on rigidity, machinable with carbide but likes diamond, and should absorb vibration well, cost for the above size is about $80 delivered. My friend who has yet to come through with anything but a promise is supposed to get me a section on his next job....... still waiting after almost 6 weeks so we will see. If I was sure it would work as hoped I would ask him to just order new and get it over with.

If you can afford or willing to spend the bucks, cast iron is the best bet, but as you can see there are alternatives, which one? it is all about $

[Mcgyver]

the 2000 lbs is why a hardinge's a hardinge - its an advantage not a detriment. the lead shot/sand dampening works, wood lathe guys use it extensively, problem is it only dampens, doesn't provide any structural strengh. read up on stuff like harcrete polymer concrete filled steel structures, numerous posts here and on google - imo that's the way to go for a diy machine tool structure

The problem with making it from solid, whatever the material, is you loose the engineered approach (webbing, torsion box etc) that maximizes the rigidity and strength for the weight involved.

The thread herein on converting one of the smaller hardinge's is a good idea - don't try to reinvent the wheel on a robust bed casting.

then again it always comes down to what you want to do. my first lathe was a unimat, the old ones with the round bar ways (still have it). although useless compared to what i have now, it did cut metal and didn't stop me from having some fun with it and learning a bunch

[jdholbrook]

I was looking over the choices I had using the advice I've received on this thread.
I tapped the 1.5" plate with a cresent wrench and it rang like a bell.
I see what you mean about using sand or some other form of deadening.

I would love to have a Hardinge and they are in my price range (on ebay) but I have no way of moving 1500 to 2000 pounds of machine.
I'm pretty sure my shop floor would hold the weight tho. It's a converted sandwich shop from many years ago. Very solid.
Any ideas?

James

[lakeside]

use a very water mix of portland cement and sand with no stone fill tube as long as you are not going to drill or tap latter if you do you could go thru with a mason drill bit

[dkowalcz]

1" or 1-1/2" steel plate is fine for a bed - you may want to weld it onto a square tube to bring the height up and if you leave an inch or so of plate width on each side sticking out you have box ways started already. I'm looking to do this to my 7x in a few months, I need about 10-12" more of turning length and so I need to whip up a new bed.

I would't get too hung up on the vibration deadening properties of CI, steel is a fine material for machine tools as it's much stiffer than CI. While it's true that a single piece of steel will ring, a machine has lots of interfaces between the tool and the work (bearings, bolted on members, ways) that make the vibration deading issue more or less moot - there's so much more dampening elsewhere that it doesn't matter if you made the bed out of lead.

The far easier way to go is rent a forklift and move your new Hardinge inside. Unless you have to go down a flight of stairs or something you're all set. I did this for the gantry pick and place I recently bought, it's about 2500 lbs, but $100 for the forklift and done. I think it took longer to get the forklift started then to actually move the machine.

[Zumba]

Take a look at the wood lathes from Oneway.



Thick steel tube with ribs welded to it. I think this is a good way to go. I'd imagine that a cylinder is less prone to vibration than a square tube. Any large flat surface is prone to vibration. The rips on top of the cylinder help even more.

The guys who turn on those big woodlathes often chuck up "natural edge" blanks, meaning pieces with bark still on them... totally imbalanced, and they can weigh quite a bit. A green log section can easily weigh over a hundred pounds.

[jdholbrook]

Never thought of renting a fork lift. It wouldn't fit thru the door but I can manage it with an engine hoist and dolly once I got it to the door.

That tube lathe is wild looking. I would call that thinking outside the box.

Next is what to make the headstock out of?
Is aluminum going to be the right choice?
Spindle?

I've got a little Taig CNC mill as well as a Taig lathe and a Harbor freight 9x20 but I need a spindle bore of 1 1/4".

[lakeside]

you can also use a flat bed ramp truck and place it on some plywood base and drag it up the bed with chains and off bed the same way

[NEATman]

jdholbrook-
Two friends and I recently moved a full sized manual bridgeport, a 36" pexto sheetmetal shear, and a hardinge DV59 second operation lathe. We did it all in one day, about 150 miles round trip using a flatbed trailer that usually hauls a friends kabota tractor. We loaded the BP directly over the main axles, with the Hardinge in front of it for tounge weight, and the lighter sheet metal shear behind. We picked them up in the same place, and dropped them off in three different locations. I took the lathe, and I'm working on converting it now. I am happy that it is a second operation lathe, and has only a simple bed with a t-slot. I am still refining a design based on parts and material that I have on hand. It will have THK rails, and preloaded ground ballscrews.

The only tools that we had on hand to move the machines were pipes, long steel prybars, various scraps of wood and aluminum, a "come-a-long" and heavy duty tie down straps. We were able to back the trailer up to the loading dock, and using it's built in ramp, slowly roll the bridgeport down the ramp on pipes with the assistance of the come a long. The lathe was even easier, as I have a set of hardwood furniture dollies (about $25 each at home depot). We used the prybars to lift each end of the lathe gradually, inch by inch, by blocking it up on wood and metal. Once it was up in the air enough, we simply dropped it on to the dolly (with 4 caster wheels under it) and rolled it out to the trailer, and controlled it down the ramp with the come a long. For transport, we took out the dolly, but left it on blocks so it would be quicker to get the dolly back under later. It weighed less than I thought, only about 1000#. The sheetmetal shear at about 600# was moved the exact same way. We unloaded each piece into a garage (3 different houses), reversing the procedure from before. No one got hurt, and as long as you take your time, you shouldn't either.

Reminded me of how the egypitans must have moved those stone blocks...

NEATman

[jdholbrook]

Ok.. talked me into it.
Back to ebay I go.
Just passed up one for $2400ish that had a nice set of collets, turrent tailstock and 3 jaw. It was in Florida and I'm in Texas but I've got plenty of time to make a trip.

NEATman.. I am interested to see how you plan on CNC'ing your Hardinge.
Are the ballscrews rolled or ground?

[wizard]

I was looking over the choices I had using the advice I've received on this thread.
I tapped the 1.5" plate with a cresent wrench and it rang like a bell.
I see what you mean about using sand or some other form of deadening.

Yes a plate of steel will ring so will alot fo other materials. Adding mass will help with some forms of vibration but It might not help to much with steels tendency to ring. Whether or not this is important to you is likely to depend on what you are machining and what you are making. I suspect that you would be very succesful making a lather for turnig pens or similar small items on a 1.5 inch think steel plate. Don't expect to turn a cannon on such a plate though.

I would love to have a Hardinge and they are in my price range (on ebay) but I have no way of moving 1500 to 2000 pounds of machine.

Seriously if you have the money go for it. Hire a rigging company to make the move. It is what all businesses do. Heck the tool and die shops around here will hire riggers to move partially finished machines from one building to the next. It take responsibility of you bank account.

As to your location it may pay to have a potential rigger come buy and evaluate where you expect to go with the machine. A good rigging comapny can put a machine just about anywhere, for a price. You just don't wnat to pay the price if the circumstances are exceptional in your area.

That isn't to say that riggers are cheap, you will have to expect to pay a good price to have the job done. It shouldn't be to bad realtive to a Hardinge lath though.
[quote]
I'm pretty sure my shop floor would hold the weight tho. It's a converted sandwich shop from many years ago. Very solid.
[/qoute]
If it doesn't have earth under it get it evaluated by a engineer. You will be putting a large load in a small space! Do realize that some machines can benefit from their own foundations.

Any ideas?

If you think you can move a Hardinge in the go for it. Taking all percautions before hand though. The biggest problem with getting a Hardinge is that you might like it to much as a manual lathe to convert to CNC. These are one of the best manual lathes made assume we are talking about Hardinges toolroom lathe.

If you have specific plans in mind for the CNC lathe then by all means consider a purpose built unit. There are many ways to go about this, inclding buying doetailed castiron slide assemblies and putting them on a granite block to casting your own iron. It is justifiable for specfic uses. On the other hand for a general purpose solution there are to any used lathes on the market to considr going that route.

Some of these used lathes are CNC (no surprise here) the only problem beign the need for modern controls and possibly mechanical work. A used CNC machine would likely to be my first CNC conversion choice. Most of the work is done for you this way. You ought to get some support here for a used CNC project machine as being the most logical starting point. The big problem here though is that they are likely to be even heavier and you might not get things like tool changers working right away. But you won't have tool changers on a tool room lathe any ways. You do have to shop smart or you culd end up spending a fortune in repair costs, but that is a problem with manual lathes also.

Dave

James

[NEATman]

JDholbrook-
Were you planning on converting a toolroom hardinge, or a secon operation hardinge? Mine is a second op lathe, without a traditional carriage or cross slide. You should be able to get one like this for under $1000 on ebay. The other two people who are doing this same conversion got them for between $400 and $800 on ebay I think.

I intend to make my own out of 7/8" ground plate that I have on hand. The ways will be THK bearings, and the ballscrews I have are very high grade ground and preloaded. They have precison ground angular contact ball bearings at one end, and a radial support bearing at the other. I plan on using one piece helical couplings between the motor and the ballscrews.

I have recently gotten the PC connected, Mach 3 loaded, the drives powered and wired, and gotten the motors spinning. There are two main things remaining for me to solve on my design. How to re-mount the turret tailstock, and where to put the ballscrew for the main carriage. I am thinking or mounting it inside the bed casting, for protection from swarf and chips. The design I have in mind also eliminates the need for bellows covers, as the rails are inverted. Attached is a more recent picture of the model that I am working on. I have created this in Solidworks 2004. Let me know if you want a copy, or have any questions.

NEATman

[jdholbrook]

Been looking thru ebay and see several different types of Hardinge.
Toolroom = $$$
HLV isn't too bad
Second operations are very attractively priced but I only see a turret tailstock.
Is it possible to add a carrage to one?
Keep looking for an HLV ?

Thanks

[jdholbrook]

What's a chucker?

I've even seen a CNC Hardinge chucker.
COuldn't tell much with that big hood over it.

The prices seem right tho

James

[nervis1]

Chucker....open chuck, put stock in, cut part, open chuck, take out part...repeat. No tailstock, no subspindle.

That's my understanding anyway.

[jdholbrook]

How does a Feeler compare to a Hardinge?
Looks identical.. even the model number is 59.
I found one close enough to home that I could pick it up myself.

Can you fit a carrage on a second operation lathe bed?
It's got a turret and that's all.