lathe

[rampa room artillery]

  Hey , can i find a lathe that can handle a 24 lb mortar? for 500?  or how much would one run?? new old i dont care, just need it to work.

trying to get started turning my own stuff instead  of paying my cannon maker. to do it.


rick bryan
 NSSA

[GGaskill]

A 24 pounder Coehorn is 8.65" OD and 5.82" ID and 16.32" long.  You will likely need a steady rest big enough for at least 9" diameter material to bore it.  You might be able to hold it in the four jaw chuck to drill and bore it but that has some risk.  It would be safer to use a steady rest or bolt it to a face plate.  Once you have bored it, turn the front band and then turn it around, center drill the breech end and use the tailstock to support the outboard end.  The rest will be relatively easy except cutting a groove for the trunnion which will require a milling machine or some creative support tooling to use the lathe.

I wish you luck in finding a good lathe; they are great fun.  As far as finding a suitable lathe for $500, it depends on your area and your luck.  I doubt you will find one that cheap in the short run, but if you look at everything you can find, you may find one.  It would be more productive to work some overtime to get more spending cash and be able pay more because it will happen sooner and you would probably get a better machine.  You will want at least a 10" swing over the carriage to be able to make a Coehorn.  This will mean a lathe that is more like a 14" swing (maybe even larger) since nominal swing is over the ways.

And then there is the question of tooling (chucks, steady rest, etc.)  You want to buy a machine that includes lots of the big pieces, as getting the right ones for an old lathe is unlikely and they would be expensive (more than the machine in total) if available.

[seacoastartillery]

     Rick,   I measured the functional swing of our 16" swing lathe over the carriage and our machine only allows a 8.880" dia. workpiece to be turned.  Since you should have at least as much clearance as your thickest lathe adjusting wrench between the work and the carriage as a rule of thumb, if I were you, I would be looking for a used 18" swing lathe.  The new prices are pretty steep in this size, but used, medium-large lathes go for less than the more popular, smaller sizes.  Look at what's being offered in the industrial auctions in the industrial center nearest your location.  I would check fleabay too, but heavy lathes come with heavy transport charges, so distance is a Big factor in total cost.

Good luck.

T&M

[KABAR2]

One thing I have found is most of the larger "cheap" lathes that are 30 or more years old will be 3 phase

which means you either live in an industrial park or you have to spend more money on equipment to have enough juice

to run it,  Check the motor on what ever you are looking at to buy & stay away from 3 phase.

Allen <><

[GGaskill]

I measured my 14" Logan and it will swing only 7.35" over the carriage so you are going to need a good sized machine to turn 9-10" work over the carriage.

Don't panic about 3 phase power.  As long as you have good service (like 220 VAC and 50 amps) to your shop, there are simple and relatively inexpensive ways for you to provide 3 phase power to your machines.  The elegant way is to use a VFD (variable frequency drive) which creates 3 phase from single phase and allows you to vary the speed of your motor electronically, but it costs more.  The simple way is adequate and easy to understand if you have basic electrical understanding.  Lack of wired 3 phase should not prevent the purchase and use of 3 phase powered machines.

[Victor3]

 I use a static phase converter on my mill. You do lose some HP and the ability to reverse the spindle rapidly, but I've found that it works fine for my needs.

 Some guys just change out the motor for a single phase.

[CaptTHighbiter]

Too bad you didnt post this a few month ago. THe company next door was giving away a big butt engine lathe. I even posted it on here.  Short bed but BIG diameter head. An all the cross slides, tail stock etc.
No one took it and it got carted away as scrap.

I am working with an ancient Clausing, trying to turn out a small mortar in naval bronze.

[Cat Whisperer]

The company I work for will be auctioning off a Bridgeport (1hp) small table.  Will likely start at 300 and go up a little.  Sale in January.

[GGaskill]

The company I work for will be auctioning off a Bridgeport (1hp) small table.  Will likely start at 300 and go up a little.  Sale in January.

And it's located in western Virginia.  Unless you have a big truck or heavy duty trailer, machinery moving is expensive.

[Cat Whisperer]

The company I work for will be auctioning off a Bridgeport (1hp) small table.  Will likely start at 300 and go up a little.  Sale in January.

And it's located in western Virginia.  Unless you have a big truck or heavy duty trailer, machinery moving is expensive.

Yea.  It's a little big for a flat-rate box.

[dominick]

Rick,

I have a 14" X 60" Hercules lathe, 5 H.P. 3 phase,  that I will sell in January for about 1000 dollars.  There is a lot of tooling and extras that go with it.  It also has the experience of building more than 500 cannons and mortars large and small. I have turned 8" diameter on it already.    

    I am not an electrician but here's my research and explanation for an very inexpensive phase convertor.  A 220 volt, three phase motor has 3 hot wires and a ground for hook-up.  A 220 volt, single phase motor has 2 hot wires and a ground.   For a phase convertor, any three phase motor will run on single phase power by connecting the two hot leads and the ground from the single phase power source. On single phase power, it will run at 2/3 the horsepower.  The problem is the start up. You have to manually rotate it to start it.  With a lathe this is difficult because of the resistance of the rotating mass.  A static convertor is basically a bank of capacitors that adds the start cycle to the three phase motor. Static convertors are ok for light duty start ups but will not start heavy duty lathes.  A rotary phase convertor is basically an "idler" motor of 2/3 more hp, with the bank of capacitors for its own [idler motor] startup, and it is used to add the 3rd phase to the lathe motor.  Now, you can start any 3 phase motor on single phase power by manually rotating the shaft.  A friend of mine simply kicks the pulley to get his started. You could also make a rope start or drill start set-up.  To run the above lathe on single phase 220 volts, you take a 7.5 hp 3 phase motor ["idler motor"] and hook your 2 hot 220 volt leads to 2 of the 3 hot leads on the 3 phase 7.5 hp "idler"motor, then run 3 hot leads from the hot terminals on  to the 3 hot terminals on the lathe motor.  Run the ground wire to both motors and also install a disconnect switch before the idler motor. This 7.5 hp motor will add the "5 hp" balanced 3rd phase to the lathe motor. [Remember, the 7.5 hp idler motor is running at 5 hp or 2/3rds the power on single phase.] If the lathe motor is running backwards, just switch any of the 2 hot leads and this will reverse the rotation.  If you have no experience with electrical hookups and are uncertain of this procedure, it's best to have a qualified electrician make this type connection.  Also, I have a source for three phase motors,  A used 7.5 hp is 100 dollars and new one, 160 dollars [last time I checked]. Here's a diagram of the connection.  Dom

[GGaskill]

My 3 phase system is basically the same as Dom's diagram except I include a static phase convertor to start the idler motor, which is manually switched out of the circuit (the static convertor, that is) once the idler is up to speed.  All my 3 phase machines are driven through this system and they all work normally.

[dan610324]

Im just curious to know what electricity you got in usa
some talks about 140 volt , some about 240
but it seem to be only single phase
dont you have 400 volt 3 phase ??
as incomming in sweden we got 3 phase in every house as standard, then from there we use 240 single phase for all household power and lights
3 phase for kitchen stove , washing machine , heating and all other heavy consumers

[Victor3]

 At home we've got 220 single phase coming in on the line, but use 110 for most items.

 In industry we use 110 single up to 440 3 phase for most stuff.

[Cat Whisperer]

Dom's advice is good.

Use a rotary converter.

You can buy (sorry for using a 4-letter word) them (either name-brand or someone else's making them for a lot less) OR you can do a search on the internet on how to make one.

I have one made by, I think, Anderson. 

A 3hp idler will run a 5hp lathe.  (A good chunk of the power goes straight through.)  Two of the phases are going to be powered with a little less voltage (as they are generated by the idler.)

The big thing to remember is to turn off the lathe first, then the rotary phase converter.

Don't let this become a hinderence - there are enough of us around to walk you through it!

[Double D]

Not important unless you are moving between system by Dan's power is 50 cycle and U.S. power is 60 Cycle.  Plays havoc with clocks and small electric motors.  Power converters-don't change the cycles.

 

[GGaskill]

If you want a lot of info on this power conversion subject, go to Practical Machinist's Transformers, Phase Converters and VFD forum.