Mill or lathe?


A piece of string is precisely 12.203452345928345623762358697 inches long. A-nuther piece of string may be a different length.
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Michael Koblic wrote:

No, there is ONE correct answer to the string question, but the lathe/mill answer is "it depends on what you make!"

Answer C is definitely out, unless your shop is limited to the floor of a small closet. They are awful, I could write a long article on why, but generally there are big limitations on workpiece size and adjustment of height range of the head. We have one of those combo machines just like your 3rd link at work, it is abominable. No head height adjustment at all! It is not a REALLY bad lathe, but nearly worthless as a mill. I take work home to do because I'd rather do "work work" in my free time than use that klunker. It is also just a poorly made piece of Chinese crap that will give you a lot of maintenance headaches if you use it a lot. Just dumping on this particular item as I know how bad it is. (Also calling it a 16" lathe with a 3" chuck is quite funny! Maybe you could turn wooden bowls on it, but no way could it turn a 16" piece of steel.
If you make a lot of round parts, then a lathe is a good choice. If you make a lot of rectangular parts, a lathe is the wrong tool. Either machine can serve as the other in a pinch. I made some serious lathe parts on my mill when I needed spherical ends, basically I was making ball joints, and didn't have a radius turning attachment. But, I had a CNC mill. Put work in spindle, mount lathe tool in mill vise, and go to it.
So, I can't go further without knowing what you need to make. I make a lot of machine panels and electronic cabinets out of sheet metal, a mill is clearly the tool of choice for that. So, years ago, when I started out, I bought the mill first, then the lathe. The only advice for the mill is check the X-Y travels and think carefully about the biggest work you will need to make, and also avoid those round-ram "mill-drills" as the head loses the X-Y alignment any time you raise or lower the head.
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Actually one can do quite a bit of turning work on a horizontal mill, even turning between centres. I have a small Japanese H mill with vertical head and it is ideal for me. Son and I regularly re-machine brake rotors for our RX7s.
As was pointed out above you have to decide what work is most prevalent, precision turning ie. fitting round parts together for sliding, press, or transition fits. Ability to turn accurate dia. and holes is vital if you plan on using commercial items such as ball bearings. If this is the case, get a lathe first. A decent sized lathe, say a robust 10" lathe and larger equipped with a good milling attachment will permit milling of smallish parts with reasonable accuracy.
If your parts have many flat features and bores of various sizes then a mill first is the way to go. Here I am swimming against the stream in advising a horizontal mill which for my money is more VERSATILE than a vertical mill. By placing a faceplate or chuck in the H spindle it makes a pretty decent lathe for short parts. Add a boring head and you have a small horizontal boring mill.
A horizontal mill will do everything that a vertical mill will do, but NOT VICE VERSA! It is agreed that a vertical mill is more CONVENIENT for many milling operations... That's why I have a vertical head on mine. But if we are talking about versatility, my advice/opinion stands.
Although there are many here advocating "bigger is better", on a lathe that isn't necessarily so. Turning small dia. on a large lathe is a royal pain because the top speed is too low for efficient chip flow. Even though my 10" lathe has a top speed of 2500 rpm, I also have a watchmaker's lathe with a top speed in excess of 10,000 rpm. For turning and drilling small parts it is a real joy to use.
I build models, the largest of which is a 3/4' scale (1/16" to the foot) Hudson steam locomotive. And we turn brake rotors. Repair stuff, make custom components for whatever, build stirling/hot air engines.
My equipment, backed by a full complement of attachments many home- built, is a 10" EMCO-MAIER lathe of 1976 vintage. A Japanese H mill 6" x 20" table with V head, 1960's vintage. A post type vertical mill built from a robust X-Y table and the milling head that came with the lathe. 1950's bench type drill press, Atlas 7" shaper, 12 Rockwell bandsaw converted to metal cutting, small gear hobbing machine, homebuilt blade welder and EDM machine, brazing/silver soldering equipment, and lately a home-built tig welder Son built from my father's old Lincoln Tombstone.
With this equipment there is very little we can't do, and except for the welder, it all fits into a 13' x 14' basement shop suitable for 2 people working, 3 if they are good friends :-)).
Decisions decisions. Perhaps if you could elaborate on your interests we could give you more specific answers.
Wolfgang
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Michael Koblic wrote:

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Per the tenor of the group, a string is as long as it is.
If I were just making car parts I'd go with a mill. Every bit of car-part stuff I've made has been turned, and it all would have come out better on a mill.
Since I'm (very slowly) teaching myself how to build small engines, I bought a combination machine, which was a big mistake. I wish that instead I'd spent my money on a lathe and a milling attachment -- if you choose your designs carefully, you can build working engines on just a lathe.
One day I'll get a mill, then I'll get a real lathe, then I'll have a party when I dispose of the damn Smithy.
--

Tim Wescott
Wescott Design Services
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you would do much better to describe the work, materials involved, quality needed, quantity of parts...

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I am sure that these will sway the answers to the lathe side on account of most things being round, however consider that I use * what is available* and *what is cheap*. So mild steel most often, occasionally brass. Many a time something grabs me in a garage sale and is put away for later use when I suddenly find its place in a project.
I am located about half-way up the Vancouver Island. I have had people make things for me in the past: The largest dial wheel (Thames) was machined for me in a Quesnel machine shop. It cost me $30 in 1994 dollars. The final piece is still around admired by many who are unwilling to part with the $195. At one stage I was toying with the idea of having the face designs etched by laser, however the cost of this process would have rendered the smaller pieces uneconomical.
Thus in general I would prefer to do as much of my own work as possible. Also it is an excuse to spend large sums on tools. At this point I am still at a stage of collecting information and, as somebody said, there are still a few avenues open for me to get my hands on a lathe or a mill for a trial.
There is no rush. Until then I shall stick with the 18th century methods :-)
--
Michael Koblic,
Campbell River, BC
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Very nice!
You are going to want a standard size mill with a rotary table plus a lathe with suitable swing for your largest pieces. I suspect that you are not holding close tolerances so really expensive equipment is not necessary.
But a CNC conversion is in your $$$$ future!!!
Michael Koblic wrote:

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Thank you. You are absolutely right - this equipment is essential! I shall tell my wife... Seriously though, you are right about the tolerances. The times I get frustrated is when I run into problems with symmetry rather than size not being quite right. Also matching angles - to get the gnomon to come out where it should there have to be sometimes 4 different angles just right. The smaller the piece the more critical it is. I have overcome many of these problems by designing things so that there is room for final adjustment but that goes only so far.
Still, if it was easy what would be the point of doing it?
--
Michael Koblic,
Campbell River, BC
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wrote:

Very nice indeed! and I agree..a decent mill with rotary table would be your first choice
CLOSELY followed by a clunker lathe.
Gunner
The hottest places in hell are reserved for those who in times of great moral crisis maintain their neutrality", John F. Kennedy.
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l
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Nice work!
Other than being round and artsy the parts aren't much different from electronic control panels; large and thin with free-hand shapes cut in them. They could be done on a low end mill-drill like the RF-31 and a rotary table with plywood top covers.
You could make the gnomon on a very small lathe, turn the end of it in the mill, or get a rotary table that stands upright and put a chuck on it. You can cut a large variety of angled flats and curves with 5C collet blocks, which will hold a long one-piece rod.
If you turn it on the mill don't let the stock extend more than 3 - 5 diameters from the collet and take light cuts. Otherwise the rod is likely to catch on the tool, bend, and then crash into the tool on the next revolution. It can bend the same way in a collet block but at least it isn't spinning. A lathe (or rotary table tailstock) supports both ends so you can cut anywhere along the rod.
Old-time mechanics cut metal with hand held chisels on wood lathes. My small lathe is set up for similar work with a 1/2" drill chuck on the spindle and a Dremel drill on the tool post. I kept it after buying the larger South Bend because it spins much faster and disassembles easily to clean off grinding grit. A lathe is fairly easy to cobble up from a drill or motor if you don't need the precision bed.
Free-hand milling is easier on a mill with a fairly short table so you can reach the cranks comfortably. That's one of the few things I don't like about a Bridgeport. The RF-31 I bought for electronics had enough table travel to drill both ends of a 19" rack panel but it was short enough that I could stand at either end of the table and turn the handle while watching the end mill approach a scribed line.
I don't think a medium-sized lathe would help you much for these projects. Possibly a combo would work if you get a really good deal on a used one that doesn't have stripped gears. You could build up a wooden support table under the end mill and use the carriage feed to move the disk for engraving. The Smithy I used was an acceptable lathe but it was crudely finished and needed cleanup. If I owned it I could have made something useful out of it eventually. That shop had a CNC lathe and Bridgeport and I only used the Smithy when they were busy.
I have an original, unused milling attachment for my South Bend. The first time I tried it I found out why it was unused. The carriage is meant to take downward thrust only and it jumps around from sideways milling forces. The clamps under the rear are only good enough for knurling.
Jim Wilkins
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MK,
Nice work indeed!
Looking at your work I would recommend a post-type milling machine with a very wide (Y direction) table, along with the largest rotary table you can handle/afford/fit. 12" diameter would not be too big. Fit motor drive to the rotary table if you can. Use a piece of MDF for custom work holding fixtures.
With a little attention to fixturing, the production of those dials would be a breeze.
Perhaps you should also consider a metal-cutting bandsaw to cut blanks from larger plate/sheet, although a recip. saw with appropriate blade would suffice.
Because accuracy is not a primary concern, Ebay and other advertisers are your friends.
For all that engraving it would be worthwhile to fit CNC control.
Let us know what you decide.
Wolfgang
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Thank you.
Your advice coincides with a few others and shall be looking in that direction in a more focussed fashion.
When you say "rotary table with motor drive" is this to allow repositioning of the table to allow, e.g. milling slots, or is it a drive to spin the table sufficiently fast to allow some lathe type operations (right now I would find it helpful to be able to spin some fo the pieces around 50 rpm and apply abrasives, particularly if the pieces are not completey flat)?
A month ago I walked away from a 7x10 band saw with a hydraulic feed in a garage sale. For the rest of the day I felt like someone cut off my arm...:-)
At this point I can still cut OK, it is the other stuff that is a priority.
Also, there has to be room for fencing in the garage!
--
Michael Koblic,
Campbell River, BC
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Thank you.
There is a lot of information to digest. I have been all over Google to find out e.g. what the heck is a rotary table etc. :-). I am trying to relate it all to what I do and it always comes down to the same thing: I gotta see it! I believe there are some good videos out there I shall try to look at.
Today, for instance, I cut off a lip off a small (9cm diameter) circular brass ashtray with a coping saw. That was easy. To restore a circular profile cleanly was done with some difficulty by rotating the ashtray with the edge along the disk sander. The clean up of the surface was even more tricky as the concave shape did not allow the use of my favorite pam sander: It was all done by hand and patience. Scotchbrite pads really helped. The result is not too bad and it is ready to receive a face of some sort.
In relation to this thread I was wondering how the machinery would have helped. Would I be able to mill the circumference with greater precision on a rotary table? What about the surface - is milling the answer? I have been trying to find a way to spin these pieces at relatively low speeds and apply the abrasives to them in a more controlled fashion. I cannot get past the issue of clamping them securely but I suspect you will tell me that there are chuck configurations that will do all that.
I was interested in your comments about cobbling up a sort-a-lathe from a drill press. I have been wondering about that for some time (and now even have a drill press to spare). I even have a live centre of sorts for the use with sanding drums. Maybe I should have a look at this again. The only problem - the said drill press does not go lower that 720 rpm. But for small parts it sould not be a problem.
It's an adventure...
--
Michael Koblic,
Campbell River, BC
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Michael Koblic wrote:

In your research, be sure to look up "Lathe faceplate". You may also consider ways to slow down the drill press.
--


Ron Thompson
Riding my '07 XL883C Sportster
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"Ronald Thompson" <"webmaster <remove> wrote in message

That is the question I forgot to ask. I cannot think of a way right now other than getting a smaler pulley for the motor. Bigger pulley for the spindle probably would not fit in the housing. Can you suggest some other ways? My understanding of AC motors is such that the speed is pretty much fixed.
--
Michael Koblic,
Campbell River, BC
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Michael Koblic wrote:

Depending on the design, you may be able to add an idler shaft to carry a combination pulley. Another way is to convert it to something like a treadmill motor with a speed control.
--


Ron Thompson
Riding my '07 XL883C Sportster
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On Aug 21, 7:57pm, Ronald Thompson <"webmaster <remove> wrote:

I gave one four dollars, a dime and two pennies when the bill was $3.87. The kid looks at me funny, enters it, sees the change is $0.25 and demands "How did you do that?"
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On Fri, 22 Aug 2008 03:42:14 -0700 (PDT), Jim Wilkins

"I'll take a dozen" - "Sorry, we only sell six, nine or twelve" Gerry :-)} London, Canada
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I get into jobs like that where machine tools don't help much. Currently I'm making a catalytic converter heat shield out of a damaged stainless steel chimney section. I haven't quite figured out how to make louvers on a curved surface yet. A new heat shield from the dealer is $120 and NOT stainless.
Sheet metal is easier to profile if you attach it to plywood. I put screws and washers around the edges and in waste areas and then fasten temporary wooden strips across the sheet close to the edges being cut to keep them from lifting, which is a problem with end mills.
My circular routing jig consists of a tapped block bolted to a laminate trimmer (small router) connected to a ball rod end (for go- kart steering) with threaded rod. The rod end pivots on a bolt, held squarely upright by a tee nut, in the center of the plywood. To feed it in or out I flip the rod end half a turn, which is more certain than two opposed nuts and accurate enough for most such jobs. You could make a similar rig without machining by bolting strips of slotted angle to opposites sides of the tool's base plate, with the holes for the threaded rod far enough out to clear the collet wrench. To start a cut I slide it onto the center bolt with the rod end raised upward and lower it level to feed outward. The rod end is a close fit on the bolt even at an angle.

My rotary table is too lightweight for serious circular milling, not that I haven't tried. Its 40:1 reduction ratio means all rotation is relatively low speed like a clock's minute hand. That's one reason for a motorized one. A hand-held tool becomes harder to control as the metal thickness increases and the rotary table keeps the cutter and work from jumping around and your hands further away. I think you could use it and the table feed to engrave the Roman numerals.
Maybe you could find or make a pottery wheel with a frame around it to support your tools. If you set it up right the rotating tool will drive the wheel. That's how I ground down the front motorcycle tire for my sawmill. I could control the speed by changing the angle that the grinding disk crossed the tire. The top speed my 7" angle grinder could drive it to was about 80 MPH which is reasonable as long as the wheel is balanced and the axle is bolted to 150 pounds of steel.
A motorcycle front wheel might work well for you since you can easily attach plywood to the brake rotor and your work to the plywood. They have enough inertia that momentarily grinding parallel to the circumference won't speed them up dangerously. The axle will catch your disk if it comes loose although spinning particle board weakened by screw holes is a hazard to whatever part of you is in line.

The chuck configuration is plywood or particle board with screws, soldered tabs, clamps, low-strength glue, XC ski wax, whatever you can loosen to remove the work. The traditional woodworking trick is to put a sheet of newspaper in the glue joint. The newspaper splits when you push a chisel into the joint.
Supposedly if you first turn the OD of the disk round you can hold it very securely in a shallow press-fit recess turned in the wood and have the entire face free. The heat from polishing tightens the grip. You can pop it out with a dowel through a small predrilled hole. The Holtzapffel book that came from says the press fit only lasts a day because the wood changes size with humidity overnight.
I flatten large surfaces with an angle grinder, sander and (rarely) buffing pad and check for flatness with a straight edge or the reflection of fluorescent light tubes. The tiny fraction of my work that could be called "art" has a matte finish to avoid the problem. I was looking over my neighbor's custom Harley the other day and noticed that none of the hand-buffed chromed surfaces were really flat, but I had to look hard to see that. It's good to have loud neighbors when you run a chop saw outdoors.

The trouble with using a drill press is that the head and table twist easily on the round column unless you add more fasteners. I chiseled out the flange at the top of the column so the head can move down and added an extra clamp screw. If necessary I could make a tailstock plug that fits the center hole in the baseplate and use the table collar to attach a toolrest. The quill's antirotation key was a setscrew that I replaced with a longer clamp screw with the end filed cylindrical to fit the quill slot and a nail for the tee handle. That was before I had any other machine tools.
A hand drill attached to a heavy plank would work if you could clamp it tight enough, maybe bed it in Bondo. You could use a steady rest instead of a tailstock and cut out to the very end of the gnomon. I've seen a suggestion (Lautard?) for a home-made wooden steady rest that simply had a screw bearing downward and another behind the work. Cutting pressure pushed the work back and up against the screws.
If I had to make a lathe by hand I'd mount four 1" pillow blocks on a heavy wooden beam, two for the headstock and two for the tail. The large drive pulley with a 1" bore came off an old clothes dryer. The first spindle would be keyed shafting and I'd grind and hand-turn a center point on the head and tail spindles. Then I'd use it to turn 3/4" pipe (1.050" OD) down to fit into the pillow blocks for a hollow threaded spindle and attach a wooden face plate with a floor flange.
The chuck would be a 1/2" Jacobs drill chuck on a long 1/2-20 bolt, centered by four setscrews at each end and driven by a cross pin. I have one on my little AA lathe where it fits the spindle thread and a larger Jacobs headstock chuck for the SB in an adapter made from a pipe coupling. They are very handy but not too rigid, so tailstock or steady rest support is necessary.
The riser blocks to increase the lathe's capacity only have to be identical, not any exact height, and the spindles can be aligned with a long shaft through all the bearings. Instead of a carriage on a precise bed it would have an X-Y table that clamps to the beam wherever it's needed, like lathes before Maudslay.
I've collected most of the parts except that the head and tailstocks came off scrapped lathes. It will be assembled only when needed for large-diameter wheels and pulleys.
Jim Wilkins
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