Tips on selecting a lathe -will it thread

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Tin Falcon

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you need to look at the details when selecting a lathe but you can not forget the big picture.
What size engines are you planning on building ?
This can be a horse cart situation. I strongly recommend deciding on a goal when starting in this hobby. There are hundreds of plan sets out there. pick one or few you want to build. the size of the parts will determine what size machine is ideal to make the parts.
but do not be dismayed. you want to get started you find a deal on a lathe and you buy it. but you see that that dream model is twice the size that your new lathe will handle. simple solution scale down the model. I have fiend that has a sherline and makes beautiful model half the size of mine. Also if you are fortunate enough to find a bigger machine scale the model up.
this hobby is for fun and learning. machining is adaptive. no book no forum can teach it all. sometime you need to make a work around.

as far as threading same thing read prints. and again adapt if needed. in most cases a 4-40 screw can be used in substitute for a 3-48 .

tin
 

Tin Falcon

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The compound slide is a part of a lathe I neglected to mention and kind of took for granted as being standard part of a lathe. I would say many if not most lathes come with this feature. Everything from the humble seig 7 x whatever up. but many better quality small hobby lathes like the sherline and taig offer this as an option.

My edestaal 5 does not have one but It is now cnc so not as important.

the compound is used for :
short tapers
angle feed when threading
fine feed set the coumpound to ten degrees and .001 in feed on the compound is .0001 cross feed.
Tin
 

ZipSnipe

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Speed is another factor when determining a lathe.

I have a 9x20 and my only complaint is it doesn't have a slower speed than 180 which makes for some standing hair on your neck threading.

Funny thing is I watched a guy on YouTube thread with the 9x20 running at 2000rpm and says he can't do it any other way.
 

Tin Falcon

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As mentioned earlier selecting a lathe can be confusing. and many of the marketing terms can be confusing or meaningless. we can all look at Google definitions and some of those are confusing so how do we sort things out.

Here is my personal view on lathe terms.
Hobby lathe : a lathe marketed for home and hobby use. These lathes may or may not be suitable for model engine building especially some of the older ones. so do your homework use common sense and look before you leap.
the unimat , craftsman 109 , Sherline ,Taig , Seig c2 and c3 are all examples of hobby lathes. In reality just about any lathe can be used for hobby use as long as it fits your budget ,shop space and needs for your style and experience machining.

Engine lathe this definition seems a bit undefined from what I have read. seems to be another term for a machinist screw cutting lathe.

Screw cutting lathe simply a metal cutting lathe designed and built to do single point threading.

Gap bed lathe . a lathe that has a removable piece of lathe bed near the head stock . removing this piece allows for a larger diameter to be turned. .

Tool room lathe. these lathes are normally made to a somewhat higher standard than engine lathes. ie higher precision. they commonly have more tooling like a collet set and a taper attachment. You may need to take lighter cuts than on a engines lathe or other production machine.

turret lathe . a lathe built to make the same part over and over all day. the tail stock has places for multiple tools . pull the lever and a tool cuts push the lever back and it advances to the next tool . typical set up by a machinist but may be operated by a less skilled operator.
turret lathe often also have production cross slides that aid in the machining. These are also lever operated.
the advantage is you can make a part in a few minutes just by pulling the lever or levers. the disadvantage is more tooling and more setup time.
but if you want to or need to make lots of copies of the same part this can be the way to go.

captain lathe: very similar to above.

down river tools sells plans for turret attachments and the tooling for them that can be mounted on various hobb lathes like sherling the seig c2/3 and the seig 9x19.
tin
 

AnvilJack

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I have bought and sold two lathes, and now bought a third. I found that a Chinese manufactured lathe (same maker as my mill) has a product called a CQ6125 that seems to appear in a dozen different places, called something similar (Brand name of a retailer plus the CQ6125), but often with different accessories, tools, etc.

Here is the spec sheet for my unit ($1300):
Lathe

22"x10" (550 x 250MM) QUICK CHANGE GEARBOX METAL LATHE W/STAND
Industrial quality machine, perfect for general machining in tool rooms and workshop, maintenance and production shops, cast iron quick-change gear box makes threading easy, machine ground, hardened iron cast bedways and come with 4 ways tool post, it has long travel automatic power feed, includes stand cabinet

specification: 

-distance between center: 550mm (22") 

-swing over bed: 250mm (10") 

-swing over cross slide: 156mm (6") 

-spindle bore: 26mm (1")

-taper of tailstock: MT3

-tailstock spindle travel: 65mm (2-1/2")

-number of longitudinal feeds: 9 (0.063-0.350mm/rev, 0.0025"-0.013"/rev)

-thread cutting: 38 kinds (metric 0.25-3.5mm & imperial 8-72tpi)

-range of spindle speed: 6 (125rpm-2000rpm) 

-motor: 750w (1HP)/240v/1ph (single phrase)

-max. tool size to use size:10mm x 10mm (3/8"x3/8")

-max. compound size travel: 95mm (3-3/4")

-max. cross size travel: 145mm (5-1/2")

-steady rest capacity: 6.35-50mm (1/4"-2")

-follow rest capacity: 6.35-50mm (1/4"-2")

-length of bed: 1050mm (41-1/4")

-width of bed: 155mm (6")

-height of bed: 200mm (8")

*accessories includes:
stand cabinet,
splash guard,
chip tray,
5" 3-jaws lathe chuck,
6" 4-jaws lathe chuck,
8" face plate,
dead center,
fixed steady,
travel steady,
change gears,
toolbox etc.


*Shipping weight (all up): 298kgs


Now, I've unpacked this new toy, assembled the cabinet/stand unit, bolted the lathe to the stand, and started to prepare it for use.

I've checked the level of the machine with several highly accurate levels placed across and along the ways, and had to shim up the back of the lathe (concrete floor). That seems to be OK now.

But I would never run my mill without bolting it down: this lathe cabinet/stand doesn't have facilities to bolt it to the floor. Is that what you would expect?

I've run the tailstock up to the head stock, centres in each, and the two points meet by eye (and, on the way back the point of the centre in the tailstock seems to be at the tool height (right knife in tool holder).

But, is this last process too imprecise (Yes, but how do you do this check properly?).

What other steps does one do to get the best set up of a new small lathe?

Also, I can comfortably hold 13mm x 13mm (1/2") tools in the tool holder: if I am managing the speed, depth of cut and rate of cut, using cutting oil when necessary, am I really silly to ignore this limit of 10mm tools?
 

gus

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CAPSTAN LATHE
During the last two months of my trade school in 1963 , I was selected to set up a brand new Capstan Lathe and cut hex head screw blanks for the Open House Day.
Gus survived and the Capstan Lathe too and we turned hundreds of hex head screw blanks.
The entire class qued up to cut some blanks with Gus guiding them.
We did not get to try out the quick release threading Die as the instructors felt we could ruin it.
 

radar

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Would the LMS 7x16 lathe work for 3/4" scale live steam engines? I realize some wheels might need a larger lathe.

Also the X2 mill that they sell- for other parts.
 

Blogwitch

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Radar,

As you have already stated the size of the lathe, 7" swing. So I doubt if 3/4" scale would have wheels anywhere near that size, plus the x2 is a very well tried and trusted small mill, and much larger items that you will make have been made on such machines.

If you are contemplating buying new, then I would suggest you spend a week or two setting up the lathe and mill to perfection as they are only assembled at the factory, not set up. If you do that, they should give you a long service with no major problems, except maybe for your own lack of knowledge about using such machinery, that only comes with experience.

John
 

radar

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Radar,

As you have already stated the size of the lathe, 7" swing. So I doubt if 3/4" scale would have wheels anywhere near that size, plus the x2 is a very well tried and trusted small mill, and much larger items that you will make have been made on such machines.

If you are contemplating buying new, then I would suggest you spend a week or two setting up the lathe and mill to perfection as they are only assembled at the factory, not set up. If you do that, they should give you a long service with no major problems, except maybe for your own lack of knowledge about using such machinery, that only comes with experience.

John
John,
Curiously enough the largest I have seen the wheels is around 5 inches.
I was mostly worried about these machines being rigid enough for that kind of work. I had planned on having my mentor help me with any set up and what not- making sure everything is aligned and the like. The dealer (Little Machine Shop) has a great reputation as far as quality and the like is concerned as well. The only other likely thing to happen is a Taiwanese Myford clone my come my way.

-Dean
 

Blogwitch

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R,

Don't worry, those two small machines are about the most popular two in the world, it 'seems' that about 50% of model engineers use one or the other or both, and you only have to look around to see what can be really made with them.

If you do start to get vibrations, it is usually to do with how you are using the machines, and experience will soon have you vibration free. You can't learn everything in a few weeks, and in my opinion, two to three years usually sees a very competent model engineer emerging, and you never cease learning.

Also, both these machines can be modified fairly easily and cheaply with new head bearings fitted, and the list goes on and on to what you can do to them to improve their machining capabilities.
I took a mini lathe back to the basics a few years back as it was unusable because of a banana shaped bed (a very early machine), but when finished with, it was a fantastic, super accurate little machine.
I have recently bought an X2 mill that is destined to become a CNC machine, so I like them as well.

[ame]https://www.youtube.com/watch?v=GnL3ipa7JO8[/ame]


BTW, if you have a little bit of time on your hands, these three links are well worth watching as even though not for a smaller lathe, they do give a good rundown on what it is all about and how to achieve what you want. They also do a set for the milling machine.

[ame]https://www.youtube.com/watch?v=Za0t2Rfjewg[/ame]

[ame]https://www.youtube.com/watch?v=jXET1-g6CJA[/ame]

[ame]https://www.youtube.com/watch?v=3ue8XtStUBA[/ame]


John
 
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Bentwings

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lathes are sizes in terms of swing or the largest diameter one can turn. this is USA definition. The other important measurement is center to center lengths.

As mentioned earlier 7x10,12,14 and 9 x 19 are common hobby sized lathes.
is bigger better. in most cases yes in general you can make small parts on big lathe but not the other way around. but beware. a 1/8 in brass rod requires a speed of 9,000 rpm this may exceed the speed limit of a large chuck. and a large lathe may not run that fast. so there are always trade offs. A good rule of thumb is get a little bigger that what you think you need in swing . as far as cts it is hard to have too much. .
If you choose a larger lathe you may need a couple different sized chucks face plates etc.
Also in general the larger the lthe the more real lathe features it will have and the less hassle changing tooling.

get what you can afford.
what you have room for
what you can move into your space safely.
Tin
Well done!

Ok I’ll add one more thing probably more on mill than lathe but here goes. Digital readouts. Yess the lathe can have then.
How necessary are they and how many decimal points?

I have an on going battle about this. I worked in a shop that had 4 brand new Bridgeport’s with three axis read outs that read 5 places or tenths. I can count on less than one hand the number of times this was of use. The standard .0005 was more than ok. The extra place was of value only on grinding machines. This shop had iOS of the line every thing. We even had a brand new jig grinder. It did all the super close stuff. The guy that generally ran it was pretty creative in what he did. I had used a gig bore but the grinder was something else.
Other shops I worked in had no read outs or .0005. At best. Even that didn’t seem necessary if you had dial indicators and measuring tools. So what is the feeling on this?
 

SmithDoor

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The new same South Bend Lathes they do not put back gears on the lathe.
You can not put the old South Bend tooling on new lathes or even buy tooling like tapper attachment.

I did know they are using plastic gears too.

Dave

One of the factors to consider when purchasing a lathe is what accessories and tooling comes with the lathe. Check everything and assume nothing.
It is hard to define standard tooling.
IMHO a well equipped lathe should have:
3 jaw scroll chuck
4 jaw independent chuck
face plate
Quick change tool holder
machinable center
live center
drill chuck or tail stock chuck

the Basic Seig C2/C3 aka 7xs come with a three jaw and a center and a basic tool post.
a 9 x 19 has a, face plate, steady rest, follow rest, and a woodworkers cheap 4 jaw .

The point here is if a lathe costs say $ 600 and adding the steady ,the follow rest the face plate and a 4 jaw these will likely add up to another $ 200. then add shipping and in the case of Harbor freight add the extended warranty cost. so you are now close to the cost of a similarly equipped 9x19.

The other question is how much do you need or want the steady rest and follow rest. IMHO there is rely no place to put a steady on a 7 x 10 a 7 x 16 maybe.
Other stuff: if you are turning on centers you need a machinable center and a drive dog as well as a drive plate or face plate with slots. You may also need mandrels.

When using a face plate you need clamps a angle plate, and often a counterweight.

You will need cutting bits. IMHO HSS is best for hobby machines
right hand bit for turning LH bit for facing and a parting grooving bit.

Drill bits. Screw machine length will save spce on short lathes but are more expensive than jobbers length at least in sets.

Buy or make a boring bar or bars generally use the largest that will fit.

reamers will help smooth and size bores of cylinders .
laps will refine cylinder bores.

A scissors knurl will save on bearing wear. as apposed to a plunge knurl.

A used lathe can come from stripped to well equipped so when looking at a used lathe take careful inventory.


Tin
 
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