Tips on selecting a lathe -will it thread

[gus]

While threading capability is great to have, on a practical basis on many hobby lathes it is difficult to practice. I have a mini & a 10 inch (5 inch center height) lathes. Both have threading capability (lead-screw, change gears, etc); however, their minimum speed (for the mini: add with adequate torque) is much too high to be able to thread. There is a reason that a Myford (and many others) has a back-gear to achieve speeds that are slow enough that everything is not happening quicker than I, at least, can think - let alone react.

For the mini there are a number of plans out there to add a spindle crank to turn the lathe manually. For the larger lathe I am toying with the idea of adding a jack-shaft to the motor drive to reduce the speed. In the meantime, I have been using taps/dies.

Hi Dunc,
For now,I make do with a 150mm Swing and 360mm between centres Japanese Watch-maker's Mini Lathe. I use taps with tapping head and Die Heads. For my mini model engine builds the above will do. I use machine taps which cost 2---3 times than hand taps. Tap and die threading with Tapmatic Oil produced very good threads.
Going for a bigger lathe and mill is out of question due to very limited space in the balcony. Presently with just a mini lathe,mini Vertical Mill,13mm cheapy China Drill press and Bosch 8" Grinder makes complete requirement.
Work Bench with 4" Record bench makes the hacksaw/fitting dept complete.
Still trying to fit in a small band saw and it will be Taiwanese for long life.
After so many sessions manual hacksawing 1 1/2" bars,I find manual sawing
quite fun and gives good excercise.

 

[jixxerbill]

What are the advantages/disadvantages of a geared head and a belt driven ? My local supplier has a 13x40 jet with a stand for $4,400, but its a belt drive..thanks..Bill

 

[Tin Falcon]

Another tip I will mention here is Download the manual for any lathe you are seriously considering for purchase. It will tell you a lot about the lathe before you have the chance to look at a floor model .
I assume you are talking about this one.

BDB-1340A Belt Drive Lathe
http://www.misgroupinc.com/partfiles/M-321360A.pdf

Page 15 of the above manual explaines how speeds are changed and has a photo of the belts in the head stock.

A geared head lathe will give faster spindle speed changes.
you want to change speeds turn off the lathe and flip a lever or two and restart the lathe.

A belt driven lathe you need to turn off lathe open the head cover. release belt tension move the belt . apply belt tension close cover then start lathe.

As far as advantages belts usually run smoother than gears. belts are easy to find and cheaper to replace.

Also keep in mind most gear head lathes still have a belt going from the motor to the gear head.
Tin

 

[Tin Falcon]

In the home shop of a newby or in a school lab it is a good idea to have some weak link on a lathe to protect the machine and to some extent the operator from a crash.
on my south bend the belt slips if I get too greedy . the mini mill and lathe have a sacrificial nylon gear that breaks. on bigger lathes the pin that connects the lead screw and the drive shaft if it has one should have a brass taper pin installed . if a crash occurres the pin shears and protects the gears in the lathe head. so when you get a new lathe find out what safeties are built in . and add them if needed. A couple hours of preperation and modification can save big down the road. A $1 pin is a lot cheaper than replacing a couple of gears.
Tin

 

[gus]

Another tip I will mention here is Download the manual for any lathe you are seriously considering for purchase. It will tell you a lot about the lathe before you have the chance to look at a floor model .
I assume you are talking about this one.

BDB-1340A Belt Drive Lathe
http://www.misgroupinc.com/partfiles/M-321360A.pdf

Page 15 of the above manual explaines how speeds are changed and has a photo of the belts in the head stock.

A geared head lathe will give faster spindle speed changes.
you want to change speeds turn off the lathe and flip a lever or two and restart the lathe.

A belt driven lathe you need to turn off lathe open the head cover. release belt tension move the belt . apply belt tension close cover then start lathe.

As far as advantages belts usually run smoother than gears. belts are easy to find and cheaper to replace.

Also keep in mind most gear head lathes still have a belt going from the motor to the gear head.
Tin

Hi Tin Falcon,
If Sakai ,Japan makes a gear lever shift mini lathe,I'll buy it. Right now with the belt drive,it is a pain in side to change speed. So I left it at 600 rpm.Now sort getting used to it.
With no electronics to worry about,I have peace of mind.

 

[ConductorX]

I have a question about threading abilities:

Two lathes: one listed as Variable Speed - the other as Gearbox

This is the specs listed:

Black is the variable speed and the red is the gear box lathe. From these numbers I take it the Variable speed (black text) is a better lathe for cutting threads. Is the difference highly significant based on the chores we would encounter to create model engines? Or would either lathe suffice?

· Leadscrew: 3/4"–12 TPI
· Lead screw: 3/4" x 8 TPI
· Number of longitudinal feeds 9
· Number of longitudinal feeds: 12
· Range of longitudinal feeds: 0.0023–0.013 IPR
· Range of longitudinal feeds: 0.0022–0.0150 IPR
· Number of inch threads 33
· Number of inch threads: 24
· Range of inch threads: 8–72 TPI
· Range of inch threads: 8–56 TPI
· Number of metric threads 26
· Number of metric threads: 10
· Range of metric threads: 0.25–3.5mm
· Range of metric threads: 0.5–3.0mm

 

[Tin Falcon]

Those numbers you give are but one consideration. What is better a green lathe or a red. HMM
what size are the lathes how do you change the threading gears. ....
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 ?
do you need to do a 72 pitch imperial thread or a .25mm metric or will a the 56/.5 do .
there are many factors and trade offs to consider and ultimately you need to decide what is best for you. Yes we can help.
Tin

 

[dman]

I have a question about threading abilities:

Two lathes: one listed as Variable Speed - the other as Gearbox

This is the specs listed:

Black is the variable speed and the red is the gear box lathe. From these numbers I take it the Variable speed (black text) is a better lathe for cutting threads. Is the difference highly significant based on the chores we would encounter to create model engines? Or would either lathe suffice?

· Leadscrew: 3/4"–12 TPI
· Lead screw: 3/4" x 8 TPI
· Number of longitudinal feeds 9
· Number of longitudinal feeds: 12
· Range of longitudinal feeds: 0.0023–0.013 IPR
· Range of longitudinal feeds: 0.0022–0.0150 IPR
· Number of inch threads 33
· Number of inch threads: 24
· Range of inch threads: 8–72 TPI
· Range of inch threads: 8–56 TPI
· Number of metric threads 26
· Number of metric threads: 10
· Range of metric threads: 0.25–3.5mm
· Range of metric threads: 0.5–3.0mm

they both sound fine. I can't remember any time I needed a 72tpi thread or a .25mm or a 3.5mm I've done as coarse as 3mm and some odd ball ones like .8mm. I can't think of an application for 72tpi. even radio control models mostly go to 40tpi for small stuff. 56 for the smallest. 72 may be for watch hardware. but why would you want to single point that small?

an 8tpi lead screw is easier to read the wheel than 12. but if he lathe with 12 tpi has a gearbox that can reverse direction with the spindle turning like on a hardinge toolroom lathe and index back to the same spindle angle it will be easier. really more information is needed but it sounds like both will do a fine job but if you need a .8mm pitch I'm not sure the second lathe will have that option.

 

[ConductorX]

Both are Grizzlys - 9x19 and the 10x22

They are both the same price but the second one is heavier (shipping weight). I am leaning to the 10x22 gear drive simply because the VW brake drum is a bit over 9" diameter. I downloaded the manuals for both and plan to do some reading and study.

Needless to say the lathe won't be exclusive to building model engines.

Thanks Tin and dman.
"G"

 

[Tin Falcon]

You will probably will be better off with the 10 x 22 you can not have too much x and z . it has a beefier frame a more modern design to the gear box . a real american style 4 jaw chuck. a 1 hp motor vs the 3/4 of the 9x.
a few folks have the 10 x 22 and it seems to be well liked.

both lathes are belt drive.Open the door on the end of the head stock and change the belt locations to change the spindle speeds. there is a variable speed version of the 10 x but it is %50 more. the 9X is used by a lot of HSM guys as well . the 4 jaw European style 4 jaw is not well liked.
so if is the same money IMHO the 10 x 22 is the more favorable choice.
Tin

 

[Tin Falcon]

A lathe accessory that gets lots of discussion is the quick change tool holder.
Likely the most popular is the aloris wedge style . there are many companies making these in various quality points and price points. Aloris brand while being the standard for quality is a bit pricey for the hobbyist. the piston style works but I have heard of complaints with them.
IMHO a QCTP is a must have and almost always used accessory for the lathe. they save lots of time and hassle in comparison to other toll holders. there are better QC tool holders but again pricey.
Tin

 

[ConductorX]

I have a question that more than likely everyone already knows. What the fuzzy is a Turret Lathe and how does it differ from the run of the mill everyday lathe. I found a place here in Louisiana that has a variety of old machine tools for sale. Craigslist seems to have still more.

Among them:
Southbend Precision Lathe 12" x 42" with taper attachment, collet draw bar and 3 jaw chuck. Cat No: CL8145C

LOGAN TURRET LATHE - Logan Engineering Co. Turret Lathe, model 825. Q C Gear box, 24" center distance, 43" bed length, 1 1/2 - 8 x #3 MT Spindle nose, 25/32 Spindle bore, Std. Tailstock, flat bed, cabinet, 830 Lbs. Screw turret gears.

The wildest looking thing (and cheapest) was the Rivett Model 112 Lathe. No information, but it looks like a drill press laying on it's back.

I appreciate your time and patience.
"G"

 

[Tin Falcon]

A turret or capstan lathe has a tail stock that holds multiple tools and rotates . it uses special tooling . it is typically set up for production or multiple part work. the beauty is once set up you can make the same part over and over all day with the pull of a couple of levers . you can make screws bolts hat bushings etc.

rivet lathes are real nice machines.
as are south bends . but remeber with old machines CONDITION unless you are planning on a rebuild, but then you still need good bones.
Tin

 

[Hopefuldave]

Just a pic for a "Stirnseitenmitnehmer". Anyone in the forum who knows the english word for this?

http://www.google.de/imgres?imgurl=...pUOG4JcOzhAe_8YCwBw&ved=0CEQQ9QEwBQ&dur=10782

I've always known it as a 'drive centre', never used on in metalworking but they're common in woodturning.

Dave H. (the other one)

 

[Hopefuldave]

One topic that hasn't been touched on so far, metric vs inch leadscrew: pick the threading system you're likely to cut most, as thread indicator dials only work in their native units! An inch leadscrew will (unless you have a single-tooth clutch leadscrew reverse - see the thread "screwcutting simplified") mean metric threads have to be cut by stopping and reversing after each pass with the half-nuts engaged, or vices versa. Not too bad once you get used to it but a hassle on long threads.

Dave H. (the other one)

 

[Tin Falcon]

Good point dave . I did touch on this in the first post.

Metric vs imperial most lathes I have seen are either designed to measure and function and are built either to be a metric machine or a imperial machine. the difference is the lead and feed screws are made to either metric or imperial standards. so if one has an imperial standard machine and wants to thread you need a transposition gear of 127 teeth or in the case of the 7 x mini lathes a 21 tooth gear. and this gives a close approximation.

So the lesson here if wanting to do serious threading get a lathe built for what you work with or are comfortable with. some machines are built metric and only approximate us decimal inches. The newer imports have corrected this and use inch based screws.

I know a LOT to read through.
Tin

 

[Tin Falcon]

One basic lathe operation and accessory I neglected to mention earlier is tapers and a taper attachment.
there are three ways to cut a taper on a lathe.
1) using the compound.
2) tail stock offset.
3) taper attachment.
And with modern cnc there is a fourth just program in a taper.

there are plans out there to make taper attachments even for the 7 x10 lathes.

adjustable ofset centers can also be made to ease with the tail stock offset method . IIRC plans in appendix of the elmers engines book.

More late
Tin

 

[Tin Falcon]

another accessory sometimes asked about and used is the tool-post grinder. as the name implies it is mounted to the tool post of a lathe . actualy it temporarily replaces the regular tool post. and instead of removing metal by cutting with a lathe tool the metal is removed by a spinning grinding wheel.

Like any other lathe accessory these com in various sizes price points etc. Entry level import grinders are about $150 for the single speed model and a little more variable speed.

Grinding is just another method of metal removal.
it is mostly considered a finish operation in other words machine in this case turn a part to a few thousands oversize then finish with a grinder.
so why grind?
grinding allows you to work hard materials , like cutting tools hardened centers. hardened crankshafts.etc...


grinding allows for a better finish. a better finish is desired for things like shafts and lathe centers . a smooth finish does not wear as much against a bearing.

grinding takes small bites so careful control will allow for tighter tolerances.

typical lathe tolerances are in thousands of an inch grinding tolerances in ten thousands of an inch. just make sure your mics read in tenths. hope this helps.
tin
__________________

 

[Hopefuldave]

RE toolpost grinding on the lathe, a little tip:

If the grinder can be mounted on the topslide (compound slide in the USA), swivel the slide around until it's almost parallel to the lathe spindle axis - if the angle between axis and topslide is 5.74 degrees (as accurately as you can set it, 5.75 is close enough ) there is a 10:1 ratio between the topslide movement and diameter, so advancing the topslide 0.001" will take off 0.0001", allowing you a bit more control over grinding depth. Grinding cuts should be of the order of "tenths", not thou", it's a finishing process, not a roughing process

Another tip: *cover the ways!* The grinding dust is incredibly destructive to machines, being a mix of fine metal dust and abrasive particles - I've used oily cloth (with a fire extinguisher handy) and a "hood" in line with the sparks, attached to my workshop vacuum, to try to keep the dust under control. I still need to go over the lathe afterwards in minute detail with a soft brush and vacuum though! Look at the hoods fitted to surface grinders for a few hints.

Yet another tip - it's good practice (and very much safer) for the work and grinding wheel to meet "head on", it prevents the wheel hogging into the work - and gives a better finish.

If the wheel and work are moving in the same direction and there's the slightest slack in the setup, the wheel and part will try to close up, possibly bursting the wheel; head-on they force themselves apart removing the load: a burst wheel is a bit like a grenade, but harder to remove the shrapnel, being non-magnetic`.

If your lathe doesn't run in reverse, the wheel wants to be running *anti-clockwise* for external grinding, *clockwise* for internal, both viewed from the tailstock. If it runs in reverse, grinder clockwise for both internal and external, and reverse the spindle for external grinding only, normal forward rotation for internal grinding. If concerned about a screw-on chuck loosening, don't be - the loads in grinding are much, much lower than cutting loads! Belt and braces would be a drawbar through the lathe spindle, pulling on a "spider" against the chuck face, but not likely to be necessary, I'd think.

Just my ha'pennorth,
Dave H. (the other one)

 

[Wizard69]

Those numbers you give are but one consideration. What is better a green lathe or a red. HMM
what size are the lathes how do you change the threading gears. ....
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 ?

I see this as critical, if the lathe isn't sized right for the jobs you expect to do you will end up frustrated. People often buy too small and end up upgrading. On the flip side some lathes end up being bigger than they should be.

do you need to do a 72 pitch imperial thread or a .25mm metric or will a the 56/.5 do .
there are many factors and trade offs to consider and ultimately you need to decide what is best for you. Yes we can help.
Tin

This highlights one problem for beginners, that is not knowing what they need. One thing to consider is that some lathes are easier to adapt for odd pitches than others. Given a little ingenuity and maybe a few more gears almost any pitch can be achieve. Well within the mechanical ability of the lathe to support that odd pitch.