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Jim H
10-07-2014, 10:56 PM
Thanks to all of you for the advise and reasons to consider one over the other. I live in Marysville, Pa. work on Band instruments and restore full scale vintage aircraft. I have found myself from time to time looking for obsolete parts for both brass, woodwinds and planes, I'm thinking with some effort and maybe a local vo-tec course I might be able to make some of the parts that are not readily available. I understand I might not be able to charge for all my labor to make the parts as I will be slow, probably will make two or three to get one correct and thats okay, it is the finished result that matters to me. I was intrigued by the variable speed on the fly as I can see cutting and ramping up the speed to finish of with some finish paper. However the larger lathes don't seem to come with that option more of an add on so why is the smaller lathe offered with it? I don't want to go over the top on this but I don't what to regret the decision a year from now. What about resale of these two lathes? While we are on resale would the 4002 or 4003 (36") have a better resale, is longer worth more? It is $200.00 more than the 24" however I don't see me needing 36" center.
Thanks in advance.
Confused--Jim

flylo
10-07-2014, 11:20 PM
I'm not familiar with those lathes but for $200 I'd buy the 36". You can do more & it will be worth more IMHO.
BTW whey what kinds of aircraft? I just sold a fully restored 1938 Taylorcraft & still have a 1st year 1947 Beechcraft Bonanza V tail that was in the factory when the one Buddy Holly died in was built, a like new 1982 Advanced Aviation Cobra, A new early '80s Rotec Sport & a Pallidan powered parachute. From 30 mph cruise thru 175 mph cruise I got it covered,LOL!

Toolguy
10-07-2014, 11:22 PM
For myself, I won't go less than a 12 x 36. Experience has shown that sometimes I need that extra foot of bed. For working on aircraft, I would go with the 12 x 36. Right now I have a 14 x 40 and it's about right for most of my stuff. You may not use the end of the bed much, but when you need it you really need it. For example, sometimes you need to work on the end of something that won't fit through the spindle in the steady rest. Then the carriage in on the right end of the lathe.

Jim H
10-08-2014, 07:40 AM
I'm not familiar with those lathes but for $200 I'd buy the 36". You can do more & it will be worth more IMHO.
BTW whey what kinds of aircraft? I just sold a fully restored 1938 Taylorcraft & still have a 1st year 1947 Beechcraft Bonanza V tail that was in the factory when the one Buddy Holly died in was built, a like new 1982 Advanced Aviation Cobra, A new early '80s Rotec Sport & a Pallidan powered parachute. From 30 mph cruise thru 175 mph cruise I got it covered,LOL!

I Am just finishing an 1947 L-16A Aeronca Liaison plane. This has been a 12 year project, in between I have built a Challenger single place, helped a buddy with a two place, rebuilt a 3/4 scale P51 Mustang, Built a Rans S-7 (this is my favorite plane to date --stall 32mph cruse 112mph rotax 912 100hp.) I have a Kitfox SS7 in my shop waiting to be started once the L16 is finished. I was hoping to use a much smaller lathe but it seems for resale I might consider the 36" Being that I have little time with a lathe and not really knowing what I am doing makes this purchase a bit confusing for me. What is the advantage of variable speed.
Thanks
Jim

flylo
10-08-2014, 08:30 AM
I have a Tcraft amfib project ready to cover with a fresh Lyc O-320 B2B 160hp, most of the Cole & Swick mods, a set of long wings with twin 40 gal wing tanks, a 27 gal baggage comp tank, a set of clip wing with no tanks, hyd disc heel brakes, & it's in the homebuilt exp class called a Taylorcoupe. A Super Cub or Husky slayer. Everything is new & done except putting the wings together, making a boot cowl, finishing the wings & covering it. But I broke my back & can't get in a Tcraft anymore. Lathes are like planes you can't just have one as you'll see. Be careful or your hanger will have a narrow path down the center & machines all around. I've seen that happen to people:rolleyes:

michigan doug
10-08-2014, 08:39 AM
One way of looking at it:

On a cheap import lathe, the continuously variable speed (by electrical means) is a cheap way to avoid putting in a real transmission with enough gears. If done poorly, the low speeds will have poor torque. These are typically cheap pulse width modulators.


The good (more expensive) electrical method of speed control is a VFD (Variable Frequency Drive) and most do a pretty good job of preserving torque at lower rpms, but don't entirely remove the need for an honest transmission.


A transmission with enough gears is the gold standard to provide lots of torque at low speeds.

Seastar
10-08-2014, 10:49 AM
Buy the 36 inch. I had a 24 inch and it took me about a month to find out I needed more.
By the way I fly an experimental CarbonCub and a CitationJet.
The Cub is the most fun I have ever had in an airplane. The Citation is for going places far away.
I don't rebuild airplanes but I have owned a lot of them. I rebuild cars and build guns and knives.
You will find a need for the larger lathe.
Bill

danlb
10-08-2014, 11:31 AM
The resale is hit and miss. It seems that a benchtop lathe (10x20 or less) will fit in most garages and run on 110v. You start getting into the 30 inch and you need a sturdy stand or bench as well as 220 power. As you increase the swing and the length, the mass goes up greatly. The g4002 is TWICE the weight of the G0752. That's a much stiffer machine. The 4003 is a longer bed but weighs almost the same as the 4002. Something uses thinner metal.

The reason that the resale price varies so much is that the price is determined by demand. More amateurs will buy a smaller lathe intsead of a bigger one and they will pay prices based on guesswork. Most pros will not buy used unless the price is real low.


I'd go with the 4003, but mainly because you will be doing longer parts on an airplane.

Dan

DR
10-08-2014, 01:23 PM
How is the market for used lathes in your area?

Have you looked for a used lathe?

$2850, shipped, for a Grizzly seems like a lot of money. At a recent west coast auction there were four 13" Colchester's all going for less than $3K. I would have taken any one of them over the Grizzly.

tmarks11
10-08-2014, 04:39 PM
I was intrigued by the variable speed on the fly as I can see cutting and ramping up the speed to finish of with some finish paper.
No different on the 12x24 or 12x36 lathe. They are 8 speed, and you shift to a higher speed for finishing. The ability to get 1723 rpm (variable speed) vs. "settling" for either 1400 or 2000 rpm (gear head lathe) is of little value. If you really, really, really need to adjust speeds, you can outfit your lathe with a three phase motor and a VFD, and get variable speed capability.

BTW, the G0752 achieves its speed range both with a variable speed motor, and by swapping a belt between two pulleys, so it quite a bit less convenient than a gear head lathe which just requires shifting gears.

http://i32.photobucket.com/albums/d50/tmarks11/ScreenShot2014-10-08at14947PM_zps353ca1a1.png

What you really need in a lathe is low speed capability. 150 rpm is NOT low-speed, as you will discover the first time you try to thread into a shoulder. Most of the small machines don't get slow enough. The 12x larches generally have a low speed of 70 rpm, which is good. The G0752 is 100 rpm, which is still kind of quick.

Btw, you can buy 12x and above variable speed lathes... usually adds $1000 to the purchase price, and I have only seen this offered on $8k+ machines.


What about resale of these two lathes? While we are on resale would the 4002 or 4003 (36") have a better resale, is longer worth more?
It is easier to sell a smaller lathe than a big one, as it is easier to move and requires less garage space, so more people will consider buying it.

One real consideration is that most of smaller asian lathes (<12") have laughable quick change gear boxes. You well have to manually swap out change gears any time you want to switch feeds or change threading... or switch from feeding to threading.

The larger lathes have a cam lock chuck, which is much easier to mount and dismount, and more widely available.

You mentioned taking classes at the local vo-tech. I strongly recommend that... before you get a lathe. While you are taking the classes, you get free access to mills and lathes, and usually can work on whatever project you want to, and get instructor help. You will learn if you like it, without saddling yourself with a big chunk of iron that maybe will get you 70% return when you sell it.

Plus, you will learn what you actually want in a machine, and will gain the knowledge needed when you shop for machinery. Being in PA, the used market should have a lot of used lathes available... you just need to avoid the ones with the glitzy paint jobs....

PStechPaul
10-08-2014, 04:58 PM
You should also plan to attend the Cabin Fever expo, held in York, PA, sometime in April. They will have some machines for sale or in auction, and lots of assorted tooling ranging from new to rusty junk.


https://www.youtube.com/watch?v=l79VJSQwDFU

Meanwhile check Craigslist and eBay for possible bargains within driving distance. I have a Harbor Freight 9x20 lathe which has given good service over the 10 years I've had it, although I've only been using it regularly for less than a year. I think I paid something like $600-$800 in 2004 and I've spent much more than that for tooling.

If you have a vo-tech school nearby that offers classes in machining, you are very fortunate. Many such courses have been discontinued and the machines possibly scrapped or practically given away. I'm attending classes at CCBCMD.

tlfamm
10-08-2014, 05:28 PM
@tmarks :

"Btw, you can buy 12x and above variable speed lathes... usually adds $1000 to the purchase price, and I have only seen this offered on $8k+ machines."

Precision Matthews has a two-speed geared head +VFD variable speed for $5695. (Not quite "full" variable speed.)

http://machinetoolonline.com/PM1440B.html

tmarks11
10-09-2014, 08:50 AM
@tmarks :

"Btw, you can buy 12x and above variable speed lathes... usually adds $1000 to the purchase price, and I have only seen this offered on $8k+ machines."

Precision Matthews has a two-speed geared head +VFD variable speed for $5695. (Not quite "full" variable speed.)

http://machinetoolonline.com/PM1440B.html
Good call, I forgot that Matt had that as an option on his chinese machines (I actually was thinking about his PM1440TS at $8k and PM1440-TV for $100 more when I mentioned the $8k above).

Two speed plus VFD is the best way to do it, IMHO. I haven't seen any reputable offerings which achieve the full range of speed just from the VFD.

Expecting a VFD to operate across the full range of speeds either sacrifices low end torque or limits your upper end. The $600 upgrade that Matt charges on the PM1440B to get variable drive is a pretty good deal (maybe not compared to what it costs to diy, but compared to what most vendors charge).


If you really, really, really need to adjust speeds, you can outfit your lathe with a three phase motor and a VFD, and get variable speed capability.
Hmm, I sounded a bit more negative there than I intended. Especially since such a conversion is on my list (not really for infinitely fine speed adjustment, but to get a smoother running motor).