Lathe size

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Gra2472
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Location: Monte Rio California

Lathe size

Post by Gra2472 »

I am sure that this is not the ideal place for this question, but perhaps you guys can help. I am looking at buying a lathe in the near future and I am having trouble determining the size I need. I am looking at a Grizzly G9972z which is an 11x26 bench lathe. I do not have any specific projects in mind yet, but I am wondering about the lathes’ actual capacity. I know that it can handle something 11” in diameter over the bed, but what is the actual machining envelope? Can I actually machine something that size or will the cross slide or tool holder only reach 9” or 10” diameter? Its tough being a novice.

Thanks in advance.

G

P.S, I chose this machine because it is the largest I can afford, and I can get a cnc conversion kit for it.
7.5" Allen Mogul
3 x 7.5" West Valley Baldwin Westinghouse Electrics
The railroad is almost done.
G. Augustus
Monte Rio, Ca.
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Bill Shields
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Re: Lathe size

Post by Bill Shields »

Consider not the cost of the lathe but the tooling necessary to do work

A rule of thumb that I have used with lathes for the last 40 years is that the $ of the lathe is about the $ of the tooling.

Chucks, tool post, cutting tools, etc add up quickly.
Too many things going on to bother listing them.
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Fender
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Re: Lathe size

Post by Fender »

On most bench lathes, when turning something close to the maximum diameter such as a flywheel, it is difficult to do any work on the periphery. Sometimes you can reach it by turning the compound around and using a boring tool, but this setup is inherently less rigid than having the tool in line with the toolpost, so lighter cuts are required. Two other factors are the spindle speeds and horsepower available. With larger diameters one generally wants to use slower speeds, unless using carbide tooling. But the slowest spindle speed may too fast for high speed steel. If using carbide at higher speeds require more power. Also the rigidity of most bench lathes limits how heavy a cut can be taken.
However, since most amateurs are not concerned with “productivity”, a lot can be done by “pushing the envelope” and taking the job slowly.
Dan Watson
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rmac
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Re: Lathe size

Post by rmac »

On Grizzly's website, If you look under the "Documents" tab on the page for that lathe, you'll find a link to a detailed spec sheet. Among other things, it gives this info:
Swing Over Bed................................................. 10-1/2 in.
Distance Between Centers........................................... 26 in.
Swing Over Cross Slide.......................................... 6-3/8 in.
Swing Over Saddle............................................... 6-3/8 in.
According to this, that 11" swing over the bed is really 10-1/2". And as you probably know already, the swing over the cross slide is much less at 6-3/8".

The other thing to think about is the distance between centers. Say you want to drill an axial hole in something. After you've put a chuck on the headstock and a drill chuck and bit in the tailstock, you may have only 16" or so left over for the actual part.

-- Russell Mac
FLtenwheeler
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Re: Lathe size

Post by FLtenwheeler »

I build an Allen 10-wheeler on a Jet 10x24 lathe. I now have a Rockwell 14x30 and I gave the Jet to my Son.

Tim
He who dies with the most unfinished projects: Should of put more time into their hobby.
Gra2472
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Re: Lathe size

Post by Gra2472 »

HI guys.

Thanks for the info for sure. Yeah I read the specs but I am glad to get some real world info too. I kind of figured that tooling is very expensive, as much as the lathe itself, but I can’t afford the 12-14’ range lathes that run about 10x what I want to spend. I figured a total budget of about $8500 to get the lathe up and running with tooling and such. Horsepower is something that I am not sure how to quantify on a lathe. Is a 1hp machine a weakling?

I kind of figured machining at the edge of the capacity of the lathe would be a problem. Just to get a better idea, if I wanted to turn something huge, like an RMI sweet creek driver which is 10” in diameter, I would need a 14-16” lathe? I’m probably not going to build anything that big. Its just academic.
7.5" Allen Mogul
3 x 7.5" West Valley Baldwin Westinghouse Electrics
The railroad is almost done.
G. Augustus
Monte Rio, Ca.
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LVRR2095
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Re: Lathe size

Post by LVRR2095 »

I don’t know about California, but here in the Northeast $8,500 will buy you a darn nice used American made substantial lathe. Something along the line of a LeBlond Regal or a nice 13” South Bend and probably reasonably well tooled.

Keith
Gra2472
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Re: Lathe size

Post by Gra2472 »

Hmm, I’ll have to look into that. But I am specifically interested in a lathe that I can convert to cnc relatively easily and stay in budget.
7.5" Allen Mogul
3 x 7.5" West Valley Baldwin Westinghouse Electrics
The railroad is almost done.
G. Augustus
Monte Rio, Ca.
Berkman
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Re: Lathe size

Post by Berkman »

Most manual lathes do not make good CNC conversion candidates. You'll still want the ability to do true manual work. 13-14 inch would make a good size for live steam work.


https://tormach.com/machines/lathes/8l-lathe.html
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Dick_Morris
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Re: Lathe size

Post by Dick_Morris »

Over a 50 year period I've had a 6" 1960s Craftsman, 10" Southbend, 12 Atlas, and 12" Select/Dashin Prince from Taiwan.

The 6" Craftsman was too small for 1-1/2" scale. Lack of a quick change gear box was a handicap. It was the only one I bought new. One major advantage was that I was in the AF when I had it and it was light enough to move from Alaska to Illinois to Texas to England to Texas to Alaska over a 15 year period.

I didn't have the Southbend very long. It was well worn but otherwise wasn't a bad lathe. a taper attachment was a nice feature but I never had a chance to use it. It had a quick change. I got the Craftsman because it was bigger and less worn.

The Craftsman had a good range of speeds, starting with a low in the 40s and a quick change. It also had a long bed (40"?). It's problem was that it wasn't really rigid enough to turn wheels easily.

The 12" select has met my needs for several years. It's plenty rigid. Although the lowest speed was around 80, that was easily decreased by fitting a 3-phase motor and VFD. I like the gear head over the belt drive in the other lathes, but it's only a nice-to-have. The bed is only 30", but the only time I've needed more was for a boiler tube that I trued up when I had the Atlas. The D-3(?) chuck mounting was an advantage over the screwed chuck mounts on the other lathes. I also like that the hole through the spindle is larger and with an adapter and drawbar/closer, it allows use with 5C collets. I've found I use collets and a collet closer about as often as I do a chuck. It can be a bit of an expense, but it nice to be able to make that upgrade in the future. I found a used closer to replace the tube type collet closer. It was well worth the expense.

If buying new and I planed to keep it a while I would insist on a 3-phase motor so I could fit a VFD. It adds considerable to the flexibility and allows a low speed when turning parts like drivers. Staying within the variation of speed offered by the VFD I only infrequently find a need to change speeds at the lathe.

One thought on tooling - my first three lathes came new from the manufacture without motor, chucks, or steady rest. The current run of Asian lathes come equipped with all of those. With the exception of a VFD, possibly a DRO, and a good tool post set up, the need for additional tooling is mostly generic items like cutters.

I can't speak to CNC.
Last edited by Dick_Morris on Sun Apr 17, 2022 1:11 am, edited 1 time in total.
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Bill Shields
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Re: Lathe size

Post by Bill Shields »

Do not think for a minute that you can lower the speed with a VFD to turn large diameter work without change gears.

Unless you know something that all the mechanical engineers in the world have not figured out
Too many things going on to bother listing them.
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gwrdriver
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Re: Lathe size

Post by gwrdriver »

The arrangement which has worked well for me is a high quality 10"-11" lathe . . . and a friend with a 14". :D
GWRdriver
Nashville TN
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