Buying a Lathe/Milling Machine

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MMH
Senior Silent Operator
Posts: 135
Joined: Sun Dec 13, 2009 3:40 pm

Buying a Lathe/Milling Machine

Post by MMH »

I am looking into buying a lathe/milling machine. I do not have personal machining experience but am familiar w/ machining, welding, engineering, etc. I was looking at a Grizzly G9729 Combo Lathe/Mill. One thing that I would like is to get a machine that I could thread my own barrels. I cannot find it in the specs but thought that I read that this machine would be limited to a 3/4" barrel OD. Is this correct?

Do used machines pop up on craigslist & the like if I am patient. Or, since I don't know what I am getting into, would I be better off buying new?
wquiles
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Joined: Mon May 13, 2013 10:51 am

Re: Buying a Lathe/Milling Machine

Post by wquiles »

I started with a Chinese 7x lathe, and later a table top mini mill. I quickly outgrew both, and upgraded the 7x to a beefier 8x lathe. I retrofitted the 8x variable speed, and although better, I also outgrew it quickly. I then bought a new PM 12x36 lathe (basically the Grizzly gunsmith lathe), and could not be happier. Mine has been outfitted with a DRO and a self-centering 6-jaw chuck that makes work easier than the prior, smaller machines.

On the milling machine I got lucky and run into a good local deal on Ebay, and got an almost new Enco 8x30 milling machine. Again, the heavier mill is "much" nicer and stiffer than the table top, with lots of room on the table (vice, indexer, etc.) and lots of Z travel.

I been there myself, when I started machining around 2005 or so. I will tell you the same thing I was told - avoid the combo machines. They are a compromise - never quite as flexible as a larger lathe and milling machine. Yes, more money. I know. But the better path.

Buying used is tricky since you don't know how the machine has been tended for, oiled, cleaned, etc., and if you don't own a lathe, you probably don't know what to look for either. Find a local machinist and have him/her help you with local, used machines, OR, save your money and buy new like I did.

Whatever method/route you pick, ask questions before you try something new, and by all means try and find a mentor. I am very fortunate to have found a mentor near Chicago through a flashlight forum (we have a machining sub-forum to discuss mods/alternations/upgrades/etc.). I have yet to meet him in person, but he has been a trusted friend/advisor/mentor for about 10 years now. He is very knowledgable, does not like shortcuts, and will not tell me what I want to hear - he gives me the right advice. Now only he helped me with machining, but has also become my welding mentor (MIG). He is now doing more and more gunsmithing, so I am always learning something new from him. As I said, I am very fortunate to have found a good mentor.

Good luck, and let us know how it goes.

Will
MMH
Senior Silent Operator
Posts: 135
Joined: Sun Dec 13, 2009 3:40 pm

Re: Buying a Lathe/Milling Machine

Post by MMH »

wquiles wrote:I started with a Chinese 7x lathe, and later a table top mini mill. I quickly outgrew both, and upgraded the 7x to a beefier 8x lathe. I retrofitted the 8x variable speed, and although better, I also outgrew it quickly. I then bought a new PM 12x36 lathe (basically the Grizzly gunsmith lathe), and could not be happier. Mine has been outfitted with a DRO and a self-centering 6-jaw chuck that makes work easier than the prior, smaller machines.

On the milling machine I got lucky and run into a good local deal on Ebay, and got an almost new Enco 8x30 milling machine. Again, the heavier mill is "much" nicer and stiffer than the table top, with lots of room on the table (vice, indexer, etc.) and lots of Z travel.

I been there myself, when I started machining around 2005 or so. I will tell you the same thing I was told - avoid the combo machines. They are a compromise - never quite as flexible as a larger lathe and milling machine. Yes, more money. I know. But the better path.

Buying used is tricky since you don't know how the machine has been tended for, oiled, cleaned, etc., and if you don't own a lathe, you probably don't know what to look for either. Find a local machinist and have him/her help you with local, used machines, OR, save your money and buy new like I did.

Whatever method/route you pick, ask questions before you try something new, and by all means try and find a mentor. I am very fortunate to have found a mentor near Chicago through a flashlight forum (we have a machining sub-forum to discuss mods/alternations/upgrades/etc.). I have yet to meet him in person, but he has been a trusted friend/advisor/mentor for about 10 years now. He is very knowledgable, does not like shortcuts, and will not tell me what I want to hear - he gives me the right advice. Now only he helped me with machining, but has also become my welding mentor (MIG). He is now doing more and more gunsmithing, so I am always learning something new from him. As I said, I am very fortunate to have found a good mentor.

Good luck, and let us know how it goes.

Will
Thanks for the well thought out, common sense response. I figured that this will be a journey. Just trying to figure out how to start.

What about manual vs. CNC? I would guess that I need to learn how to machine manually before going CNC & also do not know how much more CNC would be.
wquiles
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Posts: 18
Joined: Mon May 13, 2013 10:51 am

Re: Buying a Lathe/Milling Machine

Post by wquiles »

Please don't start with a CNC. You really need to understand "feeds and speeds" for Aluminum, Steel, Stainless, Delrin, (eventually Titanium), and the appropriate insert material selection (some inserts will work with some metals, not others), machine & setup rigidity (flex, chatter, etc.), the basic lathe operations (parting, facing, boring, turning, drilling, etc.), etc., before you embark on the awesome world of CNC. You "can" start with CNC right away, but you will be very frustrated as you break tools and inserts initially. A few CNC machines have a sort off "manual mode", and some of these are actually "usable" - but what will not teach you how to machine metal and remove a lot of that "feel" you develop on a manual machine.

By all means get a DRO. That alone has to be one of the most useful items on a lathe or mill.
BinaryAndy
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Location: Lancaster County, PA

Re: Buying a Lathe/Milling Machine

Post by BinaryAndy »

I started on CNC, I'm self-taught, and I have no regrets about any of that. Granted I learned on the job on industrial machines, which may be a bit different from learning at home. There are pros and cons to each starting point.

CNC is going to be really a lot more expensive to get into properly, and it will take a lot more reading and learning before you're making parts. It's also easier to make more expensive mistakes. On the other hand, in the end you'll be able to make better parts faster and easier than you could with a manual machine. In my opinion learning on CNC also forces you to think about what you're doing more, and it won't let you get away with as many bad habits (this could be seen as a pro or a con).

The trick to learning machining properly on a CNC, in my opinion, is to read a lot. Read about general machining and G-code until you can read through a CNC program and figure out what it's doing. Then pick a part to machine, and divide the machining process into individual steps. Then read about each step. Read about what tool to use for that operation in that material, read about how the toolpath should work, read everything the cutting tool manufacturer has ever written about that tool, until you understand what is going on and you are confident that you're using the right tool and your feeds and speeds, stepovers, toolpaths and Gcode are correct for that operation in that material with that tool. Then you can start actually machining. I've probably read the equivalent of at least a hundred books about machining.

If I were to start from scratch today, I would look for a good deal on an old, Japanese-made, industrial CNC lathe weighing at least 10,000 lbs. If you know what you're looking for you can find a good machine of this type for $5k to $10k, but you'll need the space for it, about 100 amps of 3-phase 230-volt power, and an extra $1k to $3k in the budget for shipping and rigging. Then, depending on what the lathe comes with, you'll probably need about $2k to $4k in tooling. So you'll have roughly $10,000 to $20,000 into it by the time you're done.

To go the manual lathe route, I would budget $5,000 for the machine; that buys a pretty good new machine or, if you're patient and a little bit lucky, a really excellent used machine. I would look for a Japanese or Korean machine if buying used; the old American lathes are usually nice and rigid, but it seems like they're all either too small or too slow (as in spindle RPM) for a lot of gunsmithing uses. The space and power requirements are much less than with a big CNC, and shipping and rigging will probably cost less, but I'd still figure $1k for shipping and rigging. You'll still need that $2k to $4k in tooling, putting you in the range of about $6k to $10k, so roughly half what a CNC setup costs.

You can get away with a bit less money in tooling, but I would strongly advise you to avoid any cutting tool or workholding device that is intended for hobby use. If you buy industrial level tooling it will cost three times as much, last ten times as long and work twenty times better than the hobby stuff. There are exceptions of course, but you're going to have a much better time all around if your chucks and cutters don't suck. This especially applies to indexable cutting tools. The sets of little Chinese insert holders with triangular inserts held at various angles are garbage. The inserts are ridiculously fragile, the holders don't clamp the inserts securely at all, and even if they did cut well, three out of the five holders in the kit wouldn't really be useful for anything. With the inserts I use for roughing, one cutting edge can easily last long enough to fill a 55-gal drum with chips while really hauling ass in 4140 steel. Those inserts cost $5 a piece, and there are six cutting edges per insert.
Andy Gamble
Binary Arms
07/02
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