[dlavery]

Originally Posted by sanddrag

Suppose we had $5000 to spend on machining equipment (just suppose). How far could it get us. Let's explore some different options: Combo Machine, Mill and Lathe, Small CNC, CNC retrofit, Etc.

If you had no machining equipment, but you had $5000 to purchase some, what (specifically) would you buy and why? Say you already had some access to any type of machine, but not at any time you wanted. Say you want machines to have at your normal work place that you will be able to access any time.

I've been looking at the Grizzly G3102 milling machine. Is it any good? What other machines are out there.

OK, this is going to take a while... First off, there are already some good discussions on these topics here and here. My comments below are updates of some of this information.

Based on the phrasing of the question, are we correct to assume that you are not asking about what one might consider "traditional" shop equipment such as bandsaw, table saws, drill presses, etc, but are particularly interested in metalworking equipment? Assuming so, we will stick strictly to the latter. With that, the recommended list would be:

1-5. Lathe
6. Mill or beefy mill/drill
7. All the tooling you can afford for the above two items
8. Metal-cutting bandsaw
9. Digital Read Out (DRO) for the above
10. CNC upgrade kit for mill

If there is only one metalworking tool you can afford, you have to start with a lathe. I recognize that this opinion is contrary to the earlier posts, but I am adamant about this one. Starting with this one tool you can, given sufficient time, raw materials, and some basic machining skills, make every other machine tool you will need (in fact, that is how apprentice machinists used to learn - by making their own shop tools, up to and including building new machine tools). There is a great series of books on this by Dave Gingery, if you ever have the time. And with a vertical X-Y table mounted to the cross-slide, you can perform most basic milling operations on the lathe. You will not have an equivalent capability to perform turning operations on the mill (yes, it is possible, but it is not as easy).

Next, look at your budget. One of the fundamental truths associated with buying any machine tool (mill, lathe, shaper, surface grinder, etc.) is that the associated tooling will cost as much - if not more - than the basic tool itself. So if your full budget is $5000, you need to be looking at lathes and mills that are in the $1000-1500 range per machine. So right from the start, you can eliminate anything like a brand new Bridgeport or large free-standing model. You are in the range of a bench top mill/drill, or a bench top mini-mill, or maybe a used floorstanding machine (if you are willing to put in the time to refurbish it properly). Buying your lathe or mill is only the beginning of the investment. Unless you know how (and have the time) to make all your own tooling, plan on spending AT LEAST as much as you spend on the lathe/mill for the additional tooling you will need. For the lathe, things like backplates, 4-jaw chucks, cutting tools, tailstock chucks, free centers, collet sets, tool post fixtures, center indicators, tailstock die holders, cutoff tools, tool post grinders, knurling tools, etc. all add up fast. On the mill clamping kits, cutting heads, mill holders, rotary tables, tilt tables, boring heads, edge/center finders, etc. will also create quite a dent in your wallet.

Many of the lathes and mills sold by Grizzly, Harbor Freight, Enco, MSC, Smithy, and others as "their" brands really all come from the same sources, and they just stick their labels on the machines. Most of the lower-end lathes and mills come from either Taiwan or China. Find out where the machine was made - there is a BIG difference in quality. Many of the Taiwan imports come from Rong Fu, and are good, solid machines (high quality castings, good precision on the ground surfaces, solid pulley/gear covers, etc.). Many of the Chinese import machines tend to be copies of the Rong Fu designs, but with lower quality (blowouts in the castings that have been filled with Bondo, flat grinding on the lathe ways with no oil-retention scraping, cheap sheet metal covers, etc.).

Once you start looking seriously at machines, look for and buy the largest capacity machine you can afford. If you think you only need a milling machine with an 8x24" table, but you can afford one with a 10x36" table, always pay the extra price and get the larger one. Fundamental truth number two is "the largest piece of material you have to machine will always be two inches larger than your machine can handle." A large machine can always work on small parts, but the inverse is not always true. Even if you can't think of anything on your robot that will need a big capacity machine, you never know what you will want to work on during the off-season or next year. The reality is, bigger is better. Get the largest lathe and mill you can afford and fit in your shop. The larger machines will have larger chucks and spindles, hence a larger rotating mass during cutting operations. The larger rotating mass acts as a big flywheel, making for smoother cuts. The larger machines also provide more rigid support for the tool post and tooling, reducing chatter.

Make sure you know (or can find someone who knows) how to set up the machine. It is not as simple as opening up the crate and tossing it on the stand. The lathe has to be mounted on a VERY solid support (think about really big slabs of concrete, or at the very least a really heavy workbench), and preferably bolted to the floor. To get good performance and precision, it must be very accurately leveled in all dimensions. The lathe bed needs to be checked carefully for twist and spindle alignment. The mill table needs to be leveled and the head trammed in. This is a straightforward process if you know what you are doing, but probably not something you want to try alone if you have never seen it done before.

Similarly, you need to worry about maintenance of the machine as well as the set-up. Is the manufacturer still in business and/or is there a distributor network for spare and replacement parts if you need any? Is the tooling interface a standard size, so tooling will be readily available and inexpensive? Will you have access to other people that have used this make/model machine that you can turn to if you need help? Time for fundamental truth number three: "when your made-in-the-USA machine tools breaks, the part needing replacement is the one piece that was manufactured by a defunct company formerly located in Eastern Slobovia in a factory that now produces shower curtain rings. Your custom-made replacement part will cost more than the original price of the whole machine tool." Having access to a bunch of other owners of the model XYZ mill will help you find sources for these replacement parts (one great resource is on-line user groups - check Yahoo.com for "model XYZ mill users" or whatever).

If you have someone on your team that knows what to look for (any retired - or active - machinists on your team?), consider buying a used lathe and mill. If you know what to look for and can avoid getting scammed, you can get some great deals on used machines. I picked up the 12x27" lathe that I have in my shop as a used machine for 20% of the original purchase price, and all the basic-to-moderate tooling came with it. I knew the person that owned it, and knew the entire history of the machine, so it was a good deal. eBay has some nice deals, but be sure it is a machine that you can inspect before final purchase.

If you can, get a lathe with a quick-change gearbox. Most of the larger models have them (typically, anything over a 10-inch swing and/or 30-inch bed will have them). You will save yourself lots of time and frustration associated with dealing with change gears if you get this option (and save a lot of re-training time as student operators change from year-to-year; it is a lot faster to teach someone how to use the gearbox than it is to teach them how to change the gear sets). Same thing for the lathe tool post - get a quick-change version if you can, and one that allows easy adjustment of the tool height. It will make life much easier.

I know I will get some disagreements here, but I recommend you stay away from combination machines (lathe/mills, lathe/mill/drills, etc.). In my experience (and that of a lot of people I have talked with), these machines are designed to do too many things and to cost too little for the careful design they really need. As a result, they don't do anything really well. I have never been happy with the accuracy or precision of any of the combination machines I have used.

Since you specifically mentioned the Grizzly 3102, it is worth suggesting that you also look at the Rong-Fu model JF-45. It is the source machine for the Grizzly 3102, which is basically a copy of the Rong-Fu design. Note that in the U.S. many of the directly imported Rong-Fu machines are re-labeled as "JFC" which is their primary U.S. distributor. It is in the same price range as the Grizzly model. They use R-8 tooling, which is commonly available. There are several on-line groups (such as the Yahoo Mill-Drill group) that are very active and helpful. If you go this route, be sure and look for the Rong-Fu model, which is made in Taiwan. They are good quality machines, apparently made by a company that still gives a crap about quality and tolerances. Problem reports on them are infrequent. There are several makes of Chinese knock-off copies, most of which have real problems ranging from sand-filled castings to skewed table ways to horrible backlash problems on all axes. Avoid them like the plague. Enco, MSC, Grizzly, and Penn Tools all have carried both original Rong-Fu machine tools as well as the cheap clones - if you buy from any of the re-market distributors make sure you know which version you are getting.

There are lots of on-line resources and discussion groups you can use to find out more information and get a lot of help (both before and after you buy). Here are a few resources to check:

7x10minilathe - Yahoo Groups board for owners of the Chinese 7x10 minilathes marketed by Harbor Freight, Grizzly, etc.

9x20Lathe - Yahoo Groups board for owners of the imported 9 x 20 Lathes sold by Jet, Enco, Harbor Freight, and others.

Bench Mill/Drills - Yahoo Groups board for owners of metalworking mill/drills made by Rong Fu and the knock-off clones (but includes a lot of discussion on lathes as well)

Machinists Workshop - check the "general" board for info on lathes and other tools

Metalworking Web Sites - good index of metalworking tools and suppliers, with lots of links to additional information and resources

-dave