Friday, September 19, 2014

Milling Around

A couple of months ago, when I posted about my new shop, I said I'd keep everyone up to date as tool selection proceeded.  I think I've converged a little, so let me start with the mill.

In a broad sense, mills can be classified by size.  The smallest classes are usually rather precise and are used for things like cutting small parts, model making and carving wax for jewelry casting. 
The model numbers across the top, X1 across to RF45, are common machine models.  The X1 to X3 are made by Sieg, the Shanghai Industrial Company, while the RF45 is from Rong Fu, a Taiwanese company said to make a higher quality machine.  Note the weights in pounds along the bottom.  The micro mills (like I have) are very easy to live with.  You can lift them to vacuum under, if you want.  An X2 class machine, at around 200 pounds is something you don't want to move very often, while the X3, RF45 and larger machines are something you want to move once, with serious planning.  Maybe build your house around them.  As an anonymous commenter said in that linked previous post:
A 700 pound mill not on wheels cannot be moved with body English. If you put it on wheels on a sloping concrete driveway you want a pulley to pull it up the slope. You can keep it from tipping over with your hand, but if it starts to go you can't even slow it down, jump away or have your safety buddy call for the jaws of life.
As Make Zine said, Sieg machines like X2s are one manufacturer with many brands. Not only that, the same machine is tweaked by some of the American sellers for different features: changing the table size is very common.  As always it's a bit more complicated.  There are other lines of machines, like Grizzly G0704 which is a little bigger and little more powerful than the X2 clones.  The G0704 is a representative of yet another maker's product, a BF20, sold by several suppliers. 
(Little Machine Shop's fixed column X2, their model 3990)

By now, I can hear lots of people saying "but what do I need?"  Again, it depends on what you're going to do.  If you want to carve out 80% lowers, you can do that on a good drill press.  I've done it on my Sherline.  Any of the X2 mills will do.  I'm simply not sure what tooling is needed to do a blank forging, a "0% Lower", or to make a receiver from a block of metal.  The 3990 has 10.6 inches of Z-axis travel and remember that any cutting tools or holders (collet or drill chuck) will eat up some of that.  That sort of work may need more Z-axis but it might be that those cuts can be done on a large lathe.   

Right now, I'm leaning toward this LMS 3990.  The Griz G0704 is a strong contender, though, and I'm still going back and forth between them.

8 comments:

  1. Surely you need a Bridgeport! How can anyone live without one?

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  2. One of my neighbors back in Illinois had a full-size Bridgeport in his basement.

    My Dad worked for the company that had the franchise in the Chicago area, and sold it to him.

    The delivery included setup, and my d\Dad said the delivery guys said some things he'd never even heard in the Navy getting it down the stairs!

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  3. Eric, if I can find a Bridgeport for a reasonable price, it's a really strong possibility. That "if" ends up being a bit of an issue.

    There are many machine shops in this area and one thing about Bridgeports (and a lot of other machine tools) is that with a bit of care, they'll last a long, long time. Which brings up the other issue: I'm not sure I can tell if one has had adequate care and isn't two tons worth of problems.

    And Jim, one thing I don't have to consider is stairs! It's Florida flat here. I designed the shop with double doors to allow big things to be rolled in. Just have to clear the way to the double doors.

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  4. Good discussion on mills. Are you thinking of buying it already configured with CNC?
    Just curious. Sometimes there's value in getting the machine ready-built with CNC, other times you get better value and higher precision doing it yourself.

    I'm in the market for a smaller-ish CNC mill so I'm watching with avid interest and not a small amount of shop envy!

    Thanks for the detailed writeups!

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  5. It's good to see progress continuing at the shop. I'll agree with ASICDude, consider CNC before you buy, either as a retrofit or out of the box. While it is possible to DIY CNC, it is an extra bit of grief someone with a day job probably doesn't need.

    Seig - I've heard major complaints about quality, particularly castings. Many of the Chinese tools are described as kits; some modification required.

    Grizzly has a good reputation, and I've considered one of their tools myself. I've also heard good things about Rong Fu. I've done a lot of business with LMS for tooling and the like, almost always happily, but never for tools. My expectation is they charge a bit more for additional handholding (or at least reference material) and in my case worth it.

    I tend to agree with the Chris' Tips on the LMS 3990 - a tilting base isn't really a feature (for most hobbyists). I own a Taig micromill with a tilting base and wish it didn't. You can probably accomplish the same thing with a tilting vise albeit at the expense of some work envelope. Tramming accessories are available, so if you get a tilting base include those accessories in the Out The Door cost.

    I like your R8 spindle choice, it is a heftier spindle than mine. Here's the weird part of mills. Eventually you'll probably spend more on tooling and accessories than on the tool itself. So I'd concentrate on selecting the capability of tooling before the tool itself. There may be other spindles that are more appropriate for what you have in mind. Or maybe you don't have anything particular in mind. Just fun stuff to play with.

    Please take my comments with a grain of salt. I've not done much with my mill, and it's been a while since I even paid attention to the market.

    There are some good forums out there where people will have a lot of good advice to offer. Worht looking into. Even better would be to find a local hobbyist machinist club and attend at least a couple meetings before you buy. Maybe you'll even find a mentor there.

    Good luck and 73, Jim

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  6. Friends don't let friends buy X2's. Definitely worth the $300 extra for the $1200 G0704 over the $900 LMS X2.

    The G0704 has a large following, with a clear path to a future CNC conversion. See www.g0704.com for a great resource by Hoss Machine. There is an epic 485 page thread on CNCZone on the G0704 by Hoss 2006.

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  7. Hooray for flat floors and wide doors!

    I was running a Bridgeport when I was 10 years old, and my Dad would take me in to his office on the weekends.

    Being as dad was a Tool and Die Maker, I got some pretty good instruction.

    "Speeds and Feeds" is something that will live in me forever!

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  8. Anon 1616 - your comment made me laugh.

    I've been reading the forums (fora?) and have seen references to some number of the G0704s that came with horribly unfinished ways. One guy said Griz wouldn't replace it and after he sent it back, they refused to sell him another. Don't know what to make of that, but I've always heard that with any of these Chicom tools you may be buying much more of a kit than you imagine.

    I'd be willing to pay more for someone to do a higher level of QC and not let mills like that get shipped. Jet? Precision Matthews? Don't know.

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