Thoughts on Mini Mills?

Discussion on all milling machines vertical & horizontal, including but not limited to Bridgeports, Hardinge, South Bend, Clausing, Van Norman, including imports.

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BrooklynBravest
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Thoughts on Mini Mills?

Post by BrooklynBravest » Wed Jun 17, 2015 11:30 am

Have an opportunity to buy a grizzly mini mill with some tooling and light use for $400-500 roughly.

I have a mini lathe would this be a good compliment to learn on or are they too underpowered to be useful?

spro
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Re: Thoughts on Mini Mills?

Post by spro » Wed Jun 17, 2015 12:55 pm

The very beginning would to indicate the #. Makes it easier and remember, the contributors are not paid to look up every possible mini- mill head, their differences, make a statement and find it was something else.

dcmus
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Re: Thoughts on Mini Mills?

Post by dcmus » Wed Jun 17, 2015 1:07 pm

I began with a HF round column mill. It's now a dedicated drill press FWIW.

Harold_V
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Re: Thoughts on Mini Mills?

Post by Harold_V » Wed Jun 17, 2015 3:48 pm

BrooklynBravest wrote:Have an opportunity to buy a grizzly mini mill with some tooling and light use for $400-500 roughly.

I have a mini lathe would this be a good compliment to learn on or are they too underpowered to be useful?
Difficult question to answer, as the work you hope to do would really be the determining factor. Small work is usually accomplished with less effort on small machines, so a miniature can be to advantage. By contrast, if you hope to do work that exceeds the limits of the mill in question, yeah, it would be a mistake to buy it strictly because of price, when it wouldn't be suited to the work at hand.

Harold
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WJH
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Re: Thoughts on Mini Mills?

Post by WJH » Wed Jun 17, 2015 4:56 pm

Mini Mill?
Take a long rope, tie it around the mill, tie the other end to your boat. It makes for a very good anchor.

kkgilkey
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Re: Thoughts on Mini Mills?

Post by kkgilkey » Wed Jun 17, 2015 7:36 pm

Mini mills may not fit everyone's needs but they are hardly a "boat anchor".

Assuming this is Grizzly's version of the X2, they are nice learning and small work machines. You'll learn a lot about chatter and appropriate cuts, but they do work.

Nice ... Variable speed spindle, quick head retraction for tool changes, everything is small and so less expensive, you can see and reach everything, light to move if you must.

Not nice ... Need to do belt drive conversion (plastic gears won't stand up), reach limits of work envelope soon if doing anything but small projects, tilt column is more bother than useful.

They are small, lightweight ... Stay away from difficult materials. If you can restrict yourself to aluminium, leaded steal and plastic you'll be happy. Light cuts on mild steel with sharp tools ok.

A 1/2" endmill on the "big" side for these machines. Be careful with fly cutters. The are speed limited for really tiny endmills, but what isn't?

Mine is from HF with R8 spindle which I like. I believe the Grizzly had the 3MT spindle which I don't bit LMS has conversion kits. R8 tooling will work on your next machine. 16tpi lead screws aren't as friendly as 20tpi but you learn to use them. These too can be upgraded.

I still have mine even though I've moved up. Had a LOT of fun with it and am thinking of CNC'ing it for light engraving type work and small sheet metal cutouts.

Not a Bridgeport, but still a real machine within its admitted limitations. $400 with some tooling and not wore out ... Fair and fun!

silence dogood
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Re: Thoughts on Mini Mills?

Post by silence dogood » Wed Jun 17, 2015 8:04 pm

To Brooklyn: It sounds like that you are starting out, the Grizzly will be just fine. Just make sure that you can get tooling(in this case, it should be no problem). As you learn and develop your skills, you can always upgrade to a larger machine. Or maybe not, I don't know what you plan to do in the long term. I have a LMS mini mill and a Lathemaster 8x14. For what I do, these 2 machines are just fine. As for size, a good friend of mine repairs clocks. He has several watchmaker lathes. Gary has told me he does need precision, but he does not need any thing larger. PS Harold gave a great answer, I just felt that it should had been expanded. Mark

WJH
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Re: Thoughts on Mini Mills?

Post by WJH » Wed Jun 17, 2015 9:56 pm

kkgilkey wrote:Mini mills may not fit everyone's needs but they are hardly a "boat anchor".

Assuming this is Grizzly's version of the X2, they are nice learning and small work machines. You'll learn a lot about chatter and appropriate cuts, but they do work.

Nice ... Variable speed spindle, quick head retraction for tool changes, everything is small and so less expensive, you can see and reach everything, light to move if you must.

Not nice ... Need to do belt drive conversion (plastic gears won't stand up), reach limits of work envelope soon if doing anything but small projects, tilt column is more bother than useful.

They are small, lightweight ... Stay away from difficult materials. If you can restrict yourself to aluminium, leaded steal and plastic you'll be happy. Light cuts on mild steel with sharp tools ok.

A 1/2" endmill on the "big" side for these machines. Be careful with fly cutters. The are speed limited for really tiny endmills, but what isn't?

Mine is from HF with R8 spindle which I like. I believe the Grizzly had the 3MT spindle which I don't bit LMS has conversion kits. R8 tooling will work on your next machine. 16tpi lead screws aren't as friendly as 20tpi but you learn to use them. These too can be upgraded.

I still have mine even though I've moved up. Had a LOT of fun with it and am thinking of CNC'ing it for light engraving type work and small sheet metal cutouts.

Not a Bridgeport, but still a real machine within its admitted limitations. $400 with some tooling and not wore out ... Fair and fun!
I have a x1, and a x3, wishing I skipped both and went with a knee mill. X3 is the smallest mill I would ever go with. If you do a lot of mild steel, it's a boat anchor.

pete
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Re: Thoughts on Mini Mills?

Post by pete » Fri Jun 19, 2015 1:07 am

You can take this for what it's worth. I owned a mini mill or an X2 sized mill as there commonly known as. One issue with that belt drive is you lose the lower speeds and the torque that the 2 spd geared head give's. My thought is a set of metal gears to replace the plastic OEM one's would be far better. You would need to use something like a shear pin on at least one of the gears as a way to protect the heads internals when you end up having a crash.

The column is the worst on these mills. And having a single large nut to hold the column in place yet still allow it to be angled is a waste of time since these mills don't have a movable spindle. You have to move the whole head to change the Z axis. So even with a mill with a spindle you can move it's almost alway's better to angle the work. Only for large or long workpiece's would it be better to rotate the head. And since that column makes it really hard to get the nut tight enough without tilting the whole thing it doesn't even help while tramming the mill in the X axis. And since there's no adjustment for the Y axis then your shimming for that anyway's. So you may as well either scrape or shim to the correct tram.

You can find many threads on various forums where people will bolt a 1/2" or thicker plate to the rear of the column, but while that works well in the X axis, it stiffens the column in the Y axis a whole lot less. In my opinion what I'd do if I was buying another of those mills is I'd pull the head off the column, strip that column down completely, then I'd buy a length of I beam that runs from the top of that column and right down to the bench top, and as wide or wider than the backside of that column. That will give you the needed rigidity in both X and Y. I'd have the column coordinate drilled and tapped for the largest bolts I thought would fit, coordinate clearance drill the I beam to fit the columns bolt pitch. Then because I beam isn't truly flat, and you really need a surface grinder to get it flat enough. I'd lay the column face down, mix up a batch of 1 hr. epoxy and coat both the column and the face of that I beam. After that was set for about a week, I'd then install the bolt's. You need the epoxy to fill in the low spots on the I beam. Trying to bolt the column to the I beam without a hard filler would just force the column into the same shape and accuracy that the I beam is. You could get it out of alignment so bad that the head wouldn't move on the column.

One thing to remember about mills. While I certainly understand people do have only so much money they can spend, the initial cost of a mill is almost incidental. The tooling and accesories is where you'll spend the real money. With a mill there's probably no such thing as it being "fully"tooled. You never really quit buying accessories and cutting tools for a mill. If you only built one single part all the time then yes you could do it other than replacing worn out cutting tools. My knee mill cost me about $5,000 last time I dared to add it up I've spent at least twice that on cutting tools,tooling, accessories,dro, etc. I could easily spend just as much again on some really desirable and cool accessories, even second hand Volstro, Dorian, Moore, Troyke and a whole bunch more is not cheap to buy either new or used and in excellent shape unless your really really lucky.

I have seen some amazing and very accurate work on various websites done on those little X2 mills. Educating yourself as much as possible so you can get the tram correct, any adjustments done properly, buying the correct tooling and accessories when you need them, and then understanding how to set up and correctly hold any job that comes along takes a lot of time. You never or at least shouldn't ever quit learning and educating yourself about machining if you want to keep increasing your skill level. I'd first go back and read anything in this milling sub forum that interests you. There is a fair amount here that does pertain to those X2 mills but there's also lot's here that's about other mills but is just as useful.

One more point, it's more than likely if you keep at this that you will sooner or later move up to a larger mill. So it would be a very good idea to buy your mill from somewhere that offers them in a R-8 taper. Morse taper 3 is probably the most common taper from most company's selling them. But it's a poor choice for two important reasons. R-8 is the cheapest you can buy because it is so common. MT 3 is harder to find, has much less tooling in that taper, and without an ejector to force the taper loose, you have to pound on the end of the drawbar far too much. All that does is beat your spindle bearings to death very quickly. A Morse Taper is considered a self holding taper because of it's fine taper. The R-8 is almost a self releasing taper due to it's much steeper angle. I've owned both types and I would never buy another mill that had a Morse taper. I'll freely admit that for the larger mills such as full sized knee mills there are much more rigid and better spindle tapers. Anything from an International 30 on up to a Cat 50 taper. But for us working at home and only doing parts for ourselves, we can afford to take more time and lighter cuts so the R-8 works just fine. Not many of us need 30 horse power and a Cat 50 with a 7 axis CNC anyway's.

Pete

Mr Ron
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Re: Thoughts on Mini Mills?

Post by Mr Ron » Fri Jun 19, 2015 2:50 pm

I have a 6x26 vertical mill. Originally, I rejected the idea of a "mini" mill. The 6x26 mill works fine for me, but recently I started to get serious about making miniature parts and find the 6x26 is a bit on the large side. My answer is: If all you want to do is make very small parts to support a hobby (mine is model trains), a mini mill makes a lot of sense. I also have an 11" lathe and wish I had a smaller table top lathe for very small parts. So really the size of the work you wish to produce will govern the mill (or lathe) size.
Mr.Ron from South Mississippi

WJH
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Re: Thoughts on Mini Mills?

Post by WJH » Fri Jun 19, 2015 7:11 pm

I may have called the x2 a boat anchor, but at the same time will praise the Taig micro lathe. Never used their mill but most likely would praise that as well. Have to agree, if I am making parts for an HO scale locomotive, don't want a 11" lathe

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SteveHGraham
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Re: Thoughts on Mini Mills?

Post by SteveHGraham » Fri Jun 19, 2015 7:18 pm

If it has a lot of tooling and it's in good shape, it sounds like a good buy. The nice thing about used tools is that they're free. You buy them, use them, and sell them for what you paid.

People do a lot of good work on mini mills. It's not the ideal tool, but it's a lot better than not having a mill.
Every hard-fried egg began life sunny-side up.

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