Micro Mill

[Chop]

Hey guys,

Does anyone have any experience with micro mills? I need a mill and can't afford a real one right now. Harbor Freight has one for like $300. All I need it for is small flashlight parts.

 

[scott.cr]

I have an HF drill/mill, it took a LOT of work to get that thing to any type of accuracy. You should be pretty serious about machining as a hobby before you spend the $ on something like that, imho.

Personally I would start with an HF mini lathe. The 7x10 is about the same price as the mill ($330 is what I paid), but you can build a lot more flashlight parts with one since flashlights are basically round and threaded.

 

[gadget_lover]

I have the micro mill. I've posted about it a few times.

You can do an amazing amount of good work with the micro mill. I've milled aluminum and steel. I've done some fairly complex parts with a fair degree of accuracy. It's been fairly easy to find tooling that works with it. Between Enco, HF and Little Machine Shop, I've found the appropriate end mill holders, 2MT collets, rotary table, screwless vise, clamps and other tools.

I've made tool holders for my lathe's QCTP. I've made many small parts for use around the house. I've machined parts for flashlights. I've cut custom dovetails and pockets.

The down side of the micromill is the clearance between table and spindle. Only 7.75 inches. If you add a tilting vice and an end mill holder you may run out of travel with anything bigger than a few inches tall. The micro mill table is deeper than the minimill by almost 2 inches but is 6 inches shorter.

The only flaw I've discovered with the micromill is that the fine feed mechanism gets loose with time, allowing the spindle to be pulled into the work a few thousandths under some circumstances. There is a technique for negating that.

You quickly learn how deep to make a cut, and how much is too much. It takes a lot of passes to whittle down a big part, but that's not a big problem if you plan in advance and get stock near to the correct size.

I chose the micro mill partly because of price, partly because I could reuse the MT2 collets and parts from my lathe's tailstock. I also took into account my bad back and the fact that it is light enough that I could move it if necessary. It's performed every task I've put to it.


If I were to do it again, I'd probably go straight to the mini-mill for only 160 more. It has the advantage of larger table to spindle clearance and deeper throat. The colum tilts, so you can cut angles without a tilting vise. There are a few other differences that make it sturdier so you can make deeper cuts. It also has a larger motor.

Search this thread for micro mill and you'll find the thread where I described the mill.
(http://candlepowerforums.com/vb/showthread.php?t=83463)

The only thing it really lacked, a precision measurement of downfeed. I mounted a 1 inch travel dial indicator to masure quill travel.

I made these parts on the micromill

Hmmm. I have not taken as many pictures as I thought.

Daniel

 

[Chop]

Daniel,

Thanks a lot for the advise. Micro Mark has their mini mill for $450 right now plus another $50 or so for shipping. I was looking at the micro mill because of the price and the MT2 spindle, as you said. The Micro Mark, however, has an MT3 spindle, so everything that I got to go into the head stock of my lathe will fit in the mill.

Is there any reason that I should go with the R8 in other models?

I really get the feeling that I'm about to over spend again, but I really need the mill to do things like cut flats for pocket clips and mill end caps for lanyard attachments.

I thought of just getting the milling attachment for my lathe, but that may wind up being just a waste of money in the end.

Thanks again.

 

[gadget_lover]

You are welcome, Tony. Others have shared the information with me, so it's only right that I pass it on.

The R8 VS 3MT is a matter of taste. The R8 taper is the industry standard for small mills. You should be able to find just about anything in an R8 taper, sometimes at sale prices. The 3MT and 2MT tapers are less popular, so you might end up spending a little more sine they are on sale less frequently. Morse Taper appears to be extremely popular in the UK. If you already have the 3MT tooling, then that makes a difference.

As someone said, cutting small parts on a big mill is often easier than cutting big parts on a tiny mill. I have no problems doing things like milling lanyard attachments into end caps with teh micro mill. Milling a flat is also an extremely easy thing to do on most any mill.

Just like the lathe, the cost of the mill is just the starting point. You will eventually need the rotary table, the boring bar head, the co-axial indicator. Of course you'll need the end mills and the holders and the fly cutters and all the rest of the fun toys.

I understand the lathe milling attachment is indeed usable for small, one off projects. I would not expect any kind of repeatability.

No matter which mill you get, they obey the basic rules that the professional mills follow, so all the information you glean from the web will also apply. The only difference is that the smaller mills can not cut as deep in a single pass.

I should mention that the depth of cut can be a big deal. Imagine a situation where you have a 3x3x2 block that needs a 1 inch wide groove cut .5 inches deep the entire 3 inch length. With the micro mill you could use a maximum of a 25/64 inch diameter end mill, cutting .025 deep. That means 3 passes to cover the 1 inch width. It means lowering the mill 20 times to reach .5 inches. That's a total of 60 passes. At .04 inch movement per revolution of the table crank, that's 75 revolutions per pass. Multiply it all out and you find 75 * 20 * 3 = 4500 turns of the crank to make that 1 inch wide, .5 deep by 3 inch long groove.

Use the minimill and you can use a 1/2 inch end mill and can take up to .100 deep . Two passes per layer. That cuts your cranking down to as little as 75 * 5 * 2 = 750 revolutions. If you get a mill with 20 TPI lead screws you end up with .050 per revolution, so it's 60 * 5 * 2 = 600.


It's late, and my math may be off. I can tell you that I have spent hours listening to the radio and spinning the cranks to shape parts precisely.

Daniel

 

[Chop]

OK...so the mini mill it is. Thanks Daniel.

 

[bwaites]

I'm interested in how this goes, Chop.

I've been looking at that mill for months.

Bill

 

[Tritium]

I picked up a mini-mill recently from Cummins for $399 at a local tool sale.

http://www.cumminstools.com/browse.cfm/4,1485.htm

I have not had a chance to unpack it due to a relocation to a new home.

Same thing for a mini lathe also from Cummins for $399. Both are still packed in grease awaiting cleaning and use.

It is driving me crazy having toys and not having time to play.

Thurmond

 

[gadget_lover]

If you are interested in the Cummins mill (currently $399) you might check for when a truck sale will be in the area. Their web site says to call 1-308-832-2070 for dates a dn locations.

The Cummins truck sales are typically held at meeting halls, auditoriums and service groups (elks lodge, etc). Get there when it opens and they will probably have a lathe or two in stock as well as a mill or two. They load it in your truck. You can save a lot on shipping that way.

Daniel

 

[scott.cr]

On the subject of depth-of-cut on the smaller mills. Daniel, I don't know how fast your mill can spin, but I converted my drill/mill to DC operation and can get the end mills from barely moving to wheeeee.

On the real high speeds (4,000++ RPM) I find that I can actually submerse my mill vise and the workpiece in a pan of machining coolant, effectively giving me DEEEEP cut capability without worrying about burning out an endmill.

The tub I use is a Rubbermaid and it has holes poked in it in the same pattern as the mill vise. The tub bottom gets sandwiched between the vise and X-Y table, and it seals when you tighten the bolts.

This was actually a bit of an experiment (worked well) so now I'm considering devising a way to either build a constant spray coolant system or devise a way to fill/drain the tub more easily.

BTW, coolant mixtures is practically a whole 'nother hobby. I can get fairly complex, but the coolant really helps with surface finish and so on.

 

[gadget_lover]

That coolent tray's a good idea. I've plenty of rubbermade around, so I should be able to do it.

I find that when using a roughing mill I can take some pretty deep bites. I limit it to shallow cuts to avoid chatter and possible damage to the gearing. I understand that broken gears is a common problem with the mini-mill, so I'm not taking chances by going beyond what makes the micro mill happy.

Here's a bigger selection of the pieces I've made with the micro mill. Many of them were learning excercises and are therefore rather crude. Several of the pieces do look like they are store-bought.

Daniel

 

[Ledean]

Great work gadget ,

They do like store pieces. You can start selling them .

 

[gadget_lover]

Awwww Gee. Thanks. One or two of those parts came out really great. Some of them are absolute trash. I can tell you that there's at least one (non functional) flaw in all but two of the pieces. That's why I shrink the picture.

I've actually done more with the micromill, but I can't remember what. It makes an excellent precision drill, BTW. Once you learn to locate the spot you want to drill, the placement of precise patterns is easy to do.

After you learn how to make the parts exactly to your design, the "prettying up" part comes into play. That's as much of a challenge as the machinging itself sometimes. I'm about to learn a little about metal finishing.

Daniel

 

[HarryN]

OK...so the mini mill it is. Thanks Daniel.

Chop - I have used Daniel's mill, and am very grateful for it. I have also used my brother's "full size, 3 phase power, manual mill". Last, but not least, I have had some parts machined by Rossitron on his small, CNC mill.

To be frank, for the added cost of all of the attachments and mill cutter variations needed to make a manual mill work, I just would not buy one, especially, a small, manual one. If you have nothing else to do, they are fine, but you spend so much time making small cuts, and fighting the effect of backlash, etc, that by the time you are done, you wonder if you are accomplishing anything.

You will note Daniel's comment - most of the parts he has made have a "flaw" - that he has not shown. That is the problem with these manual mills - it is just too easy to have a project take many hours of work, then end up with a "learning process" error. Maybe I am just not patient enough, but that just drives me crazy.

I have made this offer to Daniel, and I will make it to you. If you have an interest in getting a mill with some umph, and cnc control, I might be interested in going in on it with you. Umph to me means 1/ 2 - 1 hp. The big advantage I see with a cnc mill, is that it allows you to skip owning (quite) so many attachments to accomplish the same thing, and do it faster, and several times in a row.

I am sure others will disagree, but I think of the small manual mills as sufficient to do "minor corrections / cuts", not for serious work. Yes, a master can do it, but what if you just want to get it done ?

 

[guntotin_fool]

One other possible thought.

look for used tool dealers around you and look for schools selling shop equipment. I found a small South Bend tool room lathe and a Rockwell mini bridgeport that had been in schools. As the school were looking for ways to spend tax dollars they were upgrading to CNC and DRO tools and were just about giving these away. Both came with extensive accessories and tooling. Cost? under a grand for both, not each, both. Both were spotless and had been very well taken care of. advantage of bigger equipment is much more abitlity to do things in one or two passes rather than four or five. disadvantage, size and wieght both wiegh over a 1000 pounds and require 220 V for me it is not so bad as i have the space. My main use of these is for hobby use and making jigs and fixtures for work.

 

[gadget_lover]

Checking for surplus school equipment is a good idea. They often have equipment that is no longer part of their carriculum. Sometimes the equipment was donated by a machine shop as they upgraded, sometimes they have specially designed "learning" systems. As an example of the latter, many schools have CNC lathes that have only a 3 inch throw and 10 inch bed. The lathe is designed to teach the concept.

There's a vast difference between the person looking at the Mico Mill and those who can make room for a small bridgeport.

The micro mill can litterally be placed on the workbench in a "corner of the garage" workshop and it can be placed on a shelf when the workbench is needed for other things. It can be used on a kitchen table in an apartment and put away for supper. It's power requirements are lower than a vacuum cleaner.

In an ideal world I'd go for a fully appointed bridgeport. Since my space is limited and I'm under doctors orders not to lift anything, the micro mill does what I need. I can make precisely dimensioned parts. It just takes longer to do it.

The comany that makes the micro mill (model X1) also makes an enhanced version, dubbed the Super X1. It has a longer table, a deeper base and a tilting column. The deeper base gives better support when you crank the table way out and the longer table allows you to mill longer surfaces (almost 13 inches long) without having to reposition anything.

Daniel

 

[tvodrd]

Fantastic millwork, Daniel!!!! Now comes the disclaimer: Tony, I wouldn't even consider a milling machine that didn't have an R8 collet spindle. The tool locking is positive due to the draw bolt. Morse taper spindles can be scary as some cutters can be pulled from the spindle by cutting forces! E-Stop city time!

Larry

 

[cy]

thanks for the tip about possibility of morse taper releasing under cutting load with milling machine.

mine uses R8 collets

 

[gadget_lover]

Thanks for the kind words, Larry. Coming from a master like you that means a lot!

The point about the morse taper is valid, but the micro mill also uses a drawbar to hold the tools tight. All my end mill holders and collet holders use a drawbar. Even the drill chuck is held by a drawbar. I'm not sure about other advantages of an R8 over #3MT. They are a similar size, but the #3MT has more contact area. The micro mill uses a #2MT. I seem to recall reading that the R8 is easier to dismount from the spindle because of the sharper taper. Mine requires a sharp rap with a small hammer.

There are 3MT arbors designed for drills that have a tang on the end to prevent the arbor from twisting. I'm sure that is what Larry was thinking of.

I guess that there should be at least one picture in this thread. Here's my big old mill. There's a minimag on the vice for size comparison. The drawbar is barely visble at the top. It's normally covered with a plastic cap.

The drawbar:

 

[gadget_lover]

Well, there's good news and bad news.

The bad news is I just spent another $70 for an accessory for my Micro mill (which I got on sale for around $225).


The good news is that I'm fairly happy with the purchase. The part I bought was an extended table from littlemachineshop.com.

A little background...
The stock micro mill is made by Seig and is the model X1. It has a 240*145 mm (9.5 inch x 5.7 inch) table that will move about 180 mm ( 7 inches ). Realistically, the travel is only about 5 inches since the table is only 1/2 on the ways at 7 inches. Even so, this is not a bad size, since you will not be working on huge prodjects. The only time it's cramped is when I want to mount several supports (blocks, vises, etc) at once for a long piece.

But Seig makes a big brother to the X1. It's the SUPER X1 and features a significanly longer table. The table is 15.75 inches long and has 13 inches of travel.

That table is available as a replacement part from Little Machine Shop.
The Super X1 table uses the same dovetail dimesnsions so it fits on the micromill too. The replacement from LMS comes with a longer leadscrew. I measured the table and it was level and flat from end to end.

With the new table, I can mount my rotary table, a maglight and a tailstock to support the other end. I can clamp my toolmaker's vise from both ends instead of having to clamp front and back. It does not make it a bigger or stiffer mill, but it does make it able to handle larger pieces.


This shows the vise on the small table which is sitting on the longer table.

This shows the longest piece that I could use with my rotary table without the longer one.

The table is available at http://littlemachineshop.com/products/product_view.php?ProductID=2642 and is listed as "Long Table Kit, Micro Mill"

OK, I added a $70 accessory to a $250 mill. Yes. I'm crazy. Anyone want to buy a slightly used 10 inch table? For $70 ?


Daniel