you are here [x]: Scarlet Star Studios > the Scarlet Letters > if i buy a milling machine...
<< before the drill press mistake
after >> our fantastical future history

May 24, 2006

if i buy a milling machine...

by sven at 8:00 am

I very much want to build metal-jointed armatures for my puppets. I've come up with a relatively simple brass design that can be made with handheld power tools. However, I'm interested in graduating up to making steel and/or aluminum armatures. Ones with joints that make sense for the anatomy: e.g. knees that only bend on one axis of rotation.

That probably means: buying a milling machine.

Micro-Mark's MicroLux mini milling machine

I've been doing a lot of research. At this point in time, I think that I would choose to buy a MicroLux Mini Milling Machine from Micro-Mark for $590 (that's including shipping). However, I haven't fully committed to buying any machine -- not just yet.

For my own sake, I need to summarize what I've learned so far...

1. CROSS SLIDING VISE?

A while back, I bought a drill press at Home Depot -- which I returned a few days later. ...Immediately after leaving that Home Depot, I stopped at a hardware store that I'd never been in before: The Tool Peddler (9907 SE 82nd Ave). Inside, I discovered this tool I'd never seen before: a cross sliding vise. The cross sliding vise looked very much like the X/Y table on a milling machine. It made me wonder: can you use a cross sliding vise to turn a drill press into a milling machine?

cross sliding vise

I posted my question on SMA. The answer I got back was that a drill press isn't really built to deal with the sideways stress. Mike said that the machine will vibrate and give you sloppy cuts. Nick said that he's tried using a drill press to mill aluminum (which is soft) and failed. Jon Frier warned me that he had tried milling with a drill press -- and has scars from the attempt!

I went back into the store to have a second look at the vise, and was told similar things by an employee: the cross sliding vise is really just for precision-positioning. You might be able to use it for milling wood -- but trying it on metal would be a Bad Idea.

2. PRICES

For making armatures, you don't need a full-sized milling machine. There are "micro" mills and "mini" mills -- and either of these sizes will suffice. In general, it seems that micros cost more than minis -- you're paying for miniaturization.

From what I've read, it looks like a good mini is going to cost at least $500, and a good micro is going to cost at least $650. The price range for minis I've looked at runs from $399 to $525. The micros fall into two groups: $240 to $260, and $650 to $995. All of these prices are without shipping. Also, these are prices for the machines only -- milling bits, clamps, or other accessories all have to be purchased separately.

Micro mills I've looked at:

Mini mills I've looked at:

Harbor Freight's micro milling machine

The Harbor Freight micro milling machine seems to be the cheapest milling option available. Unlike the Procon (whose price is unclear), I can buy it locally and avoid shipping costs. However, it's remarkably heavy for a micro; its X/Y table is quite small; and it only has two speeds. The cheapest option is worth mentioning -- but I think I would have more confidence purchasing one of the fancier machines. We're going for precision metalworking here. (And "you get what you pay for.")

3. WEIGHT AND SIZE

For me, weight and size have probably been the most significant consideration after cost. My studio space is a spare bedroom. I don't have a proper metalworking shop -- and I don't have a lot of free space. This would seem to indicate that I should get a micro mill.

Comparing height, width, and depth is cumbersome (even for me!); a comparison of weight should give an adequate sense of how big these things are...

Micro mills I've looked at:

Mini mills I've looked at:

If weight and size are the primary considerations, then Sherline is the clear winner. Reading through the setup instructions, I see that you do need to attach the Sherline mill to a board, to create stability -- but you don't need to (and shouldn't) secure it to a workbench. It appears that all other mills (including the Taig) need to be bolted to a heavy table.

4. STRENGTH

The strength (or "beefiness") of a mill seems to be a matter of two factors: (1) what kind of metals it's able to cut, and (2) how rigid the milling column is.

On two threads over at SMA, professional armature fabricator Lionel Ivan Orozco ("LIO") advises that the extra mass and power of a mini mill (vs. a micro) can be advantageous.

LIO uses a Grizzly mini mill (as well as a 400+ Lb. Enco!) -- however, he's quick to point out that with intelligent design, there's still a lot that one can do with a micro.

Tom Brierton, another professional armature fabricator, gets good results with a Sherline. In his book Stop-Motion Armature Machining: A Construction Manual, Tom says

"Sherline miniature mills and lathes can cut the following metals quite easily: all grades of aircraft aluminum, brass, and mild to semi-hardened steel, such as the 303 and 404 series steels. Anything beyond the hardness of 440 will require very specialized cutting tools and jobber drill bits, which are very expensive. It has been the experience of the author that rarely is there a need to go beyond the 440 hardness when building stop-motion puppet armatures, as these metals are quite sufficient for armature purposes." (p.21)

...So, it appears that the Sherline is limited in terms of what materials it can deal with -- although it's unlikely that you'll need metals that it can't cut -- not within the realm of stopmo. Still, it's worthwhile to realize that size does limit the versatility of the Sherline.

[As I'm reviewing this portion of Tom's book, I now see that he says "Sherline machines must be securely mounted on a table, preferably with screws and bolts." This seems to contradict what Sherline says on its website.]

With regards to rigidity, the difference between a Sherline and a Taig is visible in their photographs.

Sherline Model 5400 micro mill

Look at the milling column of the Sherline...

Taig micro mill

Now look at the milling column of the Taig. You can see that it's much more solid. ...The Taig website boasts about their micro mill's strength:

"This is the machine you don't have to baby. The Micro Mill is a rugged precision instrument that has plenty of rigidity. Its machined, ground and stabilized steel bed has a life-time ball bearing spindle, coupled with a six speed positive vee belt drive. Spindle speeds in geometric progression from 525-5200 RPM (CR version 1000 - 10000 rpm) provide the power to "HOG" 1/8 inch cuts in mild steel or the speed and precision to "dust" a few tenths (compare that to other mills of similar size on the market, you can't!)."

It appears that if strength is the primary concern in choosing a mill, then the Taig wins out over the Sherline. However, a Taig pretty definitely has to be screwed down onto a workbench -- so at that point, you might as well go for a mini like the MicroLux.

5. MINIS VS. MICROS

There a few differences between the minis and the micros worth mentioning...

(1) The milling heads on the micros can turn 90 degrees in either direction; the milling heads on the minis can't turn -- but their milling columns can turn 45 degrees in either direction. It sounds like this is a point in favor of micros -- however, after asking folks on SMA and looking in Tom's book at how specific armature joints are made, I find that you probably want to avoid tilting the milling column entirely. It's unnecessary -- and "tramming" the column to make sure it's perfectly vertical sounds like a very tedious process.

(2) The minis can double as drill presses -- the micros can't. The minis all have a wheel on the side that allow you to easily plunge a drill bit into a work piece; the micros can only lower their drill bit slowly, using very small increments of movement. Getting two machines for the price of one -- both a milling machine and a drill press -- seems like a significant benefit to me. [Correction: It appears that the Procon and Harbor Freight micro mills can double as small drill presses.]

6. COMPARING THE MINI MILLS

An interesting fact about the minis is that at least five brands are all made at the same Chinese factory: Grizzly, Harbor Freight, Micro-Mark, Homier, and Cummins. LittleMachineShop.com has a very useful comparison chart for these five brands. [I have been unable to find any info for Homier Mobile Merchants' "Speedway" model, and have thus excluded it from consideration.] Procon appears similar to these brands, but seems to be produced in a different factory.

Now, on to comparing the various brands of mini mills with one another...

The Procon website is confusing -- and as I am looking at it today, the link to its page about mills seems to be broken. The Procon also appears to be a metric machine. I'm disqualifying it from my considerations.

The Cummins ($399) and Harbor Freight ($459.99) both seem to be somewhat less expensive because they have only two speeds. From what I read, being able to control the speed at which you mill each particular kind of metal is very important. Having only two speeds is a significant deficit. However: There are at least two Harbor Freight stores here in Multnomah county; all of the other brands seem to only be able via mail order. Thus, Harbor Freight gets some extra points... With their brand, I wouldn't have to pay shipping costs.

The Grizzly ($525) and the Micro-Mark MicroLux ($524.95) are essentially identical in price -- and even when shipping is considered, they only differ by $5. The Grizzly is heavier: 153 lbs. versus 110 lbs. The MicroLux's lighter weight should probably be considered as a point in its favor.

The tipping point in favor of the MicroLux may be that it has "true-inch" feed screws and dials. As the LittleMachineShop.com comparison chart explains,

"The MicroLux mini mill has one unique feature; the table feed dials both advance 0.050 inch per revolution. On all the other mini mills the dials advance 1/16 inch per revolution. The 0.050-inch per turn is easier to use than the 0.0625-inch per turn of the other mini mills. Micro-Mark will have you believe that the other mini mills have metric dials, but they do not."

I've looked at the Harbor Freights dials in person and can attest: .0625-inch per turn is really strange-looking and counter-intuitive. It's difficult to explain; suffice it to say that I walked away from the store not understanding how one would actually work that dial.

So, when it comes down to it, it looks like both the Grizzly and the Microlux are very good machines. LIO has a Grizzly. And, I feel it's worth mentioning, Kevin Kelly's "Cool Tools" website advocated for the Grizzly (though not in comparison to anything else). On the other hand, both Yuji and Eric Scott over on SMA have opted for the MicroLux, and seem very happy with the machine. ...For someone who's not a pro like LIO, it sounds like the "true-inch" dials make the MicroLux slightly easier to work with -- giving it a slight edge.

7. PICKING THE MACHINE FOR ME

It seems that my first choice for a milling machine would be the MicroLux ($524.95). It's strong: having both rigidity, and the power to cut different metals with ease. It's versatile: being able to serve both as a milling machine and a drill press. It's somewhat easier to use than other mini mills: having both a variable speed control, and "true-inch" dials. It's less expensive than the micro-mills. And at 110 pounds, it's not light -- but it's also not completely unmanageable.

The "big" problem with the MicroLux is that it commits me to also buying/making a sturdy workbench that it can be screwed onto. So, my second choice for a milling machine would have to be the Sherline Model 5400 Deluxe Mill ($775).

...The basic Sherline mill (Model 5000, $650) is a bit smaller than the Deluxe -- but also lacks the "laser engraved scales on the table and base" -- which seems a little unreasonable. Having an incremented ruler built into the X/Y table feels essential; the Model 5000 seems inadequate. The high-end Model 2000 ($995), on the other hand, seems like over-kill. The "Deluxe" seems to be Goldilock's "just right" compromise.

[Note: As I double-check info now, it appears that the Model 2000 may be the only Sherline with a milling head that can turn 90 degrees -- the others seem to be fixed in place.]

A Sherline is the most lightweight option. There is conflicting info, but it appears that one can merely attach it to a wooden tray -- which then allows one to put it away when it's not being used. It has variable speed -- whereas the Taig has only six speed settings, and the Procon and Harbor Freight micro mills only have two. Sherlines are the best documented of all mills (micros and minis) that I've seen, and there's a vibrant online community of users.

Really, I think the only sticking point that's really preventing me from buying a MicroLux right now is: "Where am I going to put it?" ...I'm having trouble imagining where I want to put a heavy workbench.

That makes me begin to wonder if the Sherline might be the better option after all. BUT... It's more expensive -- by $250 -- and I have to remember that there's bits, clamps, and accessories to buy, as well as the machine itself. And it's also helpful at this point to recall what Yuji said while discussing his purchase:

"I chose the mini mill and lathe because I wanted something beefier than the Sherline. I got to use Sherline equipment with Tom Brierton last year when he gave a workshop here in Los Angeles. I thought they were good little machines but there were too many little things I didn't like about them too. Now that I have been working on my Micro Mark machines for a few months, I am very happy. And the fact they are cheaper, well that's just icing on the cake."

Yuji's kind of vague -- but his comment does help me feel more confident about going for the MicroLux.

SO! I guess the question I'm left with is: what am I going to do for a workbench?

8. THE WINNERS

This post is long and rambling, so let me summarize in another way. In the "small affordable milling machines" competition, I'd like to announce awards in three categories:

...And the winner for best overall value: the Micro-Mark MicroLux mini mill ($589.95, shipping included)

posted by sven | May 24, 2006 8:00 AM | categories: miscellany, sculpture, stopmo