Sieg Super X3 Mill

Sieg Super X3 mill

Recently arrived at mini-lathe.com World Headquarters is the Sieg Super X3 mid-size mill. I’ve been hearing about it on the internet for a while and was excited when the opportunity to test one emerged.

Well, it arrived recently, and I’ve had a chance to set it up, but have not done a lot of testing so far.

Operations at mini-lathe.com & mini-mill.com tend to scale back during the summer months as I, and my readers, enjoy spending time outdoors with their families and friends.

So, to get the full scoop, you’ll have to come back again, say around the end of August, when I have more time to spend in the shop. But for now, here’s a small sample of what to expect…

There’s been some controversy on the web about the Super X3 being under-powered.

I don’t have the full story on this, and there may have been some early models for which this was true, but the one I’m testing now seems to have plenty of power - even though the motor is fully enclosed in the head.

Take a look at this 0.100" depth cut using a 1/2" end mill - it powered through this test like a mole digging through soft dirt.

I did some more tests using a 3/4" 4-flute end mill on the same block of aluminum and found that a cut at a depth of 0.060" was no problem, while at 0.080" depth, the mill would whine and growl.

This does not seem to be a limitation in the power of the motor so much as reaching the stress limit of the spindle assembly, since I did not notice any tendency for the motor to bog down.

Since I have the Super X3 sitting side-by-side with the X3, I hope to do some comparison tests on power, as well as other features of the two models, and give you the full story.

What the two models have in common is their basic framework, including the base, column, X- and Y-axis controls and table.

Where they differ is in the construction and features of the head assembly, Z-axis feeds, the motor and the control electronics.

And therein lies a whole lot of interesting news. Take a look at the heads of the Super X3 and X3 below and you’ll get the idea…

Among the more obvious differences on the Super X3 are the following features:

• Digital RPM (tachometer) display with Forward / Reverse indicator
• Push-button membrane control panel
• Fine Feed control knob (similar to that on the mini-mill - only better!)
• Emergency Stop button moved from outboard box to front of head
• Power-on pilot light
• Digital Height Gauge continuously displays spindle advance
• Reverse and Tapping mode control buttons

Of course you’ve already heard about the tilting head feature, right?

But what about those green buttons on the ends of the three-spoke handles? What’s that about?

Well, I hope that’s enough to stimulate your interest for now. Thanks for stopping by, and stay tuned for the full story!

Part 2: More of the Story#

Busy with the usual outdoor activities of summer, I haven’t had much time to do any further testing on the Super X3 mill since the last installment (07/25/06).

However, I promised an update by the end of August, so I’ve added some new material. There’s still a lot more to come, and I’ll do my best to provide weekly updates during September.

Since the construction of the base, column, table and X-,Y- controls on the Super X3 are identical to those on the X3, I won’t repeat that information here.

Instead, I’ll focus on those features that differentiate the two models.

Tilting Head Assembly#

First, let’s take a closer look at the new tilting head feature. Regular readers may remember that I am not a big fan of tilting heads in general, and as implemented on the mini-mill in particular.

On the mini-mill, the head is tilted by loosening the BIG NUT at the base of the column and then rotating the entire column/head assembly left or right as needed.

One problem with that design is that you have to swing the head pretty far over to achieve, say, a 30 angle to the table.

In the process, the head is shifted towards one end of the table or the other, and closer to the table, limiting the range of vertical movement.

Secondly, any time you move the head in this way, you are faced with a time consuming (10-20 mins.) process called tramming, to accurately realign the head square to the table.

For these reasons, I much prefer the simpler solution of using a tilting vise.

I like the tilting head feature of the Super X3 a little better:

• Head is tilted relative to the column; column remains bolted in place
• Spring-loaded pin locks the head at 0 and 90 positions

To tilt the head, loosen the two “chrome dome” nuts.

Tilt instructions on side of head

“Chrome Dome” nuts

Before you move the head, you must first release a locking bolt by inserting a 6mm hex wrench into the bolt head and twisting it clockwise about 45.

The locking bolt is spring loaded and will revert back to its original position when you remove the torque, so you must maintain pressure on it until the head is moved away from the 0 position.

Head lock release access hole

Grasp the head firmly and tilt it to the desired angle, using the protractor on the side of the head as a guide.

If you’re shooting for an angle other than 90, you will probably need to tap the head lightly with the open palm of your hand, or a dead blow hammer, to get the setting right on the mark.

Then tighten up the two chrome dome nuts, and you’re good to go.

As an illustration, I cut a 30 and a 45 V-notch into the aluminum block that I’d been using for test cuts. Of course, due to the angle at which the cutting tool ends up, you can only cut using the cross-feed to advance the tool across the workpiece.

Another factor to keep in mind is that when the head is tilted, you generally will lose the convenience of being able to use the fine spindle advance and the digital depth indicator.

30 and 45 “V” grooves

No doubt there are applications where this would not be true, but in the example I tested, I wanted the point of the “V” to be at a specific location. (In truth, it didn’t really matter for this test, but I was thinking of a real application I had done in the past, where I needed to cut a V-groove at a specific location on a workpiece.)

I you advance the tool using the spindle, rather than the Z-axis leadscrew, the edge of the tool that forms the base of the “V” moves to the right as it moves deeper.

With a little trigonometry, I suppose that I could figure all this out and make it work, but I find it easier just to use the Z-axis leadscrew.

One other consideration when using the tilting head feature is that the cutting tool swings out away from the center of the table. If you’re milling vise is centered on the table, you’ll have to move the table out to the right to compensate.

Alternatively, you could relocate the vise towards the right end of the table.

Table moved far to the right

The other way to do angled cuts, and the one I usually prefer, is to use a tilting vise with an angular scale. The particular vise I have been using this way is really a drill press vise rather than a true milling vise, but is heavy enough to handle work on the mill.

I like using the vise, because, depending on which way I orient it on the table, I can use either the X- or Y-axis feed. So, if I really needed to, I could cut a V-groove or beveled edge as long as the X-axis traversal (about 16").

Maybe there are advantages to the tilting head that I have not yet discovered. There may be experienced machinists reading this who are chuckling because I’ve missed something obvious.

But until they contact me, or I discover it on my own, I will continue my prejudice for using an angle vise.

In any case, the only downsides that I can think of are that the tilting head may add some cost and slightly reduce the rigidity of the mill.

Who, knows, maybe it will come in handy some day, in conjunction with the tilting vise, when I need to cut a compound angle.

The good news in all of this I think is this: if you have already bought the standard X3 mill and are longing for the tilting head feature, just go buy yourself a good angle vise.

On the other hand, if you have bought the Super X3, or are thinking of doing so, you may find this feature useful (but buy yourself a good angle vise anyway ;-)

Z-Axis Fine Feed Control#

Readers familiar with the mini-mill may recognize the fine-feed control as similar to the one on the mini-mill. Well, it is and it isn’t. It is in the sense that it performs a similar function.

It isn’t in that it is much more precise than the one on the mini-mill, having much less of the backlash so prevalent on the mini-mill version.

I’m not sure how this new one is engineered internally, and did not feel inclined to disassemble it, but I can report that it is smooth and precise in operation, with very little (maybe a 16th of turn) of backlash.

In any case, since on the Super X3 you have a direct-reading digital scale built into the headstock, backlash becomes pretty much a non-issue.

Handwheel for fine Z-axis movement

As on the mini-mill a three-spoke handwheel provides coarse movement of the Z-axis - particularly suitable for drilling operations where quick motion is desired, but precision vertical positioning is not a factor.

However, the mechanism on the Super X3 mill is entirely different than that on the mini-mill.

On the mini-mill, the handwheel moves the entire head assembly up and down the column using a rack and pinion arrangement.

By contrast, on the Super X3 mill, the head remains stationary, with a separate quill assembly being the moving component.

This latter arrangement is more typical of that found on industrial mills such as the famous Bridgeports.

3-spoke handwheel for coarse Z-axis movement

Tightening or loosening a small handwheel that is mounted coaxially with the hub of the 3-spoke handwheel engages or disengages the fine-feed.

A quarter turn or less is enough for either operation, so I’m a little perplexed as to why the handwheel is outfitted with a folding handle - as you would find in an application where many turns might be required.

Such mysteries are too deep for me.

Handwheel engages fine-feed

And what about those mysterious green buttons on the ends of the handwheel spokes? What are they for? Patience. We’ll get to that soon enough.