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Discussion Starter · #1 ·
The Sieg X2 mini mill is known by many names. Grizzly G8689, Harbor freight 44991, little machine shop 3900, Micro mark 84630 as well as models formerly offered by Central tool, Homier and Cummins. They are all the same mill with a few small variations. The most important of which is whether it comes equiped with a R-8 or MT-3 spindle. The R-8 is the preferred spindle due to the fact that there is more and cheaper tooling available for it.

These are nice little mills for small work, right out of the box, but there is still a lot of room for improvement. The purpose of this thread is to discuss these mods. Searching the net I have found many great threads dedicated to hotrodding these mills. One of the best sites is Tooling, parts, and accessories for bench top machinists - LittleMachineShop.com

This site is all about mini mills and lathes. They offer a ton of reference material as well as stock and upgraded parts.
reference section
Reference - LittleMachineShop.com

I have ordered from them several times. great service and same day shipping
 

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Discussion Starter · #3 ·
The biggest Achilles heel regarding the accuracy of these machines is the column attachment point. The column is designed to tilt 45 degrees both left and right. To accomplish this the attachment is limited to one big bolt in the center of the column, not solid enough for really precision work.
This seems to be the problem that most owners tackle first. About 2/3rds of the way down this page, you will find several different approaches to remedy this.
Shop Info

Here is a detailed thread on this mod.
Reducing Mini-Mill Column Flex (and Column Y-Axis Alignment) - Home Model Engine Machinist

And another.
SX2 Mini Mill Modifications - Mutiple Pictures - Home Model Engine Machinist
 

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Discussion Starter · #4 ·
I will be adding an air spring conversion to eliminate the factory torsion bar set up and DROs to all 3 axis as soon as everything shows up. I already have a set of metal gears for the gear box, I will be swapping those out at the same time.
I'll post some pics once I get underway.
 

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Excellent resources.

I have done quite a few of the mods including a home made belt drive. Will have to take pic's of my poor mans belt drive.

Filled the column with Engine Block filler, found on eBay for about $14.
 

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Discussion Starter · #6 ·
I have seen posts where they have added different substances such as that and epoxy granite etc to increase the column rigidity. I may look into that, but I don't know if I will be able to add much once I install the air spring since it attaches inside the column.
 

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Discussion Starter · #7 ·
Excellent resources.

I have done quite a few of the mods including a home made belt drive. Will have to take pic's of my poor mans belt drive.

Filled the column with Engine Block filler, found on eBay for about $14.
Kinda hard to tell from the pic. Does your plate tie into the base or is it just used to preload the Z axis
 

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Yes, the base was drilled and tapped and has 2 peices of 3/8" allthread. There is a nut on each side of the plate so that I can adjust the column front/rear.

I made my own pulleys for the belt drive and used an old brake caliper piston from my Corvette for the motor pulley.
 

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Discussion Starter · #12 ·
I may do a belt drive somewhere down the line, but since I am swapping out the gears in the gear box for metal ones, I kinda like the idea of keeping the plastic intermediate gear as sort of a "shear pin"

Here is a set of plans for a belt drive conversion.
Projects 6
 

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Don't even bother to turn your new X2 on. Just start taking it apart, all the way down, to remove the Chinese cosmoline, dirt, swarf, cigarette butts, dead animals, etc. that might be lurking in the hidden places.

You *must* "tram" the headstock to the table, or you'll get crooked holes and scalloped cuts. It may be a new thing if you haven't used a mill before, but it's not rocket surgery.

Getting the gibs properly snugged can be a hassle. It pays to use Dykem or felt tip on the gibs and both dovetails, just
to make sure they're making proper contact.

The major limit on the stock X2 is the very short Y axis travel. With a little work you can increase it quite a bit. Search "extended Y travel" on CNCzone.

A plain old Harbor Freight 4" drill press vise is low profile and fits the X2's work envelope nicely. The newer vises are only partially machined now, but squaring one up is an easy job with the X2.
 

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Discussion Starter · #14 ·
Don't even bother to turn your new X2 on. Just start taking it apart, all the way down, to remove the Chinese cosmoline, dirt, swarf, cigarette butts, dead animals, etc. that might be lurking in the hidden places.
That is exactly what I intend to do. The tracking info says it will be delivered on 3/14. I will tear it down immediately and reassemble it with the upgraded parts that I have been collecting while waiting for the mill to come off back order.

I had found this while I was researching info.
Homier Mill Review - page 1
 

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For the DROs, check out eBay too, I've seen ones like you posted on there
 

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Discussion Starter · #16 ·
The major limit on the stock X2 is the very short Y axis travel. With a little work you can increase it quite a bit. Search "extended Y travel" on CNCzone.
Yeah, the 4" Y axis is a little limited, but I mainly want this for receiver and barrel work. I can't think of an application where 4" wouldn't be enough.

LMS offers a kit to increase it to a little over 5" if needed. But, I also have access to some full size equipment if I need to do a big job.
 

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You can do temendous things with an X2 if you are creative and determined enough to do it.

I clamped a Chevy 5.3L aluminum oil pan to the teeny tiny table and used a slitting saw to cut the sump off. Had to reposition it a few times to get it cut all the way around.
 

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Found a pic of my poor man's belt drive. I broke the gears on my mill and had to come up with something simple in order to get back to work.

My plan was to build one of the fancy belt drive platforms once my mill was working again, but that was 2 years ago. It's made of 2 peices of angle iron bolted to the top of the head to form a "tray" that the motor cradle can ride in. The pic's were taken before I added bolts to tighten the cradle to the tray.

A tip on the set-up; the belt doesn't need a lot of tension in order to work. On the first belt I tightened it up just like you would an engine belt. As soon as I turned it on the belt flipped over on it's side and refused to run within the V grooves of the pulleys. After going through 2 belts I left it a little bit loose, and that was over a year ago.
 

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Didn't notice any reduction of Noise by switching to the belt drive.

Had read that the X2 is "extremely noisey" with gears and switching to a belt drive makes it much quieter. Not the case with mine, didn't really think it was noisey to begin with.

I consider a HF 4" grinder "noisey" and very loud, so would give it a 10 on the scale. The X2 is about a #4 on that scale.
 
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