[thudson]

I picked up my HF44991 Monday, and I am in the process of tearing it down and cleaning it up.

I plan on polishing the gibs and dovetails before it goes back together, but I was wondering if there are any other mods I should do while I have it apart.

What is the general consensus on filling the bottom six inches of the column with epoxy? What kind of filler should I use?

I also know that the torsion spring will have to go at some point. A counterweight like Hoss's machine or an LMS airspring kit?

I plan on using it as a manual mill to machine parts for the CNC conversion, being more included to build than buy.

Any other mods?

[port_huon]

A belt drive is a 'must have' modification but doesn't need the machine to be disassembled to fit it.
I have the air spring from LMS. It does require a couple of holes to be drilled in the mill head which may be easier with the mill in pieces.

There are various posts regarding filling the bottom of the column with epoxy - pro and con.
Try replacing the round washer under the nut that holds on the column with a larger square one. There are a number of thread on this topic - here's a very complete one from dougal.
And don't forget to visit Hoss's site for all things X2.

[hoss2006]

Cut away the throat at the front of the base, it'll give you a quick extra 3/4 inches of Y travel.
Pics located here.
http://www.hossmachine.info/cnc_conv...ml#Fabrication
Hoss

[TroyO]

I'm expecting an X2 later this week. Thudson, I hope you don't mind a "Hijack" but it looks like we are both after the exact same info... LOL.

Hoss, that mod to get the 3/4" inch... you just bring that boss down to even with the front web? Nice, I like easy! I've got just the monster file for the job too. LOL...

Any other travel hacks to gain a little here and there without anything too complicated for a newb?

I've been looking at the epoxy fill... I'm going with the KISS principle and I'm just going to get a pint of 2 hour epoxy and mix it with concrete mix as a filler. Just the regular Home Depot 8 oz bottles of the epoxy... and 2 hour cure or longer if they have it. I think, with the filler it will be enough?

I figure it can't hurt... it either sticks and bonds up solid in which case I'm good... or it's gonna NOT stick and work right, in which case I can probably get it out and try again.

[thudson]

I'm expecting an X2 later this week. Thudson, I hope you don't mind a "Hijack" but it looks like we are both after the exact same info... LOL.

No problem. It seems quite a few of us here are the next wave of X2 users. Hope we can learn from each other, as well as the experienced X2ers.

I'm using crevicereamers teardown and cleaning guide:

http://crevicereamer.com/Page_9.html

I couldn't find kerosene anywhere, but the local Lowes had mineral spirits. I've also found WD40 comes in handy for some of the tight spots for cleaning.

You'll be cursing the 'red goo' guy when you start cleaning.

[thudson]

There are various posts regarding filling the bottom of the column with epoxy - pro and con.

I've searched for 'epoxy' and found many threads, but I didn't see any cons. What are the downsides of the epoxy fill?

[hoss2006]

Hoss, that mod to get the 3/4" inch... you just bring that boss down to even with the front web? Nice, I like easy! I've got just the monster file for the job too. LOL...

Any other travel hacks to gain a little here and there without anything too complicated for a newb?

Sure , these for travels.
http://www.hossmachine.info/X2_Travel_Increases.html

these for rigidity.
http://www.hossmachine.info/Shop_Info.html#x2%20column

When it's back together, check the tram.
http://www.hossmachine.info/Shop_Info.html#tramming
Hoss

[TroyO]

Thanks Hoss! There's sooo much info on your site, half the battle is finding it (And debating whether or not I *really* have the skill to pull it off.. LOL)

My immediate list, during the initial build...

Cleaning

More cleaning

Way smoothing

Gib polish

The 3/4" boss Y Mod (That's within my abilities)

Epoxy column fill.

Back support plate. I may upgrade that to the bolt on style later.

Full tramming out of the column to base and spindle to column.


After build:

Belt drive, using Hoss's plans. I have an 8x12 lathe and a pile of round AL stock I got at 2$ a pound.
I am considering using a 1/4" motor mount plate and some washers to fill the gap between the mounting plate and the motor where the bolts are... it just seems easier to make since I don't know how to do that recessed hole with the tools I have.
For the base plate I'm thinking I can cut the big hole just using a hole saw.. it won't be exact but "close enough".

Maybe buy a spare base (I think I read somewhere that you can order a spare base for $20 and $10 shipping...) and try some of those more advanced travel mods on one I can "wreck" and not have the machine down if I screw it up.

[TroyO]

Hmmm, that air spring upgrade seems pretty reasonably priced.

If I understand correctly, it's a better balance for the head and also extends the travel? How important is that manual use, or is it primarilly a CNC thing?

[thudson]

Hmmm, that air spring upgrade seems pretty reasonably priced.

If I understand correctly, it's a better balance for the head and also extends the travel? How important is that manual use, or is it primarilly a CNC thing?

I've been debating that. Hoss's counter weight is cheaper and probably does more to balance things. I was thinking about using a lead counter weight. Check out your local tire shop for discarded lead pieces from tire balancing. At worst I can buy big lead fishing weights for pretty cheap.

But yeah, the stock scheme is pretty weak.

I picked up some great home/limit switches from Allied Electronics for cheap. I may try to install these before re-assembling things. They are snap switches with rollers and SPDT, so they can be wired up NC or NO.

Tomy

[port_huon]

I've searched for 'epoxy' and found many threads, but I didn't see any cons. What are the downsides of the epoxy fill?

What I meant was there's probably little advantage in filling the column with epoxy on such a small machine. The consensus seems to be that a column brace of some sort will give better rigidity.
The only real downside will be a hell of a mess doing it.

[thudson]

What I meant was there's probably little advantage in filling the column with epoxy on such a small machine. The consensus seems to be that a column brace of some sort will give better rigidity.
The only real downside will be a hell of a mess doing it.

Thanks. Yeah, it's a mess to clean up. And expensive. I have West System on hand from building a canoe.

[Bluedog]

Definately do not overlook the last part of Hoss's tramming section with this link:

http://homemodelenginemachinist.com/...p?topic=6007.0

This made a world of difference in the accuracy of my mill.

[BobWarfield]

I've been looking at the epoxy fill... I'm going with the KISS principle and I'm just going to get a pint of 2 hour epoxy and mix it with concrete mix as a filler. Just the regular Home Depot 8 oz bottles of the epoxy... and 2 hour cure or longer if they have it. I think, with the filler it will be enough?

I figure it can't hurt... it either sticks and bonds up solid in which case I'm good... or it's gonna NOT stick and work right, in which case I can probably get it out and try again.

Think of the epoxy granite mixture as being all about damping, rather than rigidity. By all means do the rigidity mods to the column that a lot of X2 owners do. I like the idea of bolting a full length piece of channel, for example.

How much difference will the damping make? I did a fill on my Industrial Hobbies mill, and I would estimate it as a 15-20% effect. 15-20% smoother, able to take more aggressive cuts, etc. The mill "feels" more solid and doesn't "ring" when you tap the column or base.

You can see more about my fill here:

http://www.cnccookbook.com/CCMillEpo...lEpoxyFill.htm

It actually is very easy. I would definitely recommend a mixture of "fill" and not just the concrete mix. The damping effects comes from the epoxy trying to "wiggle" around all the different aggregate sizes. There is a lot of value in different sizes. As you can see from my article, it's easy to figure out the proportions by simply experimenting with water until you get down to the percentage of epoxy you want to use in your mix. Very high quality commercial epoxy ganite gets below 10%. I got down to maybe 14% and it was very easy to work with.

Be careful of the resins--they can cause a nasty allergic reaction. DAMHIK.

Cheers,

BW

[sansbury]

I've been debating that. Hoss's counter weight is cheaper and probably does more to balance things. I was thinking about using a lead counter weight.

I have an X2 running a Hoss-based conversion with 425oz motors, and I have not found a counterweight to be necessary. I can safely run the Z up and down at 18IPM and get basically zero backlash. The Hoss plans call for a 2:1 belt reduction on the Z so there is plenty of torque to go around.

My opinion is that you not really bother with any of the "secondary" mods until you have the basic conversion running. I say this because just getting the basics going took me about three times as long as I expected. The one exception might be the Y-axis travel mods since these require pretty much a total teardown.

[TroyO]

Thanks Bob! I knew I had seen a great tutorial on the epoxy fill somewhere, but I hadn't book marked it!

http://www.cnccookbook.com/CCMillEpoxyFill.htm

The link wasn't showing right in your post... fixed it.

From what I get on the Mini-Mill, the epoxy in this case is just for support of the rear wall of the column in the first few inches... there's no "bottom" on the column and so the tube collapses several thou if pressure is put on it. By filling it up a little past the point where the bolt goes through you can support that back wall of the column and reduce the flex at that particular point. It keeps the mounting bolt from "squishing" the column.

A full epoxy granite fill could always be done later, for dampening and such. (And probably will be.. LOL.)

I may not ever go CNC... but a 15-20% difference? It may have to go on the short list of mods instead of the "someday" list.

[knudsen]

While not requiring a teardown, I tossed the torsion bar and hardware, skipped the air lift, and used this: http://lmscnc.com/1486 The result is a good foot of Z-axis. Currently running with no assist, but bought weights to make a counterweight with a pully and cable. As I recall, the head is about 30 lbs. You can get weight lifting weights. I bought a 25lb, 5 lb and a 2 1/2 lb. I already have some 1 1/2 lb weights left from PT. 25 + 5 will get you close, might have a slight negative weight, good or bad. Actually works really well with no counter weight, and a copper shim on the gibs making it on the stiff side.

On the epoxy, search for potting compound. It's made to settle in and fill voids. Very dense. Might have to seal the cavity with silicone or regular epoxy first. I would mix some lead shot with it. Again, I have not done this yet. Not had mine apart. It's only 5 years old... all in due time

[TroyO]

That same rack is part of the air spring kit... so for an extra $16 you get the spring and mounting hardware. That's why the kit seemed like such a good deal.

[knudsen]

Might be wrong, but doesn't the air shock still limit Z? It is a very good price.

[knudsen]

BTW: Interesting on the epoxy granite. I think I'll go with potting compound and lead shot, though, as it will be machinable. Not that I need to machine it per se, but if I need to drill/tap a hole somewhere, I won't have to deal with hitting granite.