# Reducing Mini-Mill Column Flex (and Column Y-Axis Alignment)



## rudydubya

After I finished the spindle-column alignment on my Harbor Freight mini-mill (http://www.homemodelenginemachinist.com/index.php?topic=6007.0), I still didn't get a good tram in the Y-axis. It measured about .004 (all my measurements are in inches) out of alignment, as if the column was tilted to the front just a tad. I also had a significant flex in the column. With a firm push or pull on the motor or top of the column in the Y-direction, I could get almost +/- .010 (2.5 tads) of up and down movement of the spindle relative to the table. I wanted to fix, or at least reduce, the flex, and planned on correcting the column-table alignment while I was at it.

From what I had read about the column flex, the consensus was that the major cause was that big Belleville washer under the big nut at the back of the column (with maybe some compression of the column wall under the washer thrown in), and by replacing the washer with a flat plate you could reduce the flex. Some folks added angle brackets and braces to the plate to make the column even more rigid. I decided on a simple flat steel plate bolted to the back of the column to replace the washer and act as a reinforcement up the column axis.





I made a column reinforcing plate (hereafter called a column plate) out of 3/4" thick, 4" wide steel, and drilled holes for some 3/8" bolts plus one 15/16" hole for the big pivot shaft. I used the center of the plate as a reference to locate the bolt holes. Most of you probably know I shouldn't have. *The pivot shaft is not on the centerline of the column.* It *is* centered on the ways, but the ways are shifted over about 1/4" on the gib side of the column. I never noticed it before. Must be a lesson in there somewhere. Anyway, my hole locations were far enough in from the sides of the plate to still work on the column, it's just a little off-center.




I match-drilled holes for the bolts into the back of the column, tapped them for 3/8" threads, and bolted the plate to the column. The flex was reduced to less than half of what it was, now about +/- .004, but still more than I wanted, and I hadn't fixed the Y-axis tram yet either.




I drilled four holes in a piece of 1/2" thick, 1" wide steel, one at each end for 3/8" bolts, and two near the center for 7/16" bolts. The end holes were far enough apart to clear the edges of the column plate. This would be a pressure plate to push on the bottom of the column plate.




I drilled and tapped holes into the base of the mill itself to match the 3/8" outside holes in the pressure plate, and drilled and tapped through the column plate only for the 7/16" holes, not into be base.




I bolted the pressure plate to the base of the mill with the outside bolts and tightened them until the column was pulled in enough to tilt the column back and eliminate the .004 Y-axis tram error. I then inserted 7/16" bolts through the center holes and screwed them through the column plate until they were snug against the mill base. With the end bolts pulling on the column, and the middle bolts pushing on the column, the bottom of the column was locked in place and the flex was reduced to about +/- .0015.







Some final notes:

With the bolts in place, I can no longer rotate the column side-to-side to mill at an angle. I have never used that feature anyway, so it was not a concern to me. Also, my mill was trammed in the X-axis to my satisfaction before I drilled the holes at the bottom of the column plate, but I left plenty of clearance around the 7/16" bolts in the pressure plate to allow some slight angle adjustment for tramming, if necessary.

My mini-mill Y-axis alignment required the bottom of the column to be pulled in toward the base, so the 3/8" outside bolts were tightened first, as evenly as possible to avoid any twist. Then the inside 7/16" bolts were screwed in just tight enough to eliminate any flex. If the required correction was the other way, the center bolts would need to be screwed in first, pushing the bottom of the column away from the base, and then the outside bolts tightened to eliminate any flex.

If I were to do this mod over, I would use a thinner column plate, say 5/8" or 1/2" so the big nut would be sure to grab all of the pivot shaft threads. The 3/4" plate I used just barely allows that. Also, my plate was 12" long. If I were planning to fit my mill with an air spring kit like the one sold by Little Machine Shop, I would shorten to column plate to maybe 10" long so it wouldn't be in the way of the hole in the column required by the kit.

The remaining minor flex in the column assembly is probably due to bending of the pivot shaft and/or the pivot plate. I couldn't think of any practical way to eliminate it entirely.

Drilling into your mill might void any existing warranties. I never had an extended warranty on my mill, so it wasn't a concern.

I think that's about it, thanks for reading.

Rudy


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## tmuir

'With the bolts in place, I can no longer rotate the column side-to-side to mill at an angle. '

Does anyone use this feature?
Personally I would prefer it wasn't there as it just allows the mill to slip out of adjustment easier.

I always like reading peoples mods as I'm very much a follower rather than a leader in machine mods.


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## Tin Falcon

interesting mod
Tmuir . 

I have actually used the angle tilting function IIRC had to put holes in some 6 foot long pieces at a 37 degree angle . but for model work it seldom if ever gets used. IMHO it is usually easier to tilt the work piece than the mill head. although tilting the head to the correct angle then tramming it back to square was a required exercise in trade school. 
IMHO tilting the mill head rather than the column would be more useful.
Tin


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## zeeprogrammer

Great thread Rudy. Really good.

While I suspect (hope) that someday I can move up to a better lathe, I think my mill will be around much longer. I have the exact same mini-mill so your mods have been very interesting too.

How did you drill/tap into the base of the mill? Drill press? Take the table off?

Thanks.


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## rudydubya

zeeprogrammer  said:
			
		

> ... How did you drill/tap into the base of the mill? Drill press? Take the table off? ...


 
zee, actually I left everything in place and used my trusty old electric drill. I used a scrap piece of steel that I milled down so it would fit between the plate and the base (from an earlier abandoned attempt to put a wedge between the plate and the base; it's a long story...) for a drill and tap guide. Two sizes of guide holes, first were sized to fit the tap drill (size "Q" as I recall) and I drilled the holes in the base. (Slow going in the cast iron, but not too bad.) Then I removed the scrap, enlarged the guide holes for a close fit on the 3/8" tap, replaced the scrap, and tapped the holes in the base. I clamped the scrap in place so it wouldn't slip. Used the same method to do the holes in the plate.







I'm not too good at drilling straight holes or tapping freehand, so I use guide holes drilled in the drill press whenever I can. Also, the holes in the base were located so they were just inside the side walls of the base. I didn't want to have to tap into blind holes.

Rudy


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## zeeprogrammer

Thanks Rudy. And while you didn't know it at the time...you gave me a clue as to what to expect when I work on my Spindex. Drilling cast iron will take some time.

Thanks.


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## rudydubya

You are quite welcome zee. I should have said "with _*MY*_ drill bit it was slow going." YMMV. Always glad when a post is helpful to someone, and always hope it's not as a bad example. ;D

Rudy


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## Bill S

Very nice work! and great photos. I have one question though, how do you keep your shop sooo clean? Seriously, my shop is a mess and I clean it regularly.

Cheers
Bill


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## rudydubya

Thank you Bill. The shop isn't normally that neat, just happened to be between projects and cleaned up that area to work on the mill and lathe. Usually tools and paper towels and chips and scrap and other assorted odds and ends scattered about.

Regards
Rudy


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## Krown Kustoms

Thats a great I dea, thanks for the post.
-B-


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## Dunc

Model Engineers' Workshop (monthly British publication) had articles in issues 150, 151 & 152 (May, June & July 2009 respectively) about modifications to various X1 mills.

Relating to rigidity - or at least, vibration damping - the author, David White, filled the base & column with "granite epoxy." It was obtained as a 2-part liquid epoxy/hardener & he added the granite chips. Near as I can determine this material would be similar to the material that is used for kitchen countertops; however, it is in the raw state and not obtained by breaking up old countertops.

I have not tried this myself. Merely passing the info along fwiw. Above author got some pointers from 
http://www.cnccookbook.com/CCMillEpoxyFill.htm

Disclaimer: I am not affiliated with any sites/commercial entities mentioned in any references in this post. Merely passing along the info.


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## Fred

Flex is one of the issues I encounter with my tiny mill. I have not acted upon it, but it is bothersome enough and I am thinking along the following lines:
1. Filling the (hollow) column with epoxy-granite as suggested above
2. Replacing the column by a solid one
3. Using a counterweight for the head as suggested in http://softsolder.wordpress.com/2009/01/11/sherline-mill-counterweight-gantry/

Fred


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## dsquire

Here is a link back to another member that used epoxy granit to fill the base for stability.

http://www.homemodelenginemachinist.com/index.php?topic=1443.0

Cheers 

Don


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## matabo

Well, I am new owner of a Sieg X2. 
I found this wonderful thread (thank you rudydubya) and the other one about spindle column alignment and I want to implement the rudydubya's ideas.

I want to show you the results of my implementation.

Sorry for the quality of pics (and the resizing didn't improve them) and for the quality of my language but english is not my mothertongue. Again, I apologize but I will use metric system. I will try to convert to imperial but I am not always sure about conversions.


Let's start.

In this pic you can see the standard setup of X2. Belleville washer. Just base and column, no milling head.






Upon the column I put a clamp and on that clamp I put a weight (a simple toolbox, weighing about 3 kg - about 7.5 pounds) to create a torque against the big bolt of the minimill.

I did put a DTI on the cross table and zeroed it against the column.






As I add the toolbox to the clamp, the DTI indicates 5/100 mm (2 thou). 
















Then, let's proceed with the experiments. Instead of the Belleville washer, I put a stainless steel plate. Dimensions are 200x100x10 mm, i.e. about 8''x 4'' x 25/64.
(I used stainless beacause I had no choice...usually I HATE stainless and drilling the big hole was a kind of nightmare. Luckily I found a workshop who did it).

No pressure plate at this stage, so the stainless plate just distributes the load of the big nut.






I check the zero on DTI, put the load on the clamp...and the DTI indicates again 5/100 mm. (2 thou). I was quite confused.
What is happening? The plate has no effect at all.


Well, then I proceeded by adding pressure plate (stainless steel too).










Zeroed the DTI, added the weight...again DTI indicates 5/100 mm (2 thou) flex. Well, now I am scratching my head.






The plate seems have no effect. No improvement on the column flex.

I kindly ask your opinion about this. Where is/are my mistake(s)?

Emanuele


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## zeeprogrammer

Congratulations on the mill Emanuele. I have the same type.

I can't answer your question but I'm sure you'll get some people chiming in.

2 thou with a weight that far from the column doesn't seem bad to me.
It wasn't clear to me from your post...when you removed the weight...did the DI return to 0?
There's still quite a bit of column left above the plate...could the flex be in that?


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## matabo

zeeprogrammer  said:
			
		

> 2 thou with a weight that far from the column doesn't seem bad to me.



Of course, I would like to compare my results with observations from other guys owning that kind of mill.
Maybe 2 thou is just great, so I can be happy 



			
				zeeprogrammer  said:
			
		

> It wasn't clear to me from your post...when you removed the weight...did the DI return to 0?
> There's still quite a bit of column left above the plate...could the flex be in that?



Yes, the DI returns to 0.

About the flex in the column: I read the document from John Pitkin (Column Flexing in the Minimill - revision 1.pdf, I can post it if there are no problem in posting PDFs); his tests say that the column doesn't bend. And that the flexing is in the base to column junction.

I trusted his tests but I didn't verify his results.

This is to say that the column shoud not bend. But of course I am not sure about that.


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## black85vette

You did a much more extensive test than I did. I approached it a little different. In looking at the design of the mill the weak link looked like the way the column was mounted.  When you get down to it the entire column is supported on about a 2" base bolted down which is just not wide enough to do the job properly.  My opinion is that most of the flex occurs here and not in the vertical column. Along that same thought; the mount has its bolts to the front of the machine. I would expect more flex of the unbolted back side, so putting weight to the front of the column is measuring the weak side of an already weak mount. Since drilling and milling puts a force to the rear of the machine and not the front I think I would hang the tool box off the rear and see what you get. Of course that is just my non-engineer, non-professional opinion which comes without a warranty or certainty of correctness. ;D


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## gunboatbay

There's literally hundreds of posts/discussions/recommendations on this particular problem. One of the best, if you haven't already read it is:
http://f1.grp.yahoofs.com/v1/cKQnS2...lumn Flexing in the Minimill - revision 1.pdf


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## itowbig

gunboat  it says page not found


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## spuddevans

I've read somewhere that some folks have filled the centre of the column with an epoxy-granite mix. This apparently helps to dampen vibration at the same time stiffening the column.

This is a mod I plan to make on my X2 in the coming months along with the same replacing-the-big-washer that you have already done.

I've also seen that others have attached a "I" beam to the back of the column, but that is a bit overkill in my view.


Tim


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## websterz

spuddevans  said:
			
		

> I've read somewhere that some folks have filled the centre of the column with an epoxy-granite mix. This apparently helps to dampen vibration at the same time stiffening the column.
> 
> This is a mod I plan to make on my X2 in the coming months along with the same replacing-the-big-washer that you have already done.
> 
> I've also seen that others have attached a "I" beam to the back of the column, but that is a bit overkill in my view.
> 
> 
> Tim



I beam huh? hmmmmm.......


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## spuddevans

websterz  said:
			
		

> I beam huh? hmmmmm.......



Or you could also use a short length of 4" box section bolted onto the back, but I guess you have to ask yourself when does it become a state of diminishing returns, less and less return on more and more effort and expense.

Tim


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## BobWarfield

Fellas, lots of great ideas here. 

One of the geniuses of the Sieg X2 world is Hoss from CNCZone. Check out his site, but in particular, this page has a whole collection of column stiffening ideas if you scroll down:

http://www.hossmachine.info/Shop_Info.html

BTW, someone mentioned my epoxy granite fill a ways up. I now have quite a lot of experience with this mill. My sense of it is that the E/G fill improved the rigidity by perhaps 15-20%. My RF-45 now performs almost identically well as a friend's brand new (you don't see those two often) Bridgeport. We were comparing runs with a 3" facemill for example. Unfortunately, it is not as good as his Fadal VMC (LOL!), but it's still pretty nice.

Check out Hoss's site for Sieg X2 stuff, it's very cool!

Cheers,

BW


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## matabo

itowbig  said:
			
		

> gunboat  it says page not found



this is the link to the document of John Pitkin (Column Flexing in the Minimill - revision 1.pdf):
(maybe you need to be registered to the group)

http://f1.grp.yahoofs.com/v1/cIUoS4...lumn Flexing in the Minimill - revision 1.pdf


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## rudydubya

Emanuele, please accept my belated welcome to the forum, pardon my delay in responding, I appreciate your interest in my post.

I don't know why you didn't see some improvement when you added the plate, I would have expected to see some. Could there be some slipping or bending of your clamp setup when you apply the weight of the toolbox? Did you try pushing or pulling directly on the top of the column and noting the deflection before and after the plate? In John Pitkin's writeup, he used a spring scale hooked at the top of the column so he could apply a desired force and measure the resulting deflection. I don't know if you would want to try that or not, but it would be a way to ensure the bending force was applied directly to the top of the column with accuracy and repeatability. I should have done it that way. Instead, I flexed the column with a "firm" push and pull with my hand at the top of the column, with the motor and head still attached. Sorry I can't quantify "firm" in terms of a weight or force, but it was probably much more than your tool box. My push and pull were somewhere between a nudge and a grunt. ;D My flexure measurements were taken from the spindle to the table, similar to the picture below.


​ 
I was able to reduce the flex to around 0.0015 inches, about 15 percent of what it was before I started. If I wanted to _*REALLY*_ push on the column I could probably at least double that.

Another major factor in the rigidity of the un-modified mill may be the amount of compression of the Belleville washer. I don't have any measurements of how much my Belleville was initially compressed. I tend to be conservative when I'm tightening bolts. More compression may be better.

To follow up on black85vette's post above, I think he's right about the ultimate rigidity of the mill being limited by the column mounting. I think most of the remaining flex in my machine is in the bolt and mount that holds the column to the base, so without a major modification to the mounting there will always be some flex. Also, as he says, you will be concerned about flexing with a rearward force on the column. As I look at your plate in your pictures, I don't see anything yet to keep the bottom of the plate from moving toward the base when a rearward force is placed on the column. You will probably want a wedge or other means in the space between the plate and base to keep the plate from moving. Additionally, as I'm sure you are aware, as you tighten those two bolts on the pressure plate you will be tilting the top of the column backwards, thus affecting your Y-axis alignment. I added those two middle bolts in threaded holes in my plate so they would butt up against the base and keep the bottom of the plate from moving inward, and also as a means to align the column in the Y-axis.

Hope this helps. Please keep us informed of your progress and findings.

Regards,
Rudy


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## matabo

rudydubya  said:
			
		

> E Also, as he says, you will be concerned about flexing with a rearward force on the column. As I look at your plate in your pictures, I don't see anything yet to keep the bottom of the plate from moving toward the base when a rearward force is placed on the column.



Of course, my plate assembly was incomplete. But I did want to check it as soon as possible.
But I don't think that the absence of the two central bolts would change the results I got.

I'll try to use a spring scale and I want to try different arrangements (the pics and links on the Hoss site are a gold mine): ie, angle plate, U profiles and similar.

Thank you.


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## Jared

black85vette  said:
			
		

> In looking at the design of the mill the weak link looked like the way the column was mounted. When you get down to it the entire column is supported on about a 2" base bolted down which is just not wide enough to do the job properly. My opinion is that most of the flex occurs here and not in the vertical column. Along that same thought; the mount has its bolts to the front of the machine. I would expect more flex of the unbolted back side, so putting weight to the front of the column is measuring the weak side of an already weak mount.



I haven't taken a close look at mine beyond noticing it seems kinda flimsy, but it seems there could be some sort of re-design of the column-tilt-to-base piece. And while he's at it, a guy might be able to mount the column a little higher and gain more Z travel.


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## black85vette

When I started my post it was focused on the tram adjustment itself. The rigidity of the column was actually secondary. I ended up doing the plate on the rear and incorporated the adjusting bolt at the bottom to help with the Y axis tram.

http://www.homemodelenginemachinist.com/index.php?topic=7098.0


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## websterz

rudydubya  said:
			
		

> Emanuele, please accept my belated welcome to the forum, pardon my delay in responding, I appreciate your interest in my post.
> 
> I don't know why you didn't see some improvement when you added the plate, I would have expected to see some. Could there be some slipping or bending of your clamp setup when you apply the weight of the toolbox? Did you try pushing or pulling directly on the top of the column and noting the deflection before and after the plate? In John Pitkin's writeup, he used a spring scale hooked at the top of the column so he could apply a desired force and measure the resulting deflection. I don't know if you would want to try that or not, but it would be a way to ensure the bending force was applied directly to the top of the column with accuracy and repeatability. I should have done it that way. Instead, I flexed the column with a "firm" push and pull with my hand at the top of the column, with the motor and head still attached. Sorry I can't quantify "firm" in terms of a weight or force, but it was probably much more than your tool box. My push and pull were somewhere between a nudge and a grunt. ;D My flexure measurements were taken from the spindle to the table, similar to the picture below.
> 
> 
> 
> 
> I was able to reduce the flex to around 0.0015 inches, about 15 percent of what it was before I started. If I wanted to _*REALLY*_ push on the column I could probably at least double that.
> 
> Another major factor in the rigidity of the un-modified mill may be the amount of compression of the Belleville washer. I don't have any measurements of how much my Belleville was initially compressed. I tend to be conservative when I'm tightening bolts. More compression may be better.
> 
> To follow up on black85vette's post above, I think he's right about the ultimate rigidity of the mill being limited by the column mounting. I think most of the remaining flex in my machine is in the bolt and mount that holds the column to the base, so without a major modification to the mounting there will always be some flex. Also, as he says, you will be concerned about flexing with a rearward force on the column. As I look at your plate in your pictures, I don't see anything yet to keep the bottom of the plate from moving toward the base when a rearward force is placed on the column. You will probably want a wedge or other means in the space between the plate and base to keep the plate from moving. Additionally, as I'm sure you are aware, as you tighten those two bolts on the pressure plate you will be tilting the top of the column backwards, thus affecting your Y-axis alignment. I added those two middle bolts in threaded holes in my plate so they would butt up against the base and keep the bottom of the plate from moving inward, and also as a means to align the column in the Y-axis.
> 
> Hope this helps. Please keep us informed of your progress and findings.
> 
> Regards,
> Rudy



Hey Rudy, can we get some close-ups of your indicator holder? Is it shop made? I need one of those!


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## prof65

http://www.littlemachineshop.com/products/product_view.php?ProductID=1251&category=

bought one six months ago, I don't like it because it can't holds the indicator firmly.


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## rudydubya

Greetings websterz, yes, bought it from LMS, see the link above from prof65. I haven't had any problem with it not holding my indicator firmly, but do have to unscrew the plastic cap on the end of the clamping screw a little to get it to clamp tight on the spindle. Been thinking of replacing the clamping screw with a longer version...

Rudy


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## Lasseah

Hi all
I'm new to this forum and taught I try to post some pictures of my X2 mods.

Here is my take on the stabilisation of the X2 column.

I didn't find a 24mm drill for the hole for big bolt in the back, but milling the hole on the rotary table worked as well, just took a little longer time.






Here is the finished modification. My intention is, when tramming the head in x direction, to first tighten the small bolt at the top then tighten the big nut. This is to prevent the column to tilt when the big nut is tighten.






Here is the modification from the side. Also my way of stabilisation the head/column while unscrewing the big nut.
I have only done a very unscientific test so far, putting a Dial Gauge in the spindle and pushing hard with one finger on the top of the column.
This gave that the flex was about half the reading after the mod. I will try this test again without the Belleville washer to see how much flex is from this washer







I have also converted my mill with the Serling steel belt drive kit.
But you might see that I have made my own, smaller primary pulley, to get some torque back.
Much needed especially when drilling.






regards
Lars


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## black85vette

Lars;

Nice looking job. Slot on the plate is a great addition. Thm:


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## New_Guy

wow that is a great idea nice work on it and thanks for posting it Thm:


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## rudydubya

Very nice work Lars, thanks for sharing the ideas and pictures, and welcome to the forum. Would love to see or hear more about your shop and equipment and your interests in the hobby. There is a welcome section in the forum if you would like to introduce yourself to the forum members.

Regards,
Rudy


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## Goldigger

rudydubya  said:
			
		

> After I finished the spindle-column alignment on my Harbor Freight mini-mill (http://www.homemodelenginemachinist.com/index.php?topic=6007.0), I still didn't get a good tram in the Y-axis. It measured about .004 (all my measurements are in inches) out of alignment, as if the column was tilted to the front just a tad. I also had a significant flex in the column. With a firm push or pull on the motor or top of the column in the Y-direction, I could get almost +/- .010 (2.5 tads) of up and down movement of the spindle relative to the table. I wanted to fix, or at least reduce, the flex, and planned on correcting the column-table alignment while I was at it.
> 
> From what I had read about the column flex, the consensus was that the major cause was that big Belleville washer under the big nut at the back of the column (with maybe some compression of the column wall under the washer thrown in), and by replacing the washer with a flat plate you could reduce the flex. Some folks added angle brackets and braces to the plate to make the column even more rigid. I decided on a simple flat steel plate bolted to the back of the column to replace the washer and act as a reinforcement up the column axis.
> 
> 
> 
> 
> 
> 
> I made a column reinforcing plate (hereafter called a column plate) out of 3/4" thick, 4" wide steel, and drilled holes for some 3/8" bolts plus one 15/16" hole for the big pivot shaft. I used the center of the plate as a reference to locate the bolt holes. Most of you probably know I shouldn't have. *The pivot shaft is not on the centerline of the column.* It *is* centered on the ways, but the ways are shifted over about 1/4" on the gib side of the column. I never noticed it before. Must be a lesson in there somewhere. Anyway, my hole locations were far enough in from the sides of the plate to still work on the column, it's just a little off-center.
> 
> 
> 
> 
> 
> 
> I match-drilled holes for the bolts into the back of the column, tapped them for 3/8" threads, and bolted the plate to the column. The flex was reduced to less than half of what it was, now about +/- .004, but still more than I wanted, and I hadn't fixed the Y-axis tram yet either.
> 
> 
> 
> 
> 
> 
> I drilled four holes in a piece of 1/2" thick, 1" wide steel, one at each end for 3/8" bolts, and two near the center for 7/16" bolts. The end holes were far enough apart to clear the edges of the column plate. This would be a pressure plate to push on the bottom of the column plate.
> 
> 
> 
> 
> 
> 
> I drilled and tapped holes into the base of the mill itself to match the 3/8" outside holes in the pressure plate, and drilled and tapped through the column plate only for the 7/16" holes, not into be base.
> 
> 
> 
> 
> 
> 
> I bolted the pressure plate to the base of the mill with the outside bolts and tightened them until the column was pulled in enough to tilt the column back and eliminate the .004 Y-axis tram error. I then inserted 7/16" bolts through the center holes and screwed them through the column plate until they were snug against the mill base. With the end bolts pulling on the column, and the middle bolts pushing on the column, the bottom of the column was locked in place and the flex was reduced to about +/- .0015.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Some final notes:
> 
> With the bolts in place, I can no longer rotate the column side-to-side to mill at an angle. I have never used that feature anyway, so it was not a concern to me. Also, my mill was trammed in the X-axis to my satisfaction before I drilled the holes at the bottom of the column plate, but I left plenty of clearance around the 7/16" bolts in the pressure plate to allow some slight angle adjustment for tramming, if necessary.
> 
> My mini-mill Y-axis alignment required the bottom of the column to be pulled in toward the base, so the 3/8" outside bolts were tightened first, as evenly as possible to avoid any twist. Then the inside 7/16" bolts were screwed in just tight enough to eliminate any flex. If the required correction was the other way, the center bolts would need to be screwed in first, pushing the bottom of the column away from the base, and then the outside bolts tightened to eliminate any flex.
> 
> If I were to do this mod over, I would use a thinner column plate, say 5/8" or 1/2" so the big nut would be sure to grab all of the pivot shaft threads. The 3/4" plate I used just barely allows that. Also, my plate was 12" long. If I were planning to fit my mill with an air spring kit like the one sold by Little Machine Shop, I would shorten to column plate to maybe 10" long so it wouldn't be in the way of the hole in the column required by the kit.
> 
> The remaining minor flex in the column assembly is probably due to bending of the pivot shaft and/or the pivot plate. I couldn't think of any practical way to eliminate it entirely.
> 
> Drilling into your mill might void any existing warranties. I never had an extended warranty on my mill, so it wasn't a concern.
> 
> I think that's about it, thanks for reading.
> 
> Rudy



Hi I know this is a old thread, I have a Sieg SX2 and want to stiffen up the column. 
I know my tram is out on my Y axis as when feed ali into the cutter away from myself the front edge of the cutter is cutting more than the rear. I've also measured it roughly when i trammed the X axis.
If i swing a dial indicator from one side of the front of the table to the other so that it touches, then move the DTI to the rear of the table it doesn't touch.
So before i start shimming the Y axis i need to sort the flex out in the column.
Can i just use a piece of black steel flat bar for the rear plate?
http://cgi.ebay.co.uk/Black-Flat-St..._Metalworking_Supplies_ET&hash=item43a57f8e0f

Do i need to machine the plate surface or can it just be slapped on as is?

Thanks


----------



## rudydubya

Goldigger, welcome to the forum. It does sound like your Y-axis is a bit out of tram. Not unusual with the Sieg X2 family of machines, from what I've read.

I'm not familiar with black steel, but the steel plate I used was nothing special, just some cold-rolled I had left over from making flywheels. I think most any good steel plate would work. I've read about some folks that just used angle iron. But if you need confirmation, maybe one of the members familiar with the material could offer an opinion if you posted a question in the questions and answers or metals forum.

If your SX2's column is identical to my X2, then a 100mm by 15mm bar sounds about right. Mine was thicker, but as I mentioned, I should have used a somewhat thinner plate to ensure the nut could get a good grab on the pivot bolt.

I didn't do any machining on the plate. I looked at it, and it didn't appear to be warped or twisted when I laid it down flat on my workbench, so I used it as it was.

Good luck with your mod, and keep us informed on your progress. When you get time, tell us a little about yourself and your interests and machines in the welcome forum. And you know we like pictures.

Regards,
Rudy


----------



## Goldigger

Hi Rudy,
Thanks for your reply, ill introduce myself in the welcome fourm.
I'll also update this thread when i have modded the column. Im 99% sure my SX2 is the same column and base as the X2, the only differences are:
500w brushless motor
Belt drive
varible speed rather than some of the X2's that had a 2 speed box.


----------



## TroyO

You will not regret the effort to do it.... this mod makes HUGE differences in the cuts you can make.


----------



## Goldigger

I hope so, its quiet annoying when the head starts to shake when using a 16mm end mill and plunge milling..


----------



## Goldigger

Finished my back plate today(120mm wide 300mm high 12mm thick), had to mill the surface that is in contact with the back of the column. Not the best finish but at least its flatter than it was to start with.
Snapped a drill bit drilling one of the holes! which has cost me a few end mills trying to get the bugger out!





Didnt make a brace bar like some of you did, as you can see i drilled my first set of holes in the wrong place! I used some M8 threaded studding, put a washer and nut in between the back plate and base. Tightened this nut up against the base, then tightened the nuts that pull the back plate back in in equal increments.
The holes in the steel plate that the M8 studs go through, i drilled 1mm larger so i've got so play for adjustment when tramming.





Thanks for the ideas guys, just need to tram it and maybe shim it for the y axis.

edit:
Turned the nuts around inbetween the backplate and base. nip up the outside ones equally and then tighten the inside nuts up nice and tight, then tighten the outside ones up again.

should i use the bottom nuts to adjust the Y tram? Or should i just shim the spindle housing if needs be?


----------



## Goldigger

Ok, I'm confused..
Put a DTI on a holder in the chuck swang it round so it was on the right side front of the table. Took the reading, swung it round to the left side front of the table. Carried on and moved the column untill they both matched left and right. So X axis is trammed and is only out by 0.01mm, I'm happy with that.
So then i swung the dti to the right side back of the table, its out by 0.014mm compared to the front. Roughly the same on both sides..
So my table is higher at the front compared to the back of the table in relation to the spindle. (Forward tilt) 
So if i tighten the nuts at the bottom on the steel plate to pull the colomn in and in theory level the head to the table...so tighten it so that i move the DTI 0.07mm.
Measure the front of the table and rear, still out by 0.14mm ???


----------



## rudydubya

Goldigger, sorry for missing your last posts. I've been away from the computer for a few days. Nice job on the back plate. Like you, I use the bottom bolts of my mod to adjust the Y-axis tram. Sorry if you're still having problems getting your Y-axis trammed. Here is my understanding of the tramming situation when using the bolts at the bottom of the back plate. It's a bit hard for me to describe, others probably could do better.

As you adjust the nuts and bolts at the bottom of that back plate to tilt the column forward or back in the Y-direction, the column's pivot point is not at the center of the spindle. It's somewhere between the back of the column and table, and when you change the tilt of the column, you change the overall distance from the spindle to the table, both front and back. So when you tighten those nuts at the bottom of the column, the measurement from the spindle to the back of the table will change, but the measurement from the spindle to the front of the table will change too, in the _*same*_ direction, but not quite by the same amount. The tram error, the difference between the readings, should actually be a little less. Eventually, after several adjustments and measurements, the difference should go away. It took me a bunch of adjustments and measurements before I got the error reduced to my satisfaction, and it should work for you too.

At least, that's what I think may be happening to your measurements. If I've made a complete mess of the explanation, let me know, and maybe I can re-word it or answer any questions.

Hope this helps.
Rudy


----------



## Goldigger

Ok, i trammed it up yesterday evening and got the x to 0.1mm and the y is 0.2mm thats good enough for me 
Now i get cuts with curves in both directions (((((()))))) rather than one (((((((((((((((((((

I assume that means my cutter is sitting flat now.

Cheers


----------



## Goldigger

I was looking on arceuro Trade last night and came accross this..
http://www.arceurotrade.co.uk/Catal...ies/Milling-Machines/Model-Super-X2-Plus-Mill
They are using the X1's table, also done away with the tilting column and had there own casting made so that the column fixes directly to the base..


----------



## lazylathe

I saw that a while ago on MadModder site.
Quite a few comments on there about it.

I have also tried the column stiffening but had a bit of an issue.
Did post it in another area but it seems to have been missed, so i will ask here if that is okay.

On my SX2L the column is set in a bit from the base of the milling machine.
I had to mill out a section of the stiffening plate in order to get it to sit flush against the column.
Anyone else have a machine built like this?
This problem lead to me not being able to have the adjustment bolts on the bottom of the plate.
So i had to shim the head a lot to get it close to being acceptable.

I will take some pics tonight when i get a chance.

Andrew


----------



## TroyO

Lazylathe, I think I may have seen that post but wasn't sure how to reply, so I didn't. ;-) Pics would help greatly... I have the "plain ole" X2, so I'd guess the SX2 is set up a little different... perhaps in an effort to stiffen up the column on the new design?


----------



## Goldigger

I have the SX2, which structurly is the same as the X2. He has the SX2L which has longer travel on the Y axis..i think its 130mm vs our 100mm


----------



## B-RAD

This is a great thread to "bump" It's a necessary mod for sure.

Also here is how I did my column brace- http://www.homemodelenginemachinist.com/index.php?topic=15848.msg162130#msg162130


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## Max762

prof65 said:


> http://www.littlemachineshop.com/products/product_view.php?ProductID=1251&category=
> 
> bought one six months ago, I don't like it because it can't holds the indicator firmly.



Is this one any better?

http://www.littlemachineshop.com/products/product_view.php?ProductID=3771&category=


----------



## SwarfMuncher

I know this thread is rather dated, but I wanted to thank the OP for sharing this information. After looking over a lot of ways to do column stiffening I have chosen to use the method around which this thread was written.


----------



## rudydubya

I'm glad you found the threads useful SwarfMuncher.  Good luck with your project.

Regards,
Rudy


----------



## Fabrickator

I have an LMS High Torque Mini Mill and have experienced some chatter when doing some heavy slot milling in steel, restricting my cuts to no more than .020" per pass.

I've researched all of the threads on this subject (ad infinitum!) and have settled on using a piece of 4" wide steel channel. I've already cut my pieces and squared them up on the mill before taking it out of commission. It will have 2 M6 bolts in the top under the control box, I have one M8 in the middle from the air-spring conversion, the 1" swivel bolt w/no bellville washer.  There are two M8 bolts into the base to prevent Y flex and another two pieces of angle iron, one bolted on each side of the column and into the base using M6 bolts for further support and to prevent twist. I'm making all of the pieces and bolting them on, and then tack welding them in place.  I'll remove the single bracket and do a bit more welding being cautious to prevent any warpage, paint and bolt it back on.  If there is any problem with re-tramming, I plan on using shims to dial it in.  It will lose the ability to use the tilt function, but I never used it anyway.

As far as actually filling the column, I believe that it wouldn't be worth the trouble, especially because my air spring runs half way down the center of it.  As someone else said in one of the threads, doing any more than this and the table becomes the weak point.

I should have it done for Monday pics.


----------



## SilverSanJuan

I'm very interested in seeing what you've done.  I've experienced the same chatter, and need to stiffen up my column as well.

Todd


----------



## SwarfMuncher

You'll be glad you did! Adding a stiffener to my Sieg X2 was one of the best modifications it has seen, and is allowing me to do much more agressive milling. Like cutting T slots in the 6" table plate I made to sit atop my 3" Grizzly Rotary Table. I can now easily mill 0.050" cuts in steel with fairly large mills, and it runs smoothly and relatively quietly - doesn't sound/act like it is going to explode. 

Only when I use a 1" end mill do I need to cut back to about 0.040" depth in steel now as my preferred maximum. I am sure it could do more, but I don't like to push it that hard. 

In 6061 aluminum I easily milled 0.1" deep with a 3/8 end mill during testing. I should mention that in this project I also aligned the head vertically with the column, and corrected the forward "droop" of the spindle so common to these machines. It is now trammed in all directions to within less than 1 mil. Good Luck!


----------



## zoltan

I pondered all the various methods to increase the stiffness of the column and the column/table interface. Then I went out and bought the LMS solid column upgrade:
http://www.littlemachineshop.com/products/product_view.php?ProductID=4483

With the necessary feed screw as well, it cost me $200 plus shipping. I couldn't be happier with it. The column now bolts to the table solidly with 4 M8 bolts, and I gained some Y travel as well. The new column also has thicker walls than the tilting column so it heavier and stiffer as well.

With the new column and table I was also able to implement a little project I'd been considering for a while:
http://benchtopmachineshop.blogspot.com/2014/04/mill-column-tuning-device.html


----------



## SwarfMuncher

I am curious if, with the solid column upgrade, you still found the forward head "droop" of several mils common to the stock X2? The modification you linked to at the bottom of your post shows dual turnbuckles, one of which is to deal with that droop. 

I had not seen it done, but got the idea to make a turnbuckle just like those, although I made mine shorter. It is mounted on the left side between the column and base, and I use it for fine adjustment when tramming along the X axis. It also holds the column from falling over, even when I have the pivot bolt nut completely removed. I put the turnbuckle on about a year before I did the stiffener plate mentioned above. 

For those not wanting to delve into turning LH thread, the components to make said turnbuckle are readily available to assemble one, including the ball ends, with LH and RH thread, both LH and RH thread female inserts for steel tube, and the steel tube to bring it all together. I welded a nut on the outside of the tube so I can turn mine with a wrench, but it actually turns very easily by hand. 

I ordered all these components from PitstopUSA.com. Mounting the threaded tube ends into the Chrome Moly tube did require some Mig welding. But there might be other ways to do it (like permanent Loctite?).


----------



## zoltan

Between shimming the solid column and modifying the gibs I was able to get rid of the droop. The turnbuckles are there to adjust it that fine 0.001-0.002" that I can't get rid of with shims. 

If you have a mini lathe (or any lathe with a reverse) there's no to be afraid of doing LH threads.


----------



## Fabrickator

I guess I forgot to post my pics as promised.

If you read my plan above, I deviated from it in the fact that I decided it didn't need the angle brkts on top of the base and bolted to the sides of the column. Simply overkill.  I also left the holes a little bit oversize in the lower base brkt for some X adjustment.  The lower brkt was tacked in place and then removed and welded on the backside. I checked it for square, painted and installed it.

I trammed my column right up with no problems within .001" over a 12" span (X axis), which is more than good enough.  The Y axis was right on the money, I would've used shims if necessary. There is no give or "droop" on the top of the column when I push it.  The main problems were no rear/bottom support to the base (resolved) and the bellvue washer (resolved).

I can easily make .100" cuts in aluminum (2-flute) and .050" in steel (4-flute) with no chatter or other negative objections w/o using roughing bits.  The one thing that may help is my power feed. It's sooo much more stable when cutting than trying to maintain a smooth hand wheel. Total, smooth control from 0 to Fast.  Heck, I set it-and have a sip of sweet tea, take a leak or look over the plans and such while keeping an eye on it. *beer*


----------



## SilverSanJuan

Thanks for pics!  That looks like a good/simple fix.

Todd


----------



## SwarfMuncher

zoltan said:


> Between shimming the solid column and modifying the gibs I was able to get rid of the droop. The turnbuckles are there to adjust it that fine 0.001-0.002" that I can't get rid of with shims.
> 
> If you have a mini lathe (or any lathe with a reverse) there's no to be afraid of doing LH threads.



Honestly I've never tried LH threads. But I guess it would work the same way. Threading was the first thing I taught myself on my mini-lathe. But I also have yet to try internal threading. For that I normally use a tap. After learning about "fast spiral" taps, I fell in love with them and never looked back. Now I hate using a regular tap.


----------



## SwarfMuncher

Nice work, Fabrickator!


----------



## Bison9

Rudydubya (and all), great thread!

So, I recently purchased the Harbor Freight 4491 Seig X2 mini mill. I am going to outfit it with the mod in this thread.

I am looking for a 1/2" x 4" x 10" steel plate like what has been recommended in this thread and I am struggling to say the least here..

The closest I have found is here: http://www.ebay.com/itm/Cold-Rolled...148?pt=LH_DefaultDomain_0&hash=item27b9b1938c

and then at speedy metals I found like this: http://www.speedymetals.com/pc-2684-8244-00478-cold-rolled-steel-sheet.aspx

Both items I would have to cut down to size. I ideally would like a sheet in the exact dimensions I am looking for. 

Does anybody have any ideas about where I should look for this? 

Thanks in advance for any replies! Great site and thread!


----------



## SilverSanJuan

Try this here:  http://www.onlinemetals.com/merchant.cfm?pid=7511&step=4&showunits=inches&id=199&top_cat=197

You can specify a 10" length.

Todd


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## SwarfMuncher

Or you can try this:

http://www.industrialmetalsales.com...1-2-x-4-x-12-1840-CF1018SteelFlat500x4x12.htm

If you email or call them they will cut it to any length you like. In fact they will sell you pretty much any dimension of the metals they carry. They are in Mount Clemens, Michigan. 

I've ordered several times from either of these 2 companies and would recommend them.


----------



## Swifty

If you hunt around you can find company's that will flame cut the plate from large sheets for you, they will even grind each side for you if you desire. They use black plate, so grinding will remove the scale, this is how we always ordered steel plate at work, sizes up to 100mm thick were regular orders.

These company's are usually happy to do a small job for cash, gives them some pocket money.

Paul.


----------



## rudydubya

Bison9, congratulations on your new mill.  As for the 1/2" x 4" x 10" steel, here it is at Speedy Metals, you can buy it by the inch if you don't need a foot.
http://www.speedymetals.com/pc-481-8213-12-x-4-cold-finished-1018.aspx

Have fun,
Rudy


----------



## zoltan

Bison9 said:


> Rudydubya (and all), great thread!
> 
> So, I recently purchased the Harbor Freight 4491 Seig X2 mini mill. I am going to outfit it with the mod in this thread.
> 
> I am looking for a 1/2" x 4" x 10" steel plate like what has been recommended in this thread and I am struggling to say the least here..
> 
> The closest I have found is here: http://www.ebay.com/itm/Cold-Rolled...148?pt=LH_DefaultDomain_0&hash=item27b9b1938c
> 
> and then at speedy metals I found like this: http://www.speedymetals.com/pc-2684-8244-00478-cold-rolled-steel-sheet.aspx
> 
> Both items I would have to cut down to size. I ideally would like a sheet in the exact dimensions I am looking for.
> 
> Does anybody have any ideas about where I should look for this?
> 
> Thanks in advance for any replies! Great site and thread!



If you can at all afford it, buy the solid column upgrade from Little Machine Shop. It works better than any column stiffening setup, and it's much, much harder to knock out a tram.


----------



## Bison9

Hey all, so I got stoooooopid busy right after this post I made above right around the 4th of July and literally dropped any work whatsoever on my mini mill  I just recently picked it back up again. I did the belt drive conversion on my mill the other night. I used this one:

http://www.littlemachineshop.com/products/product_view.php?ProductID=2560

As a totally side note, after this belt drive conversion, it looks like my machine in general has some pretty crazy runout. Actually though, the bolt end of the drawbar looks worse in terms of runout than the actual chuck side, but it looks like runout to me just eyeing it even without any measuring tools. Anybody see this at all ever with this? 

I didn't have the drawbar cover off from before the conversion when I was running it without the Belt Drive. So I have no comparison here really from before the conversion to now after the conversion. So, anybody know what is an acceptable amount of runout on that mill spindle? I am hoping it is the chuck and not the mill that has the runout but I am a newbie at all this still (even after like 30 hours of reading online about all this stuff!). I will be actually measuring the runout on it soon anyways with a Dial Indicator so we shall see soon!

So, down to the business at hand:

Rudydubya, thanks for the link above!

Zoltan, great post too! You have me curious now also... Do you have a link to this column mod then from littlemachineshop? I will look at that site again to see if I can find it.

Thanks everybody for your responses. I am going to be scratching out these 80% lowers that have been collecting dust for a year and a half now. I hope to be taking cut number 1 sooner than later!


----------



## Bison9

So, doing a simple google search, I think this is the mod?:

http://littlemachineshop.com/products/product_view.php?ProductID=4483&category=1311958022

Now, it says at the bottom of this link: 

The Solid Column Conversion Kit can be used with older (X2) mini mills with the addition of one part: the Y-axis Feed Screw. Be sure to choose the correct one for you mini mill. Micro-Mark mills need the 20 TPI Y-axis Feed Screw, while mini mills from Grizzly, Harbor Freight and other suppliers need the 16 TPI Y-axis Feed Screw.

So, that Y axis feed screw is here:

http://littlemachineshop.com/4031

So Question for you all then: Do I need to get this feed screw new at this link in order to use this conversion? Or can I use the one on my current mill now with this column mod upgrade and just swap it out with this new base?

Other questions I have too then:

1.) Can I use my existing Z and Y axis gibs on this new column in the mod then?

2.) What if my X axis tram is off on this new column? Will these directions possibly include how to adjust the X and Y axis tram then if it needs it?

Sorry for the questions, I want to know if dumping $200 into this is worth it. It definitely has tweaked my interest!


----------



## bazmak

Hi,i have just bought a fixed column model with belt drive and so
avoided all the expense and hassle.I dont understand why they
still make the swivel column ????


----------



## Bison9

Yeah, I would have totally done this too had I known...

I found a crap to of info here also:

http://www.cnczone.com/forums/benchtop-machines/159839-lms-solid-column-conversion-kit-make-big.html

Pretty much answers all of my questions... I am assuming with the fixed base you would use shims if you were out of whack on the tram in either the X or Y axises...

Had I known, I would have gone right to the solid base model and then upgraded to the large table right away too... That is also up there on the littlemachine shop here as well:

http://littlemachineshop.com/products/product_view.php?ProductID=3677&category=-269978449

I thought I had literally researched everything on the topic of mini mills but alas, I am learning more!

After reading for the past hour or so already, I will most likely end up going with the Column sturdying mod. You then do, in fact, need to buy the new Y axis lead screw (per the link I posted above - that's if you are doing like me and fitting this all to the X2 Harbor Freight mill - model 44991). And then, I am thinking strongly about the air spring conversion and the large table because after all, go big, or go home is my motto.... All in all, I paid $500.00 for my new 44991 X2 Harbor Freight Mill back in May and I will be paying upwards of this at least if I go in to what I just listed...

I am a complete newbie though yet when it comes to all this stuff. But I don't do projects and stuff like this without quality machinery and quality knowledge of what I am doing... When I say newbie though, I have never drilled and tapped before either. I am learning this as I go as well. I have some beautiful IGaging DROs all ready to go for this mini mill and have to learn how to drill and tap and whatnot to even put these on.... I have literally been all over town trying to find scrap pieces of cast iron like the one on my mini mill to practice drilling and tapping with absolutely no luck whatsoever finding this. 

All I know about machining at the moment is from the 30 hours or so I have read on the matter online. It is all theory in my brain at the moment. Past this, I know 0 so this whole experience has been very eye opening for me...

Now if I ditch the old stuff on my Harbor Freight X2 and go with these mods I discussed above, I now have the scraps I want for testing so that's a plus. Honestly, $500.00 here to basically teach myself stuff... That's basically like paying for a couple credits at some college to learn so go me I guess


----------



## Bison9

***The thing that really bothers me at the moment however on my whole setup is the perceived runout I think I have on the spindle/quill of this machine that I only noticed when the drawbar cover is removed from the top of the mill head (as you remove this cover doing the belt drive conversion)... 

Its like I can see the runout on the bolt side of the drawbar and not so much on the chuck side (this is good I would think!). It drives me nuts though watching that bolt and seeing like what looks like runout and not a true spin...

Can somebody address this for me? I sure hope it isn't the belt drive conversion giving me this... I guess only time will tell as I will be testing the runout soon anyways with an actual dial indicator... I just don't want to drop another $500.00 here only to find that my main issue is .1" runout at the spindle LOL :fan::rant:


----------



## Fabrickator

I see drawbar runout too, but it has nothing to do with the chuck/spindle.  That's the "business side" of the mill.

LMS High Torque


----------



## zoltan

Let me see if I can answer your questions.

1. Yes, that's the kit. It's an amazing deal for the price.

2. You don't NEED the new Y leadscrew, but if you don't have it then you can't run the table all the way to the column. 
2a. If you buy the large table upgrade (it's a nice mod but not necessary) then it comes with the longer Y leadscrew.

3. You reuse your gibs.

4. To tram the column you use shims. Personally I buy cheap sets of feeler gauges and then cut them up as necessary to make shims; cheap, easy, and accurate. I usually use feeler gauges side by side to get max coverage on the mating surfaces. 
4a. I also upgraded the mounting bolts from the stock ones to longer socket cap bolts. The more threads you can engage in the base (without bottoming in the hole) the better.

5. Don't worry about the percieved runout from the top of the drawbar. It's not a precision piece and it's normal. 

I know a lot of people will say upgrading an X2 isn't worth it. I see their point, but for me it was worth every penny. I don't have the space for a larger machine, and the work I do is usually rather small. So for me spending some money to make my mill nicer to use was definitely worth it, and my mods really do make it a much more enjoyable experience for me. You may want to check out my blog to see the other mods I've done, there are a couple in there I think you'd like: http://benchtopmachineshop.blogspot.com/

Also, if you haven't done it yet, doing the TouchDRO upgrade is by far the best bang for your buck. You essentially mate cheap iGaging digital scales to an Android tablet to create a very powerful and easy to use DRO for your mill. More info here: http://www.yuriystoys.com/


----------



## Bison9

Thanks Zoltan!

I just got done ordering the Solid Column Kit from LMS. Can't wait till it gets here!


----------



## SmithDoor

Have try a overarm 
 This will stop most flex in mills


----------



## zoltan

Bison9 said:


> Thanks Zoltan!
> 
> I just got done ordering the Solid Column Kit from LMS. Can't wait till it gets here!



Has it arrived yet?


----------



## Bison9

It did. And it did! 

She has arrived and I pretty much converted the necessary parts of my X2 to this Solid Column.

A couple notes on this:

1.) Dang, the thing is way more sturdy than the X2 column. Its just beefier.

2.) I followed pretty much what this guy did: http://robertsprojects.blogspot.com/2013/04/mini-mill-solid-column-conversion.html to convert my X2 over to this Solid Column. All went pretty well except for the below:

3.) I put the Air Spring conversion for the X2 (https://littlemachineshop.com/products/product_view.php?ProductID=2258&category= ) on this Solid Column kit... I tried the recommendation on the 4th post at this link for where to put the air spring hole on the back of the column: http://www.homemodelenginemachinist.com/showthread.php?t=6416&page=3 DO NOT FOLLOW THIS. It is just false. This method put my hole at about the 12 inch mark on the back of the column. However, the directions right from LMS with the air spring say to put the hole 15 inches down. My first hole (done by following the link) came out not allowing the head of the mill to go down even close to where it should be at the lower limit. The 15 inch hole that LMS recommended was correct and I have full motion now with the air spring. The reason I didn't go with the LMS directions at first for this hole is because I wasn't sure if this Solid Column kit was a different dimension than the X2 column... But alas, it was.. what did one guy call it? Mindless hand wringing here...  Stick with the 15 inch recommendation from LMS on this for that Air Spring hole in the column...

4.) I was out .004 on my X axis tram right away when I tested it... I have another thread going here on this: http://www.homemodelenginemachinist.com/showthread.php?t=23631. The interesting note here on this is: I first put in a .002 shim on the base to column mating surface (half the distance I was out of tram) and this left me with a .002 difference still on my next tram test. I went up to the .004 shim and I am dead on now with my tram. I did this out to the ends of the table and then took the tram so my sweep only went the length of the column (so like 4 inches between tram points) and I was spot on here as well. So, methinks the whole idea of putting in a shim half the size of the amount you are out of tram is a complete falsity to be honest... The tramming method I used was this one: http://www.machinistblog.com/how-i-tram-my-mini-mill/. But, what I did is take a 3/4" rod, put a 1/2" hole in it, and put a 1/2" x 8" cross bar in that hole to hold my dial indictor. I locked this bar down with a set screw like from the link. I tried with the cross bar the guy had in this article and the thing just moved too much in the whole system and I did not like this in the least. So, this bracket I made instead with a fixed 1/2" rod is kick arse - my Dial Indicator is fixtured basically to the end of the 1/2" rod and makes a very nice tramming bracket... There is literally 0 movement in the tramming bracket as a whole and gives the accuracy I was looking for.

5.) **A possible concern I still have is that the whole reason I went with this solid column kit is because of all the not favorable stuff I read about the column not being rigid on the X2's swivel base. I had read guys being out on their Y tram .003 - .006 right out the box with the X2 column. And hence, you see all these column firming mods going on and whatnot to remedy this... Well... The funny thing is I did a quick Y tram (Pitch) test last night on this new Solid Column setup and it looks like I am out .003 on this dawg as well out the box (and yes, I did the spindle to column tramming as well before all this and the differences there were negligible and I didn't make any adjustments). On that little X2 table that's .003 over like 2 inches on the Y side of things... So, into head scratching mode I went again... I can push my finger on that column and can move it as well like guys report with the X2 column so not real sure. I am going to throw an appropriate shim in on the Y side of things, 0 it all out, and crash into these AR15 80% lowers very, very soon. But, it still looks like there could be flex with this setup too unfortunately... Will it matter for an AR15 80% lower? Most likely not from what I have read...

That's where life stands with me on this mill at the present time!

Thanks for all the replies!


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## zoltan

There is flex is ANY mill. Going with the solid column only reduced it, not eliminated it.

I had to tram my column in both X and Y. Also, don't forget you need to tram the mill's head first.

There is also some play in the gibs as they're configured from the factory. On my mill I marked all the gib locations using set screws turned to points, then I milled a 55* flat at each location. I then reassembled everything using cup point set screws. I threw away the locking nuts on the set screws and used green Loctite instead (it's designed for set screws). This setup eliminated almost all the play in the gibs and also allows them to slide with less friction.


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## zoltan

Any updates?


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## Bison9

The thing was just a beast (the solid column kit that is). I scratched out my 4 80% AR15 lower receivers in no time... Everybody calls me crazy all the time for driving to get the answers to this stuff and this pays off every time. I had all the bugs chased out before starting the project...

I outfitted the mill with the solid column kit (using the methods I posted a couple posts ago), put the air spring on it, the belt drive conversion, and outfitted it with those IGuaging DROs... Thing ran like butter...

Now I am in full on finishing mode on these receivers... I dumped a month into researching anodization only to find that 7075 aluminum anodizes like poop... Completely scratched that idea right off the list... I now am going about getting a 60 gallon Quincy air compressor, a media blasting hood, some 120 grit AL Oxide, and some Cerakote!! Oh yeah!!!

Oh, and one more thing, for all you noobs like me who stumbled across this post, if you want to do your AR15 80% lowers right on this mill setup that I have, you need to do yourself a favor and watch this video (and order the darn jig too!): [ame]http://www.youtube.com/watch?v=ZKz2sLJUvGU[/ame]

And, this is the end mill in the JTactical tooling package (I found that end mill online finally): http://www.discount-tools.com/endmills/ful-3873.cfm

Its the fourth one down in that link. It took me half a day to find this online as a 2.5 inch overall length with a .5 inch cutting length (in the 3/8 diam) is all but impossible to find...

I crash and burned this one from the JTactical tooling package and didn't want to spend another $75.00 just for that one end mill... So I spent another $40.00 for just the end mill at that link LOLOLOLOLOL... But that darn end mill is better than the 14 other poop endmills I bought from Enco and tried...

No, I do not work for JTactical... Their jig and tooling is just flat out the bomb... I had the jig and tooling from billet80.com as well and those were far less superior than the JTactical stuff...

Your results will be solely based on the materials you put into it.

At ease gentlemen


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## zoltan

Thanks for the update!

If you don't mind me asking, how much does it cost to go from an 80% to a finished AR? It's a project I'd love to do sometime soon, but would like to know the total, finished cost. The other project I want to do very, very badly is an 80% 1911 frame. However, those require a lot more fitting and using either blue or soot (which sounds like fun to me)(plus I'm a better shot with a pistol than a rifle).

Now that you have the iGaging DROs, take a look at this project: http://www.yuriystoys.com/p/android-dro.html

 I have it set up on my mill and it makes it pretty darn nice to use. Amazingly nice, in fact. Plus, how many other DROs do you know which can play Pandora while you work?


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## Bison9

Sweet Setup!

So yeah, once I got past the $3,000 I dropped to get my shop up and running and all setup with mini mill, compressor, drill press, etc, I got a jig and some lower receivers. I had no shop even before I started this project... I didn't even know what milling meant 1 yr ago almost today. :fan:

I got two 80% AR15 lower receivers back in the craze in Feb of 2013 (yeah, I know, I just got to milling them about a month ago :S). They cost me $150.00 a piece at the time and I am not sure where I got them from as I did a group buy on those with a men's group I am a part of. That was all the rage back then: "Hey! Buy these 15 lower receivers as a group and receive a penny less for this arse raping we are about to charge you.." Anyhow, I digest... 

I also got two more billet lower receivers from here a couple months ago: http://billet80.com/index.php?route=product/product&path=59&product_id=80

Those also are spendy, but they are top of the line. But! If you ever want to anodize finish these lowers, then do NOT buy 7075 Aluminum as I have read just horror stories about Type II anodizing 7075. If you want to get them anodized, then you will be sending them off to be Type III anodized BEFORE finishing them (as I have read that Type III is the only legit way to anodize 7075 aluminum). As a result, I dropped about a month of researching home anodizing aluminum (Type II) and am solely going for a Cerakote finish now...

More items I got for this job:

I got one jig from billet80 for these lower receivers: http://billet80.com/index.php?route=product/product&path=59&product_id=52

But, I gotta be honest, that one was crud compared to this one from Juggernaut Tactical: http://www.jtactical.com/AR-15-80-Lower-Adjustable-Universal-Jig-Kit_p_16.html

That one was a Universal jig and it fit all 4 lowers I setup in it.

That one from JTactical is all hardened steel - I tagged the top plates a couple times pretty good with my carbide end mill flutes and that thing just kept on truckin. The billet80 one is flimsy and needs some more fixturing to work. And... it is pure aluminum and will cut like butter just as easy as the actual lowers cut. LOL :rant::fan:

Lastly, I bought the tooling package from Juggernaut tactical here: http://www.jtactical.com/Jig-Tooling-Package_p_22.html

With a mini mill, you only really need the 3/8 carbide end mill, The H drill bit, and the 1/4" end mill that comes with that package. 

Also, Watch this vid from JTactical: [ame]https://www.youtube.com/watch?v=ZKz2sLJUvGU[/ame]

I translated what they were doing in this vid to my mill...

And very Finally: I crashed and burned the carbide end mill in that tooling package after about the 3rd lower but that was my fault - I was pressing way too hard up against the guide plate on my final pass on one of the lowers I was doing and the thing just shattered. But! It is by far the best cutter I tried compared to the 14 other kinda junk ones I got from Enco. It is a 3/8", 2.5" overall length, .5" cutting length carbide end mill and those are very, very hard to find online from what I saw. But, this is absolutely the end mill I would use when doing this job - that is my recommendation. I found that you cannot make a pass with an average end mill down 1.25" on the side walls with any real success. It required doing stepped cuts with that .5" cutting length on that carbide end mill. Watch the vid, it shows you all of what you need to do....

So sorry for the tangent, but after I crashed and burned that end mill, I spent a morning trying to find it (or one like it for less that $358.27 :S) and I eventually found it here: http://www.discount-tools.com/endmills/ful-3873.cfm
Its the 4th one down in that link. 

Now, after shipping, you will pay $40.00 for this end mill, but trust me when I say these two things: 1.) This end mill was VERY hard to find, and 2.) It was BY FAR the best end mill I used on these lower receivers. I cannot stress this enough. It wasn't even close. Watch the vid I posted above form JTactical and use it exactly how they use it and you will love your results like I did.

If you are a complete noob (like I was) reading this post of mine here... You will read all over the net about different end mills for AR15 80% lower receiver finishing... About 95% of it is all BS... If you want a good finish, use that end mill. I wasted my time trying the other crap HSS and whatnot end mills from Enco and various places and none of them even came close to the finish that that one carbide end mill gave me on my lowers...

All in all, with the two jigs, tooling packages, replacement carbide end mill, and the 4 lowers I finished, it was about $1,000.00 total. But, you could do it for way cheaper with just one lower receiver, a couple end mills, and one jig...

Hope this helps!


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## zoltan

Thanks for the very detailed answer!

Once you've finished the 80% receiver, how much more does it cost to buy the additional parts to build a complete AR-15?


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## Bison9

If you're like me, then you will buy all premium parts and a really good barrel and you will come out the other end at around $1,500 - $2,000 into one AR15 :wall::hDe::fan:

But, if you play your cards right and do your research, one can put together a mid grade AR15 for around $800. You can certainly go cheaper, but you will sacrifice quality IMHO.

It does take some research to learn how to build an AR15. It took me about a month of research to figure it out, but these firearms were designed to be fairly easily assembled. Some googlin and elbow greese will teach you how to build an AR15 from parts!

Two years ago I started here: http://www.ar15fornoobs.com/ar-research

Scroll all the way to the bottom and go through the whole blog. You'll be googlin about building an AR15 from parts in no time!


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## clazman

rudydubya said:


> After I finished the spindle-column alignment on my Harbor Freight mini-mill (http://www.homemodelenginemachinist.com/index.php?topic=6007.0), I still didn't get a good tram in the Y-axis. It measured about .004 (all my measurements are in inches) out of alignment, as if the column was tilted to the front just a tad. I also had a significant flex in the column. With a firm push or pull on the motor or top of the column in the Y-direction, I could get almost +/- .010 (2.5 tads) of up and down movement of the spindle relative to the table. I wanted to fix, or at least reduce, the flex, and planned on correcting the column-table alignment while I was at it.
> 
> From what I had read about the column flex, the consensus was that the major cause was that big Belleville washer under the big nut at the back of the column (with maybe some compression of the column wall under the washer thrown in), and by replacing the washer with a flat plate you could reduce the flex. Some folks added angle brackets and braces to the plate to make the column even more rigid. I decided on a simple flat steel plate bolted to the back of the column to replace the washer and act as a reinforcement up the column axis.
> 
> 
> 
> 
> 
> 
> I made a column reinforcing plate (hereafter called a column plate) out of 3/4" thick, 4" wide steel, and drilled holes for some 3/8" bolts plus one 15/16" hole for the big pivot shaft. I used the center of the plate as a reference to locate the bolt holes. Most of you probably know I shouldn't have. *The pivot shaft is not on the centerline of the column.* It *is* centered on the ways, but the ways are shifted over about 1/4" on the gib side of the column. I never noticed it before. Must be a lesson in there somewhere. Anyway, my hole locations were far enough in from the sides of the plate to still work on the column, it's just a little off-center.
> 
> 
> 
> 
> 
> 
> I match-drilled holes for the bolts into the back of the column, tapped them for 3/8" threads, and bolted the plate to the column. The flex was reduced to less than half of what it was, now about +/- .004, but still more than I wanted, and I hadn't fixed the Y-axis tram yet either.
> 
> 
> 
> 
> 
> 
> I drilled four holes in a piece of 1/2" thick, 1" wide steel, one at each end for 3/8" bolts, and two near the center for 7/16" bolts. The end holes were far enough apart to clear the edges of the column plate. This would be a pressure plate to push on the bottom of the column plate.
> 
> 
> 
> 
> 
> 
> I drilled and tapped holes into the base of the mill itself to match the 3/8" outside holes in the pressure plate, and drilled and tapped through the column plate only for the 7/16" holes, not into be base.
> 
> 
> 
> 
> 
> 
> I bolted the pressure plate to the base of the mill with the outside bolts and tightened them until the column was pulled in enough to tilt the column back and eliminate the .004 Y-axis tram error. I then inserted 7/16" bolts through the center holes and screwed them through the column plate until they were snug against the mill base. With the end bolts pulling on the column, and the middle bolts pushing on the column, the bottom of the column was locked in place and the flex was reduced to about +/- .0015.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Some final notes:
> 
> With the bolts in place, I can no longer rotate the column side-to-side to mill at an angle. I have never used that feature anyway, so it was not a concern to me. Also, my mill was trammed in the X-axis to my satisfaction before I drilled the holes at the bottom of the column plate, but I left plenty of clearance around the 7/16" bolts in the pressure plate to allow some slight angle adjustment for tramming, if necessary.
> 
> My mini-mill Y-axis alignment required the bottom of the column to be pulled in toward the base, so the 3/8" outside bolts were tightened first, as evenly as possible to avoid any twist. Then the inside 7/16" bolts were screwed in just tight enough to eliminate any flex. If the required correction was the other way, the center bolts would need to be screwed in first, pushing the bottom of the column away from the base, and then the outside bolts tightened to eliminate any flex.
> 
> If I were to do this mod over, I would use a thinner column plate, say 5/8" or 1/2" so the big nut would be sure to grab all of the pivot shaft threads. The 3/4" plate I used just barely allows that. Also, my plate was 12" long. If I were planning to fit my mill with an air spring kit like the one sold by Little Machine Shop, I would shorten to column plate to maybe 10" long so it wouldn't be in the way of the hole in the column required by the kit.
> 
> The remaining minor flex in the column assembly is probably due to bending of the pivot shaft and/or the pivot plate. I couldn't think of any practical way to eliminate it entirely.
> 
> Drilling into your mill might void any existing warranties. I never had an extended warranty on my mill, so it wasn't a concern.
> 
> I think that's about it, thanks for reading.
> 
> Rudy


Has anyone done an analytical study on this deflection?

Just how hard did you push? Pushing at the top of the column is produces roughly twice the bending moment if you pushed at the cutter.

What is the max cutting force that this mill can produce?

Has anyone done an analytical study of what you are observing?

I think I will do just that

The column box section is a very good design. It may look "light" compared to the plate you added, but a calculation of it's section modulus (used for deflection calculations) and that of the plate you added will tell a lot.


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## rudydubya

clazman,I'm looking forward to the results of your analysis.

Regards,
Rudy


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## zoltan

clazman said:


> Has anyone done an analytical study on this deflection?
> 
> Just how hard did you push? Pushing at the top of the column is produces roughly twice the bending moment if you pushed at the cutter.
> 
> What is the max cutting force that this mill can produce?
> 
> Has anyone done an analytical study of what you are observing?
> 
> I think I will do just that
> 
> The column box section is a very good design. It may look "light" compared to the plate you added, but a calculation of it's section modulus (used for deflection calculations) and that of the plate you added will tell a lot.



Most of the flex isn't coming from the column itself, but from the column to base connection. With the tilting column it's only held down by three bolts at the front edge of the pivot, and the rest of the pivot and column is just left cantilevered out from the base. The plates you see being added to the column are there mainly to provide an additional connection to the base at the back of the column.

On a tilting column mini mill it doesn't take much for at all the deflect the cutting head.


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## Kfundarek

I did this mod and was pleased with the results.  It helped me tram the Y axis which was giving me problems. It also did a good job stiffening things up. Thanks for posting this Rudy!


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## SmithDoor

Looks great.
Round column I use concrete and tension rod.

Dave



Kfundarek said:


> I did this mod and was pleased with the results.  It helped me tram the Y axis which was giving me problems. It also did a good job stiffening things up. Thanks for posting this Rudy!


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