Z axis Column Modifications

Here is some of the work I'm doing to the Z-axis column.

The first video covers the plan for the placement of the Z axis ball screw inside the column.

Next video shows making the arm to connect the milling head to the z axis ball nut

Here is the milling of the slot into the column

More work on finishing the clearancing in the column for the Z axis ball nut and screw

Final part 3 video on the clearancing inside the column

Here's my first attempt to straighten the base.  This shows some of the challenges of the weak casting on this machine.

Here I am getting into what is being done to stiffen the column

Here is the second part explaining the stiffening of the column

Here I am cutting the gussets

Here is with the gussets mounted explaining how they will work

This is a fun video where I actually measure how square the column is before I correct it.  I also apply a force on it and measure deflection to show rigidity

Here’s the fine adjustment I’m going to use for the column

Here a test piece I made for the cam

In this video I show how I square up the casting bracket for the column 

This video shows the completion of building the gussets, mounting them, indicating the column in straight and a final test of the more rigid state of the column after the improvements.

working on the table and saddle

This weekend I got the dovetails straigtened up.  The first thing I did was make sure that the head on my larger mill was straight.  This is called tramming the head.

Here I am confirming that the head has been properly trammed.

Before starting to recut the ways the table had to be clamped in with proper alignment.

The ways of the table were re-cut with a 55 degree dovetail cutter to get them closer to straight and parrallel than I was measuring them to be out of the box from the factory.  Even on my larger Lagun Mill there is some measurable error as shown below but it was better than how I received it.

Here is an analysis of the success of the initial passes on each side.

Final finishing plan after recutting dovetails

For final flatness scraping was done on the dovetails after cutting on the mill.  Here is the first surface in progress

Conclusion on the condition of the table ways

Work on the saddle begins

The saddle now slides easily on the table X axis

Work starts on the saddle y axis

Quick way to measure the saddle y axis for scraping it to be perpendicular to the x axis

In case you were wondering how small a mini mill is take a look here.

Ahead of the mill arrival I started looking into hand scrapping to make the ways flat and parrallel to a precise level.  The first thing I did was build a scraping tool and put a file handle on the end of it.  I bought HSS in the form of two planar blades to have a lifetime supply for cheap.  I also bought some grey iron from a foundry that just closed it's doors here in Minneapolis.  A couple shots of the owner helping me out!  I couldn't resist getting to slabs of pig iron too.  Might find a use for it stiffening the column of the mill.  Anyway This cast iron that was poured right here in Minneapolis so I thought it would be cool to get some extra.  Grey iron is a stable metal that I will use to make a straight edge for using to scrap the ways of the mill.  The first scraping I attempted was to make the flat edge before the mill arrived.  I made 4 different radii blades and a fixture to grind them to those radii.  I got the scraping information from the practical machinist forum.

This is the scrap from the foundry.
The pieces of Pig iron at the top weight 80 lb's each.

Here's the owner sowing me how to notch and then break off pieces with a hammer

That's a massive bench grinder with a
14" abrasive wheel mounted to it!

This is the beginning of scrapping a piece of the grey iron

Here is the scraper tool I made

Making a sliding fit for dowel pins in grinding fixture

This fixture allows me to grind HSS blanks to 4 different radii. 

See video below.

I ended up just grinding them on 12" disc sand 

and then hone by hand w/diamond files

progress on the straight edge

More progress on the straight edge.  Here you can see there are more contact points indicated by the blue spots.  If you want to learn more about scraping there is a lot of good information on practical machinist.  scraping blades

Here is the first time I turned on the mini mill

It has this hard to remove cap that guards the top of the drawbar which will never be put back on because it's too hard.

Before tearing the machine apart I decided to set it up and try it out.  Here I am getting the column setup straight.  I bought the granite slab online for about $150

Here it is milling on a piece of aluminum.  This was a .020 deep into the side of aluminum. I had to buy a new table clamp kit with 3/8" studs because the t-slot clamps I have are to big to fit in this little thing.

Checking factory backlash X axis

Checking the factory Y axis backlash

Force check X axis with lead screws removed to analyze the friction of the saddle on the ways from the factory.

Determining the critical surfaces of the dovetails that will need to be worked on.

From the factory the gib goes crooked when the setscrew are tightened.

To solve the gib going crooked I milled some pockets so that the gib screws bottom out flat into the pockets instead of hitting an angled surface.

Here is a finished pic of the pockets.  I also surface ground the gib you can see here.

After surface grinding I scraped the surface of the gib that contacts the dovetail flat.  This is one of the critical surfaces.

short video showing the upgraded gib

This is how I determined the fix actually worked.

The inconsistent clearance in the X axis ways is shown here

Analyzing how warped the table is

Another assessment of the table

Here's the next shocker-  the milling table itself isn't flat.

I fixed that by scraping it as shown here.

I had to determine the angle of the dovetail to finish the straight edge.  This was my setup to make the measurement.

Before milling I squared un the straight edge on the surface grinder so that it would clamp up square in the milling vice.

After determining the angle of the dovetail I tilted the mill head and matched the angle with the straight edge.  This will be used to scrap in the angle surface of the dovetails on the mill.

The straight edge was scraped after milling to make it flat.

This is how I secured the piece for the scraping.

This picture shows the new angled straight edge with ink on it that transfers to the high spots on the angled dovetail surface.

Intro

Hello- This page is to document my project for converting a Sieg X2 mini mill into a CNC mill.  I already have manual machining equipment but can't justify an out of the box legit CNC mill so I decided to try building a small one.  What I'm going to do can be purchased for about 4k but I figure I'll be able to do it for a little less and more importantly it will be built the way I want and it's a learning opportunity and excuse to justify more tools that I will need to complete it DIY.  I purchased the Mini Mill from Harbor Freight.  I'll start from the beginning with it arriving at my front door in a crate.  From there I un box it, turn it on to make sure it works.  Try it out a little and then start the teardown

After much thought and research here are some of the main aspects of the project I've decided to do.  This will be a buy as I go project.  Since this is a blog I will document what I'm doing and sometimes show how I'm doing it.

1. Improve the axis motion to be more smooth and consistent than what can be expected froma  low cost import mill by "blueprinting" everything.  Also planning to stiffen the column mounting and possible the column itself.
2. convert to ball screws including fabricate all mounting hardware.  
3. use Nema 23 stepper motors on the X and Y and a Nema 34 on the Z axis. 
4. Motion Controll Breakout board AXBB-E
5. Post processor UCCNC
6. CAD/CAM: Fusion 360