Lapping ways of long X2 Column.

[nateman_doo]

I remember reading somewhere about putting some type of polishing compound in the ways and just slide back & fourth.

Has anyone done this, and what substance did you use?

[Fastest1]

I have read plenty of threads on lapping. Many dont believe in it but I cant see how it wouldnt help. I would use some form of clover valve lapping compund to start with myself if I were doing it. Most I have read about used a grease carrier and various abrasive grits, thoroughly cleaning all before moving to the next level finer.

[nateman_doo]

II also remember visiting a firearms production facility and they did a similar process to lap the slides of their handguns.

I was hoping to find something available at a walmart or autozone and lap my X2 column on my lunch break.

[Fastest1]

A good auto parts store should have some valve lapping compound. I would get the finest grit you can as a test. Just remember to remove the lead/ball screws and get the full stroke of the axis during the movement, tighten the gibs very slightly and repeat.

[LUCKY13]

What ever you do, Be Sure, that the compound you get is "NONE IMBEDDING".



If its not it will embed into the metal and then what you will have is a file for a way. It will eat it up. If it does not say none embedding on the container, then it is not.



You can go to The CNC Cookbook and Bob gives a very detailed description on how to do this.


It helps a lot to work on the gibs also. The X2 may have one tappered gib so be sure when you work on them which is tappered and which is not.


Jess

[underthetire]

We use a non embedding compound, that once it cuts its done and you can just leave it in. We don't, we still clean it out. Lapping ways has been done for years, the guys that used to work at pneumo would spend 3 or 4 weeks per machine lapping them in.

[Geof]

This topic has been covered ad nauseum and the opinions both pro and con have sometimes become quite heated. It will not do anything to improve the intrisic accuracy/precision of the machine but it might make it slide smoother. Really all that lapping is doing in this case is causing an accelerated 'running in' by acting to wear away surface roughness from crude machining and lack of deburring. But it is an uncontrolled acceleration and it will wear away material that should not be worn away.

The purists insist that hand scraping to references is the only way to go but, really, although possible, this is impractical for the home hobbyist and to a large extent ovekill on low cost machines.

My middle of the road compromise which in the past I have applied to cheap (manual) rotary tables and the ways on cross-sliding vises is to dismantle everything and go through deburring all the sharp edges and smoothing the sliding surfaces by 'draw-filing'.

The key areas to deburr are the tips of the dovetails or the corners of square ways. Very often this has not been done and the sharp corner binds against the small radius left from the tool nose radius on the mating part. See my simplified picture to see what I mean. Just putting a small chamfer along all mating corners can make a tremendous difference in how smoothly things slide together.

The other technique, draw-filing, is a semi-controlled surface finishing. I say 'semi' because it does rely on the person doing it being careful and having a delicate touch. Take a fine tooth mill file, a new one, and lay it flat on the ways that will be smoothed. It has to lay perfectly flat!. It can be along the ways or across the ways but along gives better control of flatness.

Before starting look at the surface of the way; it probably has visible machining marks and if a finger is drawn along the way these marks can probably be felt. Also try to look at it at an angle against the light; it will probably be dull (that is if it is clean and dry).

With the file flat on the way, using just gentle finger pressure on the surface of the file slide it along the way. It will be felt to bite and initially it may be necessary to hold the file down with the fingers on one hand while pushing on the tang with another. What is important is that the file slides flat along the surface.

Initially the teeth of the file are just making contact with the high spots left from the machining and are cutting them off. This process is similar to what happens during the 'running in' process, but in running in it is high spots on the two mating surfaces that bump each other and are either broken off or smeared over.

As the file teeth cut off the high spots the surface area in contact with the teeth increases and the file does not cut as much. This is why it is important to just use gentle finger pressure because all you want to do is knock off the high spots. Eventually, provided the finger pressure is gentle, the file will slide without cutting at all; this is the finish point. Of course if you bear down on the file like a demented gorilla it will cut more but that is not wanted.

Now try feeling the surface which should feel much smoother than before. Also look at an angle against the light and shiny flat spots should be visible along the tops of the machining marks; this is what you want.

It is not necessary on sliding ways to have a 'perfectly' smooth surface; actually perfectly smooth is not attainable and is undesirable. 'Perfectly' smooth surfaces sliding together have a tendency to gall up because all the lubrication gets squished out. The residual uneveness provides oil reservoirs so the sliding surfaces are adequately lubricated.

[nateman_doo]

Whole lotta lapping going on here with my X2 column.

[TXFred]

That's an interesting setup you have there. I have no idea if a welded column and siamesed heads will work. But I have to give you credit for thinking outside the box.

[nateman_doo]

it will work. my old setup had a welded column, with only a short length. This is simply 2 columns welded together. I don't plan on using the full length of it, just have the ability to move the motor mount so I can utilize the entire length. If I put the vise on my table and need more Z I can just unbolt the motor mount and slide everything up the column.

Since the mill is in my basement, I will brace the top of the mill to the floor joists that are directly above the column.

[Fastest1]

Nothing but creativity here on the Zone. Dont let Hoss' see it, How big could a G0704 be made then?

[nateman_doo]

heh... thanks!
right now I am lapping the 12" brass gib. I can't machine anything at the moment since my machine is in pieces, so everything has to be made with either a bandsaw or a drill press.

I wonder if I can "make" my own polishing compound. Take some of the fine glass beads (powder from my sandblaster) and mix it in with some grease. Goop it on and slide. Thoughts anyone?

Here is the original extension:
X2 Z column extension