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I am currently installing the Z column casting and need some information and/or advice.
In previous posts there have been several discussions regarding the Z axis cantilevering problem with the mill head installed.
Has anyone measured the effect on the Z column tramming before and after the head is installed? Right now, without the head installed, I am within about .006 variance in 12" on the y axis. In effect, the column is leaning back this much. Do I need to compensate now for the weight of the head, and if so, how much? Or is it one of those try it and see kind of things?
You have collected a measurement that will be very interesting to repeat and compare once you have the head mounted. It is too early to be trying to take out only .006. Who knows... maybe you will not even have to do anything other than torque the column bolts to get the column square. Good luck and let us know how it turns out.
the cantelevering is the head from the colomn, not the column itself, you want the column as close to true as you can get it, this is the axis ! forget the cantelevering as it is only a problem in roughing heavy, or pushing a big drill !
Don
IH v-3 early model owner
I shimmed my column to within a thou using .001" stainless steel shim stock before the head was applied. It didnt move after the head was installed. I had to shim side to side and fore to aft. JRouche
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)
I shimmed my column to within a thou using .001" stainless steel shim stock before the head was applied.
Was curious. How much material did you have to use to get your column within 0.001"? Do you remember how far off the column was before you started? Mine was 0.004" in the X & 0.002" in the Y over a distance of 6".
Originally Posted by Speeder
Yes, I kinda remember. My machine by the way is not an IH machine, enco here, but all similar.
I had to use three strips on the right (as facing) side of the column and two sheets at the forward corner of the left side. This was after completely cleaning the mating surfaces and ensuring there were not any risers causing false readings (flat file helps to check for risers).
The left, front corner was a trial and error procedure, adding and removing shim until I got a good setting.
I went to verify the shim stock. It is actually “precision brand” .0005" stainless stock. I don’t remember where I got it. I think it was an ebay buy.
I have a roll of it in a cardboard box. It is very thin. I remember while handling it one issue was trying not to kink or bend it which might cause its thickness to change.
It is very thin and fragile. Cuts easily with scissors but even then the cut leaves a slightly curled edge that needed to be flattened. JRouche
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)
I just took a new set of measurments with some better tools. It help to have a nice brown and sharp 12" parallel to work with. I found that with the indicatior clamped to the z axis and moving the table, I get less than .0005 indicated deviation to the table in both the x and y axis over 7" of travel.
With the indicator clamped to the table and moving the z axis, I get about
.0005 deviation indicating to the y axis. Clamping to the z axis and indicating to a surface square to the table gives .003 on the x axis. Both readings are over about 7" of travel
I had to have my square column base machined when I discovered that it was out of square by nearly .125 in two directions. The machinist told me that the ways were concave in the x axis direction by .005 on each side I think the higher deviation on the x axis may be caused by this problem when I move the z axis up and down.
I am inclined to leave well enough alone. Aaron thinks that the concave problem will eliminate itself with use. And .003 over 7" is only .0004 per inch of travel.
Since most of my work will be done within a 3" vertical direction, this should be sufficient for some reasonably tight tolerance work.
Comments anyone?
Bohica,
Are you saying that the base plane to which the column attaches was out of square to the ways on the base to which the table rides or not parallel to each other?
I found I had to add 0.04" of material on the left side of the column to get it to quit leaning to the left. Then added material to the front side to get the column to quit leaning forward. Then trammed the head in both X & Y axis. Finally came down to 0.0008" column error in the X & 0.002" in the Y. All the numbers were over a 6" travel. Would have liked to have done better in the Y axis but had spent 2 weeks playing with it and decided to cut parts.
Don`t have any plans to CNC for awhile so the height of the head will be stationary for most operations. I guess if a servo was pulling the head up & down, it might matter more. Did manage to get the head error down to 0.0005" or less in both X & Y. Happy with that.
The mating surface for the z column on the base was ok. The mating surface on the column itself appeared to have been "machined" with a chop saw. You could clearly see the saw marks in the metal. It was out of square to the ways in both x and y axis by differing amounts in both directions. The machine shop I took this to machined off .08 material on the square column base to get it square. They told me that they got it within +-.001 square to the column ways. I believe them considering the numbers I am getting from the dial indicator.
I also found that the the top of the z column is not square to the ways as well and is off in both the x and y axis. I had to install threaded posts and a 1/4" steel plate in order to prevent binding the bearing on the z axis motor mount.
Credit is certainly due to Aaron Moss on my base problem. He paid the machining cost and threw in an extra $30 bucks with a Merry Christmas!
Just can't ask for better service than that!
It looks like I have the same problem as Bohica with my mill. A straight edge shows a wavy surface and I can see saw marks. While standing the column vertically on the garage floor I can get it to rock quite easily.
How much does it cost to fix it?
Has anyone else had this same problem?
Hey jamiechi, Mine is off quite a bit also, I think it is pretty common on these mills. Myself and some others have drilled and tapped the column flange to install adjuster setscrews so you can easily jack up and adjust the column front and back or lt and rt as needed to see the error and find out where the bottom surface of the column needs to be ground to get the column to sit trammed correctly. I am going to grind mine myself after I get my table reinstalled after some other mods im doing. It will take several times of removing the column with a hoist and grinding and rechecking. The gearbox doesnt need to be on during this. You can attach a magnetic base to the Z axis slide and run the dial indicator on a square or angle on the table to check progress. Another option is too find somebody or a shop with a mill with a rt angle milling adapter so they can lay the column on their table supported by the Z axis ways and use a facing mill to cut the bottom surface exactly perpendicular. I would still highly reccomend putting in the adjuster screws as you still might need to tweek one corner up ever so slightly. But you dont want a huge force put on the screw cause it may just want to compress into the cast iron base material. I have hardened setscrews tapped into my base and ground flush with the upper surface that the adjusters contact exactly to prevent that. If you use shims the adjusters will still make your progress a million times easier. I spent several hours right after I got my mill trying to loosen and pry up the column and put in little shims and what a nightmare that is. I decided to find a better way. I saw after I did mine that another member : Cruiser has 5/8 setscrews in his right next to the column mount bolts. Mine are 1/2 -13 capscrews. I think that about covers it. Any questions? Dave
Also see this post for my mods Some R45-7045 mill mods
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