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Joe mentioned counterbalancing the head assembly and that reminded me that I did not say anything about it. I mentioned in an earlier post that I will be using a pneumatic counterbalance because I...

Yes, the inserts are completely buried inside the EG, ~10mm under the surface. This leaves the surface plain EG without steel islands sticking out of it. This is important because I will hand grind...

I fussed a lot about the best practical way to put the re-bar assembly together. The Z-axis linear rails, like the X and Y ones, are going to be bolted into metal inserts placed inside the EG. The...

Yeah, I did not post for a long time, did I? I've been very busy lately with... moving to a new place.

The column mold is completely finished now with all bells and whistles required (well, it was...

Thomas, can you measure the basic dimensions of the sleeve into which the collet fingers go? I just need the two external diameters and the lengths of the two cylinders. I'm going to make the sleeve...

The alignment of the X and Y axes for perpendicularity was done like this. The 'master' square is secured to the Y axis rails and adjusted so that one of the arms is parallel to the Y-axis. This is...

Thomas, there are tapped holes for four M6 bolts at the very top of the spindle shaft, what are they for? I though that there's where the pull flange bolts on for the differential drawbar but now...

Interesting...

This is not usually the case in other milling machines; most seem to have a mechanism that creates a differential force so the bearings are not put under load. Maybe this spindle...

The X and Y axes in a mill need to be adjusted perpendicular to each other. In this case, since I use linear rails, it basically means that the linear rails need to be perpendicular to each other....

I think its a 3L280 belt and it does work pretty well. Not much force is needed so even a 2L belt will work. With the router motor though, make sure you do not exceed the RPM rating of the abrasive...

On the precision mold topic.

Sure, making a very precise mold would be nice. The problem with it is that its difficult, slow and expensive. And only a few surfaces need precision anyway. A...

I do not have a separate thread for the tool post grinder. The construction is very simple. The motor and the shaft are mounted to a piece of aluminum extrusion which directly attaches to the tool...

I guess I did not think about the insert rotating vs. the epoxy: I could have machined a flat on one side. I don't think it rotated at all and as LeeWay mentioned there is little torque needed here...

One thing related to the Y ball screw installation that some people might find interesting is adding a floating support. I did not include a floating support in the original design thinking it won't...

Yes, there is a fair amount of progress since the last post: the Y ball screw was installed, the X and Y axes were adjusted for perpendicularity and I'm working on the column mold right now. I'll...

Well, I'm done with the grinding of the saddle and with the installation of the linear rails on it. Here's the first hole being drilled out. The location of each hole is copied from the actual rail...

The top of the saddle needs to be ground straight, co-planar and parallel to the bottom side - pretty challenging! The only easy way of doing this that I thought of is to "copy" the bottom plane to...

After a bit more scraping I called the four bearing pads good enough and turned my attention to the Y ball screw mounting surface. It's the steel surface in the middle here:

294300

I placed the...

Thomas,

I have a couple more questions about the spindle which you probably could answer from the top of your head.

1. To release the tool, the drawbar pushed down by a hydraulic cylinder....

Well, along the same lines, one of my future goals for this machine is to be able to attach a grinder to the bottom side of the head (maybe in place of the spindle) and use it as a CNC surface...

Yes, your understanding of the process is pretty much on the spot. If the top surface gets flattened first god knows how much steel I'd have to scrape from the bottom pads to make the two surfaces...

Anywhere between &500 and $800 on eBay it seems.



I haven't tried this but I don't think it will work very well. The surface plate is fairly heavy and the paper will tend to get worn away.

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With the saddle cast its now time to start working on the precision surfaces. I began with the bottom mounting pads which go on the carriages of the Y axis. Those pads are made of steel so some...

Ok, I think I'm staring to make up my mind. I will embed two plates on top of the column for the chain sprockets to be mounted to so that the chain will drop on the back side of the column. At first...

Yeah, a picture would be nice. And thanks for the encouragement.

Yeah, I'll need a brake for sure to prevent back driving of the ball screw. And I happen to have both motor mounting breaks as well as large standalone ones. I have to incorporate that into the...

I started finalizing the column design so I can start making a mold for it and I'm faced with an interesting design decision. Should I support the weight of the mill's head or not?
The head's...

Since the last post I made the saddle for the mill. I basically followed the same procedure as for the base: created a mold out of particle boards, an internal steel skeleton, anchors for linear...

With the mounting surfaces flat it is time to install the linear rails. I located the bolts embedded inside the concrete with a long pendulum with a tiny neodymium magnet attached to a string. The...

Casting on an already surface plate would surely simplify the process. However I have a couple general considerations which mean I would never actually do that; here they are:

1. If I had a...