# Some enhancements & adjustments to my mill



## arnoldb (Apr 18, 2010)

I've really been enjoying the new milling machine I bought in February, but with an engine build done using it, some small nigglies appeared. These were not unexpected, but do need some attention.

I've been keeping a list of notes on "enhancements and adjustments" I'd like to make to the machine and it's accessories, and before I start a new build some of these are going to get attended to.

Yesterday morning, I went on some retail therapy, and came home with this lot, much to the chagrin of my bank manager;
2 digital calipers from the shop where I bought the mill, a "new" second hand 25-50mm micrometer (the price was right; I just could not resist!) and partly visible in the photo, the bases of two goose neck 12V 20W halogen "desk lamps":






One thing that's been bugging me about the mill is the fact that I have to switch it off at the power socket for it to be "off" - it has a transformer in its control box that is always on unless this is done. The power socket is behind the mill and a bit awkward to reach since I've added a table next to the machine to carry accessories. Also, it does not have an indicator that it is "on", and I've forgotten to switch it off a couple of times at the power socket. With lighting also an issue, I decided to dump these problems into the same box for solving.

I had an old "electronics project box" lying around from my student days, and a forage in the electrical boxes turned up a lights switch with three switches and more-than-adequate current ratings. I disassembled one of the lamps I bought, and installed its transformer in the box, as well as modified the lights switch to fit the box, and added an LED with required resistors to it. With some wiring, I ended up with this:





The goose neck and head salvaged from the light was mounted on the box cover, as well as a cut-out for the switches. The lot was then assembled and mounted on the mill's electrical box with short self tapping screws. I re-wired the mill to get it's electrical supply from the box, as the one switch in it now became the "Master" switch. The LED gives me a clear indication that the machine is on. The second switch controls the light; sometimes one might want it off even though the mill is on:





It's nice to have some additional light on the mill table:





I've not adjusted the mill's backlash since I got it, and it had quite a bit - about 1mm on both X and Y. Fortunately it has adjustment screws; they are just hard to get to.

Here is a view of the X feednut and adjustment screw; I had to use a torch and the camera at the same time, so the photo is not that good. The black fuzzy arc in the foreground is the handwheel:





The previous photo is a bit deceptive; it makes the feed nut look close. In fact, I had to use the long and short extensions from my 6mm socket set with a 4mm hex bit to reach it for adjusting:





Fortunately, I left the stand I built for the mill open in the center; that makes getting to the Y feednut and adjustment screw easier. A view from the floor to the base of the mill:




This is where I love the swivel view panel on my camera, I could get a photo without crawling under the mill! Makes inspection easy as well; a lot of rust showing up that needs addressing!

Both the X and Y adjustment screws were adjusted to the point where I could feel the feed tighten up(screw too tight), and just a bit back. All in all , the backlash came down from ~1mm to 0.2mm, and that's just dandy with me. Both feeds were feeling a bit "spongy" when changing direction, but are now nice and crisp.

The next mod is (was) to the mill vise; I bought what I could find and afford when I bought the vise, which is an Asian import that is of rather poor quality-of-finish. It was either that, or nothing (until I can make my own). The next photo shows how I "shimmed" it to prevent the movable head rising ~1mm when tightening with parts in the top of the vise. I just measured the gap between the bottom guides and the vise body, and added plate strips of suitable thickness bent at both ends to prevent them from moving out:




Actually, I made this change while building my last engine. It's a bit of a bodge, and by no means very tidy, but has brought the jaw lift down to less than 0.01mm.

Today, after eventually re-mounting the vise on the right-hand side of the mill table, I checked its bed for "parallelism" to the mill table. I was expecting the worst, but was nicely surprised. In both the X and Y directions I measured, it was less than 0.005mm out according to my trusty Mitutoyo gauge. Two photos of the set-up I used to check:









On close inspection of the vise mods, I found this:




The movable jaw top is nearly 1mm lower than the fixed jaw top. A quick test with a file on the jaws, and they are pretty hard; I won't be trying out any of my HSS end mills or flycutter to correct this. I don't have access to a surface grinder to correct it either. So I'll be making up some "soft jaws" for the vise; and keep the originals for non-precision work.

More mods to come...

Regards, Arnold


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## Troutsqueezer (Apr 19, 2010)

Hi Arnold, 

Just a note about electronic components and their lifespans and I realize this may not apply to your equipment and maybe you already know this, but then again:

For solid state components and even things like transformers, most of the time failure of the circuit happens when a conductor within the device, whether it is a transistor junction (within an IC or discrete) or even a wire in a transformer, has opened up. This is generally caused by temperature cycling or sometimes bad workmanship. When the component is turned on, it heats up to a certain degree, when it is turned off it cools down. When you are bending a thick wire with your hands back and forth repeatedly, it breaks because the wire has turned brittle from heating and cooling as you've been bending it. 

Some electronic products are designed with this in mind and so will keep the electronics live (energized) which keeps the components at one temperature, lengthening the lifespan. Transistors and transformers are not like tubes which had a lifespan proportional to their "on" time. 

This scenario is not compatible with Al Gore's vision of a green planet but you can't please everyone. I deal with this phenomena everyday designing microprocessors and chipsets. 

The current your mill is drawing in standby state may be negligible when it comes to the monthly electric bill. 

-Trout


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