[jdelaney44]

A few more pics.

One is setting up the 7x12 to turn the ball screw.

The other is the VFD control panel.

[jdelaney44]

Old School Power Supply Build Pics.

So the chaos on the dinning room table there is the operational circuit after I got it all bread boarded. Note the toroidial transformer on the right and the big 18,000 uf caps up towards the center. In between is my high voltage bread board. I just got a bunch of binding posts and mounted them to a panel. I did not like the idea of hot 120v A/C flopping around.

The next pic is a close up of the circuit that controls the relays. Note the heat sink on the zener diode. In the end after much circuit tweakage it cooled down but by that time I had already done the heat sink and a little fan to keep the sucker cool.

Then there is the final assembled and installed supply. There are two toroids on this supply. I stacked them one on top of the other.

Finally there is the circuit with a parts list.

Warning, warning, warning, this electrical stuff will start fires and can kill you. OK, I feel better now. Seriously, be careful. 18,000 uf caps do some crazy stuff.

Why is this Old School? Well I chose to use relays to cut in the resistor that controls the in rush current. The higher tech methods are to use an active circuit with an SCR or a thermistor. The thermistor seems to be the component of choice for these unregulated supplies. But I didn't want any residual resistance hanging around so I went with the relays. I could not figure out the SCR until much later. Next time maybe.

[jdelaney44]

So the last problem I had was that the bearing block was over bored and the bearing at the top of the screw on the Z-Drive was hitting the oil fitting for the J-Head.

After looking at it some more tonight with the ball screw nut shells loosely in place I determined I could reduce the length of the screw by ~ 0.5 in. and still be OK on the travel.

So I put it back on the mini lathe and turned it down. I'm getting a lot better. I managed to get it right! 2nd time on that one. I've determined that I need to use a "rule of on half". That is I take off half of what I need to once I get within about .010 of the diameter I am looking for. That's a quarter of the change in diameter I am looking for. Given my flexy bendy mini lathe that allows me some room incase it does something stupid when it hits a hard spot in the metal. It also gets me to the point where I am taking off less and less with each cut thus stressing the lathe less and making for a more accurate cut.

I also got started on the new bearing block. Just got the next chunk of 4 x 1.5 bar stock cut on the band saw. I'm going to make the new block just so I feel better about getting it "right". I could loctite the bearings in there and it would work, but I want to get the boring process wired better. Practice makes perfect. I'll start milling the new block tomorrow night, maybe.

Pics below.

In the first one you can see that it now clears the oil fitting. It will be ~0.25 lower than that when I remake the bearing block.

Second pic is the partial assembly with the nut shells on the screw. No balls in there, just the brush seals holding them up.

Third pick is the bar stock getting cut. Real exciting that one! :tired: But if someone has never seen a metal cutting band saw, it might be interesting.

[jdelaney44]

Got it done! Had one more "paper weight event" and a near miss but got it done. The process was about the same.

1. Cut the block and face all the sides to make it square
2. Drill the bolt hole (I bored it last time, drilling is close enough)
3. Notch the block
4. Bore the bearing journal

The boring was the hardest as it has the real tolerances. I ended up with a pretty good press fit. I needs to be pressed in but it's not too hard.

The bearings are 1.850. The hole ended up being between 1.849 and 1.851 depending on where you measure it. I was shooting for 1.849. I've seen this on about eight attempts to bore things to fit bearings. The lathe is more accurate by nature I have determined. On the mill +/- .002 is fantastic.

What I am doing is stopping at about 10 thou and then going a thou (.001) at a pass from there. On the boring head and the lathe that means half a thou. Of course the graduations are .001 so the .005 is a bit of a guess.

The tooling marks are often about .003 deep from what I have observed too. A .002 cut will get most of the previous pass. .003 will get all of them. Again on the lathe or boring head that's .006 net.

I got my hands on some tooling for free. A guy I worl with who used to be a machinist full time before he got into computers gave me a box-o-stuff. One of the tools was a freshly sharpenned 3/4 inch roughing end mill. I have been using 1/2 in finish end mills. This 3/4 inch roughing tool can really remove some stock. I was able to take out about 0.40 at once and I think I could do more. Note, make sure the collet is really tight. It pulled itself into the work about 1/16 inch during the cut.

I'm going to get a 3/4 inch smooth end mill. I think this will help the stiffness of the rig and make for better cuts where I can use a 3/4 in. tool. Anyway, it was a really enlightenning experience.

Along the way I fixed up some splash shields for the coolant. This is working pretty well now. I ran across some pieces of plex that I got for free. It's actually too thick at 1/4 inch. 1/8 inch would be better. It doesn't need to be bullet proof.

I then used my $20.00 heat gun from Kragen to warm the pieces up and bend them into "L" shapes. Now they stand up and can be clamped together in any number of configurations.

I also leveled the machine. It was just sitting on the garage floor. The coolant was running to one end and the back. This caused overflows on the coolant channels on the Kurt vice. With it level the coolant is running off the vice much more evenly now. Big difference. Still getting some on the floor, but a lot less.

The KURT is one of the best investments I have made in the past two years.

To go with is I just got some 0.5 thick parallels. These and the vice have cut down my set up time by probably hours a day. That's a lot when you only have weekends.

It was pretty easy. Just used a 24" crow bar to pry up the front or back and put some aluminum shims under the corners to make it level.

I was looking at a Tree Journeyman mill on e-Bay. This was the first time I noticed some channels cut into the edge of the table on a CNC mill. That would be nice. The new Bridgeports have the same thing I think.


Pictures:
Some pictures of the bearing block

The KURT with the parallels holding up the block before tightening

Milling the notch in the block with a 3/4 in. roughing mill.

[Ken_Shea]

Thank you for sharing your effort jdelaney44, nice work.

Anyone one that machines and does not get a little pumped up over your work is one of two things, already done that or dead