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The machine playing daisy is mine. I also have a video of the 4th axis playing too. (http://media.adamziegler.net/cnc/ << see bottom of page) One of the videos is not the version currently delivered...

Made an update that I couldn't resist posting:
http://images.myonlinesite.com/cnc/
http://images.myonlinesite.com/cnc/use/20070830/videos.html
Feel free to sing along!

Yes, I have been using the machine... I do need to remember to start taking pictures.

Anyone have any advice on tie downs?

Side note... Those of you using plain-ol all-thread/threaded rod and threaded rod couplers for your drive screws and nut..... rub the screw down with bees wax. It makes a world of difference for...

The machine I used is 450mhz with only 64mb of ram. With the lower speed computers there will be some minor latency issues, but that means you might not be able to run your machine at 80ipm without...

Right now I am using a wimpy little 12v computer power supply for testing purposes, but I have the parts to build a larger power supply at higher voltage. I also need to add some limit / home...

Made the tool mount tonight, and wired up the cables to all 3 axis. The machine is alive!! Its great joy to see the thing run! Too bad I didn't have a single proper bit to use... well I did, but...

Added the screw and drive nut to the z box tonight. Still no clear decision on the tool holder.

I added June 5th and June 6th to my cnc log. Last night I spent most of my time tweaking the machine, and computer settings.

Tonight I finished up the Z box.. I hope to add the screw tomorrow.
...

I have have BobCAD... but it is not free, and support for 4-axis is lacking. GCAM on the open source scene is up and coming... might look into it.
http://gcam.js.cx/index.php/Main_Page

I have...

Yes... 1.5" conduit (actually about 1.74") and they are skate bearings.

If I did it again, I might go with smaller rails and a different support system for the rails... similar to the way...

I am using HobbyCNC with EMC2. I have also used my own driver with EMC2. I have talked to guys using a Xylotex driver. I have seen it used with many many other drivers.

Let me know if you need...

If it is a blanket, you just paint it on or spray it on the surface of the blanket facing the crucible. Again however... the blanket is probably stiff enough to sit in place as is.... without any...

Actually... steel is cast quite often. There are a number of steel foundries in the area, and a shop I work at gets a number of their parts made with steel investment castings.

If I can ever get...

Is it loose kaowool, or the blanket?

The blanket can be self supporting. The blanket can be attached to the walls of a furnace with ceramic buttons. The batting/loose kaowool should be stuffed...

I melt iron in about 15 lbs batches with a simple propane furnace. Reaching flames temps to melt iron is not the hard part... light a propane torch and you are already there. The difficulty comes...

As you can see from my log above, over the weekend I managed to come up with a solution for the stepper mount and drive nut mount. I also jerry rigged up a pen and was able to "plot" some code out...

Here is my updated log also found at: http://images.myonlinesite.com/cnc/index.php (you can use backspace on most browsers to return to the previous page in the frame below.)

I have spent the past couple months working on my machine. I don't know if I could say its original or not, but it has been a learning experience. (I already have plenty of ideas and changes to make...

Very good advice... my parts are not scheduled to arrive until tonight... but I am looking forward to testing as you have said!

Yes, I realize that, but in general I see some data curves that relate Ic to Vbe... with Ic = 250 Ib. My ratios will be much much smaller than that. But even if it was the same, I see Vbe = ~1.6V ...

Hmm not sure I follow... Looks like that is the max rating with Ic=3A. I realize that that Ib can effect Vbe... but it shouldn't be much more than ~1.4V.. ? right? :confused:

I assumed voltage across the diodes ~0.6V across each diode (D2s). Transistors have about the same across the BE... but the TIP120 is a darlingtion, so the BE voltage is 2 x 0.6V. Out of the 3...

I re-arranged the design a bit to remove one set of transistors. I have ordered some parts, and plan to test when I get them in. :cheers: Heres to hopping for no transistorized fireballs!

-Adam

Woah.. very nice! You know of anything like LM317 that can handle more Amps? I am also attempting to design a simple unipolar driver, but what you have looks as simple as you can get!
...

I have adjusted the schematic a bit to attempt to use a transistorized current source. Any thoughts or suggestions on it? Will the zeners work for me as a voltage source, or do I need to just use a...

Cool project samco... maybe I will tidy up my HAL file and post it here in case anyone else is interested. I know it was a bit of a learning curve for myself to get that file right.

Kreutz......

Ah yes.. I probably should have said... this is primarily a learning exercise for myself. I will tinker around with this for a few months, and after I am satisfied that I can do something that...

Ahh!! :o Yeah I feel dumb. Thank you for your patience.. I understand now!

My test circuit is setup to use NPN, but after reading various sources such as the one I posted above ( http://www.cs.uiowa.edu/~jones/step/circuits.html ) it looked as if the norm was to switch on...