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Parameter
10-09-2005, 02:48 PM
Hi guys, I know you love pictures so here are some of my mill and the cabinet I built to house it and the controler. The cab is just finished and cut noise level quite a bit.

The cabinet is 3 x 4 x 6 high made from 5/8" MDF. Its heavy!!! So to move it around it has 4 wheels rated at 300 pounds each. Heck I can get into it no problem but i'm 150 pounds only...

The window is 2 layers of 1/8" Plexyglass for a total of 1/4" thick. That is what I had on hand, but will probably add a layer of 3/16" lexan on the viewer side. Any tought on this issue? Is it safe enough? I mainly cut wood, plastics and engrave stuff. No aluminum cutting here but maybe some engraving in alu or brass.

As for the machine, it's my first one fited with 1/2-10 ACME lead screws on the x an y and 5/16 All thread for the Z. All parts of the Z and X carriage as well as the Y table will be replaced with aluminum cast parts. Some are ready, other I must first mill the patterns. All in all, I get a good 18 x 12 x 3 in the current config.

The spindle is a 5A dewalt laminate trimer with up to 30,000 RPM capability. It also has air spindle cooling using an airbrush compressor to blow air on the lower bearing area. I use a dremel speed controler which can be seen under the computer screen.

I found a computer AC plug/switch box to plug it all together, which is just under the screen there. I dream of a flat screen on a pivot on the side of the cabinet... eh, maybe some day...

This machine will soon have 3977 drivers as found on the PMINMO site. I bought a couple of the blank PCB and got my Allegro samples. Just have to build em. Should reach around 20 IPM with those drivers.

Next step is a JGRO style machine, that'll fit tight inside the cabinet. Fixed gantry + 4th axis would be great...

Also pictured, as a bonus, is the atlas mill I am rebuilding to make it cnc, but that's another story.

This has been possible thank to all who posted here before me. So if you have questions, go ahead, ask.

Para

CNCRob
10-15-2005, 07:04 AM
Looks great Para, That enclosure should really help keep dust in its place.

Ayjay
10-16-2005, 03:33 AM
Nice looking machine, Para. I like the enclosure.

I too am trying to build the A3977 boards from pminno for my JGRO machine. Soldering that chip on to the board is no picnic. My first attempt was a total disaster...solder bridges, broken traces etc. etc. resulting in a fried 3977 chip. Not a pretty site. The second one went much better and looked reasonable and actually worked but my motor would only spin in one direction. I think the problem was that the direction pin was not soldered properly, but when I tried to probe that pin with my meter (with the power on - which I WON'T do again) the probe slipped, shorting out the second chip. I am now in the process of soldering my 3rd board and having learned from my mistakes, I am hopeful that it will turn out well. You need lots of patience, a good fine tipped soldering iron and some braided solder wick to do a decent job.

Can you tell me how long it took you to get your sample chips from Allegro? I requested samples about 2 weeks ago and still have not received them.

Ayjay

pminmo
10-16-2005, 09:10 AM
Paramater,
Nice looking machine! One of my concerns when I did the boards were peoples ability to solder them. Probably the best advice I could give it to paractice some fine soldering first. The 3977SED has 12 ground pins, the center 3 on each side. Bridging those don't hurt and might be a starting point. But the downside of those is they take the most heat because of the amount of copper which is utilized as a heat sink during chip operation. I've toyed with the idea of offering the board with the 3977 soldered as the board house also does assembly. Just that it's big bucks out of my pocket, plus a number of people already have the chips.

Parameter
10-20-2005, 01:21 AM
Well, I'm up to put the chips on em. They look very good but I do expect to sweat a bit on it. It was good to build 3 boards completely without the chips just to get the soldering skills up a bit. Those a really small... I usually don't work this small but eh, this was quite a good deal and what's life without challenges! Anyway, I needed the 2.5A badly. Honestly, I'm a bit worried about a full 2.5A thru those traces, i'll try to limit that to 2.3A. With 4 axis, I expect to need a PS around 20A.

As for the sample time, I got confirmation 1 the day after, then confirmation 2 a couple hours after and then the chips a week and a half or so after filing the form. Pretty good for freebies!

I'll post updates on the boards next week as I should have em completed and tested. It's good that I have time to think about the soldering strategy, seems to be something that you want to plan right unless you have some chips to spare... That kind of thing sometime happen to me too so take it easy on yourself and flux, flux, flux.

Para

Ayjay
10-20-2005, 05:44 AM
Para

Good luck with the soldering. I have already repalced one board and will need to order at least one more from Phil, but I think I'll wait and make sure I don't need any more. I also learned that when I shorted out the 3977 chip, it also blew my 24V power supply that I was using for testing. Oh well, I now have incentive to build my 35V supply for my machine.

I finally received my sample chips from Allegro today. I wish I had ordered 6 just in case I have anymore Screw-ups.

Keep us posted on your progress and maybe post a pic of your board.

Ayjay

Parameter
10-20-2005, 10:40 AM
I got myself a soldering iron with fine tips (40w), and have to buy a new one at 25w just for the chips. I think someone should not be tired, hundry, or stressed when soldering the chips. Any hand shaking would be quite unforgiving.... I hope that'll be all right, I'll know soon enough

Para

Parameter
11-05-2005, 06:48 PM
Got the 25w soldering Iron and am ready to do the finishing touch to the boards... The enclosure for the drivers is going well.

I also cast an aluminum bracket for the dewalt trimmer, got some machining done to remake the Z carriage in aluminum from a part I cast and should replace the whole Z rail support pretty soon as well as redo the Y carriage, all aluminum. I hope I'll be able to do light pass aluminum even tough the base is MDF... we'll see...

I take the time to care about the upper parts, then the table will just go way bigger...

here's a pic of the freshly cast bracket...

Para

pminmo
11-06-2005, 11:52 AM
Hey Parameter,
Most of the 2.5A is through the jumpers, the traces from the wire ends to the connectors are plenty beefy for 2.5A. BTW, did you get my Friday email?
Phil

Parameter
11-06-2005, 12:38 PM
What size are the jumper wire? I got some 20 in there I believe. Would phone wire do? The full copper ones.

Got your mail, all is fine, just need to put the chips on. That's for today. It drag a bit but now is the time.

Para

pminmo
11-06-2005, 02:03 PM
20 Ga is fine

Parameter
11-06-2005, 11:03 PM
Cool, the bracket and new carriage are installed and tested and I went from 4ipm to 8 ipm on the Z just by taking care of binding and trueness and then tweaking the setup in tcnc. Acceleration too is much better without all the slop. Now I see the slop elsewere... lol well, that's one done. Next, the drivers and Z rails-y carriage assembly.

It's getting quite interesting now, not so much of a play thing anymore.

Para

ViperTX
11-06-2005, 11:10 PM
Nice work Parameter...you'll be fine with any thickness of plexiglass.

Parameter
11-20-2005, 08:52 PM
OKay, those PMINMO 3977SED drives are completed and kickin! I just added a 18v power supply and the same setup went from 12 IPM (at 12v) to 30 IPM!!! What a difference. I will change motors pretty soon and get the power supply at 32v. I'd expect around 40IPM.

I'm using 1/2"-10 ACME on X and Y but will go to 1/2-13 All-Thread as I can't make a good ACME tap and cannot find one... The actual nuts are not so clean. The new nuts are all done and seems much better.

I might cast some bronze nuts for 1/2"-10 ACME right and left hand with backlash adjustment... Those would be cast on the screw (with a ceramic microcoating) so fit should be near perfect.

I now cut some foamies for some sign guy that does quite a lot of em. At 30IPM with a 1/4" upcut 2 flutes, it just wheez in at 10,000 RPM for a .9" thick cut in one pass. Having the cabinet is ESSENTIAL with foam, it's incredible how much dust it makes.

Also, if you want to test different plastics, ask the commercial metal and plastic dealer around for offcuts. Most of the time they just sell em at rebate.

I asked a guys for offcuts, I said, just put a couple shovels in a bucket and make me a killer deal... See the pic for what I could get for 20$us. Plus, I had 2 sheet 1.5' x 4' - 3/16" cast acrylic (fumed). Just those are worth more than half the price I paid. In the bucket are UMHW, ABS, PVC, Acetal (Delrin), Polypro, Styrène, some cast acrylic and lexan and some other yet to identify... As always, make sure you have good vacuum on the machine when machining any plastics or foam.

I'm just having a great time. Some peoples helped quite a lot. Phil has been very helpfull and even supplied some components so I could finish the boards without beign ripped of by abusive S&H fees for a few parts.

Those board from PMINMO are really cool and the new PCB's should be an even greater deal. If you look at a nice little driver you can build for very cheap, give em a try.

Enough bragging, back on cutting... Gotta build that 28 x 50 table now and try to get more speed, more more more...

Para

Lionclaw
11-20-2005, 11:07 PM
Parameter, what kind of steppers are you using with the 3977 boards?

Parameter
11-20-2005, 11:54 PM
As of now, X and Y must be around 90-95 oz-in torque. They're 3.9v, 1.3A unipolars connected as serial bipolars (they're 6 wire so I had no other choice). I set them at about .8A because inductance is now double per phase and will limit the amount of current the phase can take. My power supply is just standard diodes and RFE capacitors.

The darn transfo is expensive... about 20$ US for a 24vAC 4A. That should give me 32v DC which is exactly what I want. WRONG! The transfo output 26vAC so this gives me 36v DC which is over what my drives can take. I'll have to string a few very big diodes (like 6A 1n560x) to bring it down. It's said to be around 1.4v per diode. It would take at least 3 of them to bring it to the level the board can take. Hence I use the center tap to get 14vAC which is 18vDC and this suits my need at the moment. The diodes string should be done this week.

Z is 4v 1.1A, 6 wire unipolars and around 85 oz-in. I run it at .7A. There I only have about 10 IPM on 5/16-18 all-thread but it's sufficient. The head is quite heavy with the dewalt trimer so I might go to 1/2-13 all-thread there too when I rebuild the Z rails support and back.

I love being able to use odd endmills. I got the 5/32, 1/8, 3/16 and 1/4 collets for my dewalt because I found a place for end of stock endmills at killer prices. Sometimes as low as 2$. Those are often new or barely used. Cutting foam is not like cutting steel and it does well for me.

Para

Parameter
11-22-2005, 10:04 AM
I changed the Z motor yesterday from a 6 wire unipolar, 4v 1.1 A (which I had to run at .6A in bipolar configuration) to a 4 wire bipolar, 4v 1.4A ran at it's full 1.4Amps.

Well, accceleration went up 3 times (from 3000 to 9000 in 1/8th steps) and speed is now a stiff and torky 16IPM. I really think that inductance in the motors does'nt make running 6 wires unipolars as bipolars such a good deal. Lowering amps also lower torque and the motor does'nt seem to hold to accelerations as good.

All in all, it took 15 minutes doing the move and adjusting the drive and I know I'll recoup that 15 minutes on the next picture I carve.

When doing pic carving, the Z is quite active. I has to be fast. Just the mod above will probably cut as much as 15-20% from previous runtimes.

Parameter

Ayjay
11-22-2005, 02:51 PM
Para

Glad to hear you got your machine up and running. I am still trying to get my 3977 boards up and running... just not enough hours in the day!

What kind of pic carving are you doing? Do you have any pictures of some of your work? This is something that I would like to try when I get my machine going.