Messages

61

General Mach Discussion / Re: Microstepping & Torque

« on: September 01, 2008, 05:54:08 PM »

Ray,

Been on a capacitor search, closest I have found is a 10,000Uf but only rated 30V BUT with 40V surge listed right next to that. So what does that mean? First time I have seen a surge voltage listed on one of these things. Looks like it will work with my 25VAC transformer from the wheel chair charger, that has two 25 Volt secondaries that seem to be wired in parallel through the charge control board. Any Ideas as to figuring phase on the secondaries, I was thinking just connect one lead from one to one from the other, one way (the wrong way) should cancel out to zero the other should show 50VAC series voltage.

From what I figure 25*1.414= 28.535VDC after the diode and cap and not accounting for the diode drop so the 30V cap should work with out providing me with the "big bang theory".

Kristin

Kristin,
 Put lotsa capacitance on whatever you use. I would think you'd want 10,000 uF at an absolute minimum, so you don't get voltage sag under heavy load.

Regards,
Ray L.

62

General Mach Discussion / Re: Microstepping & Torque

« on: August 31, 2008, 11:08:50 PM »

I have some big honking caps in the Astron and a couple of other saved junk electronics  just have to make sure the voltage on them is enough, don't want them to go boom and fly around! 

Getting to late tonight to fool around, I'll report my findings tomorrow.

Kristin

63

General Mach Discussion / Re: Microstepping & Torque

« on: August 31, 2008, 10:41:44 PM »

Thanks Ray,

I did use WD-40 (actually Walmart spray oil or "SPROIL" as I am fond of calling it) but I think your right about the voltage, I have to tear the cover off of one of these wheelchair chargers I have here and check the transformer voltage, I recall something like near 30V output when I was charging a couple of batteries in series, I just don't remember if it had any internal filtering except the regulator board. That would give me a 25% boost in power right there and I can hunt down another transformer later.

Kristin

64

General Mach Discussion / Re: Microstepping & Torque

« on: August 31, 2008, 10:11:22 PM »

Kristin,
Find where the steppers start to skip. Back acceleration down to 60 or 70%of where they started skipping. Make some test cuts in material and see if you left enough of a margin in the settings for cutting. Of course, like Ray noted,
the tuning and capabilites change with electrical supply available.
What you really want is power and that is achieved by the combination of speed and torque. If you had a motor curve
you could get in the ball park rather quickly. Even with or without a motor curve some testing will pay dividends.
RICH

Rich,

I think the problem is really my power supply plenty of amps but low by 1/3 to 1/2 the rated voltage. Or it could have just been the dead soft aluminum didn't like being cut, the other day I was cutting some acrylic with a 1/8 mill and it took the end off of the 1/8"x1" steel hold down strap without a cough or hicup proabably a .05 slice full depth!

Kristin

65

General Mach Discussion / Re: VFD and noise questions

« on: August 31, 2008, 09:47:56 PM »

Do you have any ceramic or other non-polarized caps around? Might try connecting one to each signal lead at the BOB and to signal ground.

Kristin

66

General Mach Discussion / Re: Microstepping & Torque

« on: August 31, 2008, 09:33:03 PM »

Questions, questions...

It's a Taig mill, motors are 205 Oz unipolar, HobbyCNC Pro driver board (hey for $25 on eBay I couldn't pass it up), 20TPI leadscrews & adjustable nuts (new a couple of weeks ago). I think you hit it with supply voltage, think I am only getting about 20 VDC @ 10A  out of the gutted Astron PS I am using, got to dig out another transformer and build another for 30-32 Volts I can run the board up to 42VDC but don't have a transformer on hand with 36V output. 

I have adjusted the gibs, adjusted the leadscrew nuts and it's not mechanicaly binding anywhere, really not trying to run fast(6 IPM) or take more than .01/cut with a sharp USA made four flute 3/8"end mill. Could just have been the heatsink was pretty soft aluminum and was giving me fits?

Kristin

67

General Mach Discussion / Microstepping & Torque

« on: August 31, 2008, 08:28:34 PM »

I can't really find any clear information on the effects of microstepping and torque, right now I have my board set for 8 microsteps (jumper selectable) just happened that way as I was careless reading the settings. I have been just getting set up but last night I had to mill off some fins on the heatsinks I was making and the machine groaned and jammed a couple of times. So I am wondering if I should pop another jumper or two and go to 1/4 step or 1/2 step or even full step mode? Seems from what I have been able to find microstepping will not improve resolution and may actually make it worse if it takes a few bumps to get the motor to move or switch direction.

Kristin

68

LazyCam (Beta) / Re: Learning Curve ahead!

« on: August 30, 2008, 07:39:22 PM »

Kristin

you missing what i am saying . pull that 256 strip out and you might be ok. if your cmos and drivers are not up to snuff when you past one gig the memory managers have a hard time cache
memory between the strips and video when using drawing and cad programs.but your data and file programs will run perfect. one of my computers has a motherboard that can handle 32gig
and i have 16gig installed. it is triple booted with winxp home,xppro 64 and linux. the 64 and linux run great but the xphome has no chance.

bill

Bill,

The factory spec for my PC states 2GB memory, so I can't see that as the problem, I did check for BIOS updates when I got it and it was fine. So I am still lost as to how the memory could be affecting things, also the other machine PC also has some wierd things with LC not the same but others I have encountered. I really need to start documenting the strange things, I am a little ticked with parting with $75 for added "features" that don't really work right and still no documentation. Guess I'll have to take it up with the management on Tuesday afte the weekend. Overall it works but is as full of bugs as a Motel matress at the "no tell motel"

Time to take a rest from this for the holiday, I'll get mad all over later.

Kristin

69

LazyCam (Beta) / Re: Learning Curve ahead!

« on: August 30, 2008, 12:13:27 AM »

Bill,

It's an IBM desktop, originaly with 256Meg of mem, I added a gig about a year ago, aside from that it works flawlessly. The other PC I run the machine on has only 512megs of memory and processes the files fine, I guess that is the trade off I can create files in my office and have to spend a few min in the shop to process the code. I still find it interesting that too much memory causes a problem, bet Vista users are sunk as I hear 2 Gig is recomended minimum memory.

Kristin

70

LazyCam (Beta) / Re: Learning Curve ahead!

« on: August 29, 2008, 09:46:11 PM »

Dave,
Struck me as odd too, never heard of too much memory but perhaps it's possible, I tried it on the machine PC w/512Meg and it worked without a problem.

Krisitin