Messages

1001

General Mach Discussion / Re: Really need help

« on: August 15, 2009, 07:38:50 AM »

TurnerTom,

I noticed that you have the pulse width set to 5.     Just curious if you have tried setting it at 2.

Also noticed someone posted a description of your 'RF isolator.' Seems like a bad strategy to me. What keeps the RF from one pin from bleeding over to receivers in other pins? That would certainly be one potential explanation as to why you only have problems only while two axis run simultaneously.

I have had a bad time with RF problems. For example, if I plug in a wireless network adapter (USB), the steppers immediately start stalling. This behavior is completely repeatable. Unplug adapter, problem goes away. Plug in adapter . . immediate stalling. I has similar problem with wireless Xbox controller.

Others will chime in and say that they have had no such problems with this or that wireless device. 

This does not say that you will or will not have RF interference problems.  What it does say is that the question of whether RF can interfere with the CNC operation is NOT a debatable issue. It is a fact.

Based on my own experience, I would not voluntarily introduce any RF devices unless there was no alternative.

1002

General Mach Discussion / Re: Really need help

« on: August 14, 2009, 10:33:39 PM »

IF this is a commercial machine making money do yourself a favor and bring in a machine TECH that understands the process.

Exactly. While your solution is a bit on the extreme side, methinks there is not enough recognition that in a business environment, the priorities change and the costs are not the same as on a hobby level . . . possibly due to the large proportion of hobbyists on the forum . . . just a guess. Employees tend to think only in terms of purchases and don't consider thier wages to be a 'cost'.

COmmon myths tell you stepper are not as good as servos. BULL, if properly engineered steppers can be MORE accurate and last longer than servos in most low speed applications. AND are much easier to setup and maintain. GOOD steppers are almost indestructable.

A similar common myth is that a dump truck is not as good as a Ferrarri. What are these people thinking 

OK seriously, how does one go about 'properly engineering a stepper'?  . . and  . .  how does one identify a 'GOOD stepper'. Cost? Brand name? I'm not going to use any more steppers, but I think it would be valuable info to share. 

1003

General Mach Discussion / Re: Really need help

« on: August 14, 2009, 10:03:11 PM »

I happened to do another drivertest and it was fine.. left it running while i was lloking for a way to tell this customer i thought the controller was a duck. drivertest suddenly went to fail then jumped back. noticed it happened as customer moved the mouse. it would work fine until the mouse was moved then would go to fail mode. completely bizarre. further testing revealed that ANY other activity on the pc would cause this behaviour even at 24K rung up my mate in the US and his first question was "is it an AMD?", it was, then next question was "is it a newer one, multicore?"  yes again.

he suggested taking windows over to standard install from acpi, and lo and behold. worked perfect after that, even at 100K kernel.

soo.....   never overlook even the most bizarre bit of hardware that can be interfering with mach3 signal.

Great tip! Someone should collect all of these gems into a FAQ or tech tips document.

Just to add to the stew, my Jurassic dual P3 server died yesterday (finally) and I replaced it with my wife's old 1.8ghz Intel Pentium on a Gigabyte MB . . Windows XP home. Still really old machine, but plenty to run Mach.

Passes driver test at 60 and 65 with 'excellent' rating. Set Mach to 60, steppers get sbout 6" and lock up. Set to 45, all is well smooth as silk.

For $155 all of the PP issues can be sidestepped (yuck, yuck). Only hold up for me is swap axis. Once that is implimented  . . or . . . I find another method to replace it, I'm going to go with the SS.

1004

General Mach Discussion / Re: Really need help

« on: August 14, 2009, 09:33:20 PM »

I will order the C1 - Parallel Port Interface Card as soon as I hear from you about the following relay board
I have a relay board that I bought with the RF Isolator. It has screw-terminal inputs & outputs. Any reason you think I should replace it with your C15 - Dual Relay Board?

If the relay is operating something now and the relay can be triggered with 5V, you should ne OK . . . . . unless it is RF isolated . . LOL! Be careful though that the relay doesn't draw more juice than the BOB can provide, or you can hurt the BOB. The chips are socketed, so it's easy to replace them (don't ask). Specs on the BOB are available on the site, you'd need to look up the specs on your relays.

You have some distance to go yet with this project and you are already getting plenty of opinions on this what-not and that doo-dad, so I am going to give you my best advice on the project menagement level. You stated that this is not a hobby project, so that changes the game. In my view, your decisions should boil down to how much your time is worth, and any losses associated with the machine not producing anything.These CNC parts are dirt cheap in comparison to what I might guess your wages are. You *might* be able to reuse an old piece and save $18, but if it takes you three hours and you need to buy or buld test equipment to figure that out, you have not saved anything for your company money AND, you still have an old part that nobody can give you advice on and now you also have a 'production' machine of unknown reliability. Would the relays shut down production if they fail?

As a matter of personal preference, I avoid 'multi function' stuff if possible. Problem is when one component goes bad, you need to replace the whole thing if you don't have room to add another board or if the failed feature can't be disabled, or if it took other stuff with it.

1005

General Mach Discussion / Re: Really need help

« on: August 14, 2009, 09:23:36 PM »

So, what is an RF isolator? . . answer; something you probably don't need. If nobody here knows what it is . . . .  likely you aren't going to need it.

That is kind of an odd attitude. Ignorance on your or other folks part should never be a determining factor. 

Tom - The RF isolation BOB you have looks interesting. I went and looked up the types of isolation IC's it uses and they seem like it would work well, it is just a newer style of isolation. It accomplishes the same things as an optically isolated BOB but used Radio Frequencies instead of light.

You have it backward. Ignorance is recommending something that you do not know works simply because you read a spec and *think* it will work.

SMART, is trusting the knowledgeable people on this forum who have may years of MACH specific experience and *know* what works.

Beating one's head against a walll for days on end with no result is usually the first step toward a CNC troubleshooting, but it would appear the OP has already accomplished that task and perhaps is ready to move on to step two; . . . making it actually work.


Lastly, the fellow with the problem has stated that this is for a business and not a hobby, and there is an objective here to diagnose a NON working system and get the thing going. Wasting time dinking around with oddball unknown components from an old system that are NOT working with MACH for the sake of saving a company $70 is just foolish . . . in my humble opinion.

Your mileage may vary . . . .

1006

General Mach Discussion / Re: Really need help

« on: August 14, 2009, 12:24:20 PM »

Can't speak for others but I am not offendable in this venue. I'm like Seargent Friday on Dragnet . "Just the facts, maam".  Personalities are pretty much irrelevant on a CNC forum. You might have a bunch of unpopular people buried under your house . . but that's not a CNC topic.

This stuff is really not complicated. Think of it like the old Vaudeville joke where the patient says "Doc, it hurts when I do this",  Doc answers: "then don't do that !"
So, what is an RF isolator? . . answer; something you probably don't need. If nobody here knows what it is . . . .  likely you aren't going to need it.

So here's the plan . . very simple: You need to connect the parallel port to a Break Out Board with an everyday all-pins-connected straight thru parallel cable, preferably short and shielded.  That protects your computer and provides nice convenient pins to connect to. You then connect the breakout board pins to the step and dir pins on your stepper drives. Light gage solid wire is ideal for this. Use nice bright insulation colors, otherwise it won't work right . .  nobody knows why      Your stepper drives should already be correctly connected to the motors, so that's a gimme.

How do you sculpt an elephant? Start with a big rock and chip off everything that does not look like an elephant. Anything you have left over that is not mentioned in the above plan . .  chip off.

This is similar to one of my breakout boards. Note the LEDs on every pin. No guesswork here. The lights tell you what the port is 'saying' and on which pin. http://www.cnc4pc.com/Store/osc/product_info.php?cPath=33&products_id=47

You are going to need a BOB no matter what, so it is not going to be wasted $$$ regardless of what your problem turns out to be. And my guess is that the problem may go away when you get rid of the strange leftover junk from the DOS setup. You are just digging yourself a deeper hole dinking around with a scope. All it is going to tell you is to get rid of something that you need to get rid of anyway.

If all of the above fails, then just put the whole thing in a box and send it to Hood. He'll fix it for ya  

1007

General Mach Discussion / Re: Really need help

« on: August 13, 2009, 06:22:35 PM »

Hey Guys...   I hate to say this, but I fear we are straying from my original question.
I think we might be digressing from the original subject a bit...

Didn't realize that when you leave the room, eveybody has to remain seated quietly until you return 

You have a host of suggestions, but you haven't done anything but try the same stuff over again that you already did, so there is really not much new to talk about on your issue.

If I remeber it correctly, the smooth stepper is less than $200 or there about. Your salary is a cost to your employer, yes?  It will probably cost your employer more for you to dink around with scopes and building pulse counters than to buy the solution the gurus here have suggested  . . meanwhile zero production.

Here is the real question: is this a critical path issue or not? If it is, and I were your boss, I'd be asking why you haven't already had Jeff-Birt overnight you a Smooth stepper. If it's not critical, by all means build yourself some new toys and play.

1008

General Mach Discussion / Re: Really need help

« on: August 13, 2009, 05:59:40 PM »

The big benefit of the SS is the pulserate, especially whe you are talking 2000 plus line encoders which is common on the industrial orientated servos, heck the spindle motors I have on the mill and lathe have intelligent encoders which can be set to 2 million counts per rev, even the SS wouldnt be much use there

The drives I am looking at all have pulse multipliers, so pulse rate not an issue unless you don't have enough resolution for the accuracy you need.

What is important for the hi-res encoders is the bandwidth of the drives on the encoder side. The drives I am looking into at the moment can read 1mhz from the encoder. That's 6,000RPM with a 2500line encoider . . . plenty plenty for what I need.  The step/dir pulse input is far less than that, but the multiplier saves the day. One order of magnitude is plenty for what I'm doing.

My only hesitation on the SS is the lack of swap axis,  . . . deal breaker for me. I've been talking to some people about a completely different approach to that issue. May need programming assist from some of the big-dogs on that, but we shall see.

1009

General Mach Discussion / Re: CAT30 vs BT30 vs NMTB30 vs ????

« on: August 13, 2009, 01:52:59 PM »

1k to 2k drawbar tension and 3.3K release tension  . . . . . this seems to me like reasonable numbers.

In my many years of using R8, I've always had to whack the loosened drawbar with a hammer to free the collet. (the drawbar wrench qualifies as a 'hammer', incidentally  )  Releasing MT tapers requires an act of congress. 

I would err on the side of 'way too much' force for releasing any taper, even a steep solid one.

1010

General Mach Discussion / Re: Linear encoders and steppers (newbie ?)

« on: August 13, 2009, 01:03:33 PM »

"If I screw up, it won't cost too much to fix my mistake, and maybe I won't get fired."

Time for a bedtime story "Why bosses actually fire people"  .

I had a designer working for me many years ago who came into my office and proudly announced he had saved my department money by repairing a tool. Turns out the clogged hot melt glue gun was brought to him by one of the model makers who then proceeded to spend the next hour watching the senior designer fix the glue gun. To his surprise, rather than kudos, I informed him that his pay would be docked for any time he spent in the future fixing tools. Employees have a tendency to not regard their own salaries as 'cost'. In effect, I now had a $150 'Refurbished' hot melt glue gun charged against my billable man-hours account instead of a new $20 tool charged to the general shop equipment budget. More importantly, I was now two man-hours in the hole on the project they were supposed to be working on. I explained to the designer the priorities at issue and that neither the CEO nor the client is going to ask me in a project meeting why I spent $20 on a new glue gun, but they are going to be keenly interested in why my design group held up a critical path item.

I'm just glad there was not a shop crew at $hundreds per hour sitting idle waiting for a drawing while the designer was fixing a $20 glue gun? The shop forman would certainly have been asking for one of my budgets to charge the time to. Those are the realities that bosses deal with.
  
In my opinion, if one is concerned about the success of an assigned project, steppers are a bigger risk due to some of their peculiarities. Employee salaries are going to be a very large portion of the total cost to implement the capability. Mo' better to do it right the first time, even if the cost is initially higher, and be in a defensible position if things get messy. Things to consider:

However much the hardware and man-hour cost to implement the new CNC capability would be appropriated up front and since it a first endeavor, could probably go over budget without too much repercussion. Lost production and man hours lost to endless diagnostics trying to figure out why the steppers are suddenly loosing register and ruining parts is going to be visible to the degree of being a neon sign on the bosses office.

Servos will not eventually be found inadequate and need to be upgraded to steppers, thereby converting all hardware and labor costs (from the original conversion) from investment to loss. Bosses do not like loss.
Servos are not disposed to mysteriously 'learning' new bad behaviors that were absent yesterday and will take three days to track down and fix. Numerous active posts attest to that.
Servos do not stealthily and with no warning or cause (seemingly) ruin parts by happily cutting along many invisible silent steps from where they should be.

Your boss will never come to you and say 'why didn't you go with steppers in the first place?"

 
FWIW . . .