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Messages - simpson36

691
General Mach Discussion / Re: Another 2nd parallel port question
« on: October 19, 2011, 11:33:28 AM »
Couple things;

1) only the fist number in the address is relevant.

2) Mach anomaly (may or may not still be with us in current versions)   For me, Mach would not tolerate changing the address in the config unless I first zeroed the address, disabled the port and closed and restarted Mach. Upon restarting Mach, I could then enable the port, put in a new port address and Mach would use it. Note that this is just an observation and I do not know why it happens this way. I might speculate that this is because the port driver has a death grip on the port while running as a separate process outside Mach, but whatever the cause, I found you have to slap Mach in a face to get it to let go of the address it is clinging to before it will consider changing to a new port address.

692
General Mach Discussion / Re: Stepper motors seem a LITTLE slow
« on: October 19, 2011, 11:19:43 AM »
Unless I missed it in my quick read, the motor voltage has not been stated. A common problem with newbees and steppers is to supply the voltage that the motor spec states. Steppers should run on 3 to 6 times their 'rated' voltage. I have not messed with steppers in a long time and I don't recall exactly the technical reasons why the stepper rating is so far below the correct operating voltage, the rating is voltage per phase or per winding or something like that. In any case, a stepper will be very lethargic running at its 'rated' voltage and the proof here is the inability for the stepper to accelerate to keep up with the step stream. Steppers are very slow in any case and certainly should be able to reach the few hundred RPM they are capable of. If your voltage is correct, I would suggest you remove the motor from the machine and try to spin it up on the bench. Even an 'un manly' stepper can reach full speed with zero load    :P

Steppers draw full power whether they are moving or not, that is why they hold so well, and as a consequence they are designed (insulation and lubrication temp specs primarily) to run hot . . . that's hot, not warm. Perfectly normal, even if they are not moving. Imagine a skinny old guy with his neck stretched out as far as it will go, holding his breath with his face beet red and his eyes bugging out . . .  that's how steppers are all of the time . .  :D

However, they will only get to a certain temp and then just stay there. On the other hand, a normal DC motor under a heavy load (holding up an uncounterweighted Z axis, or otherwise held off of its commanded position for example) will continue to heat more and more until it self destructs, so you do have to pay attention to temp on those motors. 

 

693
General Mach Discussion / Re: Manual chipbreaking script?
« on: October 19, 2011, 10:11:07 AM »
You follow BR549's sound advice and still monitor your drilling. I do it all the time.

If you think differently and learn the Code for drilling by heart, you can slap one in there in a few seconds and then manually monitor and adjust out chatter, stalling (maybe), flexing of fixtures or whatever my mousing over the feed and speed overrides.

Typically there is more than one hole to drill and once you have the params 'felt out', an huge advantage of using the g-code is that you just type in the next coord and the machine will automaticall drill the next hole with the 'feel good' params you just manually adjusted.

If your machine can not drill two identical holes with the same settings, then you need to think differently . .  like about getting another machine.

OK, kidding aside, if you want to think differently, then consider this;  Rigidity issues in drilling are normally caused primarily by the force needed to displace the metal at the center non-cutting part of the bit. If you have a rigidity problem, but you have some power in the spindle, try drilling a small pilot hole first, say a 1/16" hole followed by the 3/8 drill.You may also benefit greatly by using split point bits. Either of these solutions will dramatically reduce the amount of down force needed to move the drill bit into the work. If it takes you over an hour to make a 3/8" hole in 6061, then I can just about guarantee you will same time making a pilot hole first. Don't make the pilot hole bigger than the non-cutting part of the follow-on drill bit or you may get chattering.

694
General Mach Discussion / Re: cutter comp
« on: October 19, 2011, 09:42:43 AM »
Cutter comp requires a lead-in move in order for it to know what direction the tool path is moving  . . in order to determine which side to offset to.

The lead-in has to be of sufficient length (one diameter or one radius, I don't recall which) or you will get an error.

Once the direction is established, you can then get on with your cut. In the case of a small hole or a hole you want to cut by spiralling down, youcan make the lead-in move above the part and then go down in Z to make your cuts.

I would advise that you put all of your setup G-codes (G17, etc) early and not spread them thru your code. Have them done before you enter cutter comp. I would think you need a diameter in the tool table for whatever tool you are compensating for. If you have a 'tool path' (meaning the path has a specific tool size already taken into account), then the tool table diameter would be the amount of adjustment you want and not the actual tool size . . .  or more accurately twice the adjustment since it assumes a radius adjust and not diameter . . .  if all that makes any sense  . . .

I have had the best luck by putting cutter comp on the same line with the lead-in move. Lastly, cutter comp can behave erratically if you have any axis scales set to -1 for mirroring a part.

 

695
General Mach Discussion / Re: Another 2nd parallel port question
« on: October 19, 2011, 09:27:05 AM »
I just checked and the chip on the lastest card (the link provided in a previous post) is the same as the one on my old card.

Couple things to check:

1) Make sure you get the drives from the MOSCHIP site and do not use the drivers that come with the card. The versions may have changed by now so this may not still be valid, but I had no success with the drivers from Roswell.

2) The pin header is indeed for the second port. Don't assume that the first set of addresses reported by Windows is on the built in port and that the second set of numbers is the pin header. It could be either way and also the windows port numbers have no relevance to Mach's port numbers. Mach talks to the port addresses. You may have given Mach the address of the pin header. Try the other address.

3) Just FWIW, I had some odd behavior from the built-in port on the motherboard, and it would not run above the default lowest speed for Mach so I have it disabled and use both ports on the Roswell card. I can run at 60 thru the Rosewell card with an otherwise mediocre computer.


696
Videos showing the new tailstock and trunnion table:

Tail stock is finally completed. It has the original planned features as well as some new features. The ball bearing supported hollow 5C spindle is probably the largest difference between this tails stock and any other. The version shown in the video is the first prototype whick has now been sold and the latest version is similar, but the leadscrew redundancy has been removed and a new adjustable drag and spindle lock have been added. Some new videos of that version will be added soon.

http://www.youtube.com/watch?v=DJXg1u4D3Y0
Some testing of the new tail stock:
http://www.youtube.com/watch?v=yM06Ro7y_oUhttp://www.youtube.com/watch?v=K4rziDNTu5A
And finally the first tests of the trunnion table:
http://www.youtube.com/watch?v=itJqDwl7X2o

697
Thanks for the compliments. I do not have time for forums these days, but I can provide a few design tips that may prove useful if you intend to build your own machine. First, there will always be 'doom sayers' who will condemn any idea as unworkable or unnecessary . . usually because they have not been able to accomplish the same task. Some people demeaned the idea of this 4th axis, yet I cannot keep up with the demand for them. I am finishing the last three of another batch of 7 and when shipped in a week or so, that will be 14 units shipped so far this year. And there is a waitring list for more. So, do not be discouraged by the untalented who preach impossibility. Even the infamous R8 power drawbar and other 'impossible' projects are very doable.

That being said, every machine designer works to a spec and design criteria. Pretty much all things are doable, particularly in the realm of prototypes, but nobody will purchase a 4 million dollar mouse trap so cost is usually one of the criteria. Because of the pneumatic disk caliper and custom spindle drive pulley, this 4th axis is not an easy DIY project.
 
Note in the photo that there is no real estate available internally for additional components for an auto shifter mechanism. The spindle lock is a critical need and cannot be eliminated. In fact, the current model is even more crammed as it has a larger air cylinder which required the frame to be expanded slightly. Automatic shifting IS doable, but all features must be evaluated based on cost/benefit and there is also no 'room' in the pricing to add such a feature and remain affordable to the target market. Some challenges with your proposed scheme will be retaining a hollow 5C spindle, very high rotating mass and perhaps there would be consequences to having large electro magnets in close proximity to CNC equipment. I think syncronizers might be a reasonable alternative if automatic shifting is a requirement in your application. Note that on my 4th axis, you do not loosen the motor or the idler. Both are mounted on a moveable plate which is how the belts are changed/adjusted and the same belt is used for both high and low ranges. 

You are quite correct in that integrating the unique capabilities of a combined lathe/indexer into Mach3 (or others) is the largest challenge. Lastly a comment on encoders; the motor you see in the above posting is a 400 watt  Mitsubishi industrial AC servo with an absolute encoder of over 100,000 counts. That motor has been replaced now by a 75-0watt version and I have acquired three of the current Mitsubishi J3 series for my new mill. That series has 262,000 pulses per rev absolute encoders. However, in practical terms, Mach3 cannot utilize an absolute encoder in a useful way and a typical 2000 line (8000 in quadrature) encoder is completely adequate for most indexing.
Good luck in your project and please do post a link to a build thread if you start one somewhere.


698
By request here is a freebee for anyone who needs a differential signal converter board or just wants to mess around with routing a PCB for the fun of it. Traces are best cut with a 30 degree engraving bit at a DOC of only a few thou. then .032" drill and .047" drill. Componets are listed on the drawing. Rev1 does not use terminal blocks. It is meant to have the wires soldered to the board andthen have the whole thing encased in tape or heat shrink and become more or less part of the cable.

No warranty express or implied. Use at your own risk. Routing PC boards is fun and can be addictive. Links to G-code set is at end of post. Setting up a little mill to do engraving is as easy as mounting a die grinder on the head like this:

http://www.youtube.com/watch?v=r9Zf_5yHB1I



www.thecubestudio.com/DifferentialPCB/DifferentialTracesRev1.tap
www.thecubestudio.com/DifferentialPCB/DifferentialDrill032Rev1.tap
www.thecubestudio.com/DifferentialPCB/DifferentialDrill047Rev1.tap

699
If you are getting any communication pins that work, it is likely all of them are working. The card would not be selective about which pins are functional.

The best port debugger is a BOB that has led indicator lights on each pin. No guesswork. Any voltmeter will suffice also (to see if the pins are changing state), but at a huge cost in time and convenience.

So it is easy enough to check out the LPT lines and see if Mach is talking to anything, but it does sound like you have a different problem than the parallel port.

700
Device manager says I am using 2.0.0.16 dated 12/24/2008.  I will need to check to make sure my card has the same xx15CV  chip as the current version.

XP home 32bit.   

I have the computer's built in parallel port disabled and am using the two ports on the card only.

What problem are you having, specifically?