Messages

611

General Mach Discussion / Re: Steppers very choppy and slow problem

« on: May 10, 2008, 03:43:19 PM »

Basically what Phil said is sound - check the support  documentation on this site.

You do no say what motors you are using, what steppers you are using or what gearing you are using on your set up. To give you an idea of mine - then you may get an idea where you have gone wrong - look in Config/Motor Tuning.

The first question is "steps per unit". This is a misleading term. It should be pulses per unit.
My motors are 1.8 degree - 200 steps per rev. My drivers are Gecko, which put out 10 microsteps per step - therefore I need 2000 pulses to turn the motors one rev. These are connected via a 3 to 1 reduction gear to my lathe main shaft  - 6000 pulses per rev.
My mainshaft needs to turn 10 times to move the saddle 1 inch. 60,000 pulses.

Therefore if your machine follows along those lines - your pulses (or steps) per unit (assuming inches) - should be well above the 3200 you are quoting.

We then get on to inches per minute movement of your saddle/table. This also is entered into the Motor tuning page (do not foget to save each axis as you complete it) If you want your axis to move at say 20 or even 40 inches per minute (remember this is fast speed - not cutting speed) - then set the speed at that and the acceleration at say 1 or 2. You may even want the table to move faster - but I would wait til you get it all connected up before you get into that.

Finally you can jog - if you use Mach 3 mill you jog at full speed, lathe - there is a percentage figure that you can change - put it up to 100% - I dont know if the plasma screens have any  adjustment.

You should find that the motors now turn in a fair representation of the speed they should move on your machine. You can fine tune them to get higher speeds out of them, and adjust the acceleration to get the best response. The number of "pulses" per unit is however, fixed, and should be calculated accurately.

612

General Mach Discussion / Re: Hot stepper Motor

« on: May 10, 2008, 03:21:56 PM »

Sorry about the misleading info on the stepper motor - I found the info on the internet - but now I can't go back to it - so Stirling is probably a lot nearer the mark than I.

As to your other question - there isn't really any way to test the axis to find if it is loosing steps. I can write a program to check that the direction of A is correct in relation to X and Y movement which was your other question, but, in the absence of any feedback as to which way the knife is actuall pointing, then any check merely relies on the DRO's of the system - and since these keep accurate position (even is the axis misses steps) that is not much good - it would always say it is correct.

I have not had any experience of tangential control so cannot comment on absolute stop - v - continuous

I personally would get a bigger motor, or gear down the one you have got. The Gecko drive - if it is like mine - will take a substatially larger motor. Mine are eight wire, 2.5amp per segment, at 7.5v and give 220 Ncm - and they work well and at £23 are cheap. You could probably run them with your 56 v supply.

I cannot get my head ropund your speed figures, however - you are quoting 5000 m (metres)/min - do you mean mm (millimeters). If you also have this acceleration and speed on your knife - IS IT NECESSARY. The knife, at best will only be moving a short time and only moving a few degrees, I would seriously cut down the speed of the knife rotation - you don't need it, and this is always one of the main reasons for missing steps. I have managed to coax 40 ins per minute out of my motors, with Geckos - but I have cut this to 20 ins per minute in deference to accuracy over speed.

The time you would loose by cutting your knife rotational speed by half would be minimal, but might just give you the accuracy you are looking for.

613

General Mach Discussion / Re: Can Mch run more 'professional' machine

« on: May 10, 2008, 02:09:34 PM »

I think you will have sussed the reply.

You are asking the wrong question - of course Mach 3 will run any number of axis in a professional manner - comparable with the any bespoke software (and you also get the benefit of this forum)

The output from Mach 3 is 2 wires per axis (step and dir) so all you need is a system to convert this to drive your machine.

Now you'll get the forum arguing about the best system !!!

614

General Mach Discussion / Re: Spindle Index problem.

« on: May 10, 2008, 01:57:56 PM »

I would suggest that the problem lies in the speed you are trying to do this. Cutting a thread - e.g. an 8 mm thread - this is 1.25mm pitch. That is 10mm movement for every 8 revs of the spindle. If you can move your axis at 500 mm per min, this means a spindle rev of only 400 revs per min. This is slow for the average 3 phase motor on an inverter, and you will loose power.

Really you need to be in the equivelant of backgear on the lathe to get the spindle speed down to these low speeds, but still retain the power of the reduction gearing to maintain a smooth cut. You need to have everything working well with parameters to do a nice thread.

On the old lathes, with thread cutting gearing, they were usually cut in backgear.

615

General Mach Discussion / Re: More noob questions i'm afraid

« on: May 10, 2008, 01:39:24 PM »

If you are saying that you are reversing the direction of movement of the Z axis, but it keeps going the same way (I assume you are using MDI commands however - not jogging). - then

If you are jogging - are you sure your jogging hot keys are properly assigned ( to Z++ and Z--) (I use page up and page down)

What pin is your "Dir" output on - either this changes - if which case your driver card is kna**kered -  or it doesn't change.

If it doesn't change - and you say you have tried all the available pins to output, then I am at a loss to suggest what is wrong. I can't see 5 pins all being faulty - and there is no other reason I can think of why it shouldn't change.

616

General Mach Discussion / Re: LPT2 input pin problem

« on: May 10, 2008, 05:04:16 AM »

Unfortunately I can't find any information on the PCI2LPT - so I can only suggest it may be faulty. However - the thing to check is the cable - always a good start. The only other way I can suggest is come out of Mach and Peek and Poke to the addresses and see if you get a reaction. If it is in the LPT2 slot (as it's name suggests - the addresses are &h278 (8 bits), 279 (bits 3 - 7)  and 27A (bits 0 - 4).

617

General Mach Discussion / Re: error in drill wizard?

« on: May 10, 2008, 04:38:38 AM »

I think you have probably found the problem - the formatting seems to work correctly here, but obviously not for you.

618

General Mach Discussion / Re: Mach3 Turn... Pro?

« on: May 10, 2008, 04:26:27 AM »

Ah - are you talking about having the tailstock rotate to do the drilling, or move along the axis in a self feed mode.

If you are drilling you will need a big motor - drilling takes a lot of power.

If you  are using drills in your boring bar holder - then you have the idea - when you say you are not programng yet fine - I assume you are using the jogging keys.

All my drill holder will be is a square block of metal - I will mount it firmly at the back of the cross-slide. I will bring the block across to a know point opposite the chuck (a point I can go to again - hence the homing switch) - and then drill it with a drill in the chuck. I therefore have a hole on the centreline of the lathe. I never thought of drills with standard shanks - that makes it easier - if the hole in the block is the right size. There are macros in Mach 3 for doing most drilling jobs - so - drill the drill holder across, put in a drill and call up the macro !!

You can look at Mach 3 Mill screen - and use it on the lathe - there may be features that you do not need - but it doesn't matter.
All you need do is Configure it for your lathe. The only problem is you won't have access to the lathe wizards - so you would be better to ammend the lathe screens - which doesn't take a lot of doing.

619

General Mach Discussion / Re: More noob questions i'm afraid

« on: May 10, 2008, 04:10:17 AM »

Just a quickie to see if everything is working ok - how about using the other output pins just to get the axis up and running. It would only take a few minutes - unless you already have something else connected to them. The other pins available are 1,14,16,17.

620

General Mach Discussion / Re: Help needed Connecting NPN Proximity sensors to BB`s

« on: May 10, 2008, 03:59:14 AM »

According to the PDF file these sensors connect to 12 v and 0v with an output wire. The module will drive up to 100 milliamps.

It should switch between 12 volts (NOT sensing) and 0v (sensing)
Connect up on your workbench the 12 and 0v to a suitable power supply and connect your multimeter between  the output and 0v. You should get 12v reading. There is no directly connected internal pull up resistor - so the 12 v side perhaps will not show up. Move a metal (iron) object towards the sensor and the reading should change when the object is approx 2 mm from the sensor.There is also some detection indicator on the device.
The voltages will be approximate, not exact - but should be near say 11.5 and 0.5v.
 
To limit the pull up to a suitable voltage, then you need a pair of resistors in series connected between the 12 volts and the 0volts wires. These should be of the value 680ohms and 470 ohms  (preferred values). The output of the device should be connected to the junction of this "ladder".

If you check again with you multimeter the output should now be at 5 volts and when you bring the object within sensing range this should drop to 0v (or very near).

The problem is your breakout board - the input should be normally high (5v). This is what the input to the computer is . The signals goes low to indicate sensing. Read the blurb on your breakout board - there will be some way to alter the bias on the board.