Messages

6751

FAQs / Re: plug and play with old machine?

« on: August 07, 2010, 12:37:29 PM »

Hi Tom,

I have done a bit of searching on this but no luck. HME Technology are very cagey with their information but it appears to be a Rishton CNC designed machine. There is more than a good chance that your control board is for Serial operation using the (2) setup of pins 14,16, 17 and a computer installed driver.

If you are unable to get the necessary info from HME (bearing in mind that all suppliers to schools and the educational market are very guarded with their info and software) then the best bet would be to remove the board and fit another cheap 3 axis driver such as this one http://cgi.ebay.co.uk/3-AXIS-TB6560-CNC-DRIVER-BOARD-4-STEPPER-MOTOR-ROUTER-/110570269975?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item19be806d17
There are plenty of these type of boards available on ebay and, in my opinion, they represent an economic solution.

Hope this helps,

Tweakie.

6752

FAQs / Re: plug and play with old machine?

« on: August 07, 2010, 11:32:48 AM »

Tom,

From that information I would think this is not designed to connect to the computers parallel port at all but to a, perhaps PCI, driver card fitted in the controlling PC.

Tweakie.

6753

FAQs / Re: plug and play with old machine?

« on: August 07, 2010, 08:47:35 AM »

Tom,

Just one point that is very important - do not disconnect any of the motors whilst the board is powered up.

Tweakie.

6754

FAQs / Re: plug and play with old machine?

« on: August 07, 2010, 08:11:38 AM »

OK Tom, excellent photos. This looks like it will be an easy one, well at least not very complicated.

A common convention (but there is no defined standard) is;
LPT Port Pin      2   X Step
                       3   X Direction
                       4   Y Step
                       5   Y Direction
                       6   Z Step
                       7   Z Direction

With pins 18-25 as GND or 0 Volts.

This is the very basic and initial connections required to move the motors but there may be an enable signal (e-stop) to be found also.
If it was me, I would connect the cable to your computers printer port and try configuring Mach with the above pin allocations (2 to 7) as trial and error and see what happens. Once you get axis movement then you need to set the steps per and velocity / acceleration etc. for each axis and get the directions right. (the Mach manual and videos will give you more details of this).

The next step is to find the limit / homing switch, e-stop and spindle control pins (2-9, 1[seldom used], 14, 16 & 17 are all output pins driving the machine functions) (10-13 &15 are all input pins connected to e-stop, limits, safety interlocks etc.) (18-25 are ground)

Good luck with the experiments.

Tweakie.

6755

FAQs / Re: plug and play with old machine?

« on: August 07, 2010, 06:19:14 AM »

Tom,

I have never seen one of these machines before and their website doesn't give much away either but if the machine is operated by 'step and direction' signals generated by the PC then there is a good chance that it can be used with Mach without too much hassle.

If,on the other hand, the stepper motor pulses are generated by the machines internal controller then there may be quite a lot of work to do.

A photo of the machines internal electronics might help.

Tweakie.

6756

FAQs / Re: plug and play with old machine?

« on: August 07, 2010, 05:57:11 AM »

Hi Tom,

In answer to your questions it is just about a 'no' to all of them. 

There is no easy solution without knowing more information, it may be possible but most solutions with old DOS machines is to replace the internal driver board.

Does the router operate from a 'parallel port' cable (as opposed to serial) ?.
Do you know the type and model of the router ?

Tweakie.

6757

General Mach Discussion / Re: Z stepper movement

« on: August 07, 2010, 01:46:57 AM »

Hi Bernie,

I suggest that your 'steps per' are incorrect. Is there any possibility that you are not saving the axis settings after you are making the changes ?

Tweakie.

6758

General Mach Discussion / Re: Unipolar stepper motor with ULN2003?

« on: August 07, 2010, 01:26:40 AM »

Well done Sage for getting it right - I forgot to subtract the motor coil resistance, and I had two goes at it 

(My tutors always said that the degree in Mathematics and Computing was wasted on me - I think they were right  )

Tweakie.

6759

General Mach Discussion / Re: Help with 4th axis

« on: August 06, 2010, 01:09:08 PM »

Just something to think about.......

Angular mode is the most common and also the most useful way in which a rotary axis is used but there are alternatives to this,

When engraving on the surface of a cylinder, for example, it is convenient to have the rotary axis set for (linear) movement in mm but as this will vary, depending on the diameter of the work, there is a trick to getting it just right. One method for finding the ‘Steps Per’ is to calculate how many steps are necessary for the axis to complete one revolution and divide this figure by pi. In my case this is 200 (steps) x 8 (micro steps) x 60 (reduction ratio 60:1) / 3.142 (pi) = 30553.787 steps per to enter in Mach. Now this figure represents a linear movement of 1mm around the circumference of a 1mm diameter cylinder. In order that this can be used for any diameter of cylinder another calculation has to be performed and that is 1 divided by the diameter of the work (1/diameter). The result of this calculation is then entered into the rotary axis scale DRO within Mach. (My version of Mach did not have an A axis scale DRO (like the X,Y &Z axis have) so this had to be added using Screen4 (For reference the A axis scale DRO is OEM Code 62 and it’s associated LED is OEM Code 44).

As an example, to engrave on the surface of an 80mm diameter cylinder it is 1 / 80 = 0.0125 so 0.0125 is entered in the A axis scale DRO now a GCode command of G0 A10 will rotate the axis so that the surface of the 80mm diameter work rotates 10mm. Using this method means that simple, conventional, engraving programs and existing GCode programs can be used for engraving onto curved surfaces.

Although perhaps not quite as accurate as when the axis has been set up for angular movement in the first place - entering pi / 360 or 0.00873 into the A axis scale DRO will allow the axis to then operate in degrees ie. G0 A10 will rotate the axis 10 degrees.

Tweakie.

6760

Show"N"Tell ( What you have made with your CNC machine.) / Re: 3D Printing.

« on: August 06, 2010, 11:53:22 AM »

Got some more parts made – well just one part really (times 4). I have a fascination for identical parts that interlock and this seemed like a good opportunity to laser cut some 6mm acrylic for the walls of  my build jig (there is no doubt about it, a laser is the Dogs B’s for cutting acrylic). The tabs are a little on the tight side so they have not been fully pressed home yet, but this is how it will assemble and then be bonded with acrylic solvent. The lifting mechanism will sit inside and support the build table. Lots more parts to make but I am getting there slowly.

Tweakie.