Messages

341

General Mach Discussion / Re: Accuracy of Homing Devices? Pro's and Con's of Different Sensors

« on: October 17, 2012, 04:16:56 PM »

Thanks Hood. These are not plastic however - it's an anodized aluminium there

Mounting them to trigger against an inclined surface could be used to solve the overtavel problem. But I mount them just before the hard stop.

Dan

342

General Mach Discussion / Re: Accuracy of Homing Devices? Pro's and Con's of Different Sensors

« on: October 17, 2012, 04:00:18 PM »

Thanks.

These are single sided, Russ. First intention was making them double sided, but it interfered with the requirement of making them smallest possible and I decided to make them this way. The plunger stroke is 5mm, dimensions are 29x23x14mm. You supply anything between 5 to 15VDC and output is active low. Price is $30.

Hood, yes, they are based on the same concept. The new ones are an entirely different design (round frame with M12x1 external thread - like the industrial proximity switches) and they are single ended as well.

Dan

343

Show"N"Tell ( Your Machines) / Re: 1997 DYNA MYTE DM4800 VMC to Mach3 Conversion

« on: October 17, 2012, 02:30:15 PM »

Cool looking panel. Where did you get the buttons?

Dan

344

General Mach Discussion / Re: Accuracy of Homing Devices? Pro's and Con's of Different Sensors

« on: October 17, 2012, 02:25:14 PM »

Hi,

I used to make these home switches with the integral photo sensor. Now there is a new version that will soon be available but still have some of these left if that's of interest to you. Repeatability of these is better than 0.003mm and they are fully waterproof.

Dan

345

Show"N"Tell ( Your Machines) / Re: I wanted to show my homemade CNC.

« on: October 17, 2012, 02:00:22 PM »

Nice and well constructed machine! Good work on the signs too.

Dan

346

VB and the development of wizards / Re: Any new WIZARD ideas to work on ???

« on: October 17, 2012, 01:56:46 PM »

Yes, I was meaning the math behind the arc programming. Just can't figure it.

Afraid I still don't understand what you mean with the threading like flats cutting.

Very busty now. Will check what happens if I enter 2 flats in a couple of days.

Dan

347

VB and the development of wizards / Re: Any new WIZARD ideas to work on ???

« on: October 16, 2012, 03:21:24 AM »

Found the problem of the part being twisted - had the wrong setting for the A axis steps in Mach3 tuning. See a new one - now perfect. Only problem remaining now is the number of sides cut being wrong. This octagon is cut with the number of sides to 4. I can't find the error in the code, it looks correct to me.

Now regarding the ability to do arcs on a rotary axis, I have a workaround for this. I tried to asign the Y axis to the rotary - works fine only problem is I can't get my head around to figure how to program the arcs. Do you have any idea?

Dan

348

VB and the development of wizards / Re: Any new WIZARD ideas to work on ???

« on: October 16, 2012, 02:16:54 AM »

Hi Terry,

Ah... this was a good idea. I didn't think of changing the rotation axis to Z. Now I see the toolpath more nicely. And for some reason I am seeing it twisted in the Z instead of getting continuously lower. This is probably why the part gets twisted too.

I am using my A axis in revolution mode, as stated in the Gcode heading, not in degrees mode, so 1 in the A DRO means one revolution of the axis. This is why you think it's not rotating all the way around.

Dan

349

VB and the development of wizards / Re: Any new WIZARD ideas to work on ???

« on: October 15, 2012, 04:03:54 PM »

Hi Alex,

You are right the tool has to have a larger clearance angle as the number of flats gets smaller.

Dan

350

VB and the development of wizards / Re: Any new WIZARD ideas to work on ???

« on: October 15, 2012, 03:59:21 PM »

OK. Found the working version. Appears I made some modifications to the code at the machine itself. This one moves the A axis:

G0 G40  G17 G80 G50 G90

(A axis is in revolution mode)
(Program in Diameter mode)

#1 = 4  (number of sides)
#2 = 13 (distance across flats)
#3 = 300 (feed: mm/min)
#4 = 0.2 (Z feed per revolution)
#9 = 2 (length along Z)
#17 = 50 (resolution - number of segments in half flat size)

#5 =  [360/#1] (root angle)
#6 =  [2*[0.5*#2]/cos[0.5*#5]] (distance across corners)
#7 =  [[0.5*#2]*tan[0.5*#5]]  (half side length)
#10 = [[0.5*#5]/360] (single segment revolution amount of A axis)
#11 = [#10/#17] (single rotation fraction of A)
#16 = 0
#12 = [[-1*[#4/[#1*2]]]/#17] (Z advance per segment)
#13 = #12

G0 X[#2+1] A0
G0 Z1
G1 X#2 Z.1 F#3

#14 = [-1*[#4/#1]] (Z advance per main subroutine execution)

#15 = FIX[#9/#14] (Number of subroutine executions required - 'L')

#18 = #11

M98 P100 L100;#15

G0 X[#6+3]
G0 Z1 A0
M30

O100

M98 P101 L#17
#16 = 0
#18 = [#18 + [0.5*#5/360]]

M98 P102 L#17
#16 = 0
M99

O101
G1 X[2*[0.5*#2]/cos[#16*360]] A#18 Z#13
#16 = [#16 + #11]
#13 = [#13 + #12]
#18 = [#18 + #11]
M99

O102
G1 X[2*[0.5*#2]/cos[0.5*#5-#16*360]] A#18 Z#13
#16 = [#16 + #11]
#13 = [#13 + #12]
#18 = [#18 + #11]
M99
%

Just tested it on a piece of delrin and the concept works - see attached picture. Flats seem perfectly straight with resolution variable set to 50 and corners are sharp. Only thing is it's still twisted along Z. And the code has some problems with the variables as it cut the octagon in the pic with the flats number set to 4. If I set it to 3 it cuts two flats and if 5 it appears to cut 10 flats. But at least it shows that the concept works. Just requires some more thought and refinement. See if you find what's the problem.

Dan