Hello Guest it is March 28, 2024, 11:09:11 AM

Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.


Messages - BluePinnacle

Pages: « 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 »
71
This is the story of how we built one of the largest spinning tools you are ever likely to see. This is a parabolic spinning tool for making aluminium reflectors for satellite antennas and weather radar systems. It weighs around 2.5 tons. We had a 3.0m tool which was bought as part of a factory closure. it had originally been the centre of a 4.5m tool, but the outer segments had been scrapped. so we had to remake them. It was no small job.

fig.1. The 3.0m tool


Fig. 2 After making a pattern and having the new segments cast, the machining references were milled and holes tapped for fixturing. They were milled on a large 3-axis machine, tilted as they would be in service to allow the sides to come parallel when assembled.


Fig. 3. Assembling the tool for finish turning


Fig. 4. The tool in position on the lathe headstock where it will be used, driven at around 60RPM using a 20hp motor. Note the pit needed to clear the tool to put the axis at a workable height.


Fig. 5. Turning the tool. The 2-axis slide is not at 90 degrees to the machine axis as this would require too much slide movement, Instead a minimal Y axis moving only 300mm or so is used, and an angular offset applied. The software is used in mill configuration using the radius of the lathe tool tip as an offset.


Fig. 6. The finished tool With its eventual operator for scale.


Programming was simple since a parabolic curve is simply defined mathematically, so parametrics are used to recalculate the next pair of X and Y coordinates based on a subroutine that runs several times a second to change the value of two parameters which are then translated to X and Y before movement. The program as it was run was about 30 lines long. This and the angular offset made the programming easy.

Turning took six days, day and night. This was a long job and the first I've seen where the job was bigger than the machine! a number of visitors called their friends and just said "get down here. You've got to see this". As far as we know this is the largest metallic spinning tool in europe - and it was made using Mach3.

72
Show"N"Tell ( Your Machines) / Re: Zero gravity Z
« on: December 08, 2013, 10:23:41 AM »
I can see the problem now, the weight of the head is backdriving the stepper when it is unpowered. Took a while to see whay that could be, it's not a problem a regular mill would suffer from as it's just the weight of the quill against a fairly highly geared ballscrew. I certainly can't backdrive any of my axes  :D

The air cylinder looks as good a solution as any that doesn't add mass to the arrangement like a counterweight. Gas struts also for the same reason.

73
^ That's how I've always done it on every sort of equipment I've worked on. For tidiness, pop a bit of self-adhesive heat shrink over the transition between the braid and the insulated wire tail ;)

74
Show"N"Tell ( Your Machines) / Re: Zero gravity Z
« on: November 30, 2013, 06:34:45 PM »
Not a particularly safe system if Z drops at all. How is it moved and held in normal use?

You may want to set the air pressure a bit high so that in the event of estop or losing the axis for any reason it rises out and clears the cut. Just my thoughts ;)

75
General Mach Discussion / Re: Gcode help need?
« on: June 03, 2012, 10:21:05 PM »
Hi, this will depend on how your machine is wired up.
I'm thinking you could use the spindle and flood coolant outputs to control the valves. Your Gcode will depend on what positions and rates you want to use but I have an outline here if it is useful. I think you can get the job done with just conventional coding.

If you only use valve 1 for tool changes, why not just use a switch? Hardware solutions are robust, cheap and easy to fit.

Usual caveats apply: ymmv.

1- go to tool position - simple G0 commands
2- activate valve 1 to lock tool( stay locked till need change tool) use M8 command, usually flood coolant (or hardware switch)

Lines 3-10 need to go in a subroutine. Line 3a goes here: command M98 P1 L1000 (repeat subroutine 1 a thousand times)

M30 (stops and rewinds when the 1000 cycles are complete)
% (ensures the program rolls over the M30 correctly)


Subroutine here:

o1 (marks the start of the subroutine)
3- go to waiting position (stay till input signal come on line 4) G0 commands and M1 optional stop
4- input signal to enable job start - Click cycle start
5- go to circle start position - G0 commands to position
6- lower Z to position - G0 again
7- activate valve 2 to dispense glue - Use M3 (spindle forward)
8- start circle job - G02 OR G03 depending on direction. you can't have spindle commands in the middle of a move. But you can program delays for spindle on/off which may be useful as the glue gets going.
9- deactivate valve 2 at the circle end - Use M5 (spindle off)
10- go to waiting position on line 3
M99 (end of subroutine)

You will need to do some of the programming - Be careful and see how you get on.

76
General Mach Discussion / Re: weird parallel port issue
« on: June 03, 2012, 09:57:34 PM »
the add-on card can have a port address forced by moving it to a different slot on the board. Or remove it, run the computer, then refit it.

77
Tangent Corner / World's finest work holding system
« on: May 30, 2012, 07:52:03 PM »
At first I was like   ???
But then I was like >:(

http://www.ebay.co.uk/itm/Robust-Clamp-Fixture-for-Milling-or-CNC-machines-Secure-items-up-to-45mm-deep-/300714176245

I bet this would be just fine when I clamp down a chunk of 40mm square section steel and drive an 18mm slot drill into it at 1000rpm. Obviously "robust" has changed it's meaning some time this week.

78
I frequently use this. Ie, use parametric values to define Z movement during a circular cut, and decrease that value every time the subroutine is called. Result: helical paths for boring, thread milling etc. Parametrics can save you a lot of time and coding.

Remember that a parameter will persist between cycles ... Make sure your program resets the parameters to a safe starting point before they are called for the first time in the movement phases.

79
General Mach Discussion / Re: Kasuga NC mill to CNC ?'s
« on: May 25, 2012, 08:58:42 AM »
Either way, this should be a be a very capable machine when it's sorted out. Do keep us informed :)

80
General Mach Discussion / Re: Auto Open Program
« on: May 25, 2012, 08:52:34 AM »
Nice, didn't realise this was possible.

I can get my operator starting runs without me now :D

Pages: « 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 »