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Messages - Davek0974

1921
General Mach Discussion / Re: Physical buttons for plasma
« on: March 05, 2016, 11:59:23 AM »
Nice control cabinet, luv the keyboard.

Is that a water table tray, my concern is that it will not work for downdraft??

I would also fit some hard stops so that the tilting system can jam solidly against them to remove any twist in the tilting frame.

1922
General Mach Discussion / Re: M3 M4 switching
« on: March 05, 2016, 03:24:31 AM »
I would use relay 1 & 2 - of course you will need to fit two relays, most BOB's only have one.
I would have BOTH relays working, one to start stop the drive, one to switch direction as this is done later in the supply line...

The hard bit is reversing the motor - treadmills generally only go one way ;)

Is it a permanent magnet motor or field wound DC motor - permanent magnet just reverse the supply wires, field wound generally reverse the relationship between the field and brush wires - a bit harder to do and sometimes not that simple.

The drive for the motor must be powered off before switching of course and the motor stationary or the back-emf might kill the drive so no instant reversing the lathe i think;)

1923
Ok, cool, then its 99% a mechanical i.e. build problem. Forget about axis labelling it's irrelevant at this stage as you will need slaving on two axes but this is really simple - my breakout board can run two drives from each output as standard, not many can so that would work there.

Picture a bog standard x/x/z plasma table, then remove the frame between the two sides and chuck the torch out. make the side frames self supporting, I don't know if there is room to join them, maybe you need a crane or forklift to load the pipe?

So now we have two carriages running along two side frames on linear rail probably. On those carriages build another linear motion unit - a trapezoidal screw lifter would be good as it holds its position and does not self-drive from the weight on it, probably decent belt reduction from the stepper motor as speed is unimportant.

Now we have two points (the nuts on the trapezoidal screws) that can move in horizontal as well as vertical planes, separated by a distance that could theoretically be many metres, both these points will move in sync as they are both slaved.

Now we just need to bridge those points with a support, maybe a box section with triangulated support etc to keep it rigid and light, then fit some possibly nylon rack along it, build a carriage to hold the scanner, the traverse motor and coffee machine ;) then some type of cable manager under the rail and it will run up and down all day happy in the knowledge that both ends are perfectly in sync.

Is this a field or lab machine, as if field, dust and crud will need to be factored in.

1924
General Mach Discussion / Re: Budget CNC build questions
« on: March 05, 2016, 03:01:10 AM »
Sounds like a good start, have you tried another parallel cable?

Looks like the BOB has USB power supply as well, have you tried that instead of your PSU?

1925
General Mach Discussion / Re: Pictures to GCode?
« on: March 04, 2016, 02:51:02 PM »
I am thinking of doing something similar, basically have a picture, convert to Gcode and make a 3D relief using router/mill and small ball nose end mill.
I did read that having the subject in black and white gives better results? But what to use, I did have a mess around with CamBam, but couldn't fathom how to get it right.

If it's any help http://openbuilds.com/threads/producing-3d-reliefs-for-free.380/

Tweakie.

I downloaded Mach1Filter but when i try it i just get "No File loaded, error in file" tried a few different jpeg files, all the same????


Sorted - I use a Mac laptop with Windows as a virtual machine and the jpegs were saved in Mac format, a quick conversion fixed it.

:)

1926
General Mach Discussion / Re: Pictures to GCode?
« on: March 04, 2016, 02:22:32 PM »
I am not totally sure exactly what i want to do yet ;)

i presumed i could take a picture, convert to B/W and somehow convert to code for engraving with a v tool or ball-end mill??

I guess the depth would be related to the scale from white (little depth) to black (max depth) but as i said, no idea really yet.

Just educatin' meself ;)

1927
General Mach Discussion / Pictures to GCode?
« on: March 04, 2016, 07:37:00 AM »
Looking for the best way  to get a picture into code for engraving?

I have no idea but is that what LazyCam does?

I did try it last night but not very intuitive I think?

:)

1928
General Mach Discussion / Re: Can’t get Probe to Work
« on: March 03, 2016, 02:04:36 PM »
DB connectors are a pain in the wotsit, very close pin spacing and close to shell (if metal) it was probably a single loose strand of wire touching the shell.

1929
I think I can see the target here - you want to build a pipe bore scanner that has a travelling head on a support that runs up and down the centre of the pipe?

You want to control the vertical and horizontal position of the scanner within the bore?

If so then its an interesting project ;)

In my mind, X axis is the scanner head, Y axis would be towards/away from centre of pipe, Z axis is up/down from centre of pipe. This would be with my view having the pipe running left to right.

I would have my X on a removable support track, probably belt driven or nylon rack & pinion for weight saving, this would simply sit in two supports, one at each end and have both ends running slaved Y & Z motors so they track each other and keep the X axis / scanner support true to the bore of the pipe.

Am I following?

How big is the pipe?

It just sounds like two vertical X/Y tables facing each other and running slaved motors on both axes, apart from the mechanics, probably quite easy to do?

Obviously all we need is a travelling linear device - could be a trapezoidal screw in the vertical plane running on a linear rail, doesn't sound like there is a need for any serious rigidity or speed here. No idea how fast the scanner runs though??

Just thinking out loud ;)

1930
General Mach Discussion / Re: Can’t get Probe to Work
« on: March 03, 2016, 06:20:57 AM »
Probably because its easy - the board is ready and tested and simple to mount.

I guess if you are building machines daily then you could have your own board made at a fraction of the cost, but when that cost is what ? £10 £20? It seems pointless bothering to build it yourself.

I have used three BOBs so far and all have worked fine, no odd issues with pull-up or down yet, and all have been opto isolated ones. Plus you get the relay and its associated snubber diode etc, nice easy screw terminals, the list goes on - its just easy thats all :)