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dirtyhanfri said:
http://www.instructables.com/id/Make-Your-Own-GRBL-CNC-Pendant/

Looks even easier, according  to the image in the second step you just wire the buttons to arduino pins, maybe you can save the usb gamepad..

Yesterday I used it in real work and I really love this thing, adjusting axis to zero and start working is way faster than before.

Thanks for the link. I was planning to put the Arduino in a box so now I could include the switches as well. The feed hold switch will be very useful.

Cheers

Ian
 
I'm having fun with my mill and maybe is useful for someone

Archivo_000.jpg


The huge holding makes a difference.

It's milling a 20x26x60mm aluminium block to hold those cheap clamps. Surprisingly it's working like a champion with 3mm bit, 200mm/sec and 0.2 mm depth passes. (This makes another difference I think)

Archivo_001.jpg


I'll thread the holes for M4 screws and maybe try to anodise them.

EDIT: I forgot to say, there's no coolant for the piece, and just a cold beer for me (it's like 40ºC out there)
 
Good work!

There is a definite relationship between feed rate and cut depth. You use 200 mm/min and 0.2 mm; I use 50 mm/min and 0.5 mm. The advantage of a smaller cut depth is is should be easier to get rid of the cut material. I will try your values.

Cheers

Ian
 
I have been doing some more experiments. I got fed up with writing the gcode for front panels by hand so I decided to write a Python program that would automate at least some of it. So far I have created two main functions and a number of support ones. The main ones create the gcode forholes or the final cut out that is the outline of the front panel, For the holes fucntion you tell it where the hole is, its diameter, the diameter of the tool, the thickness of the panel and the cut increment and it creates the entire gcode necessary. If you don't input anything for the tool size, panel thickness orcut incrmemeni it assumes default values. The cut out funtion works in a siimilar way. If you just enter an x and y coordinate it assumes the cutout starts at 0,0 and uses defualt for tool diameter etc. At the moment you just run the program and it prints the gcode to the screen. I then cut and paste that into a file which I then feed to the CNC. Later I will add a user interface

So I used it to make a 50mm by 50mm panel with a 6.5mm hole at 20,20.  Tool diamter was 0.8mm, feed rate 200mm/min and cut increment was 0.1mm. After I ironed out a few bugs I got it running. Making the holes seemed OK but when it cot to cutting out the outline it broke a drill  when truning a corner. So I changed the feed rate to 50mm/min. Holes were again fine but this time it got round the cut out a few times and the drill broke half way down on side. Lastly I repeated the run but this time used colloant throughout and the job completed without breaking a drill.

I conclude that milling aluminium with a 0.8mm drill must be done with coolant. The problem with a 0.1mm cut and a 50mm/min feed rate is that this simple job takes a couple of hors to complete  and that's a long time to stand there occasionally spraying coolant on the job. I have use a 0.5mm cut increment in the past with a 50mm/min feed rate and coolant with no broken drills so I might go for 0.25mm and 50mm/min. I think I really need a means of slowly dripping coolant on the job.

Cheers

Ian
 
Yesterday morning when my good wife went into my workshop on the top floor of our house she had to open some windows because she said it stank of alcohol. No, I had not been drinking but I had been standing over my CNC machine for over two hours spraying meths on the workpiece as a coolant. Last night about 10pm I got a stinking headache that I still have this morning at just gone 9am.

I won't be using meths as a collant again.

Cheers

IAn
 
I've been seriously thinking about coolant these days too.

The last aluminium pieces I machined (those clamp holders I shown a few days ago) worked nicely without coolant, just some compressed air to take away the chips, using a 3mm bit, which supposedly generates more heat on the piece.

I also did some engraving on powder coated aluminium, the same, no coolant, just some compressed air after the machining to clean the engraved zones, nice results.

Now, the biggest advantage I see on coolant is the noise reduction.

I didn't know you wrote your code manually, maybe it's because I'm eager, but it seems so time consuming for me, I strongly advice you to try some CAM software, not sure if you're familiar with it, but basically it's a bridge between CAD design and manufacturing, I load DXF or Gerber files and get GCode according to the specs I set. Also lot of CAM programs includes CAD capabilities, so you can even work in just one software.

I use Cambam, it's a cheap and very comprehensive software, includes advanced drawing functions and lots of machining possibilities, from simple engraving or drilling to 3D profiling. It has a nice workflow, ie I have some "Styles" (machining parameters layouts) for pcb engraving, drilling, cutting, and the same for aluminium, so I just load my design, assign machining operations to drawing entities, tweak some parameters if necessary and I get the code along with a nice machining simulation to see which will be actually the spindle movements, this helps me with piece holding so I can avoid crashes (you can even set your "holding tabs" in software to avoid them in the spindle movements, but I need to think more about it before implementing in my workflow)
 
Thanks for the Cambam tip. I use FrontPanelDesigner to design my front panels and you can export dxf files from this. I tried a dxf to gcode convertor but the output it produced needed a lot of massaging before it would work with grbl. Looking at the Cambam video is see it does not have a post processor for grbl. However I woill download the evaluation version and try it out.

Cheers

Ian
 
ruffrecords said:
I won't be using meths as a collant again.

I like tapping wax sticks.  The swarf bunches up and you can either brush it away or blow it away with compressed air if you have it.
 
I use the small sticks. http://www.mcmaster.com/#1009k221/=13oj0au  Part number 1009K221

They may call them something else there. They are also called lubricant sticks here.

They are  1/2" round by 4.5" long. Just touch the cutter with it every once in a while. I keep a chip brush handy as well.
 
Gold said:
I use the small sticks. http://www.mcmaster.com/#1009k221/=13oj0au  Part number 1009K221

They may call them something else there. They are also called lubricant sticks here.

They are  1/2" round by 4.5" long. Just touch the cutter with it every once in a while. I keep a chip brush handy as well.

Having no luck finding anything wax in the UL. What about this stuff:

http://www.draketooling.co.uk/Products/00360004/MOL40004

Cheers

Ian
 
Gold said:
ruffrecords said:
Having no luck finding anything wax in the UL. What about this stuff:

http://www.draketooling.co.uk/Products/00360004/MOL40004

I think that is "molly grease" judging from the name.  Since it's white in the photo I'd guess its a close cousin to lithium grease. It's not what I am talking about but it might work. It's not meant for this application though.


What is attractive is that you can paste it on the work piece where you know milling is going to take place and he stuff stays where you put it. It sounds a lot less messy and I can leave the machine and do something else knowing the tool path is lubricated. But as you say, perhaps its not ideal. I'll keep looking for wax.

Cheers

ian
 
I read the link but I'm not sure this is meant for swarf clearing. To me it looks like a grease. Not that it won't work. It says it has a low melting temperature which is what you want. Tapping wax kind of melts away like spirits evaporate. As long as this stuff doesn't gum up the works it might be good.


Maybe stop into your local machine shop and see if they have a name for it. Hand tapping compound or something like that. The wax isn't toxic as far as I know so I doubt its an environmental restriction.
 
ruffrecords said:
Looks promising?

That looks like the stuff.  That's a big tube of it. I find the small sticks more useful because you can get it right on the cutter easily.
 
I'm using paraffine oil for cutting, drilling and tapping (and for protecting anodized surfaces) - IKEA has that in ½L-bottles under the name "Skydd"

Jakob E.
 

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