Thread: Grf - cnc #2

OOOOOO so much extruded aluminium. Looks good so far, those belts are massive.

Thanks guys,

Rod, your correct about the bracing. Just playing around shows that the frame is lacking. I will bolt some diagonals so as not to distort the frame. This should provide some nice rigidity which is lacking.

There has been a suggestion to use a compound between the gantry and the frame when i bolt it together. has anyone used anything that they would recommend. I was thinking maybe gasket compound which doesn't go solid.

I prefer to see a mechanical fixing rather than compounds or glue. Perhaps a piece of angle or a flat bar joining the two. Maybe you can extend the braces on the stand to pick up the machine sides. Packers will take up any variation between the two components.
Another thought would be to drill through the top rails on the stand and tap into the bottom of the machine. You only need 4 x 6mm bolts or cap crews to do the job. If you are going to do it this way then use shims to pick up any gaps between the two components otherwise you will pull your machine out of whack. Coke cans cut into strips are good for this.

Okay after years of re-work, well seems like years I have it to a point where i'm happy to show people my progress.

I re-worked the X axis drive and kept the 4:1 reduction.
The y-axis was re-worked to allow the tension on the pulley not to bow the linear screw.

Next is the comissioning which will involve getting each axis set just right with respect to Mach3 and add a table top, the HF spindle, then some limit switches, blah, etc, blah, etc.

Man when you write it down it seems like there is a lot more still to do.
All i want to do it cut stuff into sawdust

Maybe by the next BBQ

Link to video run on youtube:
[ame="http://www.youtube.com/watch?v=I32GC50Xqy8"]YouTube - MVI 3778[/ame]

/M

Getting there now.
it's funny, you churn away for weeks on end and you see no progress.
Then one nights works and the spindle is on and the base is nearly laid. Gotta love acrylic sheet.

Looks Great

Frank

Lookin good

Hi Mike,
Good to see it back together again. I agree acrylic is a great product to work with and I like the idea of it used on your table.

Work is crappy, i just want to get to my CNC and finish her off.

I was thinking of using the simple lever armed units, but I would prefer the optical type.
Has anyone got any recommendations for limit and home switches.

The X4 also uses the limt as a home switch. Any pro/cons thoughts on this setup for ther GRF, is there a better way?

/M

Opticals can be prone to failure in dusty environments. Proximity are better but there are good quality micro switches that Greolt put me on to. They are around $15 each and I will post the details here tonight. The lever type are a waste of time for home switches as they are not accurate enough - ok if you only want limit switches.

Hi Mike
Took a while but I found them here
Tend Model TZ7311
The idea is you set them up to roll over an adjustable screw. Mount one on a gantry side and have the adjustable screw at each end of the table.
Greg is getting very accurate and repeatable limits.
Hope that helps

Thanks Rod,

So the idea it to locate one of these units in the middle and have 2 screws fixed on either end. reduces the cost I suspect.

Okay have to order three then

Thanks for looking them up
/M

You got it
The roller glides past or onto the top of the screw and not end on - you could get fancy and make a ramp but I find a cap screw with locking nut good enough. Running it end on will crush the micro switch in a bad crash.
On Z axis just put the limit at the top of the travel. No use having one on the bottom of the travel for obvious reasons.