El Beast - Initial design phase, comments and critique welcomed!

[Zeeflyboy]

Nothing particularly clever I'm afraid... I took some more photos today of the second carriage mount so perhaps an explanation with the pictures is best.

So on this part for example, I have some 5.4mm holes in the part for M5 screws.... After I've finished drilling/milling those holes while the part is held down using external clamps I would add an extra drill cycle using a mm drill bit on the holes I want to use as a fixture, setting the hole top as the stock bottom and the hole bottom as stock bottom minus eg 10mm.


External clamps, run the milling/drilling of internal holes to be used as hold down points, then run jig drilling cycle.




Once that's done I used compressed air to blow the SRBP dust clear, using a hand drill I whizzed a spiral m5 tap down through to the bottom of the hole and again give another blast of compressed air to clear the hole.

While the part is still clamped down with the external clamps, I then find some appropriate length screws (important that they aren't too long, thus preventing proper tightening down of the part, but you want to make sure they at least get a good 5-6 turns of engagement so that you can snug them down tight. It pays to have a nice assortment of various length screws in typical sizes - m4, m5, m6, m8 is what I tend to use.

Once those are tightened up you can remove the external clamps which lets you run the remaining cycles... just be sure to check your tool paths to make sure it isn't going to try to mill out those holes again as it'll find a bolt there of course (adaptive can be a little bugger for that, just make sure you have ticked "rest maching" and selected "from prior operations" so that it doesn't try to remove the same material twice).








If you've thought about it a little before hand and the part is suitable, you can use the same holes to hold it down on any bottom side operation, I like to use 6mm dowel pins in the bed to butt the part up against to ensure it's aligned to the axis.

With it held down, I find a suitable area to probe to define zero again




If possible I do a quick gross error check to make sure zero looks good:




And then run the rear operations:

[Chaz]

Thanks, excellent explanation.

I suspect you can also just set your retract height higher than the bolt height. It might waste a bit of time but better than cutting into the metal etc.

Certainly easier if you do rest machining or similar as you have said but you never know what path it will take when it crosses over. Always good to watch the CAM 'preview' before actual cutting IMHO.