CNC Crash Compilation

[Stilldrillin]

Video?...... Hmmm........ 

Awww..... Phil. Sorry mate! 

Strange, isn't it. You never think of the video facility at that precise moment.   

Only taking the odd (flash) still, occasionally.......



                           


David D

[philf]

David,

That's an interesting looking lump - what is it?

I'm glad to see it's held properly. I noticed one round item in the video held in a normal machine vice - before it let go of it!

 

Phil.

[sparky961]

David D. definitely has the right idea.  Considering the number of years vs. number of crashes he can recall, it sounds like he got along pretty well with that machine.

Not to criticize, rather to clarify for the uninitiated, consider that single-stepping by itself can still result in severe crashes.  Additionally, while proving the program the rapid speed needs to be turned WAY down to a point where you can react when you see things not going as planned.  Same goes for the feed speed.  I tend to program some pretty quick feeds (instead of rapid) so that I get coordinated axis movement to a certain point.  They can be very surprising when you're stepping through a program if you're not expecting it.

All of this said, a lot of hobby-class machines aren't going to move at 1000 IPM rapid, like the machine I work with so you already have a bit more time to react.

Sometimes it just can't be avoided though.  I wish I had a video of the drill that was "flow drilling" while glowing bright orange under flood coolant.  It had lost it's edge after a few hundred holes.  I now have a pretty good idea how many holes that drill can do per sharpening.

[Stilldrillin]

David,

That's an interesting looking lump - what is it?

Phil.

Ohhhh........ Phil!!! 

If I'd known you were going to ask me that. I'd have taken a lot more pics, back in 2003. 

They were called segments...... A fat, wobbly profile "flag", on a stumpy post.

(The post hasn't been machined yet, in this shot)........




The post, goes in the hole bored in the bottom of the recess.......




Allowing it to swing outward, under drilling forces. So, producing a larger hole, than the body. Allowing a steel casing to follow down the hole.

At the bottom of the hole, a reverse turn rotates the segments back into their recesses. Allowing the drill string, and body to be extracted, leaving the casing in place.

As explained here.....     http://www.americawestdrillingsupply.com/bulroc/CDS745.asp


Watching the film, shown some weeks after the event. I believe this was the equipment used, to open the hole to rescue the Chilean miners, in 2010.

David D

[philf]

Thanks David,

So, those are the bits that do the actual cutting - no inserts fastened on to them?

It's a giant, three toothed version of a Cogsdill deburrer - I'm sure we had those in our toolroom:



 

Phil.

[Stilldrillin]

Hi Phil.
The component parts are heat treated, then drilled for bullet shaped carbide inserts which do the cutting.
Also, inserts flush to the outer surfaces, to prevent rubbing wear.

Here's a much smaller version, ready for pack/ despatch.........




Here's a different type of bit. Inserts fitted. The different colours denote different grades of hole size.....




If only I'd taken more pics at the time! 

David D

[philf]

David,

Thanks for completing the picture. I suppose the bullet shaped inserts don't wear very quickly like they would if they hard sharp edges. I guess they work by crumbling away the rock by inflicting great pressure on it rather than a normal cutting action.

Cheers.

Phil.

[awemawson]

A similar shaped insert is used on 'road planers' that strip tarmac off before resurfacing. Also used on trenching equipment designed for rocky soils. I have bought many tons of road planings, and it's not uncommon to find a cutter insert among the other detritus that gets tossed into the lorry.