Wednesday, November 3, 2010

Ungluing accident.

See my coolant delivery system in action in the video.

I had a problem with this part. The sawn piece was a tight fit in the pocket in the wood sub-table, so it didn't glue well, so it came unstuck soon after the start of machining. You can see the bent path left in the metal, in the video. I remachined the wood and chiselled the side of the pocket bigger and everything else went well, but there is a bit of a gouge out of the top of the circular post feature. Maybe it won't matter too much? The surface finish doesn't seem any different ( the one on the left of the picture is the most recent part ), despite lowering the feedrate to 50 mm/min instead of 100 mm/min. The tool looked slightly worn after the ungluing accident. It doesn't look much more worn after all the machining, so I think that 200 mm/min is better than 300 mm/min. Hopefully the next one I make won't have any mistakes in it.


Perry E. Metzger said...

Since you are milling a pocket, why not hold the part in place using a vice? That's what I've been taught to do under such circumstances. (I want to emphasize that I don't really know what I'm doing yet, I've only been working in a machine shop for a couple of months now. Still, we would probably use a vice firmly mounted to the mill to hold the part.)

Dan Falck said...

I would agree with Perry about using the vise. The wood backing is going to expand from the coolant and the glue gives up, as you have seen.
Toe clamping down to the table would work too and it would be more solid/rigid.
I can hear the chatter of the cutter against the part as it's cutting. You will get much better surface finishes with a more rigid setup.
You could use some pins in the T-slots to push the stock up against for alignment. Toe clamp the work down as close to the cutting zone as possible, then make your G-code stop in strategic places, so that you can move the clamps out of the way of the cutter.

Kurt said...

I was trained to use a vice as well. Dan pretty much covered the whole procedure. You might want to go to Youtube as well if you find it hard to picture the whole thing. A good tool organizer would come in handy during these situations wouldn't you agree?