bahed
01-06-2007, 11:07 AM
I have a cable drive SB. Using a Whiteside 1/8", 2 blade spiral, 1/4" shank, carbide bit on a 3-1/4 Hp PC router at 9000 rpm (I think that is its lowest setting), cutting 0.125" thick Dibond material (made of two pre-painted sheets of .012" thick aluminum with a solid polyethylene core.)
I was cutting a 40" diameter circle out of a 4' x 4' piece, in 4 passes of 0.035" depth each pass. After ~3- 1/4 revolutions (and cutting beautifully up to this point) it inexplicably jumped ~3/4" to the outside and continued cutting at the final 0.140" final depth, exactly parallel to the original cut. I paused the job, edited the code to remove the first 3 revolutions and re-ran the file again - very nervously as the client was watching, half aware as to what was going on.
It finished the last pass exactly on top of the previously cut out groove - cutting out the circle perfectly for a very happy client.
What happened ?
I looked over the code: nothing. I looked at the spoil board: nothing to make it jump. I am just lucky that it jumped outside to the spoil area - not inside !! I was being very careful and could have cut it on 2 - 0.070" depth cuts, instead of 4 passes. Was it just getting bored going over the same old ground for the 4th time ?!?
I have an otherwise accurate, albeit old, cable drive SB. I have not cut much lately to see if this is a trend or an anomaly - I mean, it went right back to the original groove and cut out a circle with the exact dimensions that I asked of it !!
I would love some thoughts on what might have been the causes ?
Suggestions ?
I was cutting a 40" diameter circle out of a 4' x 4' piece, in 4 passes of 0.035" depth each pass. After ~3- 1/4 revolutions (and cutting beautifully up to this point) it inexplicably jumped ~3/4" to the outside and continued cutting at the final 0.140" final depth, exactly parallel to the original cut. I paused the job, edited the code to remove the first 3 revolutions and re-ran the file again - very nervously as the client was watching, half aware as to what was going on.
It finished the last pass exactly on top of the previously cut out groove - cutting out the circle perfectly for a very happy client.
What happened ?
I looked over the code: nothing. I looked at the spoil board: nothing to make it jump. I am just lucky that it jumped outside to the spoil area - not inside !! I was being very careful and could have cut it on 2 - 0.070" depth cuts, instead of 4 passes. Was it just getting bored going over the same old ground for the 4th time ?!?
I have an otherwise accurate, albeit old, cable drive SB. I have not cut much lately to see if this is a trend or an anomaly - I mean, it went right back to the original groove and cut out a circle with the exact dimensions that I asked of it !!
I would love some thoughts on what might have been the causes ?
Suggestions ?