I wonder if any of the more experianced chaps out there can shed some light on my milling problem.
I have a 3HP horizontal mill (Adcock & Shipley later badged Brigeport - 1ES) - which has a vertical head .
I was attempting to mill mild steel (easy machining normally) with a nearly new good condition 5/8" dia HSS 4 flute end mill running 500 rpm, full width cut at 1/4" DOC - hand feeding and I watched the rev counter drop to 380 rpm as soon as I did anything much past a fine feed - as if the drive was stalling out.
I switched to a 2" side & face shell mill and took 5/8" wide cut @ c 1/4" DOC and it was 'ok' as long as I didn't push it too much. Now I know the shell mill has more flutes / edges and thus each is doing less work than the slot mill. The 3ph motor is powered via a vfd on 240v. It 'should be wired in delta' and has to th ebest of my knowledge been fine for the last 2 years of use I have made of it as I learnt my way around it manily in th elow rev's area for horizontal milling (50 to 150 rpm max) the pulley system consists of 4 step motor to 4 step intermediate, 4 step final then a back gear for horizontal low ratio - this all connects to a gear box for table feed to give feed per rev of the cutter.... this was disengaged in my cut above.
What concerns me is that the mill should easily cope with the original cut and the cutter looks and feels fine as did the steel - any pointers for what to look at ?
My initial thoughts are the 3ph motor may have a phase down or may infact be wired in star still - the VFD is set to give a 15 second start up ramp as initial start up blew the vfd feed fuse (13amp single phase 240 v)
To check the motor connections will require around 4 hrs work lying on the deck to pull the motor out from the base unit - something I would like to avoid if possible by checking everything else first.
Advice appreciated
Lurk
UK
I have a 3HP horizontal mill (Adcock & Shipley later badged Brigeport - 1ES) - which has a vertical head .
I was attempting to mill mild steel (easy machining normally) with a nearly new good condition 5/8" dia HSS 4 flute end mill running 500 rpm, full width cut at 1/4" DOC - hand feeding and I watched the rev counter drop to 380 rpm as soon as I did anything much past a fine feed - as if the drive was stalling out.
I switched to a 2" side & face shell mill and took 5/8" wide cut @ c 1/4" DOC and it was 'ok' as long as I didn't push it too much. Now I know the shell mill has more flutes / edges and thus each is doing less work than the slot mill. The 3ph motor is powered via a vfd on 240v. It 'should be wired in delta' and has to th ebest of my knowledge been fine for the last 2 years of use I have made of it as I learnt my way around it manily in th elow rev's area for horizontal milling (50 to 150 rpm max) the pulley system consists of 4 step motor to 4 step intermediate, 4 step final then a back gear for horizontal low ratio - this all connects to a gear box for table feed to give feed per rev of the cutter.... this was disengaged in my cut above.
What concerns me is that the mill should easily cope with the original cut and the cutter looks and feels fine as did the steel - any pointers for what to look at ?
My initial thoughts are the 3ph motor may have a phase down or may infact be wired in star still - the VFD is set to give a 15 second start up ramp as initial start up blew the vfd feed fuse (13amp single phase 240 v)
To check the motor connections will require around 4 hrs work lying on the deck to pull the motor out from the base unit - something I would like to avoid if possible by checking everything else first.
Advice appreciated
Lurk
UK
