Denford Software & Machines

After lots of searching i am now the proud owner of a Triac PC with Atc 1996 that was upgraded with a nextstepES in 2006. i have made a couple of test pieces in Aluminium which have turned out well. But I am a bit puzzled about it starting to eat Fuses, seems to be related to the spindle. it has blown the fuse on the sprint on 1 occasion, F1 4 times and tripped the house once at the same time as blowing F1. i have used a 63mm slab mill 0.5 depth of cut, 40 mm wide at 500mm/min and it coped fine at 1000RPM, i can hear the rpm slow slightly then it picks back up again. but using a 3mm drill at 3500RPM and 150mm/min chip breaking took out 2 F1's. Changed the routine to a peck drill with full retract and it managed the next 9 holes ok. I would have thought a 1.5hp spindle motor would have snapped the 3mm drill before blowing out a 10amp fuse. Any advice would be welcome

Paul

Not quite sure why, but it seems to have sorted itself out now. Touch wood!

The spindle may have just loosened up

its Possible, im now roughing aluminium at 1000mm/min 3200rpm 2.7mm depth using a 12 ripper at 65% step over with ease
i have however noticed that tapping a M8x 1.25 thread at 250rpm has to have a feed of 420mm/min so i think the spindle is running too fast 250x1.25 should only be 312mm/min. i have ordered a laser tacho to check the spindle speed
i have checked the feed on all axis seperatly in MDI by timing a 100mm move at a feed of 100mm/min and they are correct to the second

Just to warn you that I don't think those motor/drives are that great at low speed anyway, ie, don't expect too much or for it to be accurate

Well the Digital Tacho arrived today and i think i found the problem. At a programmed S4000 rpm the Spindle was was actually running at 4906rpm, so probably drawing too much current hence the fuses blowing. The milling i have done recently was done at a max of S3200 which worked out at just under 4000rpm, so i presume within the max speed and current.

Anyway with the help of a previous post viewtopic.php?f=47&t=1657 on how to setup the Triac spindle, i have made the adjustments and its now so close its not worth playing with the adjustment any more.

Paul

don't expect too much or for it to be accurate

I'll take that comment back