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| Speeds and Feeds ?. |
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| bright spark:
Its definately not steel, magnets don't grip, plus its too light. Could it just have been that I was far too slow in both RPM and feed, and the poor tool was rubbing rather than cutting ?. Or possibly, someone could have broken off a drill bit in the metal and I didn't notice ?. The metal is not that hard, there are hammer marks on the bottom, someone has drilled 3off 6mm holes through the base, plus I took several cuts with a 45Deg on the side without any problem. Admittedly those cuts were about 20thou, and the cut on the top is about 120thou deep. I'll try again over the weekend, with the X axis gib locked and a faster spindle speed Ken |
| Jonny:
Most of the problem is that you didnt lock the Y axis. Other probs, cutter too long for depth of cut, hence veer off with flex. More than likely cutter already no good, aluminium really wears respectable hss cutters more than you can imaginge. Heat generated? Something like that you need coolant. Chip removal whilst milling? May even be not getting a feel for the cut rather than selecting a speed by the book, if it aint cutting dont force it hence no need for rev meter. Could well be the miller is flexing, this can be in numerous places inc the castings, X, Y and Z axis plus quill play etc MT3 tooling is in abundance just avoid the chinky ER and Clarkson types. |
| w0rksh0p:
--- Quote from: bright spark on May 11, 2010, 05:06:43 PM --- I have plenty Clarkson screwed chank cutters, but have yet to find a Clarkson Autolock for MT3. One disadvantage of the mini-mill's popularity is that accessories with an MT3 taper are very popular and are a bit hard to find. --- End quote --- I have a Vertex autolock chuck from Chronos (http://www.chronos.ltd.uk/cgi-local/ss000001.pl?page=search&SS=PC38EB&search.x=0&search.y=0&search=ACTION&PR=-1&TB=A. Use the drop-down list to select the shank type. IMHO it is well made and reasonably priced. Edward |
| HS93:
are these what you want MT3 http://www.arceurotrade.co.uk/Catalogue/Collets/Morse-Taper-Collets/Morse-Taper-Collets---METRIC Peter |
| AdeV:
1/4" is a fair depth of cut, especially on a small mill, doubly-especially if you've got the cutter in a drill chuck, and triply-especially if you're using a "finishing" (smooth fluted) cutter... Now, I will cheerfully admit to under-loading my machine - I typically take a 0.200" cut with a roughing cutter when carving up aluminium, but I'm working on a Bridgeport which is decently rigid at those sorts of pressures. Even so, I have to use plenty of WD40 to clear the heat... I vary my RPM based on a table I took from Machinery's Handbook - basically, take their feeds'n'speeds, and halve them. It works well, my machine rarely complains to me that I'm being too hard with it... You never said what size endmill/slot drill you were using, so I shall assume 1/2": Therefore, the RPM in ali is basically whatever your machine is capable of; keep your DOC (depth of cut) low (try 0.100", and keep reducing it until the machine cuts with only a "gentle" thrumm noise, no clattering, rattling or serious vibration allowed). You should be able to improve your DOC with a proper collet-based toolholder, and I'm sure there are modifications you can make to the machine to improve its rigidity. All this is IMHO BTW, I've had my mill less than a year, there are far more experience machinists than I who may wish to chime in & contradict me... |
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