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Model Forum / General / Models / May 2008I'm sure this has been asked before
and quite possibly by me, but I've forgotten the answer. Anyone got a link to a list of tool speeds for things like slot drills, end mills and such? I know in theory you can work it out. But I'm lazy. Actually been doing some milling on the mill/drill, got some 10mm slot drills, and been making slots (shallow ones) to lighten a bit of plate - so it ends up a bit like a mini-I-beam. Whether it's worth the effort, I don't know. But it looks the part.  SignatureAustin Shackles. www.ddol-las.net my opinions are just that Travel The Galaxy! Meet Fascinating Life Forms... ------------------------------------------------\ >> http://www.schlockmercenary.com/ << \ ...and Kill them. a webcartoon by Howard Tayler; I like it, maybe you will too! >and quite possibly by me, but I've forgotten the answer. > [quoted text clipped - 7 lines] > >Whether it's worth the effort, I don't know. But it looks the part. Tom Martin's site is always worth a look. http://shopswarf.orconhosting.net.nz/sindex.html Charles http://www.homeworkshop.org.uk > and quite possibly by me, but I've forgotten the answer. > > Anyone got a link to a list of tool speeds for things like slot drills, > end > mills and such? I never bother with suggested tool speed formulae. Most of the time they are designed for high volume production needs where you balance tool wear against getting the job done quicker. For home shop use just go slower and never burn anything out. I run at what the tool, the machine and me feel comfortable with. If a tool cuts ok at a certain speed and feed than the only reason to go quicker is to save time. If you're machining many off of something then that makes sense. For one offs you spend longer dicking about with the speeds and feeds than doing the job. On the Student I change speeds more because it's easy. Just move a couple of levers. On the mill it means changing the belt to another set of pulleys so if I'm using lots of different tools on one job I try and find a speed they'll all at least work at even if that's a bit slow for the smaller ones and leave it at that. SignatureDave Baker Puma Race Engines >> and quite possibly by me, but I've forgotten the answer. >> [quoted text clipped - 16 lines] >they'll all at least work at even if that's a bit slow for the smaller ones >and leave it at that. While I broadly agree, it can be expensive if you use very small cutters at too slow a speed. It's a question of the amount you expect each tooth to cut on each rotation; if your feed rate cannot be slowed enough, you end up expecting the tooth to cut a bigger slice than it can manage, and *snap* you need a new cutter. Feeding by hand to get a slower rate can also be fraught, as it only takes a slight twitch of the hand to go faster for an instant, with the same result. David SignatureDavid Littlewood > and quite possibly by me, but I've forgotten the answer. > [quoted text clipped - 9 lines] > > Whether it's worth the effort, I don't know. But it looks the part. Model Engineering Handbook by Tubal Cain has tables (lots of tables for all sorts of stuff) and the speeds and feeds for lathes and mills are supposedly mindful of Myford Man rather than big production machines. Sorry about this, but I only use HSS cutters in the mill and for general purpose use 12 mm 4 flute cutters (words chosen carefully to avoid another controversy). In steel, say EN1 then I run a 12mm 4 flute at c 600rpm. If you use a 2 flute cutter, you should double the speed. In Aluminium, I'd be looking at c 1600rpm for a four flute cutter and the mill only goes upto 2500rpm so that's what I use for a 12mm slot drill in Al. You can go faster and slower, but these seem to work OK as a starter for ten. Halve the diameter and double the speed, double the diameter and halve the speed is another rule of thumb. So on the mill I don't bother with the tables. Lots of other rules I follow, like I don't cut slots (even open ended ones) with a 4 flute cutter, you can but you shouldn't really. I tend not to take cuts with a 4 flute greater the 1/4 the diameter or depth wise. So a 12mm 4 flute doesn't get asked to do more than 3mm in and 3mm down at one go (I do but it's back to starting points). Steve >Lots of other rules I follow, like I don't cut slots (even open ended >ones) with a 4 flute cutter, you can but you shouldn't really. This is good advice. The reason for not using end mills (4-flute cutters) for cutting slots was well explained by (IIRC) GHT in one of his books (may possibly have been Tubal Cain). Briefly, the leading tooth of a 4-flute cutter puts a sideways stress on the cutter, which means it deflects sideways a bit, thus it is not exactly where you wanted it. If it runs out (of an open-ended slot) or you vary the feed, this deflection ceases, and you get a wobbly slot; if you run back the other way, the deflection is in the opposite direction and the slot comes out wide. Of course, best practice is to rough out the slot with one size smaller cutter and finish it with the correct size, if it is the desired width coincides with a standard size, or clean up the edges on both sides if it is between standard sizes. David SignatureDavid Littlewood >>Lots of other rules I follow, like I don't cut slots (even open ended >>ones) with a 4 flute cutter, you can but you shouldn't really. [quoted text clipped - 8 lines] >other way, the deflection is in the opposite direction and the slot >comes out wide. Makes sense. The 10mm ones I was using recently are 2-flute, and I also have a 3-flute 5/8" which I've yet to actually use for anything, but it might come in handy one day. SignatureAustin Shackles. www.ddol-las.net my opinions are just that Travel The Galaxy! Meet Fascinating Life Forms... ------------------------------------------------\ >> http://www.schlockmercenary.com/ << \ ...and Kill them. a webcartoon by Howard Tayler; I like it, maybe you will too! > The reason for not using end mills (4-flute > cutters) for cutting slots was well explained by (IIRC) GHT in one of > his books (may possibly have been Tubal Cain). Briefly, the leading > tooth of a 4-flute cutter puts a sideways stress on the cutter, which > means it deflects sideways a bit, thus it is not exactly where you > wanted it. Can I provide an addendum to this argument ? Obviously the leading tooth on any cutter puts a sideways force on it and this is also true for a 2 tooth cutter. The question is why does the effect not occur for 2 tooth cutters when it does for 4 tooth ones ? The reason is because the 4 tooth cutter has a tooth engaged at the side to which the force is acting and so it can cut itself in sideways whereas the 2 tooth cutter has its back tooth in open space at the time when the fron tooth is applying the maximum sideways force. SignatureBoo >> The reason for not using end mills (4-flute cutters) for cutting >>slots was well explained by (IIRC) GHT in one of his books (may [quoted text clipped - 10 lines] >cutter has its back tooth in open space at the time when the fron tooth >is applying the maximum sideways force. Yes, omitted to mention the reason, but that is exactly it. David SignatureDavid Littlewood >and quite possibly by me, but I've forgotten the answer. > [quoted text clipped - 7 lines] > >Whether it's worth the effort, I don't know. But it looks the part. http://colinusher.info/Software/Model%20Engineers%20Utilities.html -- Richard Email address is valid but remove burrs before sending! The ones on this site are quite easy to follow, gives speeds related t tool/work diameter and material being cut. http://www.aonx97.dsl.pipex.com/WS-page/table-page/tables.htm#Lathe Jaso -- jasonballam |
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