Cutting rpm's

[GlenP]

Hey guys. Now that I have my bot cutting at 5-6 ips it has me relearning my tools all over again. I was always using 1/4" endmills at .28" depth and 2-2.5 ips. Now with the faster speed I find the endmills are breaking. They are cheaper ones and have always worked well in the past. Just wondered what others are using for rpms etc when cutting 3/4" plywood material like baltic birch and other species. I have a PC 7518 router and maybe next step is spindle but can't do that right now. ??

[gerryv]

Hey Glen,
I've got the solution; we get together and bring Brady up to do a few days with us, or a bit of a loop if some can't leave home :)

[bleeth]

Glen:

Have you stepped up your spin speed to go along with the increased move speed?
Remember when you got your first good turntable with a diamond stylus and heard **** in the record you never heard before?
When you push tools harder you need better tools. It comes out in the wash since they last longer. You may find yourself needing to tune your axis's (or is that axees?) for more accurate square and tighter slop as well as better maintained pinions too.

[Ajcoholic]

Glen,
I cut most of my Baltic Birch (6, 12, and 18mm) with two flute down cut Onsrud or BC Saw & Tool bits.

I have been running from 180 to 360 IPM (3 to 6 IPS) and running at 11,000 rpm with the HSD spindle.

I have cut in the past year, about 60 to 70 sheets of Baltic Birch, and a whole whack of 8/4 solid maple, birch and walnut.

I haven't broken a bit yet! (I did chip two early on, hitting one of my hold down screws).

I basically run as fast as I can with an acceptable finish - and adjust the rpm and/or the feed to eliminate the whistle/whine of the bit.

AJC

[GlenP]

Hey guys, thanks. I looked back at my bit log for this router and my past router. I didn't break many bits with the last porter cable router but this one breaks them very easy. I think there is too much runout on the router. The PC routers used to me made in Mexico but now I believe in China....like every other friggin thing. I even lost a bid to make mini hockey sticks for the Olympics in British Columbia CANADA to a china company. Oh well they probably would have taken 6 months to pay anyway. I am using Kempston endmills. I tried one of my Precise Bits end mills and it is working great. Perhaps a spindle will be next....???

[gundog]

Use a feed and speed calculator there are many free ones on line to play with here is one I use. http://www.whitneytool.com/calculatorSpeedFeed.html this is a machining type but if you know your old speed and feed just enter that and calculate it then change the feed rate and it will figure your new speed and it should cut like before.

Mike

[gundog]

It looks like you are needing 21000 RPM to maintain the same ratio of feed and speed that is if you are using a 2 flute bit .008" chip load. I don't know how fast your RPM was before but with that old chip load I used 14000 RPM to get your your old feed if you supply that I could help but you can do it yourself using a calculator. Just keep plugging in numbers until you get the feed you used before that will give you some numbers to use then apply what you learned for your new speed and feed you have an advantage in that you know what works. Feed and speed is just a ratio the hard part is finding the right surface feed per minute but you can get that from your old numbers. The proper way is too look up a bunch of formulas but I am lazy and find this works for me and I suck at calculating formulas.

Mike

Here is another one. http://americanmachinist.com/speedsfeeds-conversions-calculator