Deep pocket cutting steel on 1100mx

Hey there everyone, I’m struggling with cutting some steel (1018) om my 1100mx and I’m looking for some pointers. the tool is a .500" 2"LOC 5 flute radius nose endmill and its in a set screw tool holder. the issue I’m having is the chatter is so sever on entry to the cut that it will stall the spindle. Ive tried countless tool paths and tool loads, i could fill up 3 pages with all ive tried. I’m looking for someone that has used a endmill with that long of a LOC and had success and maybe how you got it to not chatter. thanks in advance

Have you predrilled to depth and tried a trochoidal path? If your slot is the same width as the endmill you need to use a smaller endmill.

Are you are clearing the whole pocket with that tool? Also are you in low belt or high?

i bored a hole and then tried it that way yes

im on high belt and yes clearing the whole thing with this tool. 1.5deep, 1.9 wide and 4.5 long is the pocket size

That is a lot of endmill for the 1100mx IMO. I would try going to low belt for more torque. You are engaging a lot of material all at once with a 5 fl, I wouldn’t be surprised if it’s just too much, especially on high belt. In steel I usually end up liking lower rpm than what the mfg calls for to deal with chatter. 1800 rpm might be nicer and around peak power too. If you are helical ramping try going conventional if you haven’t also.

I cut only 4140 annealed on my 1100mx and use all sizes of EM’s including 1/2" with no problem
It’s just a matter of staying within the power that we have available on these machines.

Two suggestions - First loose the end mill tool holder and use a holder with better runout - such as an ER collet holder, and second drop down to a 3/8" EM and see what you get

you dont mention DOC and WOC - maybe you’re just being to aggressive
you could also use a shorter EM (1") and stair step down into the slot - say .010 step half way down and then come back with your 2" for a finish pass only

that way you dont have all that stick out and tool deflection for the entire cut - if you can go shorter - do it - I think thats the crux of your problem - that and the set screw holder (which have tons of runout esp at 2"+)


Ditto what Lockheed says.
Bigger holder, more mass, absorbs more vibes. Maybe ER32? Wouldn’t a 5 flute be better suited for light finish cut?

The other thing you could do is try some different strategies to rough out most of the material before the finish cuts. I use a Kennametal Stellram Hi-Feed insert face mill to remove the HAT in my second OP - its a 1.25 - 5 insert mill with an min diameter of 0.88 (the inserts are canted - you cant really take a 1.25 cut) I have found that, at least on 4140, taking a .02 DOC with 2700 RPM and 55 IPM works well - blue chips fly - using something like that would remove the bulk of your material pretty quickly

good luck

thank you everyone for all the help and reply’s. I did find that the tool was just too long for this machine but i needed the length for the part i was working on. a few things i did to make it work was a different tool path other than adaptive since it was only chattering on the entry to the cut but on adaptive you cant change angle of lead in. one i got the tool coming straight into the cut and it wasn’t changing directions shortly after it entered the cut, it no longer chattered. i will definitely take all of this advice and store it in my memory bank to try on the next part. thank you all

I just finished cutting 1020 steel on my 770MX 1" thick. I used a 1/2" Lakeshore Carbide roughing endmill with about 1.75" stick out. You have to be on low belt or it will significantly slow down or even stop the machine (learned the hard way). Also, the best axial depth of cut I found for my cuts was not more than 0.2, but wound up using 0.15 as it “sounded” better. Radial depth of cut was no more than 20% of the cutter diameter, but I used 15% (.075) and had good results, although the machining time is longer using these values. This is just what worked for me and there are others who might push the machine harder with good results.