Thread: Indexable carbide end mill for keyway cutting.

Hopefully a simple one, but has anybody had any experience using indexable carbide insert end mills for cutting keyways? I can buy a 14mm tool such as this one

for $45 and the APMT1135 inserts can be had very cheaply. I compare this to a 14mm four flute HSS end mill, (which will require sharpening through it's life) for $50 and the attraction of the carbide tooling is clear. I also realise that nothing is free in this life, so I'm wondering just what I'm missing? I did wonder how close the tolerances of the slot created would be as any tolerances in tool or insert could easily add up.
What are the thoughts of the more experienced machinists here?

I have the 16mm and 20mm versions of those and use them wherever I can because of the economics of inserts vs HSS end mills.
They tend to come with long shanks which means a lot of stick out, I've cut mine down to increase rigidity.
As a face mill it leaves a good finish, as a side mill its not as good as HSS.
I limit myself to 1mm DOC per pass full width in mild steel which leaves an untidy wall. If I'm cutting a keyway I usually leave .5mm on the keyway width and tidy that up with a full depth (5mm? max) x .25mm wide cut. Or if know I'm going to need a better finish than the insert cutter will give I reluctantly reach for the HSS.

Thanks Bob, I had heard in several Youtube videos that the side finish was lacking and also that they benefited from being shortened.

The APMT inserts for steel are quite blunt on the vertical edges (or at least the ones I have here are). I haven't looked into whether there are sharp edged uncoated ones intended for aluminium but if available they could probably be used for a finishing cut in steel to get a better finish.

$50 for a 4 flute 14mm HSS endmill is pretty dear I'd say. You can get the Mag-pro carbide ones in 12mm for under that.

Steve

In my opinion you may be better off using a 12 mm indexable cutter and after roughing to within a few hundreds of depth move the cutter in and out to within a few hundreds of correct width and then finish to full width and depth in two passes, one in and one out, remove burs from top of Keyway.

I have one of those carbide insert end mills and agree with what others have said. The side cutting finish is inferior compared to a sharp HSS end mill and they are way too long.

If you are cutting a large keyway, I would rough it out with the indeable carbide insert to near full depth (within 0.05mm or so) and then use a nice and sharp HSS end mill (smaller than the width of the keyway) to finish to required width and depth with several passes. Climb cutting the shoulders to finished width if possible.

Simon

Hi Guys,

I've never had or used an indexable carbide cutter like that ! My take would be to use a "T" slot cutter and get the right keyway width and depth first time around.

Originally Posted by BaronJ

Hi Guys,

I've never had or used an indexable carbide cutter like that ! My take would be to use a "T" slot cutter and get the right keyway width and depth first time around.

Hello Baron,
could you describe your machining process for this when machining a keyway with a tee slot cutter please.

Hi Pipclay,

Originally Posted by pipeclay

Hello Baron,
could you describe your machining process for this when machining a keyway with a tee slot cutter please.

Set the shaft horizontal to the mill bed and use the "T" slot cutter in the vertical head as normal. If it was for a feather key then it would be a normal centre cutting four flute end mill to get the rounded ends.

Why cut more material than you have to , and what do you do with slot?

Sent from my T85 using Tapatalk

Originally Posted by pipeclay

Why cut more material than you have to , and what do you do with slot?

Sent from my T85 using Tapatalk

???

Sorry had some idea you were cutting the keyway vertically.

I have several different sizes up to 20mm and they are my go to end mills daily and they take a good beating in machining steel welds etc, also do great on aluminum even with steel inserts.

I agree with others for a keyway, use one of these a couple of mm smaller to remove most material, then a smaller HSS end mill for a good finish on the sides and climb mill if your backlash is good.

Thanks to all for the replies, there is much good sense in what has been said.
I agree that $50 is on the dear side for a 14mm HSS end mill, but that is the going rate for one sourced locally. I try to plan on the worst case scenario, as a substantial part of what I end up doing is short notice, overnight jobs to get gear up and running, hence the attraction of a cutter system that had easily replaceable and cheap inserts that could be kept on hand to safeguard against unintentional whoopsies at the most inopportune times. Currently I do not have the means to resharpen in house and my locality has only two businesses that could undertake resharpening. One does a great job, but time has no meaning to him and the other will get them done in under a week, but you flip a coin to see whether they cut at all upon their return.
I think I will grab a 12mm indexable end mill and a couple of 12mm carbide end mills to finish off the work (mostly 14mm keyways in 50mm shafts). By nature, I'd like to have one of everything, but the $$$ quickly add up and I have to rein myself in.
The consensus seems to be that Chinese HSS is quite suspect, but their carbide isn't too bad at all. I hope so as I have a Taegutec 63mm helical shell mill that I need to load up with 9 APKT 1705 inserts and that can be either a $190 experience or a $40 one.

I run some pretty expensive, high quality indexible tooling and work and it barely does a satisfactory job of finishing things like keyways, I always use solid tools for finishing stuff like that.