topic Re: Countersinks in Fusion Manufacture Forum

Countersinks

BillGEGHV — Thu, 31 Aug 2023 18:03:35 GMT

Hey all,

I have a bunch of parts with an m3.5 flat head. I have both the 90 & 82-degree chamfer mill cutters shown here by Shars. Ive never run a tool like this and was hoping to get some input on F&S for these tools.

I was also wondering if I would need to run a pre-drill with a larger diameter to clear out some of the countersink pockets before I run the countersink tool. Just looks like clearance of the actual tool could be an issue. or once the clearance hole is in place is it all good to go?

https://www.shars.com/1-4-90-degree-countersink

Re: Countersinks

jonathanBUCVS — Thu, 31 Aug 2023 19:08:43 GMT

Drill the bolt clearance hole first, then countersink. No need for an intermediate drill.

The material being cut is required to determine the proper SFM > RPM. Look up similar feeds and speeds for a drill of similar size to the diameter of the countersunk hole. It'll get you close enough to start.

Re: Countersinks

BillGEGHV — Thu, 31 Aug 2023 19:35:36 GMT

Sorry 6061-T6. Makes sense to use a similar diameter of the countersink.

Re: Countersinks

programming2C78B — Fri, 01 Sep 2023 11:50:37 GMT

drill thru hole (150sfm, F12. with HSS drills, 50% peck)

csink

~250 SFM at cutting DIA

.001-.003 CPT

.02 CHIP BREAK, .08 ACCUMALATED,

0.1 DWELL

COOLANT

this'll get you close. You can technically run a higher sfm but chatter starts to present itself as the tool itself is steel, in my experience. Obviously changes on how wide you are actually cutting.

Re: Countersinks

BillGEGHV — Fri, 01 Sep 2023 17:07:36 GMT

Cool thank you. Is there a specific drilling op that is best for countersink? I assume a counterbore would be fine with .1 dwell.

When you say 50% peck I assume this is 50% of diameter??

Re: Countersinks

programming2C78B — Fri, 01 Sep 2023 17:46:31 GMT

I use the Chip break, but feel free to do Cbore if you wanna one shot it. In stainless we need the pecks. Alu should be ok, use your judgement.

Yes percantage of tool Dia.

Re: Countersinks

BillGEGHV — Fri, 01 Sep 2023 19:24:23 GMT

Since you say you use chip break I will go with it as well, I see it has a dwell. With a .02 chip break, how much would you peck? Im thinking like .03 or so would be good?

Re: Countersinks

programming2C78B — Tue, 05 Sep 2023 12:37:43 GMT

the chip break IS a peck of .02. Try one and see how it does, we just do it smaller so that the chips aren't so long that they end up scratching the face of the part. I can only speak on the MA ford single flute C sinks we use here.