-
Scam Alert. Members are reminded to NOT send money to buy anything. Don't buy things remote and have it shipped - go get it yourself, pay in person, and take your equipment with you. Scammers have burned people on this forum. Urgency, secrecy, excuses, selling for friend, newish members, FUD, are RED FLAGS. A video conference call is not adequate assurance. Face to face interactions are required. Please report suspicions to the forum admins. Stay Safe - anyone can get scammed.
Cobalt End Mills
- Thread starter YYCHM
- Start date
If I were buying I think I would go directly to solid carbide end mills. At least in the smaller sizes. I have two, 1/4 and 3/8 two flute. I bought them originally to do some machining on a rifle receiver They were not that expensive and I only use them on hard materials. HSS works for the rest.
Yes solid carbide endmills are commonly in stock in all sizes from .063"-1." from manufacturers like harvey tools, kanametal, sandvik, widia hanita, and iscar. These tools are popular because they save time when machining when compaired to hss or highspeed cobalt.
I guess I view this somewhat differently. I realize that labour cost is a big expense in modern commercial machining and tooling that is fast and efficient is essential. As a hobbyist I look for the minimum that will do the job and that I can afford. My time costs me nothing. To that end I'm phasing out all my carbide insert tooling in favor of HSS and Brazed Carbide. An hour grinding a lathe bit is time well spent. CHEERS
Just for curiosity I did a look up on KBC. 3/8 4 Flute end mill. KBC branded. HSS $11.10, Cobalt $21.88, Solid Carbide $24.88. I've only ever used cobalt drill bits and carbide end mills a few times. I'd say the carbide is the toughest. I guess it comes down to budget, time and what type of materials you work on?
Downwindtracker2
Well-Known Member
I consider the common sized end mills as disposable , but I have a sloppy mill/drill. If I want it close, there is no way I can hog. So I don't feel bad buying the $5 special at KMS.
I took this picture to show the difference between these two drills. The right drill is HSS with a black oxide coating. I notice it comes sharpened with a 118 degree point. The left drill is Cobalt which is sharpened at 135 deg. I imagine they do this becuase when drilling harder materials the 135 deg grind is stronger.
Attachments
Johnwa
Ultra Member
I found this on Grainger.
https://www.grainger.com/know-how/industry/metalworking/kh-which-drill-bit-does-the-job
The 135 starts faster which is probable a good idea with stainless to avoid work hardening.
https://www.grainger.com/know-how/industry/metalworking/kh-which-drill-bit-does-the-job
The 135 starts faster which is probable a good idea with stainless to avoid work hardening.
trlvn
Ultra Member
Since we're talking about drill bits...
I got a few larger drill bits in an auction lot. Of those, the 3/4" and 1" drills are both really dull. They're also both 135º points. I will always be using a pilot hole with these drills and almost certainly using 118º drills to make that. Is the mismatch in angles a problem? When I resharpen the dull drills, should I try to convert them to 118º points? That's a lot of metal on the 1" drill!
Just noticed that the 1" is marked "P&N Australia". Wonder how it found its way to the GTA?!?
Craig
I got a few larger drill bits in an auction lot. Of those, the 3/4" and 1" drills are both really dull. They're also both 135º points. I will always be using a pilot hole with these drills and almost certainly using 118º drills to make that. Is the mismatch in angles a problem? When I resharpen the dull drills, should I try to convert them to 118º points? That's a lot of metal on the 1" drill!
Just noticed that the 1" is marked "P&N Australia". Wonder how it found its way to the GTA?!?
Craig
Tom Kitta
Ultra Member
I would skip cobalt and go to carbide directly. They last a very long time. They take "speed" abuse well. You can run cobalt a bit faster then regular HSS but not much - like 10%. They are also a tiny step up in hardness. Essentially cobalt with even 8% is just a touch tougher HSS. Its no match for even uncoated carbide. It is totally outmatched by expensive coated carbide.
Note there are grades - many of carbide - some are harder some are tougher - but even the "soft" carbide is usually rated for at least 35-45 HRS - so it will take care of any common annealed steel including 4330. It is simply not rated for hardened stuff.
I use cobalt drill bits a lot through. Have a lot of carbide ones as well, but cobalt drill bits seem to hold up much better then cobalt EM. Drilling in general is not as "intense" as milling. Also its easier to quickly sharpen drill bits - not so easy with EM.
"Just for curiosity I did a look up on KBC. 3/8 4 Flute end mill. KBC branded. HSS $11.10, Cobalt $21.88, Solid Carbide $24.88."
Wow there is a reason I never buy anything that cuts at KMS/ BB/ PA etc. Prices are outragous.
12mm solid coated TiAn end mill from China - new == 14CAD shipped (on sale). Works very well. If you don't care for sales get it for 17/18 CAD shipped. 10mm is a bit less - like 14CAD non-sale. The smaller sizes you see are more expensive as singles due to shipping costs included - just get more than 1.
You can get 1/2" US made carbide coated off ebay new for around 20 USD. I got uncoated 3/4" for under 30USD new wester made (I think Israel).
HSS 3/8 for 11 CAD??? Seriously? Who pays that kind of money? You can get brand new US HSS of eBay for around 3-4 pieces for 10 USD or so.
Tom Kitta
Ultra Member
I would not worry about change in angle - the whole point of a pilot is to drill it at least the size of the web on the larger drill so it doesn't have to "push" any metal. The pilot is just a hole - what made the whole is not very important.
Changing the angle will not hurt through - 135 is for harder stuff while 118 is general purpose. Other angles exist - like more > 135 for plastics.
BTW you can get a set of drill bits (5) at PA for $30 on sale - it goes from 9/16 to 1" and has 1/2" shank. I have used them a lot lately and they do work great in mild steel. The golden paint wears out quickly but what is under it seems like a solid M2.
Dabbler
ersatz engineer
I learned quite a few things from an old school tool and die maker. I don't want to seem contrary, but if you want holes that are true to size, you pilot with the same angle as the larger drill. This man has drilled and reamed many thousands of accurately sized holes, in precise locations for 60 odd years. If you can manage it, using the same angle pilot is always better.
How much better? well that is up for debate. The real difference is when people use a centre drill at 60 degrees and follow it with a 118 degree drill. A great way to dull the web, add heat and cut an oversized hole. The proper way to use a centre drill for following with another is to use the pilot section only, which is almost always at 118 degrees.
How much better? well that is up for debate. The real difference is when people use a centre drill at 60 degrees and follow it with a 118 degree drill. A great way to dull the web, add heat and cut an oversized hole. The proper way to use a centre drill for following with another is to use the pilot section only, which is almost always at 118 degrees.
Chicken lights
Forum Pony Express Driver
What part is the “web” that you guys refer to, please?
Dabbler
ersatz engineer
Look down a drill from the point end. The web is the little bit of steel that connect the two flutes of the drill.
When you pilot a hole there is no need to drill larger than the web, and drilling it much larger is counterproductive: the drill bites too fast and you risk breaking or chipping the drill.
When you pilot a hole there is no need to drill larger than the web, and drilling it much larger is counterproductive: the drill bites too fast and you risk breaking or chipping the drill.