Carbide insert screw, countersink angle?

Is the countersink angle on a carbide insert 90 degrees?

I dropped the M3x8 screw for my mini grooving tool. Called the manufacturer and they want $5.25 plus shipping for one screw. Seemed a bit pricey for one screw. I can get a box of 100 M3x8 from mcmaster for that much...but they are 90degree countersinks.

Are the ones used for inserts different? I see MSC and Enco have them listed as insert screws for ~$4 each. So, are these different, or are they just regular screws with the price jacked up?

Thanks,
V

It will work , kind of, if the head does not get in the way of chips too much or you grind the OD down a bit.
It is the wrong screw. The standard ISO insert hole will tolerate a head taper of 40-60 degrees. It is a radiused or tech term, a "Partly Cylindrical" hole.
http://tungstemet.com/wp-content/uploads/2011/10/ISO_Hole_Details_Blanks.pdf
Your 90 will seat on the top of the entry C-bore and get chewed up fast and will lock on that sharp edge. It will also be too big and get in the way of chip flow.
If it locks you get to find out how to remove stripped head screws from a holder with a B-Port.
Bob

I'll pass on the bridgeport screw remover. I'll just get the correct screws for it. Thanks for clarifying.

V

the 4th letter of the insert part number is the hole type and hole shape i believe. But i think for some it is a range, for example, 40-60 degree countersink. Lookup an 'insert designation chart'.

ah, those damn custom screws, just another way they get you to shell out more cash.

Thomas Paine said:

ah, those damn custom screws, just another way they get you to shell out more cash.

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No.
You think I like having to work with hundreds of screws?
It's a IC size against what you can fit for a screw head, hold decent and stay out of the chip flow.
In the early days it was easy, standard 90/82, That does not work anymore.
It's not a scam, just needed size to work and these are not made in the same volumes.
I and everyone else could give a piss about selling screws, they are a money loser even at $5.25.
Bob

You have touched on my pet hate.l think its CRITICAL to use the correct screw-Then its the correct thread so doesnt need forced in damaging the exising thread in seating,The head is right size for the insert hole.l worked at one company that would send on average of 10+ tipped tools out a month to be refurbished most explode during cutting.A large pop is the sound when the tip applies the pressure the the screw its head is smaller than it should be so the tip pops over it and crash the tool is ruined.Really pisses me off if I say have you got such/such screw and the store keeper says no but this one will do-lt wont do thats why dicks are ruining 10+tools a week-get the right screw for the job

The screw head taper and diameter are important for several reasons, one is so that it puts pressure in the direction that forces the insert into the locating surfaces. Wrong angle and diameter won't do that properly, also as mentioned it may stick up and the chips will wear the top of it off or it may be to small and the insert could pull out. Best to use what is supposed to be in there and also the proper insert. It's really not worth the headaches to play around with it.
Dan

Name cutter manufacturers screws are (were) super tough alloy and quality threads.. if buying alternate screws get the highest grade you can.
and the dif locks need just the right stuff to make them pull tight the locating wall.

but yes if the screw does not pull the insert away the work force will push it tight to the wall.

Seems to me that if an insert needs a special screw then they should be provided with the inserts. Perhaps one or two with each box of 10 or 12 inserts. I am sure the price would go down because the volume would go up and there would be no separate handling involved: no packaging, no warehouse bins, no part number, no one picking and packaging them, etc. And they would always be the perfect mate for the inserts they are distributed with.

Okay, okay, I'll get the right screws! I agree that if it's a specialty screw, it needs to be correct to work properly.

However, I've seen manufacturers (Graco) charge $3 for the same o-ring that I can buy for $2 for a bag of 100. Figured this would be the place to find out the proper part.

I agree with EPAIII, wouldn't hurt to throw an extra screw in, especially when they're that small. With inserts at $15 each (0.040" grooving tool), I think that would be reasonable.

Thanks,
V

I got them from this guy on ebay - eBay

Seemed reasonably priced, and having extras for all my inserts is a no brainer to me. They are so tiny, so critical, just asking to fly away...

The biggest gripe that I have is that I always think I can change the insert while the tool is still in the holder in the lathe toolpost. Then I drop the screw into the chip tray, just like the OP has done. If I beat myself into taking the holder off the toolpost (a few seconds with a QC toolpost), then did the insert change over a tray, I'd probably never loose another screw. As it is, I have to look on the wastage as a way to ensure that the screws aren't getting worn out.

Screws being driving against a rough piece of carbide wear.
After a while although still usable they don't pull back like they should.
It may sound weird but after about 10-20 times they should be tossed. Some shops where time is big money will only use them 2 or three times.

The deal at one piece is simply the selling cost. Lets say you run $1.00 a minute.
Take an order, pull one screw out of stock, pack it separately , do a shipper, process the payment.
How many seconds did this take? You do count the seconds here.
You are paying for the package and order processing not the screw
It is best to buy then in packs of ten and the packages on the E-bay link above are very familiar to anyone in the insert/holder business as with the exception of the very biggest we all buy from the same place.
The linked to source prices are very reasonable, actually IMO just this side of nuts, he/she must be buying in decent sized lots.

I would think exkenna would have this source as a private label but I don't see screws prominent on his website.
If you are buying special inserts, the holders came from us, and I'm not chasing pennies I do put extra screws in with the inserts just so life is easier for the user.
Throwing in a nice quality torx wrench once in a while also sometimes helps
You can't do this on a low price CCMT at 1-5 pieces across the internet. A $50.00 order may net $2-$3.00 in income if you are lucky.
I know it seems you are getting the shaft but this standard tool racket runs on very small markups.

You see many come and go battling low price tag. My hat is off to exkenna (C. Payne) for making it work in the long term.
I have always stayed as far away from this side of the game as possible. I'm not sure I want to enter the fray.
Bob

The devil's in the details...

When you say, "throw a spare screw in" -- where, exactly?

The manufacturers are not likely to build/modify insert case molds to accommodate spare screws and I sure don't want a loose screw damaging the cutting edges on my inserts before I get them!

Duh, its a separate pack or insert box.
With the effort we go though to make sure no two inserts ever touch each other in manufacturing you think we would miss this?

Nobody wants a chipped tool getting in the users hands, dropping an insert is immediate quarantine until inspected for edge quality. (it gets colored blue and put aside).
There is no concern for operator penalty and they know that, I want the fumbles found and checked, not hidden.
I've dropped many inserts when hustling. Shit, .....there goes 5 minutes to save 2 seconds. We all oops sometimes.
What really sucks is to run a tray of 100 to clean and pack needed for a today ship and trip, dropping them all on the floor.
Carbide against carbide on the way down, most will not survive.
Clean and pack knocks a tray off the bench, or the entire shelf of finished tools collapses under the weight and 20,000 plus inserts on the floor.
You'd be amazed the things that can go wrong in the simple process of grinding inserts. Murphy has a permanent home in my building.
We try to learn from the oops and battle him off.
Bob

CarbideBob said:

Duh, its a separate pack or insert box.
With the effort we go though to make sure no two inserts ever touch each other in manufacturing you think we would miss this?
.
.
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Bob, I should have been more clear. A couple of posts suggested throwing in extra inserts and I interpreted it literally, i.e.- screws with the inserts in the insert box, which we agree is not acceptable in standard box. I was directing my reply at them.