counter sinking without chatter

[james butler]

hi guys n gels
i need to put a chamfer on some brake unions ive cut down to size but when i tried using my countersunk bit it leaves me with a chattered edge!
ive tried varying the speed but it doesnt seem to make much difference?
what am i doing wrong and is there another way of doing it?

 

[eddie49]

What type of countersink are you using? Is it new? ( an old worn one is less likely to dig in and skip, which causes the chatter )
Are you using a pillar drill? A very low speed ( 100 rpm ) and a lot of pressure, for a very short time, may help.
A single-flute countersink, or a "zero flute" - where the cutting edge is actually a hole - may be better.

 

[james butler]

yes its a new countersink with three flutes.
im using it in my lathe so the hole in the union is in line with the tailstock holding the countersink and at a low speed.
i have an older countersink i could try so maybe like you say that one wont skip.

 

[Rig Pig]

Just turn the Taper with the lathe, no chatter problems.

 

[Screwdriver]

Different materials require differing relief on the cutting tool. My guess is a countersink will be a "generic" one size fits all. You need one suitable for use on steel which should almost look like zero rake at the cutting edge (about 10-15 degrees). Aluminium needs a much steeper rake, brass a zero rake 90 degree cutting edge.

I think that's right, whether or not that's the issue here...

 

[james butler]

Just turn the Taper with the lathe, no chatter problems.

i would do but its a taper inside a 3/16" hole and i dont have tooling small enough, i will give it a go and might try the boring bar as its got quite a sharp tip/edge that hopefully wont foul the job as i cut.

i will try another countersink and see how it goes.

thanks for the help everyone

 

[Bill Edwards]

I find chatter is usually dealt with best by increasing pressure, even if it seems natural to back off and go steady - was taught that early on in college while trying to chamfer a hole and easing off and being told to push - it worked.

 

[sardine]

Step drills never chatter, less flutes seems to be the way to go.

 

[RichardM]

rotate the chuck by hand for the last turns

 

[julianf]

Someone posted an odd video on here the other day of someone drilling a hole with a bit of cloth - it seemed to stop the hole getting misshapen.

I wonder if that would make a difference here.

Note- I don't really understand why it made a difference there either, but it seemed to!

 

[dobbslc]

I've been using that cloth idea for this last couple of days and it seems to help. No idea why though!!!
On thin 2mm steel it does seem to make the hole rounder.

 

[Pete.]

I find chatter is usually dealt with best by increasing pressure, even if it seems natural to back off and go steady - was taught that early on in college while trying to chamfer a hole and easing off and being told to push - it worked.

I've found this too. I have rectified chatter by countersinking with short hard pecks. If you want really nice countersinks get a single flute countersink they don't chatter at all.

 

[Wallace]

Do you mean these Pete? I have a couple and the work well.

 

[Pete.]

No, that's a zero-flute countersink, though they do work too.

I have a tiny countersinking tool that you fit into a drill, has positive depth stop. It's brilliant for getting tidy repetitive results on panels etc where all the screws sit flush. Can use a battery drill or a pillar drill it always does a nice job.

 

[Bill Edwards]

I'm guessing these:
http://www.ebay.co.uk/itm/3pcs-82-S...940523?hash=item2ef3cf3c6b:g:P8gAAOSw9IpXyRto

Like ordinary ones but with just one flute, not two, three, six etc.

 

[slim_boy_fat]

I got these in the 'great Cromwell robbery', only tried one to see and seem to do a good job.

https://www.cromwell.co.uk/shop/cro...ss-single-flute-countersink-set/p/SHR0209250K

 

[james butler]

success!!
used an old countersink ive had knocking around somewhere and it worked great!
i think the new one i have must have too keen an edge so digs in too much causing it to skip, just to think if i had found it earlier i would have thrown it away because i have a new one.
thanks for the help every one much appreciated

 

[Hood]

Just a bit of a heads up. You probably need an account with them to order but WNT have a deal on at the moment that is pretty good. A set of 6 countersinks from 6.3 to 20.5mm which usually retail at £108, you can get them at the moment for £12 a set. I ordered 4 sets (max for offer is 5) so in total with the VAT it came to £55.87 as I got a £1.44 (before VAT) online discount and shipping is free next day.
Not used them in anger yet but WNT stuff is top notch so I have no doubts that they will be good.

Edit
Actually I told a lie, just got the invoice through the post and delivery is not free, it was £5 plus VAT, so total cost for 4 sets delivered next day (from Germany) was £61.87.

 

[chris y]

No need for an account, I just went on the website and you can buy as a guest with Paypal which I will be doing when I get home from work.

Great tip off thanks.

 

[Hood]

That is good news, I know when I tried to buy stuff maybe 10 years ago they needed me to set up an account. I declined as I do not really like accounts. I sent them an email saying I just wanted to buy something by paying with my card instead of jumping through hoops to set up an account. A guy from WNT UK came back and said the German parent company didn't like doing that they preferred people have accounts, so I said no probs, cheerio. Next thing I get an email from someone else saying here are your account details

I still prefer paying by card or bank transfer as I know what has to be paid each month so maybe I will look at paying with PayPal the next time, so thanks for that info