How to prevent chatter?
|390 forum posts|
When using HSS "rose" style countersink bits to countersink and chamfer holes in mild steel, how do I prevent them chattering? It occurs with both machine and hand operations.
It doesn't happen all the time, but when it does, it's impossible to correct.
I guess speed and lubrication might be the main considerations.
|Michael Gilligan||27/02/2021 11:27:10|
17641 forum posts
Try putting a small piece of thin cotton fabric between the cutter and the work.
P.S. 1, 2 or 3 flute cutters are usually less troublesome
Edited By Michael Gilligan on 27/02/2021 11:30:15
|Rod Renshaw||27/02/2021 11:30:42|
|254 forum posts|
I think I read somewhere that rose bits were really woodworkers' tools.
Single cutting edge countersink bits, of which there are several patterns, cut mild steel without chattering.
|390 forum posts|
Thank you Michael. Now you mention it, I remember one of the guys at work using a piece of spent emery cloth.
Rod. I did try the "snail" type bits, and they worked realy well, but they didn't appear to be very hard. Probably meant for woodwork. I'll do a search and see if I can find them in HSS.
|Howard Lewis||27/02/2021 11:44:35|
|4662 forum posts|
In my experience, Chamfering tools chatter unless the speed is kept low, and fed very gently.
The 1/2 " one is better than the 3/4" when they are used in the 3 MT Tailstock..
|1980 forum posts|
I have experienced the same but found low speed (200) and lube with 1 good hit does the job and leaves a smooth finish if countersinking, for de-burring of small holes I use the same cutter but held in a chuck and operated by hand.
|Mike Hurley||27/02/2021 12:06:45|
|97 forum posts|
After years getting oval, off centre or chattered countersinks with these type of cutters, I now get pretty well 100% success with the following 'rules'
1. Work firmly clamped down
2. Slow speed
3. (Probably the key one) be decisive! By this I mean, decide on your depth of countersink, set your stop on the drill press or equivalent on lathe/mill, then 'drill' in ONE FIRM motion to full depth. It always seemed to be the intermittent and 'bit less / or a tiny bit more' approach that causes issues.
|414 forum posts|
While we are on the topic of countersink bits does anyone have any recommendations for good value/performance?
I always found the cheap ones are shockingly bad and the good ones are shockingly expensive.
|1980 forum posts|
You can make your own single point from silver steel hardened of course, just make sure you back off to give clearance.
Or if you have access to a tool grinder do the same from HSS.
|Bill Phinn||27/02/2021 12:38:32|
|470 forum posts|
The range of Sherwood single-flute csks from Zoro are excellent in performance and value.
Alpen three-flute csks give very good performance as well though are a little pricier.
Machine countersinking shouldn't cause chattering as long as you keep the speed and downfeed pressure low, and have good stiffness in the set-up. I tend to use Vactra no.2 as a lubricant, when I do use a lubricant.
Edited By Bill Phinn on 27/02/2021 12:46:23
|bernard towers||27/02/2021 12:54:26|
|138 forum posts|
I use the through hole ones in various sizes as I have zero success with any that have more than one cutting edge, and speed is definitely a factor.
|Philip Rowe||27/02/2021 13:41:43|
|205 forum posts|
Since I switched to using spotting drills instead of centre drills, I have found that they also make excellent countersink bits with no chatter at all.
|Douglas Johnston||27/02/2021 14:26:55|
738 forum posts
|Martin Dowing||27/02/2021 16:13:26|
350 forum posts
There are *asymmetrical* countersinks where 3 segments with cutting edges are at different angles to each other.
This design is implemmented explicitly to reduce / prevent chatter.
|Henry Brown||27/02/2021 17:47:25|
434 forum posts
The RDG 3 flute ones are good. I've got a few, 25mm is the largest, they need to be run slowly with lots of cutting oil, I use CT90.
|502 forum posts|
Dad had one he made when he was an apprentice which had just one 'tooth' at a different angle from the others. It was a delight to use. I think one of my brothers had it when we sorted out Dad's workshop.
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