Center drilling problems

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VicHobbyGuy

Ultra Member
Beginner here, using a 7x mini lathe. I need some help with a problem center drilling.
Sometimes it's straightforward, but often I get the following problem: When I advance the center drill into the spinning workpiece, the drill 'kicks' off center by about a mm (or two) and then proceeds to cut a small circle with a 'pip' in the center. NB this is a 'mini-lathe' so nothing about the tailstock is extremely solid, but it is adjusted to be on-center. Is this a problem with the tailstock, the drill (I've tried a few), the speed of rotation of the work, or a technique issue? I usually don't advance the drill very forcefully into the workpiece; should I? This happens with both brass and steel workpieces, and not every time, so it is frustrating. I generally have to re-face the part and try again, and sometimes that does the trick. Any hints would be much appreciated.
 
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V

VicHobbyGuy

Ultra Member
David_R8 said:
Is there play in the tailstock
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There's as little as I can manage - it's only really solid when the quill lock is full on, but then I can't advance the drill. The tailsotck is solid, but the quill isn't. I thought the idea was that the drill should 'self-center' on a spinning workpiece?
 
PaulL

PaulL

Technologist at Large
Premium Member
I had this problem early on (only weeks ago!). I height-centered my facing cutter better, getting rid of every trace of a little nubbin at the center of the face and now my centers go in better and I break fewer center drills. Though I still blow them out too often.
 
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VicHobbyGuy

Ultra Member
PaulL said:
I had this problem early on (only weeks ago!). I height-centered my facing cutter better, getting rid of every trace of a little nubbin at the center of the face and now my centers go in better and I break fewer center drills. Though I still blow them out too often.
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Thanks, I need to check the center finish better with the magnifier Optivisor on, I guess. I haven't broken a center drill yet, so there's still 'room to grow' for me :)
 
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VicHobbyGuy

Ultra Member
On the same topic- Recommendations for good quality center drills would be appreciated. I'm not interested in paying KBC/Accusize triple the price for the same ones I got from Ali Express, Banggood but $40+ seems a lot...https://www.toolstoday.com/global/v-12361-51670.html
I usually use the center drill I got in my night school class in the 1970s - it's been waiting all these years for me to get a lathe! :) Truly 'old school quality', I guess, but even with it I have these problems.
 
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DPittman

DPittman

Ultra Member
Premium Member
DavidR8

DavidR8

Scrap maker
Administrator
Moderator
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I also had (emphasis on had) a set from Banggood. Basically one-use items.
 
V

VicHobbyGuy

Ultra Member
DPittman said:
I ordered a set from Aliexpress and they were pure garbage. I've also had some worthless ones from Amazon. I also paid $45 for an American made set from KBC and am happy with them. There has to be some that are reasonable price but decent quality out there, but I haven't found them yet.
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I saw these at KBC, but since the country of origin isn't marked, I'd assumed they were not from the USA.
https://www.kbctools.ca/itemdetail/1-033-100 $52

https://www.kbctools.ca/itemdetail/1-031-200 KEO $62 KEO brand
 
Tomc938

Tomc938

Ultra Member
Premium Member
I barely know what I'm talking about, but I wonder if you have checked that the spindle and tailstock are in-line? I'm wondering if the tailstock is a bit off front to back if that might not be part of the problem. Drill would be working like a cutting tool close to, but not on, centre.
 
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