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Center drilling problems

Janger

Janger

(John)
Administrator
Vendor
Here try this - you should not get any deflection when pulling towards the camera. If it moves then the drill will wander when it engages the material. Also make sure the tailstock is clean and the taper on the chuck is also clean. Wipe them both off when installing the chuck. If there is any swarf interfering the chuck won't be seated.

Post pictures. Much easier to spot problems with pictures.

Use a big fat drill too. the one there is a #5
 

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VicHobbyGuy

Ultra Member
Thanks for all the suggestions. I'll keep them in mind as I work on the problem. I still don't have a lead on high quality center drills, at a reasonable price.
 
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VicHobbyGuy

Ultra Member
Janger said:
Actually watch all of Tom's videos. I found them very helpful.
Click to expand...
I agree. I've watched hours of them! Seeing the work sequence he uses has been helpful. Equipment ideas: Our lathes have one thing in common - something rotates...that's about it! :)
 
Susquatch

Susquatch

Ultra Member
Administrator
Moderator
Premium Member
Confession here - I've been using a lathe for some 30 years. In all those years, I have never used a spotting drill. In fact, I didn't know that they existed until I got a bigger mill.

I guess nobody knows what they don't know.......

I have ALWAYS used a centering drill to start my drill holes. That practice has NEVER been a problem. So I've NEVER needed to look beyond what I always did. A centering drill doesn't wander - at least not on any of my lathes.

That said, I have read elsewhere that you use a spotting drill on a mill not a centering drill. I've wondered why but never dug into it.

So this thread has been wonderful for me as I digest it and begin to realize how much I am learning here.

A thank you to @VicHobbyGuy for posting about his problems, and an apology for my misleading comments earlier.

And a thank you to @gerritv, @PeterT, @Degen, and others whose comments caused me to noodle their rationale and then realize my experience gap.

Now I gotta go find some high quality / low cost spotting drills in an appropriate range of angles. Prolly not a bad thing (an excuse to buy some cool tools I never had before) but I sorta wish that low cost part wasn't counter-productive to the high quality part.....

Question - So here is a question related to the OP's thread. Drilling a larger hole often requires drilling with successively larger drill bits. I often find that the next size up drill catches the side of the previous hole and tries to go off center a bit. It is rarely a problem if I go slow enough to let the drill act a bit like a boring bar until the hole takes over to guide the bit. I believe this is an artifact of my drill bit assortments which do not have perfectly ground tips. I rarely have this problem with my high quality drills which are all individually purchased and stored in marked envelopes. But I don't like to use high quality drills just for roughing out successively larger holes. So when I am being really fussy, I will sometimes use a larger centering drill as a sort of chamferring tool to help guide/start the next size drill. Is it possible or advisable to use a spotting drill in the same way?
 
gerritv

gerritv

Gerrit
@Susquatch no need to apologize for anything IMO. A lot of 'stuff' is part of repeated repetition, and so things such as centre drill to spot for drilling get placed into habit, much like the 29.5dg thing for threading. If it is repeated often enough it is assumed to be true and/or necessary. I re-learned early on with my 1022 lathe that these are not required and in many cases not desired habits.
The challenge is that sooooo many YT creators keep perpeptuating the same stuff, esp. US based ones. Perhaps because I an Dutch I lean toward the European way of thinking and doing things, hence following Stefan (and others on IG). E.g I have a solid toolpost mount and have 0 problems threading anywhere from 70tpi to 1.5mm pitch using bought inserts and shop made cutters. I also part at 400-600 rpm in Al, 300-400 in most steel. Heresy I know :)

Re: enlarging holes, it is actually a perfect example of why using the 60dg centre drill is not correct, the edge of one flute catches the edge. :) I use boring bars to open up after .5"/12mm since I have few drills larger than that. As the hole increases in diameter I swap out to heftier bars. Even with my AliExpress inserts and bars I can hog deep cuts to get near my desired dimension. I often get coloured chips that way (I try to avoid getting to the blue stage :))

Now I gotta go find some high quality / low cost spotting drills in an appropriate range of angles. Prolly not a bad thing (an excuse to buy some cool tools I never had before) but I sorta wish that low cost part wasn't counter-productive to the high quality part.....
Click to expand...
I buy my cutters from AliExpress, all of them. HSS and carbide. Never been disapppointed although with threading inserts you sometimes get A55 mixed in with A60 :-(. If you have an broken/dull.25" HSS or carbide milling cutter you can grind up a 3 facet spotting drill with a bit of care. Test to see that the point is centred by using it in a drill press.
And again, Stefan:
on the diff between centre and spotting as well as making a pyramid cutter.

Gerrit
 
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VicHobbyGuy

Ultra Member
gerritv said:
A 6 or 8mm x 120dg would be good enough, you are only spotting with it.
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Thanks, I've ordered a couple.
gerritv said:
Re: Tom's Techniques video above, again it is a great vid about drilling a centre hole to mount a part on centres. Not for spot drilling.
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Yes. He doesn't really have 'problems' to solve, he talks about how deep to drill, etc.. Still, I always learn something from Tom's videos.
 
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VicHobbyGuy

Ultra Member
Degen said:
Pickup or order from KBC
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Thanks. Anything from KBC? There's a big range of prices- 'standard' and cobalt and 'NEO' brand. I had the impression that the 'KBC' brand stuff was the same quality I've gotten direct from China, with a markup.
 
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VicHobbyGuy

Ultra Member
gerritv said:
And again, Stefan:
on the diff between centre and spotting as well as making a pyramid cutter.

Gerrit
Click to expand...
Thanks, that second video you listed is really informative. One thing from the video that I plan to try is using one of the big center drills for spotting, using just the 120 deg tip. I've watched a few of Stefan's videos and they are good, though generally there's a lot of 'just use the DRO' or 'use your tool grinder/surface grinder/whatever' which will appeal to the owner of a more complete and higher priced workshop! :)
 
V

VicHobbyGuy

Ultra Member
gerritv said:
A 6 or 8mm x 120dg would be good enough, you are only spotting with it.
Click to expand...
The Stefan video you kindly linked discusses the effect of the chisel point on the very center of the 'divot'. So I think I'll add a smaller 120 deg to my shopping list for starting smaller drills like 4 mm. Fortunately, the smaller ones are cheaper. :)
 
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gerritv

gerritv

Gerrit
VicHobbyGuy said:
Thanks, that second video you listed is really informative. One thing from the video that I plan to try is using one of the big center drills for spotting, using just the 120 deg tip. I've watched a few of Stefan's videos and they are good, though generally there's a lot of 'just use the DRO' or 'use your tool grinder/surface grinder/whatever' which will appeal to the owner of a more complete and higher priced workshop! :)
Click to expand...
there are many ways to get your shop equiped. E.g. Hald Hall has a fabulous website full of shop made tools, including several grinding rests. Nothing too difficult and no esoteric machines, tools or materials needed. http://www.homews.co.uk/page463.html

Yes, it is great to have a d-bit grinder etc. but I did ok before I scored that :)

Gerrit
 
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VicHobbyGuy

Ultra Member
This is a bit off-topic but it does involve drilling...
Drilling on the lathe it's easy to see the chips. Wth a twist drill it's rare for me to see two identical (long) chips coming out. This means that the two flutes are not cutting equally, I think? Is this just a consequence of my very average quality drills? With good drills (or drills made good by expert re-grinding) do you always get two similar 'chips' (metal strands) issuing from the drill? Assuming that the feed rate/prssure is good enough to keep the drill cutting, not rubbing.
 
gerritv

gerritv

Gerrit
KBC is no longer a viable option IMO unless you can pick up at the store. Flat rate shipping is gone. I now use BDI Express because they have a local-to-me presence in St Catharines. OTOH never had issues with any of their non-branded items. Not all are from Asia, I get Poland, Bosnia and others as country of origin as well.

As for quaility, sadly higher price is not always a valid indicator of quality in my experience over the past decades. e.g. my expensive Starrett pin punches are like butter, as was the tap handle. Not inexpensive by any measure. AliExpress and Banggood though for me provide a good balance between cost and quality with the ocassional exception. I am a hobby user so not expecting production level life out of the tools.

gerrit
 
gerritv

gerritv

Gerrit
VicHobbyGuy said:
Thanks for that link. For me, a milling machine is esoteric right now. :)
Click to expand...
Get or make a milling slide for your lathe. Don't listen to the nay sayers on that, it is superior in every way to not have milling facilities at all. For decades there were steam engines, gas engines, entire steam locomotive models built using a lathe and milling attachment.
I still have the one for my Taig lathe, it did some stellar work for me prior to getting my basement work shop.

gerrit
 
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