drill wobble.

[Speedy]

I know drills should spin true but I am noticing wobble.
at my friends shop I was going to drill #21 holes in my engines head but his 115 piece drill set showed wobbling, so I waited as I did not want to ruin my hole for tapping.
I go home and open up my new 115 piece cobalt drill set and my #21 also wobbles!!!!!

is this normal?

 

[lensman57]

I know drills should spin true but I am noticing wobble.
at my friends shop I was going to drill #21 holes in my engines head but his 115 piece drill set showed wobbling, so I waited as I did not want to ruin my hole for tapping.
I go home and open up my new 115 piece cobalt drill set and my #21 also wobbles!!!!!

is this normal?

Hi speedy,

I have two sets of these import drill sets, one set is the no's imperial and the other a metric in 0.1 mm steps. Both sets have a no of drills that are not straight and true. For a long while I blamed my jacobs chucks for this but it is the drill. I also have quite a few Dormer, Titex and some German brand drill and these seem to be quite straight. Your hit of one drill out of 115 is quite good I think. I also noticed that the numbering on the shank of some of the drills had raised a burr of considerable size, I try and avoid gripping the drill on the markings if possible. The other problem that I have found with these drills is that they could be as much as 0.05 mm under or oversize. This normally is not a problem as I just use them to drill prior to boring and reaming, But the problem of the wobble is serious.

Regards,

A.G

 

[Swifty]

The first thing that you should do is check the chuck with a know straight piece of steel. This will show that the chuck is either the problem or OK. If the chuck is fine, then put the drill bit in a V block and use an indicator to check for runout as you slowly rotate the drill in the V block.

Paul.

 

[Walsheng]

Are you sure it is wobbling and not an illusion due to the flutes spinning?
There should be no wobble if the drill is straight, the chuck runs true and the drill is in the chuck correctly. Spin the drill as you tighten the chuck on the drill and it should feel smooth up until it is snug.

John

 

[chipenter]

A no 21 drill will have enough flex to drill straight if opening out from a smaller drill , step drilling , try a test on some scrap invert the drill and try the shank for wobble .

 

[Speedy]

what a shame, these kits are not cheap either.

its not my chuck or mill as I tested it after with a center drill that always runs true.
I will check for burrs on the drill.

I think I will also run as many of the drills as I can and see how bad they really are.

Chip. I always center drill my holes so I am thinking it might still work as there is a guide,but do I really want to risk it?

no engine building today

 

[retailer]

I have 3 of those chinese sets that have a full set of fractional, number and letter drills from a local Cheap Auto shop, I originally picked up one at the marked shelf price of $28 but at the checkout I found they scanned at $14.00 so I picked up the remainder of the stock. Marked HSS I thought good value for money, and for the most part they are except they do have drills with runout, mostly in the small sizes, I have found the same as lensman57 that they can be under or over size and also the stamping on the shank can have a burr that contributes to the wobble, sometimes the runout can be minimised by loosening the chuck, rotating the drill and re-tightening, sometimes I do this a number of times and eventually find a spot with minimal runout and then again sometimes it doesn't help. I also centre drill every time, and if possible ream or bore the hole to the correct size.
I guess that you get what you pay for, I have a set of locally made Sutton drills, considerably more cost but no runout.
I also have a set of those gold coloured coated drills and have found that they are very brittle, I've had them shatter when the drill breaks through especially if the material being drilled is a bit tough.
Cheers

 

[gus]

The micro drills bought from TokyuHands,SHinjuku,Tokyo,Japan were good but costly.Used them to drill gas nozzle holes and IC engine fuel nozzle jets.
No wobble at all. Drilling on the lathe was nerve breaking with very minute feeds and frequent backing out to clear chips.
These drills are throways.After use every time,I would check for wear which means potential breakage and job ruined.
Chinese micro drill bits not my cup of tea.
Trying hard to justify buying a quality high speed mini drill press. Sakai,Japan Drill press cost a fortune. Seen some Chinese micro drill press being used by street craftsmen in Bangkok. They claim
it was good enough for them.Will see.

 

[Omnimill]

Put something longer than a centre drill in your chuck to check runout, say a piece of drill rod about 10mm dia and 100mm long.

 

[Antman]

Do any of you like the Chee Po split point drills? Sometimes you get sets like 2mm to 6.5 , 8 or 10mm by halves quite cheap here in RSA, split point drills Ti coated that I found cut pretty straight. Once you get them started even quite big ones drill easily deeper than their pilot hole. So far I've only found a max of 1 or 2 bad ones per set. Cheers,
Ant

 

[Speedy]

ill check runout again but I am positive im fine.
didnt have time yet to check for burrs.

this is the kit I bought
http://www.princessauto.com/pal/product/8314882/Drill-Bit-Sets/Pro.Point-115-pc-Cobalt-Drill-Bit-Set

 

[lensman57]

Do any of you like the Chee Po split point drills? Sometimes you get sets like 2mm to 6.5 , 8 or 10mm by halves quite cheap here in RSA, split point drills Ti coated that I found cut pretty straight. Once you get them started even quite big ones drill easily deeper than their pilot hole. So far I've only found a max of 1 or 2 bad ones per set. Cheers,
Ant

Hi Antman,

I have got a new set of these drills that you mentioned, have not had a chance to try them yet, the split point is supposed to help with centering and drilling pressure. The last time I used my cobalt split points there were fine with the exception of brass, it just grabs the brass much mre than single point. With the single point I find that a constant pressure on the drill gets rid of the grabbing to a large extent ( I think it is combination of feed rate and drilling pressure ), not so with split points.

Regards,

A.G

 

[MachineTom]

Each piece in the chain from spindle bearings to drill bit add to the runout you have. You have an R8 bore in your spindle, then an ER collet chuck is added, then a collet, then an arbor, and a chuck, and finally a bit. Not that the OP has all these things its just a point, to begin the thought process.

So back up and check each part as they are added, it decide is it the chinese bit, or some other part in the chain. Myself I buy my bits always the same brand PTD Precision Twist Drill, always straight, sharp, available. In addition you should have spotting drills in small sizes, very inexpensive, dead on, even the chinese ones, now you have a good spot to get a drill going straight.

 

[gus]

Each piece in the chain from spindle bearings to drill bit add to the runout you have. You have an R8 bore in your spindle, then an ER collet chuck is added, then a collet, then an arbor, and a chuck, and finally a bit. Not that the OP has all these things its just a point, to begin the thought process.

So back up and check each part as they are added, it decide is it the chinese bit, or some other part in the chain. Myself I buy my bits always the same brand PTD Precision Twist Drill, always straight, sharp, available. In addition you should have spotting drills in small sizes, very inexpensive, dead on, even the chinese ones, now you have a good spot to get a drill going straight.

Hi MachineTom,

Need to buy some spot drills.Please advise source. Nobody stocks same here in Singapore. Getting old and tired to manual spotting with a series of standard drills.