Drill bit keeps wandering!

[Kaleb]

I've been trying to make the bottom end cap for my "S.T." oscillator, but the drill bit just won't play ball. :redface2: Even if I centre drill it first, it still wanders. I'm trying to drill a 3/32" hole, and my centre drills are 2.5mm.

 

[aheg1220]

Center drills don't help much when they're bigger than the drill bit. If you don't have a smaller center drill, try a nice fat punch mark or a split point drill bit without a center drill or punch mark

 

[Ken I]

As stated previously - use a much smaller centredrill - or use a spotting drill (that's a stubby split point sharpened drill).

Check your drill bit is properly sharpened and that the cutting edges are symetrical (ie when you drill a piece of scrap it produces two equal looking strands of swarf).

If you are doing this on a lathe - check that your tailstock is properly aligned.

Ken

 

[Blogwitch]

What is really required is a spot drill.

A centre drill is just that, for putting a centre in the end of a bar for holding between centres on the lathe. The drill bit on the end is just like any other drill bit and can wander almost anywhere, that is why small ones break off the tips so often, when they wander, they are just too rigid and so break.

A spot drill is a specially ground drill that is self starting and gives a perfect spot for a drill to start into.

BTW, you could use even say a 10mm one for starting off a hole for a 1mm drill, just depends how deep you go. I tend to go a tiny bit deeper than required, that saves me having to deburr the top of the hole afterwards.


John

 

[willisZ]

after years of dreaming, i finally found a drill press at a garage sale this summer - and it's awesome. Don't know how I got by without it. I've made several jigs to line up small parts so that the holes are all dead-on.

 

[flatbelter]

Everyone else has already posted some great advice.

A good center punch really makes a difference if you need to get a drill started in the right spot.

The other trick is to be sure that you have everything lined up properly. I put a small x/y table on my drill press, probably one of the handiest accessories I own.

Make sure that the drill is sharp, not bent, and the chuck is free of chips.

fb

 

[tattoomike68]

Redline the drills RPM and it will not walk near as much, run it full blast, you dont need a spot or center drill. done it thousands of times.

 

[velocette]

Hi Lots of great advice on drilling small holes. Full speed yes 2500 RPM to 3200 RPM for "Mild Steel" is O K

Use the "Toolmakers" Method Firm centre pop and file or carefully grind off flush the burr of upset metal level with the surface. Sometimes the Burr is Uneven and will kick the drill off slightly.

Fix the Job Clamp it in the vice or to the drill press table. Brass some bronzes and most cast irons are inclined to "Grab"
This can be remedied by "Backing Off" the cutting edge with a small oil stone or a diamond file until the cutting edge is parallel to the drill shank. Like th old "Blacksmiths Drills"

If the problem is using the lathe for drilling start with a "Centre Drill". Bring the drill up to almost touching the Job.

Bring the "Tool post" to touch the Tail Stock chuck apply a slight pressure to the chuck an carefully advance the tail stock to start drilling then when you get the point to start cutting ease the pressure by backing of with the tool post and continuing to drill the hole

This will help to get the "Centre Drill" on a perfect Centre in the work piece

 

[Springbok]

You maybe to young for to the saying slowly slowly cachee monkey. As a now old engineer we were taught that putting
in the specified drill say 1/4" onto a spot either with a punch or a centre was waiting for a disaster.
Use a good known clean preferably Dormer drill about 1/8" to drill your pilot hole then keeping your coordinates work up your drill sizes if it it has to be reamed stop at 1/32 below insert your reamer and useing cutting oil to finish. The drill sizes are only for an example to can be used on any size of hole you wish to make.
Thought. Metals what are you wanting to drill though the speed could also be a problem and the machinery that you are useing is it a pillar drill. or mill and what type and has it collets or a chuck.

bob

 

[Gedeon Spilett]

Hi,
I made for myself a small tool for this purpose, it take a few seconds with a dremel.
it is a kind of tiny coned (around 60°) D-bit with a gramophone needle. I put it in a punch mark, give it a twist to remove the raised burr by the punch, I can easily correct the position of the spot on the scribed lines with it, and I drill the hole with a sharp, and not wobbling drill (like cheap chinese drills so often do)

Zephyrin

 

[Swede]

As my drill collection has increased in size, I am more and more buying screw machine sized drills. These are shorter than regular jobbers drills, and as a result, are stiffer, and more likely to drill true.

After all, how often do we need the full length of the jobbers drill? Rarely enough. It's best to have examples of both on hand, but given a choice, I'll reach for the screw machine drill.

When drill collections become too large, one of those Huot or similar organizers are a huge help and worth every penny.

 

[Springbok]

Hi Swede
My old age pension would never rise to something as posh as that made some stands out of old wood blocks that were being thrown out from a parquate floor. Agree with you on the drills have a set of jobbers but rarely use them. Anyway how do you get the smaller drills out of these slots...

Bob

 

[Swede]

Do you mean from the cabinet, Bob? They just rest in there loose, and the slots are rounded at the bottom so the really tiny ones are easy to fetch.

My cabinet has wire gauge, fractional, A-Z, and a fourth drawer for reamers and the like. There are dozens of extra slots for taps, counterbores, countersinks, etc. I don't have a huge collection, but try to keep three or four of each drill size handy, jobbers and screw length. For drills I use a lot, like #4, 6, 8, 10 tap and fractionals like 1/4 and 3/8, the more the merrier. A ten-pack of # 4 tap will last for many years and is cheaper than one at a time in the long run.

I like generic but "Western-made" bits. Not a huge fan of cheaper drill bits. Some of the Chinese drills are just awful. At the same time, I don't buy the super brand-names often.

Anyway, a cabinet like this (used) isn't too bad and is very useful. I find organization makes me more productive and the shop a nicer place to work.

 

[Dan Rowe]

My wife bought me a drill cabinet for Christmas several years ago and it is very handy to keep organized indeed.

Here is an article I found by googling 'spot vs center drill'
http://www.ctemag.com/dynamic.articles.php?id=31

I have to admit I had never heard of spot drills before reading this forum. I did pay attention in shop class and even took advanced machine shop as an elective course in the 70's.

I checked my machine shop books that I used for the course work and two methods are mentioned center drills and a layout method to check then use a chisel to correct the wander before tip cuts the full diameter.

On the US Merchant ships there is only a lathe, drill press and a large bench grinder. All the machine repairs had to be done with what we had on board no internet and no quick trip to the machine supply store. I checked an old McMaster Carr catalog #95 from 1989 and spot drills are not in the catalog. So even if I had known about spot drills I could not have ordered them.

I plan to get some spot drills soon after all I have a nifty place to store them.

Dan

 

[Blogwitch]

Dan,

I gave up using spot drills because they were just too expensive when my free supply dried up.

I fuddled along with centre drills for a couple of years, putting up with their terrible ways, then I found a source of reasonably priced ones, so I invested about 20 squid and bought myself a set from 3mm to 8mm in both 90 & 120 degs, plus a couple of small carbide ones.

They are one of those items that when you have used them, you don't want to use anything else, purely because of the spotting accuracy that you just can't get with either a centre pop or a centre drill.

Four 'facet' split point drills are supposed to be self starting, but I have had wandering problems with those as well.


You won't regret buying yourself a few.


John

 

[deverett]

... then I found a source of reasonably priced ones, so I invested about 20 squid and bought myself a set from 3mm to 8mm in both 90 & 120 degs, plus a couple of small carbide ones.

You won't regret buying yourself a few.
John

John

Would you mind divulging your source of 'reasonably priced' spot drills. Does the supplier do mail order?

Thanks

Dave
The Emerald Isle

 

[Blogwitch]

Sorry Dave, I should've put the link in my other post.

Pages 2 & 3 contain the ones that should interest you.

http://www.engineeringsupplies.co.uk/drilling-c-160.html?page=2&sort=4a&9=172

If you stay with the cobalt ones, the prices are very good, in fact unbeatable. As I said, I bought a full set up to 8mm, in both 90 & 120, plus I bought one of each angle in 3mm solid carbide, for those little difficult jobs, stainless, ali bronze etc. I bought a few extra afterwards, thinking that they would soon go blunt, but as yet, they are still sitting in the draw.

I find them great to use in the lathe before using a centre drill, they give you a perfect location.

The supplier is very good, and even when out of stock of some items, they usually turn up a couple of days later from their Scotland branch, not like other suppliers where you have to remind them to send back orders. They take the normal credit or debit cards.

John

 

[deverett]

Many thanks for that link and info, John.

Dave
The Emerald Isle

 

[tel]

Those are good prices! About 25% of the best I can do here. Hmmmm ... take off VAT, add postage and I think I'd still be on a winner!