Runout drilling 2mm hole

[Men IfrParticipant @menifr84251]

Hi,

I need to drill a small hole (I selected 2mm) in a steel plate and aluminium plate.

I then put some 2mm rod through both to create a pivot point.

The problem is the pivot is very sloppy – the hole I drill (with Sieg equivelent x2/x3 milling machine and R8 taper) in the alloy is obviously bigger than the jobber bit I'm using.

I've measured the run-out of possible parts:

1-10mm 3 jaw chuck 0.07mm (arc euro part)

ER 16 collet holder 0.01 (ebay part)

2mm collet when fitted in holder 0.07

So I'm thinking the 2mm ER16 collet adds 0.06mm run out – the problem is with buying any of these parts I don't see a run-out specification.

Is 0.07mm normal/acceptable? I'm a bit dissapointed in the arc euro chuck but maybe all 3 jaw chucks are very poor?

Also – I can't measure the hole I drill… maybe its much further out than +0.07?

I thought maybe I can try to get some ~2.1mm rod or make some but the 2mm rod seems a reasonably tight fit in the steel so I think (but can't measure) the hole in steel is closer to the 2mm and the hole in alloy is 2.07mm or more…

Any tips or am I expecting far too much?

I thought about making a bigger hole but it would still have the same error in the size wouldn't it?

[Men IfrParticipant @menifr84251]

[JasonBModerator @jasonb]

I'd be looking at the drill bit and your method for drilling aluminium. Is it a known brand of drill bit, how did you start/locate the hole, did you use any lubricant, you don't say how deep the holes are but did you clear the swarf regularly, etc

If you want an accurate hole then you should also consider drilling under size and then reaming

That is not a bad run out for the 3-jaw, they are never perfect

[OldironParticipant @oldiron]

Never seen a drill bit that does not drill oversize. Most times its best to drill with an undersize drill then measure & ream or bore to size. If you decide to make the hole bigger try getting to the required size by reaming it or using an undersize drill. Metric drills can be purchased in 0.1mm increments.

[OldironParticipant @oldiron]

mmm JasonB beat me to it.

[JohnFParticipant @johnf59703]

Hmm! You have to keep in mind the tools you have are not "top class" , very acceptable but you cannot expect super precision at those prices. High precision chucks, collets etc will cost you many time the price you paid.

However I think part of your problem may be the drill bit — is this a high quality product by Dormer, Hertel etc? Is it new or re-sharpened?

I would suggest it may also be how you are tackling the job, are you drilling the hole in one ? I would suggest you drill a smaller hole first say 0.1 or 0.2mm undersize then open up to the 2mm — it would also be better with a reamer if available. Another solution if you can't make the parts agin may be to use a taper reamer and pin to suit with a thread on the small end so you can hold it in place with minimum clearance by use of 2 nuts loved together — assuming there is room to do this.
hope this helps John

Edited By JohnF on 08/11/2017 20:19:57

[JohnFParticipant @johnf59703]

Ha! both beat me !!!

[SillyOldDufferModerator @sillyoldduffer]

I too think the chief suspect is the drill bit. I don't think it's runout because spinning drills stabilise around an axis.

Twist drills cut oversize if the drill is blunt, or unequally ground, or gets aluminium welded to it, or the flutes fill with swarf, or if forced in too hard by the operator. Lubricate to keep the tip sharp and to stop aluminium sticking to it. Helps very much to start with a centre drill and small drills should be spun as fast as possible, whilst 'letting the tool do the work'. (Hard enough to cut rather than rub, not so hard that the flutes splay while the edge overheats.)

Quite difficult to keep deep holes straight and to size at the best of times.

Dave

[MWParticipant @mw27036]

Posted by SillyOldDuffer on 08/11/2017 20:40:42:

I too think the chief suspect is the drill bit. I don't think it's runout because spinning drills stabilise around an axis.

Quite difficult to keep deep holes straight and to size at the best of times.

Dave

The only real way to do it is to use progressively longer drills but it's not a cheap solution i'll admit.

Michael W

[HOWARDTParticipant @howardt]

Use a drill/guide bush to guide the drill. You would need to make a simple fixture to hold the part and bush, but it negates any inaccuracy in the spindle holding the drill.

[Paul LousickParticipant @paullousick59116]

For precistion holes, drill hole slightly undersize and use a machine reamer to finish. Even the cheaper ones on ebay will produce an acceptable hole for most jobs that we do and are not expensive.

For accurate positioning of holes, use a centre drill or spotting drill to start the hole, then drill thru with a twist drill. Remember to use cutting fluid while drilling and reaming.

Paul.

[Men IfrParticipant @menifr84251]

Thanks for the replies the hole only needs to be drilled to about 4 mm I have tried a test hole drilling to 1.8 mm and then to 2mm and that seems a bit better but still not perfect I think I’ll try and get hold of a 1.9 mm drill bit and see if I drill to 1.9 if I can fit a 2mm rid in there or drill to 1.9 and then 2mm to see if that’s slightly better. Any ideas where to get good drill bits from for this and what to look for preferrably available to order online for mail order thanks

[Men IfrParticipant @menifr84251]

Oh one more thing I’m using oil to lubricate for the hole is that bad?

[Mike PooleParticipant @mikepoole82104]

The top brands for drills are Dormer , Ghuring, Titex and others but drilling method and sharpening play their part. Drilling to a fit is always going to be a matter of chance for all the reasons posted. Reaming is more likely to get you where you want to be but even that can be fine tuned by choice of lubricant and adjustments made to the reamer. Double drilling can get very close but as you have found the results can be variable. a bit of practice with techniques should get you homed in on a method that works for you. Check that the rod is on size as well as stock materials are often undersize, even silver steel can be slightly under as everything has a tolerance. To get the fit you are seeking the rod and hole dimensions are going to need to be accurate within a few ten thousandths of an inch.

Mike

[HopperParticipant @hopper]

If you want a precision hole, use a reamer. Drills are a roughing tool.

[Chris TriceParticipant @christrice43267]

Make a D bit from some 2mm silver steel and use lots of lubricant, if the hole size is that crucial.

[Neil WyattModerator @neilwyatt]

Ideally, drill slightly undersize and broach the hole which will give a slightly tapered fit you can make perfect for what you need.

If a blind hole, more difficult but assuming a steel pin the best solution might be to make it a force fit (or use retainer) in an undersize hole in the steel and use a bit of the pin material with a long, shallow bevel on the end to ream a hole in the aluminium.

[Martin KyteParticipant @martinkyte99762]

Posted by Oldiron on 08/11/2017 20:09:23:

Never seen a drill bit that does not drill oversize. Most times its best to drill with an undersize drill then measure & ream or bore to size. If you decide to make the hole bigger try getting to the required size by reaming it or using an undersize drill. Metric drills can be purchased in 0.1mm increments.

If you stone the corners from a point to a radius you can get twist drills to cut undersize to the extent that you cannot fit the shank into the hole you just drilled.

It's more party piece than usefull.

:0)

Martin

[Danny M2ZParticipant @dannym2z]

Posted by Chris Trice on 09/11/2017 02:55:33:

Make a D bit from some 2mm silver steel and use lots of lubricant, if the hole size is that crucial.

That is excellent advice Chris, simple is good but surprisingly accurate with a sharp tool.

* Danny M *

[Andy CarruthersParticipant @andycarruthers33275]

Every day is a school day – thanks to everyone for the education

I have experienced the same problem and co-incidentally awaiting 2mm reamers from the Bay of E

I read recently about 10,000 hours being the number required to become an expert in anything, only 9,999 to go…

[Men IfrParticipant @menifr84251]

Sorry Chris can you explain what you mean?

[Men IfrParticipant @menifr84251]

Ive ordered a 1.9 mm ground drill bit and a 2mm reamer so interested to see how that turns out.

[Men IfrParticipant @menifr84251]

Ive ordered a 1.9 mm ground drill bit and a 2mm reamer so interested to see how that turns out.

Also I looked at the supposed accuracy of my cheapo collet set and it claims 0.008mm so I submitted a claim for a refund showing 0.1mm runout and got a refund for most of the money and can keep the collets until I find something more accurate. I notice RDG engineering sell a set for ?50 so ive asked them what the accuracy is.

[Russell EberhardtParticipant @russelleberhardt48058]

Posted by Men Ifr on 09/11/2017 10:51:12:
Sorry Chris can you explain what you mean?

Our editor explains it well here

Russell

[VicParticipant @vic]

I had a problem once with drilling a small hole on the lathe, starting it off with a spotting drill solved the issue.

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