paul
Member
Posts: 8
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Post by paul on Mar 7, 2006 14:34:14 GMT
Can anyone give me any tips on drilling a true vertical hole when using a pillar drill (or drill press if you prefer)?
A part that I've spent about 2 hours making by hand has just been trashed by a hole that has wandered way off centre and I thought I got it nicely set up. Arrggghhh!!
It was a square sided brass part about 35mm top to bottom held securely in a vice clamped to the drill table but the hole at the bottom is probably 2.5mm off centre. As far as I can see the bit is straight (it's new) as is the drill assembly itself... maybe I need to put a spirit level on the table... What's the best way to make sure a piece is square in the vice - I tried my try-square but it doesn't seem accurate enough and is too bulky.
General tips most welcome, I don't want to waste that much time and effort again...
TIA
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Post by havoc on Mar 7, 2006 15:34:41 GMT
Drills never drill straight. But using a vise isn't helping. Clamp the piece directly to your table.
Did you drill starting with something small and then enlarged the hole? Starting too large will also make that problem worse. So will putting too much pressure on the drill.
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Post by the_viffer on Mar 7, 2006 15:45:08 GMT
There are loads of things that make drills wander. I've seen a bit go in the top of a job and come out the side.
Sharp drills going into well centred punched marks without being forced are a good start. Keep clearing the swarf from the hole
You didn't say how big your bit is but once the hole is more than about 5 times deeper than the diameter of the hole you are likely to find it tricky to stop the drill from wandering.
In some case you can start the hole from both top and bottom and accept a slight mismatch somewhere in the middle.
You can consider start off with a pilot drill (ie smaller diameter).
Other tricks are to think about using stub drills and core drills (for opening out pilot holes) or if you have access to a lathe to bore (which my wife thinks I could do for England). I think boring is the best way of ensuring a true hole in most cases.
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Post by ron on Mar 7, 2006 16:51:23 GMT
Paul, a few more tips, I usually drill in the milling machine with the vice bolted to the table, I usually start with a centre drill, if the hole is of any reasonable size I put a smaller drill through first, you need good quality sharp drills and if the hole is a small dia never have any more of the bit protruding from the chuck than necessary. To square up things in the vice I use a small engineers square or a small spirit level depending on the job.
Ron
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paul
Member
Posts: 8
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Post by paul on Mar 7, 2006 17:29:56 GMT
It was a 2.5mm bit started in a nice centre punched hole - so the diameter to depth ratio is well over 10 times let alone mr_viffer's 5x. As it was a fairly small dia hole I didn't use a pilot hole (I douby my 1mm bit would be long enough anyway), and I 'backed off' and removed the swarf regularly. I did consider drilling from either end but thought it might be tricky to get the holes to line up when each would be about 17mm deep. I need to get an engineers square I think! If clamping directly to the table how would this be done if drilling a thin rod or bar longitudinally? When 'the management' recover from my recent acquisition of a telescope a lathe will be in order! Does anyone have an opinion on the small 'desktop' hobby type lathes like this one... www.machinemart.co.uk/product.asp?p=060710250&r=2043&g=106 |
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Post by Phil Sutton on Mar 7, 2006 20:25:10 GMT
Hi Paul.I bought a Warco "Mini" lathe and at £425 inc.a3 jaw 4 jaw chuck,faceplate,drill chuck,box of turning tools,spanners ect.seems b****y good value and is light enough to shift about by hand if you want to mve it about.Works well too!
Phil
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Post by chris vine on Mar 7, 2006 20:36:38 GMT
Hi Paul, Sorry to hear your drill wandered off course, but it sounds like rather a lot of wandering went on.
I wonder (not wander, although I do that as well) if the centre was not really under the centre of the drill. This would push it off course as it went through. IE it was pushed at an angle right from the start.
Or, is the vice you used square? Some will push crooked as they are tightened.
Or, Did the part slip in the vice? Some drill vices, which push from the centre and have poor guides, (which is most of them) will not hold something which is much off the centre of the jaws if you see what I mean. Or a bar being drilled near the end of the jaws can slip down at the end you are drilling.
When it is a few thou which you are looking for it will be difficult to see but with 2.5 mm it should be possible to see by eye where it went wrong.
On a different tack, you are asking about a lathe. Seeing your determination to succeed even without one, I wonder if there isn't a member of this board who has an old lathe under a bench which could be looking for a good home. Sadly I don't have one. You could have a lot of fun attaching a motor if needed, setting it up etc etc. There is plenty of advice on hand here for getting it to turn true etc etc. Obviously something "free" will not be perfect but then the brand new machines seldom are either!!
Cheers
Chris.
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Post by the_viffer on Mar 7, 2006 21:36:05 GMT
Paul, there is no doubt you need a lathe. you are doing great work but you'll do more and better with a lathe.
Like Phil Sutton I've the next size up (the CL300M) of the lathe you mention but sold by Warco which I use for jobs that need a higher speed than my 50 year old ML7 likes.
I just wonder whether for GBP300 you wouldn't get something better secondhand. By way of example I bought a few weeks ago a beautiful English made clockmakers lathe of about the same size with several chucks and collets, change wheels and various bits of other tooling all set up and ready to go for GBP350 on ebay. Someone on this list sold a CL300 type lathe second hand for GBP200 a few weeks ago so stuff is around.
The other thing I'd say is if you've room there is a lot to be said for getting a slightly bigger lathe than the one you mention which you might grow out of sooner rather than later. A small light lathe can be a bit frustrating with smaller cuts possibly worse finish and of course sometime you are bound to want the lathe to hold something a tad bigger than its capacity.
However almost any lathe is going to do wonders for your productivity and pleasure.
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paul
Member
Posts: 8
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Post by paul on Mar 7, 2006 21:59:27 GMT
Phil and the_viffer: thanks for those suggestions, I'll make a note for when the time is right ;-) I'm not averse to buying a secondhand lathe but I must confess I know absolutely nothing about them <blush> so some research is required! I'd prefer to work in metric so I suppose the likelihood of a secondhand model is somewhat diminished.
On the original topic I took a close look at things tonight and found that that vice I've been using is undoubtedly the main culprit; although it can be level left to right, in the opposite direction it is *miles* off when tightened! The drill table itself seems fine in both directions with a spirit level.
Tonight I had a 'practice session'...I took on board suggestions above with regard to stepping up drill sizes ,depth of holes, pressure etc and took great care to set things up carefully. I managed to drill 2.5mm holes from opposite ends to meet a transverse 5mm hole pretty accurately. The smaller holes were drilled out to a depth of about 6mm to 5.5mm dia (newbie question: is this called 'counter boring'?) then tapped to take 6mm bolts. It's the most precise job I've achieved so far and the thread is great!... except I made a marking out error of 1mm!! (I was paying so much attention to the drilling that I probably rushed it). It hasn't made any real difference to the job so regulator #2 is underway!
Just to repeat my question from further up the thread - how would I clamp a rod/bar vertically to drill it centrally along it's length?
Sincere thanks for all the help chaps, I am learning honest and sooner or later I will stop asking silly questions!
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Post by the_viffer on Mar 7, 2006 23:12:52 GMT
Just to repeat my question from further up the thread - how would I clamp a rod/bar vertically to drill it centrally along it's length? Sincere thanks for all the help chaps, I am learning honest and sooner or later I will stop asking silly questions! I think I missed the silly questions Paul. To drill a hole down the end of a length of rod using a drill press you really need a V block. I suppose it might be possible to cut an end off a piece of angle and use that as you V block but as your square is a bit iffy that is not going to be easy to do accurately. I'm afraid V blocks are not cheap. Of course if you had a lathe... |
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SteveW
Elder Statesman
Posts: 1,463
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Post by SteveW on Mar 7, 2006 23:25:01 GMT
Paul,
Re clapping stuff vertically: Get yourself a set of 'V' blocks. I've found them to be relatively cheap verses how useful they are. You can use them for holding round stuff horizontal or vertical (once clamped) They would also hold a bit of square section vertically (or at 45 degrees).
They are also great for marking out and double up as a means of ensuring a plate is vertical (on your cheap marble floor tile 'surface table').
set of 'V' blocks == money well spent.
A sharp pointy thing is also very handy but the current climate makes this difficult to recommend.
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Post by ron on Mar 8, 2006 11:02:55 GMT
Paul
A lot of milling and drill vices have cross V slots in one face for holding round stock, and if you don't need a heavy duty one they are quite cheap at the likes of Chronos etc nowadays, I also agree with the Viffer, I think you would soon 'outgrow' that size of lathe, aim for the size equivalent of a Myford either new or SH, I've a 3 1/2" Warco and they supply them in a choice of imperial or metric.
Ron
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