Perpendicular Drilling

Use a spotting drill or centre drill to get a true start. Then proceed as usual with a good quality drill bit either new or correctly ground. If the start is not vertically under the chuck the hole 'aint going to be true to the surface.

regards Martin

I think you will find that if the table is square to the drill spindle with nothing on it, you will find that it is quite a bit out with the cross/swivel vice on the table, and even more so with the weight of the action of drilling. Also how much does the head, and column flex.

Ian S C

Hello all,

Thank you all so much for such a wealth of good advice and very helpful opinions; really appreciated.

The XY table was summarily dismissed from duty, at dawn, this morning.

Now, please don't shout at me, but I took the table off and gave it a facing job in the lathe. It was certainly not flat. I don't expect any miracles from the excercise, but at least I have a flat surface on which to place the square.

David - I have also had this drill for about 20 years. It's not badged Rexon, but may well be from the same source. Until now it has served me fine but, moving onto finer work, perhaps I've suddenly found it's limitations.

I will certainly fabricate a screw jack to go under the table ( I hadn't considered deflection issues).

Agreed, also, that precise drilling may well be best executed in the lathe; I'm getting along nicely with the 4 jaw chuck.

Also, I take the point about over zealous clamping. Sometimes we fall into rigid trains of thought, and it's good to be brought out of them from time to time. Roy Underhill school .

Will drill some test pieces this evening.

Thank you all once again.

Nick,

I completely agree with your comment on sourcing.

I'm in Central France, so naming the supplier serves no purpose, suffice to say that they are a local industrial supplier who would not get away with supplying sub standard goods. I expect, in truth, the drills will not be the very best available, but of a servicable quality.

In view of the level I'm at right now, it's probably best to stick with those. They're relatively cheap to replace.

Regards, Daniel

When contemplating how to process a job accuracy beyond what is needed can be a great time waster. does the job really need to position the hole with pinpoint accuracy or will within maybe .0015" to .002" do? achievable on a good day if my glasses are clean.

I can set a drill in key less chuck on the pillar drill in a few seconds, Maybe a spotting drill first if needed, Position the work in vice and set the centre pop on the work under the drill in less time than it takes to write this. If needed In goes a chamfer cutter to remove the sharp edges around the hole flip the work do the same on the other side and the job is done.

Alternatively do it in the vertical mill this will require centre finding the punch mark locating x and y, the big table is heavy and there will be a fair amount of winding. then Fitting a drill chuck in quill and tightening up the the draw bar.... as we all know the wrong tool is always in the draw bar... then finally drilling the hole.

Yes with care I can get better accuracy maybe one or two thousandths of an inch better, The purists will claim they can do .0001" (In their dreams) unless they have a jig borer in temperature controlled room! yeah.

Time waits for no one.

Regards
John

I thought the OP's issue was getting a vertical hole?

Martin

Mark - summing up my sentiments right now

John - (sorry for referring to you as David, earlier), It was while trying to make Mr Pete 222's Wobbler engine, that the problem came to light. He kept emphasising the importance of the perpendicularity between the cylinder block and it's pivot pin. Upon screwing in the pivot pin, even with all the optimistic enthusiasm I could muster, the thing was anything but perpendicular. I would guess a good 10° off.

The point regarding appropriate accuracy is one I subscribe too also. However, in this example, it would have been an abuse of the word, to have used it in relation to what I had just produced.

Martin - Yes, my problem was to get a vertical (ish), hole. However, with all the input from the others, I would guess that achieving a hole of any predefined angle would yield similar, albeit random, results.

In my experience no matter how perpendicular the drilling spindle is to the worktable the chances of a hole being absolutely perpendicular are not very good. If there is the slightest difference of position between the start of the hole and the axis of the drilling spindle the drill will bend, maybe imperceptibly at first, but as the hole proceeds the drill will increasingly divert from where it should be. Having the work clamped down actually makes it worse.

If the part to be drilled has a flat underside surface than can sit on the worktable I frequently do not use a vice, once the drill has created a dimple (and I know its in the right place) I peck drill whilst frequently rotating the job half a turn at a time. By turning the job to different positions any spindle/table misalignment is cancelled out

Ian P

Hi Daniel

Don't know how relevant this is, but anyway -

OK, the pivot screws into the cylinder. Has the pivot got a shoulder, larger in diameter than the threaded part, turned on it? If it has, and the shoulder doesn't seat squarely against the cylinder, then there is something wrong with the hole. If there is no shoulder and the design relies on the thread coming to an end to locate the pivot, there is a good chance that it may end up cocked over anyway (unless the thread is a very close fit) even if the hole is perfect. Another thought - the hole may be perpendicular but was the axis of the tap when it went in?

Just thinking aloud ...

I don't know if this is the right place to ask, but I am trying to drill three holes on porcelain tea saucers. My challenge is getting a hole started as the drill bit constantly slides all over. I did see that there are drill guides but it cannot lay flush on the plate as the plate is not flat. The lip goes up on the edges.

I am using a diamond drill bit and start at an angle.

I hope you have some tips for me as this is frustrating!

Don't know about drilling porcelain with a diamond bit, but have drilled a few tiles. Put a bit of masking tape on and drill thru' that.

Two options

1. make a drill guide like the one shown from something that is a bit flexible, lid off a plastic container will do, just use a normal drill to make a hole the size of your diamond coated drill. Then hold the flexible guide against the saucer and away you go.

2. Not for the faint hearted or those who don't know what they are doing, tilt the drill over slightly, guide the end of the drill bit with your finger and as it starts to cut slowly bring the drill perpendicular to the surface.

I drill a lot of holes through ceramic, glass and porcelain tile and the above two methods work fine.

Masking tape is more suited to the spear point tile drills than the diamond coated ones though I use a centre punch to start them, again need to know what you are doing.

To drill through glass, hardened steel and the likes, I made a drill from a bit of tube that slides on a shaft that fits in the drill chuck on the vertical milling machine. The tube is spring loaded to bear on the artcel being drilled, the cutting medium is grinding paste.

Daniel, you should be able to find a suitable hole, maybe a washer, then glue it to the surface of the saucer and drill the hole.

Ian S C

Thank alot, you guys are GREAT!

Good drilling practice, coolant, rigid fixing, tight chuck bearings, well ground drills and finally "pecking". That is taking a very, very small cuts, say 1/2 a turn band pulling the drill out, yes its laborious but it makes sure that the swarf is removed and does not jam in the side of a fluke so deflecting the drill. The problem is once the drill deviates from the true vertical, the forces then increase the deflection. An American website has a lot of chat about this and it seems that a diam/depth ratio of 1:48 still lead to holes being within thous of their correct position.

Frank