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How do I

drill through a round bar

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Wolfie18/11/2011 09:24:36
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502 forum posts
OK next question.
 
How do I drill accurately through a piece of round bar. I don't mean end-on, I know that one, but through it side to side.
 
I tried it, centrepunched a mark on it and drilled to find I hadn't gone through the centre of the bar so the hole was off centre so to speak. Am I making sense here?
Richard Parsons18/11/2011 09:59:06
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645 forum posts
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Wolfie


Here is a simple method of cross drilling a round bar. You set up a Vee block under the drill centring it with a Vee shaped mandrel. And lock it down to the drill table.


Next mark and centre punch the hole you wish to drill. Put the drill you are going to use in the drill. Now using the drill to make sure that the centre punch mark is under the drill. Drill the hole. A coconut every time (within a couple of thou)!


The set up





Rdgs

Dick
Martin W18/11/2011 09:59:37
940 forum posts
30 photos
Hi Wolfie
 
The way I would drill a hole through the center of a round bar on my mill, assuming that the vice etc have been set square, would be:-
 
a. Use the edge finder to establish the fixed jaw of the vice and zero the 'y' (front to back) axis to this.
 
b. Measure the diameter of the round bar to be drilled and move the table on the 'y' axis in by half of the measured diameter and lock the 'y' axis.
 
c. Using either a spot or center drill bit drill a starter hole at the required distance from the end of the rod. Then lock the 'x' (sideways motion) axis to this point.
 
d. Fit the required size drill bit to the chuck and drill into the starter hole using it to stop the drill bit skidding off the surface.
 
This assumes that the rod/bar will be clamped against the face of the rear jaw of the vice. If your vice has a V groove running horizontally in the rear/fixed jaw then the bar MUST NOT be clamped in the groove as this will offset the bar center, relative to the measured datum, by the amount it sets into this recess.
 
It may not be the accepted or best way but it works for me .
 
 
I have tried a couple of inexpensive center finders that are held in the chuck and use a lever and indicator system to identify when the chuck is centralised on the rod but these have never given accurate or sensibly repeatable results.
 
Hope this helps.
 
Martin
 
Just seen what Dick has posted using a V block on a drill table. The big advantage of this method is that, assuming you don't move the V blocks between operations, you can use it for a variety of round bar/rod sizes and it will center every time. As I said there are going to be alternative solutions to the problem .

Edited By Martin W on 18/11/2011 10:09:43

Edited By Martin W on 18/11/2011 10:10:09

Laurence B18/11/2011 10:50:26
58 forum posts
A method that I read in M.E (where else!) and that I use,is to turn up a short bush the same diameter as the bar you wish to cross-drill,and with the same hole size through the bush.
Hold the bar you wish to cross drill in your machine vice (best if the vice is bolted/clamped to your drilling machine table) with the drilling bush set on top of the bar,along the bar where you wish to drill your hole.
The machine vice will hold the bush (being the same diameter as the bar) exactly on the centre line of the bar and will guide the drill accurately as you require.
As with the other methods you'd have to position the bush accurately along the length of the bar.Hope this helps.
Ian S C18/11/2011 12:11:54
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I go along with Dicks method,get a bar as big as will fit in your chuck, face it square and remove the sharp edge, fitted in chuck bring it down on the V block then clamp the V block in place. I actually use a cam follower out of a car engine, it has a stem bit about 9/16: dia X 1 1./2" long, with a disc shape bit at the end 1" dia X 1/4" thick, this last bit is what sits down in the V block. On the mill I set the V block square so that I can then move the table back and forth (or side to side)keeping it centered. Set up time, about a miniute. Ian S C
chris stephens18/11/2011 13:08:14
1049 forum posts
1 photos
Hi Wolfie,
The best method for drilling cross holes in round bar is to use a "V" pad in your lathe tail stock whilst the drill is held in the chuck. This is an age old way of doing things, Myford even used to sell the required bit of kit, and I still do it this way despite having decent DROs fitted to my mill. The reason I still do it this way is because it requires no set up, just plonk the pad in the tail stock and off you go.
chriStephens
Martin W18/11/2011 14:41:35
940 forum posts
30 photos
Wolfie
 
Following on from Chris S comment re using a V pad in the tailstock, these are available commercially and here is one from RDG but I have seen them with a clamping bar as part of the V block assembly. Other tool stockists will have them so it would be wise to look round first to see what is available and if there are better priced units about.
 
Must admit I had seen these advertised some time ago but totally forgotten about them so thanks Chris S for jogging my ancient grey cells; or should that read 'cell' .
 
 
Cheers
 
 
Martin
Martin W18/11/2011 15:34:54
940 forum posts
30 photos
Hi
 
Knew I had seen a unit with the clamping bar as standard. Its being sold by Arc as a Tail Stock V Adaptor here. Gives you more hands free to field the unexpected.
 
Martin
chris stephens18/11/2011 16:36:10
1049 forum posts
1 photos
Hi Martin,
You are welcome, it's nice to be able to do something useful once in a while.
 
 
As for where to buy, personally, I make my own that way I can be certain they are 100% accurate. ( if you work for the NPL or the Swiss watch industry, ignore the 100% bit and insert that they are near enough)
chriStephens
mick18/11/2011 17:13:32
421 forum posts
49 photos
If you don't have access to all the kit described and you do have a simple drilling vice with a horizontal V groove and your bench drill has a round table which coupled with the main support arm allows you to position a component any within the 360 degree arc, then clamp the vice to the table with the bar also securely clamped. Put a centre drill in the chuck with the bar directly beneath the spindle, place a thin, but flat strip of metal on top of the bar and bring the centre down till it holds the strip. Depending on which side of the bar isn't directly uder the centre line of the spindle, the strip will dip to one side. The centre line of the bar is directly under the centre line of the spindle when the strip is completely horizontal.
Billy Mills18/11/2011 17:22:40
377 forum posts
This one could run for some time...... If the rod will go in the chuck then chuck it.Position the fixed jaw of the drilling vice against the chucked rod then bolt or clamp the vice down. Now put the bar in the vice and tighten. and the drill in the chuck, drill the hole. No other bits needed. ( yes the drill is smaller than the rod!) ( you also need a plain face on the vice)
 
A nice gadget to do centre drilling is in Stan Bray's "Useful Workshop Tools"( as is the previous tip). It has two bars held parallel by three equal length links which are bolted to the bars. The middle link is drilled in the middle. You close the bars each side of what you want to centre drill then drill through the middle link hole.
 
A very quick and simple device is a short bit of U channel. Square the ends to be about twice the length of the width then scribe lines to join the corners on the outside of the lower U face. Drill the intersection. Put the channel over the narrower bar/rod you want to drill then rotate the channel so that opposite ends of the channel are against the job. Drill through the hole.
 
Billy.
Billy Mills18/11/2011 17:30:04
377 forum posts
Yet another version..... Drill a strip with two holes then find the centre with a compass or whatever and drill. Turn two cylinders to the same diameter and centre drill. Bolt the cylinders to the outside holes of the strip. Same use as the channel version, rotate the strip until both cylinders are against the opposite sides of the job then drill through the centre hole.
 
Billy.

Edited By Billy Mills on 18/11/2011 17:33:27

Stub Mandrel18/11/2011 17:39:27
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4318 forum posts
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1 articles
Heresey time!
 
If I used a v-block method I wlould end up drilling a hole in my nice v-block. Plus teh drill would probably wander.
 
For holes that don't need to be perfect, I file a small flat, then put the centre punch on that and drill by eye.
 
For critical holes, I use the mill. First I clamp the work, then I mill a tiny flat with a small end mill. I pop or centre drill in the middle of the flat, then drill through that.
 
Neil
Ian S C19/11/2011 10:19:22
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7468 forum posts
230 photos
Neil, you won't damage your V block if the area you are going to drill is over hanging the V block, if the bar is long, use two V blocks (they usually come in pairs). Withy my Starrett V blocks, you would damage the drill rather than the block, they are hardened. Ian S C
John Stevenson19/11/2011 10:37:15
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5068 forum posts
3 photos
My drilling machine has a fixed rise and fall table. There is a 1/2" clearance hole under the drill so you can't drill into the table.
Seems to work well as the table has never been accidentally drilled since 1923 when the drill was made !

So I got an old piece of Vee material off a press, drilled a small pilot hole thru it dead centre, upended it and drill for 1/2" clearance and fitted a short dowel.

I now just pop this into the hole and the block is bang on centre.
 

You can do the same with a moveable table if you line the table up first with a dowel in the chuck.
 
This is one of those processes where there are umpteen ways to do it, none wrong but requiring different bits of kit. Select the method that suits you and your kit.
 
 
BTW bit of commercial advertising seeing as it's been mentioned.
I designed' the Vee tailstock support for ARC so should it be called the Stevenson Tailstock support ?
 
Personally I think Ketan at ARC ought to come out with a designer label for model engineers.
 
The K10 range.
 
OK I'll get me coat.
 
John S.
 

Edited By John Stevenson on 19/11/2011 10:39:09

michael cole19/11/2011 13:08:16
166 forum posts
John I understand that you will take payment in kippers. Any possibltiy of converting ARC to the new money standard. ( Safer than Euro's)
 
Mike
David Clark 119/11/2011 13:47:18
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3357 forum posts
112 photos
10 articles
Hi There
Sorry, Arc Kipper Trade does not sound so good.
regards David
 
John Stevenson19/11/2011 13:55:27
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5068 forum posts
3 photos
True David,
I think it's liable to flounder......................................
 
 
 
John S.
Richard Parsons19/11/2011 14:19:15
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645 forum posts
33 photos

Oh my God ‘flounder’ indeed this site is the ‘place’ for a ‘dab’ of humour but I think we had better ‘skate’ around that

Bogstandard19/11/2011 15:02:34
263 forum posts
Tailstock V holder
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