Round holes - is it possibl e ?

Asked my local engineers to drill me two accurate holes 5/8 dia in the vertical plane, parallel to each other.

They said they could set up on a mill and ream for accuracy.

Picked up a piece of tube with both at least 3/4 inch diameter by 11/16 inch.  Looked as if chewed out and certainly not round.

Was I expecting too much ?

Jason, thanks for your help, opened album and I think it worked.

Edited By reg c on 14/10/2013 16:35:57

Edited By reg c on 14/10/2013 16:40:24

Edited By JasonB on 14/10/2013 16:52:54

Reg

I don't see why this can't be done but there are a couple of questions. What was the material that was being drilled and did you specify the finish you wanted. As for the size then there is no excuse.

Using my cheap pillar drill I would expect to get a hole pretty close to the drill size and if predrilled with a pilot hole and opened up with a to size drill I would expect to get a reasonable finish almost spot on the size.

Cheers

Martin

PS

Just looked at the picture. Can see it is a copper tube and fairly thin walled. While this makes the task more difficult there is, in my opinion, no excuse not to get it right especially if you have crossed their palms with silver.

Edited By Martin W on 14/10/2013 16:49:21

Hello Martin.

Tube is copper, 4 inch, 16swg.

I specified a 5/8 dia hole, reamed, and both parallel to each other.

I will try and explain. I wanted it mounted in the mill so that the centre line of the tube was in line with the centre of the mill bit. I then wanted it wound 1 inch to the left and the hole drilled, then the process reversed.

This would enable me to have two tubes running parallel to each other exiting the tube that I could then solder in place.

Hope this makes sense. I can do a drawing and attach if it helps.

Thanks.

Reg

edited - spelling mistakes.

Edited By reg c on 14/10/2013 16:52:05

Edited By reg c on 14/10/2013 16:54:02

Yes should have been possible to get it virtually spot on, though they may well have been better using a boring head to finish the holes or maybe plunging with a 5/8" slotdrill as a reamer may want to wander.

Martin - went back with the tube and the 5/8 piece and showed them.

Refunded immediately with the offer of another go free of charge, politely declined, as it had already cost me one piece of tube.

Thanks for confirming, Jason.

Now I know that, I will have to find another company as I do not have the facilities.

Hi Reg

I think I understand what you wanted and as such each hole in the tube would be slightly elliptical to accommodate the pipes needing to be parallel to each other and both off center from the tube axis by 1 inch.

While in no way excusing the work done it can be difficult to secure a thin walled tube for drilling, you can't lock it up in a vice unless you make a mandrel, and it tends to grab as the drill cuts through; copper only makes this worse. My guess is that the tube wasn't held properly and the work grabbed the bit resulting in the mess that's been returned to you!!

I will bow to the more experienced here but I don't know if it is accepted practice to ream thin wall sections especially material like copper.

I am going away to have a quick go at replicating you job, scaled down a bit. If I post a picture displaying a black eye or bruised finger you will know that the job came loose!!!

Sorry I can't be of more help.

Cheers

Martin

PS

Jason I was still typing when you replied so you beat me to it.

Edited By Martin W on 14/10/2013 17:21:40

Jason, will do a sketch and attach shortly.

Thanks for your interest and help.

Jason you are right , it is an elliptical hole. I have a drawing that I have added to my album.

Edited By reg c on 14/10/2013 17:54:45

Rest assured ...

those holes are [or should be] circular when viewed on-axis.

[and, viewed on a radius of the big tube; they will be egg-shaped, not elliptical]

MichaelG.

This job is not at all difficult if you go about it the right way and have the equipment. A drill press won't be up to the job. I would use a mill and slot drills to start the job, stepping up to 5/8" diameter to finish or possibly a boring head to achieve final size.

Tony

Plenty of ways to skin this cat, but i wouldn't use a reamer.

Neil

bit like this?   see album "pipe"

Edited By jason udall on 15/10/2013 00:46:05

Plug it with a good fit hardwood or plastic and use a good endmill

Setting it up right is 95% of the job in this case

Edited By Ady1 on 15/10/2013 01:05:30

Slot drill followed by a boring head, not a problem. If the tube is a little mobile then wooden plugs turned to size would stabilise it. See first photo in My Album for similar job.

Edited By KWIL on 15/10/2013 09:26:20