Shelves, building kitchen units, making the misses a Jewelry Box. They are fantastic, but not if you want to be a serious grown up engineer and play with the big boys.
So lets bin all the shitty cheap HSS drills and buy some decent stuff. Oh by the way don’t blame me if your boss says “dream on”
Why Am I Saying This
Well because modern drills are amazing.
They hold accurate size.
Don’t need a spot drill.
Really super fast.
Last longer.
Oh did I mention they are bloody expensive.
Now with HSS drills you can buy thousands of em for a fiver and still have change to buy Robbie Williams concert tickets.
Authors Note
Please don’t read any of my articles if you like Robbie Williams, it means your a twat. Now Robin Williams, that’s totally different. Don’t you just love “Mrs Doubtfire” my favourite film.
Drills Drills More About Drills
But good quality modern drills are expensive. The good news is they easily pay for themselves. You need to treat them carefully because if they are carbide then they can chip and smash easily. You know in that James Bond movie where he is disarming a nuclear bomb? Well treat them like that and you’ll be just fine.
Anyway that’s not what this article is about.
CNC Tooling Centre Drill
A centre drill has a 60 degree point which is not good to start a drill. With a spot drill you can get a 120 degree point which is roughly the same as your drill point so it gives the drill a great start.
The drill won’t wander but if you heed my advice and use a super duper new drill then it will drill perfectly without any spot drill.
Spot Drill Last
I would always use good quality CNC Tooling.
Use a good quality modern drill and then use a 90 degree point spot drill after to chamfer your holes.
This means you can rapid the spot drill right into the hole and then feed in just a tiny amount to create the chamfer.
Spot Drills The Good Bit
You can deburr with a spot drill. Just program it to go around your shape and put a nice clean chamfer around you part.
CNC Tooling Conclusion Spot Drill Centre Drill
Always use good quality CNC Tooling
Use a centre drill only if you have to.
Make sure your turret is aligned on a CNC Lathe.
Centre drills are for centre locations on long or ground parts.
Centre drills are for grinding between centres
Spot drill can be same angle as drill.
Spot drill after drilling.
Use spot drills to deburr parts.
Thanks
If you have been affected by any of the issues in this post or need CNC Counselling then contact me.
If you want to learn to program CNC Milling Machines
This program will rapid to X66. Z3. it will then machine the face down to Z0 in three cuts. The first G94 line tells it to face past centreline to X-1.6 at a feed-rate of F.2 The Z axis moves to Z2.
Cuts
1: Z2.
2: Z1.
3: Z0
The cycle stays in the control until cancelled by a G0 rapid command.
So it remembers exactly what you told it, a bit like my wife, she keeps reminding me of the time I got so hammered I pissed in her wardrobe (some of the shoes still smell to this day).
The G0 G28 U0 W0 will move the turret back to machine reference point.
The G0 will cancel the G94 Facing cycle.
G94 Facing Example Is It Any Good?
Well personally I think it is.
Now I’ll tell you why. You could say it’s really easy to write the program to face a part.
G0 X50. Z0 G1 X-1.6 F.2 G0 X50. Z2.
So that’s easy to do but….
Some one wrote a comment on one of my posts the other day and he started it by saying “back in the real world”.
Can’t lie and say it didn’t piss me off but being the mature well balanced man that I am I ignored it.
Now my inner nasty, immature, unbalanced me said “look mate I was in the real world when you were still shitting yellow”. Obviously I didn’t post it and if your reading this now thinking it’s you, well it isn’t.
Anyway as to the G94 Facing Example
In the “real world” you get to the end of the batch of parts and find that one of them is way too long and you need to face a shit load off the front.
Now had you used the cycle as below and got into the habit of always using it.
G0 X50. Z3. G94 X-1.6 Z0 F.2 G0 G28 U0 W0
The alteration would be really easy.
G0 X50. Z12. (Imagine You Have An Extra 12mm On the Face) G94 X-1.6 Z10.5 F.2 Z9. Z7.5 Z6. Z4.5 Z3. Z1.5 Z0 G0 G28 U0 W0
Rapid Move Cancels G94
Note don’t forget you must have the G0 rapid move at the end to cancel the G94.
I found quite a few errors in the code quite quickly and congratulating myself confidently told him to run the program.
This guy has been my best friend since I was 17 and I couldn’t resist a bit of sarcasm (we call it piss taking here in England).
You have to be careful when you have a go at Garry. Ever since our days together as apprentices at Rolls Royce (circa 1971) whenever I took the piss out of him he would get me back 10 fold.
(It’s no coincidence that Rolls Royce went bust in 1971)
I remember my first time at arc welding nervously trying to master the technique. Garry thought it might be amusing to smash a large mallet into the underside of the metal clad welding both.
I have always been the type of person who jumps and alarms quite easily.
Panic struck I threw the complete welding torch into the air and spontaneously evacuated my bowels. It sparked and flashed around the cabinet, which I had long since vacated, for a good minute before the instructor intervened.
I was the subject of ridicule and derision for the next few days by the whole of the Rolls Royce training school (about 200 teenagers).
For the younger generation, it was in those strange halcyon days when the UK invested in manufacturing. Oh and we had Black Sabbath, Led Zeppelin, Deep Purple and the fuckin Osmonds.
The CNC Program
Anyway enough of that. So yea I thought the program was OK but it alarmed out again.
A sarcastic laugh ensued and comments about “how the Mighty Fall”.
Needless to say I hadn’t found the real error in the code.
I have to call it a school boy error, mind you when I was at school I couldn’t even write my fuckin’ name, let alone error check a complex CNC Program.
I must have demonstrated this a hundred times on a whiteboard. My students took it all in but obviously I didn’t….. So what’s the error?
