Lots of holes!!

[neilgrahamirwin@hotmail.c]

Hi Chaps, I have to drill lots (about 30 per week) of 32mm holes in 2.5mm-3mm mild box, I use a 'Faithful' 32mm hole saw and cutting fluid-it works ok but is a bit hard work getting through. Any body know any really good holesaws for steel-is it worth looking into getting an adapter for my drill to take those mag drill rotabroach bits?? I also drill loads of 10mm holes with a good quality bosch drill bit and same question applies?? Also I use a rexon pillar drill, about 700w i think, it's reasonably heavy duty but do you think something bigger might make this task much easier??
Many thnaks in advance, Neil

 

[neilgrahamirwin@hotmail.c]

just seen the answer to the first part a few threads down! The Bosch power change seem to be recommended, I might give them a try as the rotabroach adapter seems to need the chuck removing and i'm not sure if it's a good idea to keep removing the chuck very regularly??

 

[astro_al]

Its absolutely fine. You can remove the chuck as often as you like, assuming you have a morse taper spindle. Its a 5 second job. I must do it a couple of times a day on average.

Yes, it is absolutely worth getting a mag drill arbor for this kind of repeat work. Honestly, trust me, you'll never look back.

Rigidity of the tool is a definite bonus, mag drills seem to like a decent bit of pressure to help cut. The other thing you need to consider is whether you can drill at the correct speed for the cutting tool.

Al.

 

[neilgrahamirwin@hotmail.c]

What sort of speed do the mag bits work at? Also how to you remove the chuck-it is a MT2, do they just pull out?
When i'm drilling with the holesaw the shaft of the drill does oscillate a bit-surprising as it's bloody thick bit of steel, I might invest in a more industrial drill-it's just that they are so bloody heavy but I guess once it's in i won't be moving it anywhere.

 

[neilgrahamirwin@hotmail.c]

Also with the mag drill bits, do you have to drill the pilot hole first or do they have a pilot drill bit?

 

[wyn]

Also with the mag drill bits, do you have to drill the pilot hole first or do they have a pilot drill bit?

You don't need a pilot hole...maybe a centre pop mark.....the cutters have a guide pin that lines it up and they cut through in a similar way to a holesaw.
The centre pin also ejects the 'slug' from the cutter once you have drilled through.


This pic shows the business end of one.




To remove the drill chuck have a look at this thread

 

[astro_al]

Drills are only heavy until you move something bigger. They can easily be 'walked' around a workshop by a single person.

To eject the morse taper chuck arbor, 2 methods depending on your drill:

1. lower the spindle using the handwheel/lever and look for a slot in the side of the spindle, if there is a slot, rotate the chuck so that the slot in the outer spindle lines up with the slot in the inner spindle (i.e. you can see straight through the spindle). You should see the back end of the arbor in the centre of the inner spindle. Insert a drift which is just a vaguely triangular strip of metal (gradual slope), and tap it in until the chuck falls out. OR...

2. If there is no slot in the spindle, you can drift the chuck / arbor out by lowering the spindle a little and placing a 'U' shape spacer around the arbor just above the top of the chuck, when you release the feed lever, it will exert pressure between the bottom of the drill head casting and the top of the chuck & should eventually drift it out of the taper (may need some encouragement). Some drills have a mechanism built in to do this.

Hope that makes sense!

For the mag drills - yo need to put a centre punch mark (pref a nice solid deep one), but no prior drilling necessary / desirable. Speeds can be found here:
http://www.gjhall.co.uk/em/uploads/docs/48b50d7876b3d09c0e19bf2218884d2d.pdf

(To save you loading it - a 32mm cutter in mild steel needs a spindle speed of 239 rpm).

Al.

 

[neilgrahamirwin@hotmail.c]

Thanks-so the guid pin doesn't penetrate the metal, it's just to hold the whole lot central?

You don't need a pilot hole...maybe a centre pop mark.....the cutters have a guide pin that lines it up and they cut through in a similar way to a holesaw.
The centre pin also ejects the 'slug' from the cutter once you have drilled through.


This pic shows the business end of one.

View attachment 18412


To remove the drill chuck have a look at this thread

 

[neilgrahamirwin@hotmail.c]

Thanks, it has got a slot so will give that a try. I did by a nice Meddings drill of ebay but almost blew an o ring trying to get it in and out of the boot and also the first time i used it the motor burnt out (it looked older than me!). So i thought ****** it and bought the Rexon drill as it was only a year old-still pretty heavy mind at about 90kg but you can tell the spindle and base plate aren't as heavy duty. When i'm drilling holes the chuck will stop sometimes if i press too hard or the drill bit cathches, i'm guessing it's the belts slipping as opposed to the motor stopping? Would a better drill eliminate this do you think?

Drills are only heavy until you move something bigger. They can easily be 'walked' around a workshop by a single person.

To eject the morse taper chuck arbor, 2 methods depending on your drill:

1. lower the spindle using the handwheel/lever and look for a slot in the side of the spindle, if there is a slot, rotate the chuck so that the slot in the outer spindle lines up with the slot in the inner spindle (i.e. you can see straight through the spindle). You should see the back end of the arbor in the centre of the inner spindle. Insert a drift which is just a vaguely triangular strip of metal (gradual slope), and tap it in until the chuck falls out. OR...

2. If there is no slot in the spindle, you can drift the chuck / arbor out by lowering the spindle a little and placing a 'U' shape spacer around the arbor just above the top of the chuck, when you release the feed lever, it will exert pressure between the bottom of the drill head casting and the top of the chuck & should eventually drift it out of the taper (may need some encouragement). Some drills have a mechanism built in to do this.

Hope that makes sense!

For the mag drills - yo need to put a centre punch mark (pref a nice solid deep one), but no prior drilling necessary / desirable. Speeds can be found here:
http://www.gjhall.co.uk/em/uploads/docs/48b50d7876b3d09c0e19bf2218884d2d.pdf

(To save you loading it - a 32mm cutter in mild steel needs a spindle speed of 239 rpm).

Al.

 

[astro_al]

Not necessarily, no. Unless you buys a geared head drill (which isn't necessary for this drilling with this type of cutter). Yes, its almost certainly the belt slipping. You should check the belt tension and adjust it if necessary.

Also check that its not the arbor spinning in the spindle (is the spindle still rotating, but the arbor stationary?).

Maybe a new motor for the Meddings?

Yes, the guide pin is to ensure the cut is on target (sits in centre-pop you made previously) and to eject the slug of metal from the cutter once the cut is complete (it is sprung, so you can feed the drill into the material).

Al.

 

[neilgrahamirwin@hotmail.c]

The only problem i can see is the fact that at the moment i have a jig set up for doing these holes, i put the 50x25 in jig and just make the hole in the right position, if i had to centre punch first it just adds another task to do which is a pain when i have lots to do-i'm guessing you can't use these cutters without the punch mark as it will just keep moving on the surface?

 

[neilgrahamirwin@hotmail.c]

regarding the meddings, i looked into getting a new motor but as it was all imperial (shaft/footplate etc) it was becoming an expensive pain so i just flogged it on ebay and made 20 quid for my effort. I might get another newer one though as they are great bits of kit. Looking at some used machinery companies i could get a decent one for about 200 quid-money well spent for the amount of use it would get.

 

[neilgrahamirwin@hotmail.c]

one last thing on decent pillar drills, when i'm looking for one, is there a difference between drills designed for metal work and for wood work as i wouldn't want to buy one thats was more for woodwork?

 

[astro_al]

At the cheaper end, people get away with 'general' drills, which are ok for metal up to a certain point (size of cut, basically). After that you're looking at things with lower speeds and more structure, which are the key elements of metalworking drills.

There are so many questions on drilling machines here, perhaps we need a guide for looking at them (there have been a few drill related questions in the last few weeks in this section of the forum - have a look through them for general drill advice).

If you have a decent jig and a good clamping system, you don't 'need' to centre-pop the holes, but it should be clamped very well. I just did a job using these cutters at an angle - about 16 deg, 28 deg and even 45 degrees. It worked fine with the edge of the cutter biting first and no centre to locate it (used the cutter without the pin in), but I'd recommend it for general work. I'm sure you could adapt you jig to suit, but leave the pin in to help eject the slug.

Al.

 

[neilgrahamirwin@hotmail.c]

right, i will go down that route then and get the arbor and 32mm bit, looks like ebay is probably my best bet.
many thanks, neil