How to drill through metal???

[smoothcut5]

I've drilled a small perpendicular hole through a metal (stainless steel) 6mm motor rod (one from a normal air circulator turbo fan the Honeywell ones) and i've used a centre puncher to mark for drilling and have successfully drilled a small 1/16 hole in the motor shaft.
However I decided to drill through the already drilled out hole using a bigger drill bits (1.8mm) to create a bigger hole (1.8mm sized hole) which was an obvious mistake.
As the already drilled out hole closed up and seemed to have gotten hardened so now i can't even drill through the clogged up, hardened hole.

What can I do to fix this? I just want the drilled out 1/16 hole back but I can't seem to drill through it.

I used a tungsten and molybdenum with 5% cobalt added drill bits and used a homemade drill cooling/lubricant oil using two parts water and one part olive oil.

Any advice would be appreciated thanks.

 

[Burnerman]

As you have been able to drill the motor spindle already, then obviously the carbon steel is tough, but possible to drill. It will however take the cutting edge off the drill bit as it's fairly hard.
If you need to drill through an existing hole, use a new HSS drill - fairly high speed as it's small, and use something like WD40 as a lubricant and coolant.
John

 

[bernardgreen]

Use a cutting paste for drilling metal. such as Rocol RTD Compound. Not cheap but pays for itself by prolonging drill life and makes the drill much more effective as it has abrasives as as well as lubricants

or http://www.screwfix.com/p/exact-cutting-paste-50g/46289 but haven't used this one spop have noidea how good it is.

 

[smoothcut5]

Thank you for the advice John and Bernard! Yes I will try that! I too believe a better lubricant/paste would be effective. And as for the HSS drilling bit since the end is pointy so i think that'll kind dig out the clogged, hardened bit!

 

[Mikefromlondon]

I done hundreds of holes on various metals using my bench drill press, without any cutting fluids or coolants, normally I have no problem as long as a sharp drill bit is used and I never have keep any lubricants, as sometimes they tend to work the opposite, I only ever use a bit of tallow when cutting threads, and even have used butter when tallow is not at hand, you are cutting metal not trying to lubricate it to glide drill's cutting edge over lubricated surface, coolant is used to keep the temperatures low to prolong the drill life, so I would try a normal jobber drill sharp as new, and you started with 1/16 which is about 1.6mm and then tried to enlarge it with a 1.8mm, I would have used 1.8mm drill all the way in the first place keeping its speed at a reasonable level so as not to allow it to overheat, something around 2000 rpm, and feeding it with a steady pressure and drill dry.

 

[smoothcut5]

Thanks for the advice Mike! I might also try carbide die drill bits or straight flute carbide drills.

 

[Burnerman]

Straight flute drills are really for non ferrous materials such as copper, brass and aluminium - they have less tendency to grab into the material like a spiral flute drill.
Nothing to stop you trying though!
Hopefully with only 6mm to drill, there shouldn't be much wander of the bit, and use plenty of liquid to wash the chips out.
John

 

[theprinceofdarkness]

As you have found out, stainless steel work hardens, low speed and lots of feed (pressure). Do not allow the drill to rub.
Frank

 

[smoothcut5]

Thanks John and Frank! actually I'm only going to be drilling either the sizes 1/16 (1.6mm) or 1.8mm so I think it's going to be fairly easier than drilling 6mm. What do you think would be the best type of drill bits for stainless steel? It's a lot harder as it got hardened so I'll probably look for a stronger drill bits! Sorry Im a complete novice on things like this but I'm learning! Thank goodness for forums like here!

 

[Burnerman]

This could be quite a difficult one, but as you've found, stainless steel work hardens if it's allowed to get too hot - and if it's in this state then HSS drills probably aren't good enough. Drilling comparatively slowly with loads of coolant is the way to go.
Anyway, consider a cobalt alloyed drill to complete your task.
When I mentioned 6mm I was referring to the distance to drill, rather than the diameter......!
Just wondering if the motor shaft is actually stainless or carbon steel.....don't know!
John

 

[smoothcut5]

Thank you for the reply oops sorry I understand now!
I believe the motor shaft is stainless steel but I'm not 100% sure, (the carbon steel is softer than stainless I believe?) The drill bits i have are Tungsten and molybdenum with 5% cobalt added so perhaps i'll continue to use that but I'll purchase a proper coolant/paste to use this time instead of the homemade ones. Thanks for the advice!

Though one thing I'd like to ask is if you've drilled a 1.6mm hole and you want to make it bigger (1.8mm) would that be possible by using lots of cutting oil or paste? since I made this mistake as I should have used 1.8mm from the beginning but now it's clogged up and hardened

 

[Burnerman]

Just a wee thought on this one......you haven't a broken drill tip in the hole, by any chance?
Anyway, plenty of WD, Duck Oil or whatever, and try again with the (new) 1.8mm drill - nothing to lose now! Proper drilling coolant won't make any huge difference. One slight comfort, the hardening of the stainless is likely to be pretty local so another hole probably could be drilled close by, if that's acceptable or possible.
There are different grades of stainless steel, just as there are with other steels, just to add to the quandry.
Can we ask what it is you are trying to achieve?
John

 

[smoothcut5]

No there was a tiny broken drill tip but it fell on the table, so I know it's not stuck inside the hole. I just bought the Rocol RTD Compound online so just waiting for that to arrive.
Yes actually I might just drill another hole right underneath it if i can't seem to drill through the hardened one but I'm sure it'll be no problem!
I'm pretty sure the type of stainless is the normal 304 ones but again I can't be 100% sure.
What I'm trying to do is, drill a small perpendicular hole on the motor shaft (as mentioned above) through both the motor shaft and the fan blade plastic housing so that I can thread a wire through it to hold the fan blade in place. The purpose of this is to bind the fan blade to the motor shaft.
I know i can just use a lock washer but I also have a wooden dowel placed on the other side and that too will be held in place by the wire threaded through the hole. I've attached a photo for better understanding.
It's for like a science project and i'm trying to achieve like a water tornado device thing haha

 

[Mikefromlondon]

Good luck with your project, you should try to use a low voltage DC motor if you can get one from somewhere, since you are going to create a water tornado, experiments can go wrong and water and electricity don't mix, so beware of the dangers. You seem to have a open frame mains synchronous motor, Use RCD supply to safeguard against any possible dangers from electricity and water coming together with you in between! (You may have got a cheap battery drill for about a tenner, on ebay, and used its motor and speed control, would have been more safe, also you could have mounted the propeller (fan blade) in its chuck and would not need all that hassle any ways good luck and hope your project wins merit and proves the concept of water tornados.

 

[smoothcut5]

Thank you for the helpful advice Mike! I haven't thought of using those appliances you've suggested so that's a really good idea. At the end of the wooden dowel I'm going to be attaching a piece of ceramic or something horizontally using a wire wrapped. And I will build a small wooden frame/table for placing the fan over it, facing it down and the wood rod with the ceramic attached will go inside a container of water and once switched on, It'll create a tornado. So to summarise It'll be a normal 8" air circulator fan with the front mesh guard removed and with the motor+fan blade I'll place a wooden dowel in the fan blade sleeving.
Also may I ask, what you meant by placing the fan blade in its chuck? Sorry for my lack of understanding haha but i'm learning