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9th Feb 2019, 7:47 pm | #1 |
Hexode
Join Date: Sep 2004
Location: Newcastle upon Tyne, Tyne & Wear, UK.
Posts: 475
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Using hole punches on die cast boxes
I am building a small valve amplifier and needs to punch 30mm holes in a die cast aluminium box. I have used the Q-max-type punches on sheet aluminium but just wondered if they work well on die cast?
I don't want to damage my expensive box. The box material is aluminium alloy ADC12 and wall thickness is 2mm. |
9th Feb 2019, 8:15 pm | #2 |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 14,007
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Re: Using hole punches on die cast boxes
I'd be reluctant to do it - the biggest hole I've ever free-punched in cast-alloy was for a RCA "Nuvistor" triode and that was only about 0.7 inch.
For 'holing' diecast where I can't specify the holes as part of the original casting, I've used "cone-cut" stepped borers, or when it comes to an 8x6 hole for a loudspeaker, drilling a load of 3mm holes. knocking-out the centre, then taking-out the rough edges with a rotary file. |
9th Feb 2019, 8:46 pm | #3 |
Moderator
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 21,289
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Re: Using hole punches on die cast boxes
Don't do it! The aluminium is guaranteed to crack.
Chain drilling and filing is the way to go.
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9th Feb 2019, 8:53 pm | #4 |
Heptode
Join Date: Feb 2003
Location: Garnant, near Ammanford, South Wales, UK.
Posts: 657
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Re: Using hole punches on die cast boxes
Agree, don't do it, your chances of success are slim.
Use a hole saw, nice and slow with a bit of oil. Richard
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9th Feb 2019, 8:59 pm | #5 |
Dekatron
Join Date: Oct 2003
Location: Croydon, Surrey, UK.
Posts: 7,580
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Re: Using hole punches on die cast boxes
No don't chance a Q-Max type hole punch. They are excellent for soft metal but die-cast is hard and brittle. I tried it in my early days when I wanted to build a pre-selector for my shortwave radio when I was around 17. I needed a 3/4 hole for the slow-motion drive and drilled a pilot in the lid of the die-cast box (which would become the front), inserted the Q-Max and began to turn the screw barrel down....it started to cut and then there was a bang and a large chunk of the die-cast broke out...I had to wait another week to go to Home Radio and buy another.... I think a cone cutter or maybe one of those hole cutters you can fit to a drill will work. Failing that, a circle of smaller holes and then punch out the centre, finishing off with a rotary file
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9th Feb 2019, 9:15 pm | #6 |
Dekatron
Join Date: Nov 2011
Location: Surrey, UK.
Posts: 4,400
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Re: Using hole punches on die cast boxes
Well, I defer to the majority view expressed above- but I regularly used to use small and large Q-Max cutters on Eddystone die-cast boxes at work for one-offs and interface boxes. It tested the biceps on a long-arm Allen key- but the result was invariably a crisp hole without distorting, cracking or otherwise harming the box, though the waste punch-out was almost always cracked and sometimes crumbled.
This was with someone else paying for punches and Eddy-boxes though!- had it been my own stuff, I might (would) have been more hesitant. It's possible that other makes of die-cast box might not have been so forgiving or robust. Maybe play it safe and go the somewhat longer route. |
9th Feb 2019, 9:45 pm | #7 |
Octode
Join Date: Jul 2009
Location: Cheshire, UK.
Posts: 1,740
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Re: Using hole punches on die cast boxes
I've also tried this once at work & it did work OK producing a nice clean hole, the waste part ended in bits too.
The reason for not using a hole saw, well someone had borrowed the kit and returned it with the needed one missing of course. David |
9th Feb 2019, 9:47 pm | #8 |
Dekatron
Join Date: Feb 2003
Location: Cottingham, East Yorkshire, UK.
Posts: 5,766
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Re: Using hole punches on die cast boxes
In my experience, far and away the best tool for drilling sheet metal, diecast boxes and acrylic sheet is a 'step drill' also known as a 'cone drill'. They start their own pilot hole, don't snatch or grab, and are easy to use in a pillar drill (not a hand held electric drill). You just continue drilling one step at a time till you get to the desired sized hole. No dramas. EG. This one drills in thirteen steps from 5mm to 35mm:
https://www.amazon.co.uk/gp/offer-li...&condition=new You can get more expensive ones, but as they tend not to get used too often, a cheap one is good enough for most requirements. Hope that helps.
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9th Feb 2019, 9:58 pm | #9 |
Dekatron
Join Date: Feb 2005
Location: St.Ippolyts, Hitchin, Hertfordshire QRA IO91UW
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Re: Using hole punches on die cast boxes
I have had good experience using "qmax" on diecast as well - I wouldnt want to go much above 30mm though, gets a bit demanding on the allen key
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9th Feb 2019, 10:04 pm | #10 |
Hexode
Join Date: Sep 2004
Location: Newcastle upon Tyne, Tyne & Wear, UK.
Posts: 475
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Re: Using hole punches on die cast boxes
Thanks everyone for your replies. I will go the step/cone drill route, as I have one that will do 30mm.
I've just tried using a punch on a spare die cast box lid and it worked OK but I could see the lid deforming as I tightened the punch Allen screw. The punched-out circle was cracked into several pieces. I actually want to punch the holes in the box part, rather than a flat lid, and fear it might just crack or shatter under stress. At £20 for the box, I'll take the less risky option. Last edited by Steve_Bell; 9th Feb 2019 at 10:12 pm. |
9th Feb 2019, 10:25 pm | #11 |
Nonode
Join Date: Jun 2013
Location: Surbiton, SW London, UK.
Posts: 2,801
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Re: Using hole punches on die cast boxes
I've never had a problem, and I also use a cone cut bit, especially in plastics. You need
to make a large hole for the bolt on an 85 mm cutter. If you have a couple of thin pieces of ally scrap, use them both sides of the diecast box wall this will reduce the risk of fracture. It is imperative that the bolt and cutter are well lubricated. |
9th Feb 2019, 10:39 pm | #12 | |
Dekatron
Join Date: Dec 2004
Location: East Yorkshire, UK.
Posts: 3,988
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Re: Using hole punches on die cast boxes
Quote:
Another vote for cone drill, take it easy as you go. Mine quite surprised me, I had 18 holes in 6mm steel to drill 25mm diameter. I managed real easy with no signs of blunting. John. |
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9th Feb 2019, 10:59 pm | #13 |
Nonode
Join Date: May 2007
Location: Preston, Lancashire, UK.
Posts: 2,511
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Re: Using hole punches on die cast boxes
I've used hole saws on diecast boxes with great success.
Andy |
10th Feb 2019, 12:39 am | #14 |
Nonode
Join Date: Jun 2013
Location: Surbiton, SW London, UK.
Posts: 2,801
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Re: Using hole punches on die cast boxes
Step drill is not the same as a conecut bit - I have used the latter in a hand drill but for
plastic and ally but a slow drill speed is needed. https://www.kelvinpowertools.com/con...-c-443-p-10890 |
10th Feb 2019, 1:01 am | #15 |
Hexode
Join Date: Sep 2004
Location: Newcastle upon Tyne, Tyne & Wear, UK.
Posts: 475
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Re: Using hole punches on die cast boxes
I've got both step and cone drills but will use the step. I have a bench drill press, so better control than a hand-held.
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10th Feb 2019, 7:41 am | #16 |
No Longer a Member
Join Date: Oct 2016
Location: Maroochydore, Queensland, Australia.
Posts: 2,679
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Re: Using hole punches on die cast boxes
If you are going to use a cone or step drill, make sure it is in a drill press with the work clamped. Or if you start of from a small diameter initially and enlarge it over multiple steps, the hole center will wander.
However, if you file out the hole to within a mm or two of the size you want, on the correct center, then with the stepped drill, it will be pretty close to accurate centering after only one step to enlarge it, even if the work is not clamped. The cumulative centering errors add up if it is not clamped and you start from a small hole. |
10th Feb 2019, 10:28 am | #17 | |
Dekatron
Join Date: Dec 2004
Location: East Yorkshire, UK.
Posts: 3,988
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Re: Using hole punches on die cast boxes
Quote:
OOPS, My mistake, I have both and I know the difference. I agree with every word above. Step drill cutting progressive steps should not wander. John. |
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10th Feb 2019, 11:13 am | #18 |
Rest in Peace
Join Date: Feb 2004
Location: Hexham, Northumberland, UK.
Posts: 2,234
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Re: Using hole punches on die cast boxes
Step drills tend to leave a ridge from the next layer up so drilling the last bit out from the other side can provide a cleaner hole. With cone cuts the hole has a bevel on it too. Also, be very aware of snagging and snatching which can be painful if cutting with a handheld drill. I tend to use the slip clutch on the drill if there is a risk of this happening. If you can secure the work in a vice or clamp better still. All from bitter experience...I should have known better.
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10th Feb 2019, 11:18 am | #19 |
Octode
Join Date: Dec 2017
Location: Morden, Surrey, UK.
Posts: 1,561
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Re: Using hole punches on die cast boxes
I`ve never had a problem using Q-max type cutters on die cast boxes but step drills also work well - I don't much like conecuts as they seem to require inordinate pressure to work.
If you don`t already have a Q-max step a stepdrill may be cheaper - I picked up a couple in Lidl a little while ago for next to nothing. |
10th Feb 2019, 12:04 pm | #20 |
Dekatron
Join Date: Apr 2012
Location: Worksop, Nottinghamshire, UK.
Posts: 5,554
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Re: Using hole punches on die cast boxes
It is not unknown for step and cone drills to be seen on sale in Aldi too at an equally competitive price as Lidl do them for.
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