Cutting holes in sheet metal - quest for metal 'spur drill'

[isoparix]

I once used (at Decca Radar) a set of cutters that were a bit like spur drills, but these had powerful spring loaded centre spikes and would whisk a clean and accurate 12 mm hole through the lid of a die-cast box using just a centre-punch dot as a guide.
I have been searching in vain for such a thing on the internet to no avail. Would these have been just a specially made set of tools, or are there current commercial variants? And what would be their correct name? Thanks

 

[Hitachimad]

We use them now and then, similar to a broaching cutter....

Two mfrs i can think of are armeg and alfra....

 

[isoparix]

Thanks for that. Looking at http://armeg.co.uk/files/literature/lit-ldx-flyer.pdf there's obviously a whole new (to me) family of useful-looking tools there! BUT... the problem is that they start at 18 mm, and I want to cut 10 mm.

The devices I have in mind are like the ones in the pdf, but the spring-loaded, cutter-locating piece in mine is a spring-loaded steel cone with a sharp point, not a pilot drill. I'm grateful for your input, but any more thoughts? Thank you.[/i]

 

[kevplumb]

would a step drill not work

http://www.northerntool.com/shop/to...step%20drill&Ntk=All&Ntx=mode+matchallpartial

 

[isoparix]

Well, that's another interesting option - thank you. (And I can buy them from Screwfix...). But the broach cutter/holders still look like the closest to my original memory, and these http://www.srita.com/download/catalog/nkmctool/Tk103d_12_JETBROACH CUTTERS & HI-BROACH CUTTERS1.pdf seem like the closest realisation, even though they don't go below 12 mm. Perhaps there's a marketing opportunity here!
Thanks to all for your help and guidance.

 

[Hitachimad]

Rotabroach make a set with 5/6 sizes, think about 8 -20mm in a little case.

do a google for 'rotabroach mini cutters' Make sure you are sat down when you look at the price mind!

 

[isoparix]

Hmmm.. I see what you mean! I'm sure that they're a delight to use and perfect in their field, but for the number of holes that I have to cut I'm finding that a £10 2-12 x1 mm step drill is doing a really nice job... Case closed, I guess, but thanks again to all for a lot of interesting information.

 

[onetenor]

glad the step-cutter works for you but you might wish ----just for interests sake---at watch and clock makers tool suppliers as I think that you would find that they do a similar tool Good luck. j.m.(onetenor )

 

[isoparix]

Thanks for that - I will take a look. Any recommended sites?

 

[Deluks]

You mean, 3 years on you haven't yet drilled those holes?

 

[RF Lighting]

Is this the sort of thing you're after?

I know them as spot weld drill bits. They're about a fiver each.

 

[Awstriker]

something like this?


http://www.machinemart.co.uk/shop/product/details/cht467-38in-spot-weld-drill