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Cabinet and Chassis Restoration and Refinishing For help with cabinet or chassis restoration (non-electrical), please leave a message here. |
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16th Mar 2021, 1:03 pm | #21 | |
Dekatron
Join Date: Feb 2003
Location: Cottingham, East Yorkshire, UK.
Posts: 5,766
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Re: Enlarging an existing hole in a steel chassis.
Quote:
I do quite a lot of metalwork and woodwork/woodturning, and the step drill set that I use as branded as Bergen' which market quite a wide range of budget priced but quality tools. I've had my set for maybe five years or so and have drilled countless holes in steel, acrylic, aluminium sheet and diecast. For front panels for my home-brew projects which I've posted about on the forum, (most recently the 'mini-mod), I invariably use scrap double sided PCB FR4 laminate, which quickly blunts normal twist drills. Sometimes I use 2mm clear acrylic as a protection on front panels too, and a step drill overcomes the risk of 'snatching' and cracking the sheet, which can happen with normal twist drills. Before I started using step drills, if I wanted to drill say a 15mm diameter hole in any material, I'd do it in the time-honoured way of starting with a pilot hole, then progressively larger bits, and even with a table vice clamped on the pillar drill table, you get lots of jitter. I don't have any sheet steel to hand to demonstrate the drilling capability, so I've drilled a couple of holes in 2mm aluminium to show the results. The smaller hole is 22mm - the larger holes is the maximum diameter - 32mm. In some respects, though aluminium is softer, it's more problematic to drill than steel, especially with twist drills, as the swarf 'picks up' on the flute, whereas with steel is tends not to. You'll see how cleanly the drill leaves the holes, with no burrs. It took under five minutes to drill those two holes. I've attached some pictures of my step drills, which as I recall cost £10.00 five years ago. There's also a pic of a set of Bergen countersink bits which I bought last summer, still with the £10.00 sticker inside. (When conditions allow, I visit a large monthly 'autojumble' at Rufforth near York, which is where both Bergen sets came from). Cheap though they are, but in my experience, not 'cheap tat'. They're been fine and get lots of use. If they cease to do the job, no drams - I'll bin them and get another set. Bergen seem to be also marketed un the 'U.S. Pro' brand. Might be worth a bit extra for the nice metal box: https://www.ebay.co.uk/c/2073337928 At the other end of the scale, for those who are spending the firm's money - not there own, RS do one for £73.63 inc VAT: https://uk.rs-online.com/web/p/speci...B&gclsrc=aw.ds The only hole I've drilled in steel recently with a step drill was to fit a BNC socket to the steel rear chassis apron of a Heathkit RF1U signal generator. No need to centre punch, no pilot hole needed, all done in a iffy. The only downside of step drills is that you really need to use them in a pillar drill rather than a hand-held power drill, but knowing the antics of some DIYers, I don't doubt that some will have attempted it and may have succeeded. Hope that's helpful. Every success with the project. Pic 1: Bergen set of three step drills. Pic 2: 22mm & 32mm holes drill cleanly in 2mm aluminium sheet. Pic 3 & 4: Bergen C/S bits Pic 5: Hole drilled with step drill in Heathkit RF1U steel chassis for BNC socket.
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David. BVWS Member. G-QRP Club member 1339. |
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16th Mar 2021, 2:37 pm | #22 |
Heptode
Join Date: Nov 2017
Location: London, UK. Bury, Lancashire quite regularly :)
Posts: 611
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Re: Enlarging an existing hole in a steel chassis.
To David:
Thank you again kindly for your input. N.B. I have given my thoughts on the TUOFENG wire in the thread (per your comment) having had it delivered this morning much earlier than predicted by Amazon. Best Wishes N.B. Regrettably my resources do not include a Pillar Drill, just hand tools.
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Thermionic Emission, warms the cockles of your tubes. |
6th Jun 2021, 2:00 pm | #23 |
Heptode
Join Date: Nov 2017
Location: London, UK. Bury, Lancashire quite regularly :)
Posts: 611
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Re: Enlarging an existing hole in a steel chassis.
Just to put this one to bed, and thanking all contributors for their thoughts and experiences.... I did eventually purchase a cone drill set - but decided against using it in case it "grabbed" at the metal and distorted the hole.
In the end, I placed a card template over each hole to define the new diameter required and reamed the hole out gradually with an abrasive drum on my Dremel. Worked quite satisfactorily. Thread may be closed at Mod discretion.
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Thermionic Emission, warms the cockles of your tubes. |