Enclosure making essentials (metalworking, holepunching, etc.)

[defaced]

trying to picture this mentally as sort of a scraping action by the drill bit flute that the backing wood helps to maintain by compressing up the metal against the flute until the drill bit breaks through. Sort of more consistent force being used that way whereas if it broke through there would be more metal for the flute to contact making it more difficult for the chiseling action to take place. So I suppose this would have to do with the operator's physical technique (feeding rate, choosing correct speed, pressure applied?) making a difference in the outcome? And maybe different techniques such as "pecking"? (IOW not so simple as some guy mindlessly lowering a drill onto a work piece.)

The wood does that, but it also keep the bit centered in the work piece and doesn't let it chatter around. Yes, the operator technique is important, and pecking is what you do to break chips while you drill. If instead of getting small chips you start to get long stands of metal, you can really hurt yourself if your finger gets caught up in them. Lathes and mills use bits are shaped to break chips as they cut, drill bits don't, so you have to do it manually by pecking.

The other thing I didn't mention, is you'll have alot less problem drilling with a stapped drill bit than a twist drill bit. A stepped drill bit is shaped differently on its cutting surface which prevents it from grabbing the metal. Also, sized step smaller than they size you're using helps support the bit.

[dai h.]

thanks for the additional tips mike,

The wood does that, but it also keep the bit centered in the work piece and doesn't let it chatter around. Yes, the operator technique is important, and pecking is what you do to break chips while you drill. If instead of getting small chips you start to get long stands of metal, you can really hurt yourself if your finger gets caught up in them. Lathes and mills use bits are shaped to break chips as they cut, drill bits don't, so you have to do it manually by pecking.

sometimes you get packaging with products that use lots of plastic. Would it be "stupid-cheap" (or "smart-cheap") to try to use that (if big enough--and cut into appropriate shape) as the "backing wood", say when cutting thin aluminum?

The other thing I didn't mention, is you'll have alot less problem drilling with a stapped drill bit than a twist drill bit. A stepped drill bit is shaped differently on its cutting surface which prevents it from grabbing the metal. Also, sized step smaller than they size you're using helps support the bit.

So the different shape of the cutting surface (maybe the rigidity too?) sounds like it's safer for making big holes. I don't quite remember everything else I read on stepped drill bits, but I think it was more advantageous in being able to make rounder holes IIRC and (easier and more efficient since you don't need to switch bits) compared to starting with a thin (regular) drill bit and working your way up fatter to increase the hole size.

this last bit here, could you explain this? Trying to figure it out but I feel like I need a Ctrl+Alt+Delete here.

Also, sized step smaller than they size you're using helps support the bit.

[tubeswell]

I have only worked with sheetmetal aluminium for my chasses for far (I use about 16 or 18 gauge so I can get it as thick as possible and still use bending by hand and basic benchtop tools to get the results). I bend the chasses on my bench top with timber formers and other smooth bits of wood clamped to the bench. I figure out the folds and bends so that I only bend the main part of the chassis in one direction and then I rivet on end caps, and I do all the hammering etc on the corners that don't get to see the light of day, so that I leave the dashboard flawless. For the last chassis, I found some freshly roller-milled Aluminium that was sold with a really-durable plastic contact film adhered on one side, which can be worked with before removal. This stuff is amazingly able to withstand scratches bumps and other minor catastrophies, so I'm a convert. You can do all the drilling punching bending hammering engraving, riveting etc and then when you peel off the film - presto! not a scratch anywhere you don't want one!

[dai h.]

thanks. Sounds like some good stuff. I will definitely keep that in mind.

[jrfrond]

I use UniBit's for about 95% of my chassis drilling. For holes bigger than 1", I go to the Greenlee punches. I also use a rectangular Greenlee that I special-ordered for the IEC input, which I prefer over the permanent cable with strain relief. I RARELY use a drill press, usually just picking up my Makita and going for it, but everything is center-punched for accuracy. Everything gets transferred over from graph paper. I do not like twist drills. Unibit's cut inheretly rounder holes and are self-deburring.

For new custom stuff, I usually use Hammond steel chassis, but when I had low-level production going, I had the chassis made in California by Hamilton Metalcraft, punched, powdercoated and silk-screened...TURNKEY! It's nice when it all comes ready to assemble!

[dai h.]

thanks! so another vote for the stepped drill bit.

I RARELY use a drill press, usually just picking up my Makita and going for it, but everything is center-punched for accuracy.

I thought about this before, and it seemed to me that if the material was very thin hand-drilling might be okay, but as the material became thicker you'd get more accuracy if the drill and work piece were put in a constant perpendicular position.

[jrfrond]

thanks! so another vote for the stepped drill bit.



I thought about this before, and it seemed to me that if the material was very thin hand-drilling might be okay, but as the material became thicker you'd get more accuracy if the drill and work piece were put in a constant perpendicular position.

On chassis, it's not really an issue, plus I can get the feel of the material a bit better. I also have bubble levels on my Makita, just in case I start nodding off.

[Alex R]

One a they stepped 'Unibit' drill bits is indeed handy. If you get one look for the long thin cone rather than the short fat one, makes cleaner holes in slightly thicker material. They work just fine with a hand drill and don't make triangular holes because they have only two cutters diametrically opposed. Hand drill with a torque limiting clutch is best because these things do grab the metal and try to spin the piece just as the hole is about to go through. I like my small weak rechargeable hand drill, keeps me out of trouble!

A set of metal burrs for a hand drill is also useful - worth paying for good ones.

Handy punches include as jrf says a dedicated rectangular one that fits IEC sockets, available from RS in the UK (at a price) and a square one, 9m I think, for captive nuts (too big for the hammond enclosures though, unfortunately).

[Steve Conner]

That Ryobi drill press looks a lot better than mine.

Like you discovered, the Japanese cater for the ninja end of the machine tool market, with insanely accurate CNC machines bigger than your car. I'm surprised Toshiba even make a drill press as cheap as $800

And drilling a hole in the end of a rod has as much to do with how stiff the drill bit is, and how the end of the rod is prepared, as anything else. I believe you'd normally bore it in a lathe.

[dai h.]

On chassis, it's not really an issue, plus I can get the feel of the material a bit better. I also have bubble levels on my Makita, just in case I start nodding off.

yeah I saw that little trick of attaching levels(for anyone who hasn't seen this it's basically sticking some small round level or levels to give yourself a visual guide of what position your drill is in to help get a more accurate result when drilling). (Some hand drills already have them?) I did have a cheap (hand opd.) power drill but unfortunately the tail end of it isn't flat, so I couldn't stick one on there. I actually bought a cheap drill stand which looks exactly like this one (except for the brand mark on it) :

http://www.biltema.se/products/produ...iItemId=116194

but 1. I guess I measured my drill collar wrong so it wouldn't fit and 2. I was checking out the operation, movement of the thing and due to the amount of play in the mechanism it basically looked like I could conceivably hit a different spot with the drill bit each time I brought it down. I tried taking the whole thing apart and closely examining it too see if it'd be possible to reduce the play, but concluded there was no easy way to do it without other machine tools(and know how) although I did have an idea of how to make an improvement. So I became afraid of nickel and diming myself, maybe ending up buying cheap and not quite satisfactory stuff over and over, so that's part of why I ended up choosing the drill press.

Handy punches include as jrf says a dedicated rectangular one that fits IEC sockets, available from RS in the UK (at a price) and a square one, 9m I think, for captive nuts (too big for the hammond enclosures though, unfortunately).

thanks that's a really good idea (and I forgot about the power connector), but I think I'll have to tough it out with a hack saw and some files since I think those were kind of expensive.

That Ryobi drill press looks a lot better than mine.

yes but I don't have your brains so no guarantee I can outdo the ninja toaster chassis even with my DP.

Like you discovered, the Japanese cater for the ninja end of the machine tool market, with insanely accurate CNC machines bigger than your car. I'm surprised Toshiba even make a drill press as cheap as $800

apparently so but what is a little worrying is it seems precision tool makers get busted every once in a while exporting things they aren't supposed to. Maybe they've ended up in Libya or maybe Iran or whereever. Or maybe I suppose it isn't too bad as long as they can't make things like that.

And drilling a hole in the end of a rod has as much to do with how stiff the drill bit is, and how the end of the rod is prepared, as anything else. I believe you'd normally bore it in a lathe.

I don't really know much about that but IIRC that was on a vendor site re: the Toshiba("pro") DPs vs. the lesser Ryobi, etc. From what I read the thing to do (if you really know what you're doing when it comes to the used machine tool market) is to look for a used Toshiba or other MIJ DP. But the downside apparently (if you don't) is you could end up with some broken junk and not get your money back. Maybe I could've got lucky but didn't want to take the risk.

[jrfrond]

Another handy tool I failed to mention is the good ol' Nibbler Tool, if you need to cut out a chassis box for a core-mount transformer. It goes slow, but it does work well. Just another tool for the arsenal.

http://www.mytoolstore.com/klein/76011b.html

Another SUPER cool tool I have is called the ThreadSetter, for adding threaded inserts to chassis. I use this so much, for repairs as well as new builds, that it has become nearly indispensable.

http://www.huck.com/marsoncorp/threadedInserttools.htm

[defaced]

I believe you'd normally bore it in a lathe.

That would be the smart way. You could, using a vice with V-blocks, stand the piece up on end and drill it using a drill press, but you're relying on the drill press table to drill axis tolerances to ensure you have a bore that's centered in your piece.

You could also flip the two, put the drill int he vice and the piece in the drill, but I still think there's a good possibility you'll get less than desirable results.

I also use a rectangular Greenlee that I special-ordered for the IEC input,

How much did that cost you? I've been making mine with a dremel with an abrasive blade - not fun.

[dai h.]

"nibbler, threadsetter..." (scribble scribble)...

[jrfrond]

I see that Electronics Plus has the rectangular punch for $400.I purchased mine close to ten years ago for under $200. A heavy hit, but it gets the job done. I also use it a lot for retrofitting IEC sockets to existing chassis.

The nibbler will work for this too, if you don't want to drop four bills on a punch.

If you are using prefab boxes, then really, there is not a lot of tool-up to do. You need a good drill, a couple of UniBits (small and large), twist drill set, center punch, a nibbler tool and for me, the ThreadSetter, which is worth every penny, because not only can you use the threaded inserts for chassis retaining screws, but also for circuit board standoffs. I'd buy this before a fancy punch for an IEC socket. Also, a Dremel is nice for "those" situations.

After these hand tool, it's really just so basic layout paraphernalia. The ones I find I use most are: precision ruler, T-square, digital calipers, center-finding ruler, plus graph paper, good ol' pencils, extra-fine Sharpies and painter's blue tape.

[hasserl]

I use UniBit's for about 95% of my chassis drilling. For holes bigger than 1", I go to the Greenlee punches. I also use a rectangular Greenlee that I special-ordered for the IEC input, which I prefer over the permanent cable with strain relief. I RARELY use a drill press, usually just picking up my Makita and going for it, but everything is center-punched for accuracy. Everything gets transferred over from graph paper. I do not like twist drills. Unibit's cut inheretly rounder holes and are self-deburring.

For new custom stuff, I usually use Hammond steel chassis, but when I had low-level production going, I had the chassis made in California by Hamilton Metalcraft, punched, powdercoated and silk-screened...TURNKEY! It's nice when it all comes ready to assemble!

I do a lot of drilling new holes in existing chassis, I much prefer to use a drill press if at all possible. I'll only use a hand drill if I have to.

For drill bits I recommend split point bits to reduce walking. I use cobalt steel bits I have from my days as a heavy equipment mechanic, Snap On naturally.