I am about to begin assembling my Gainclone enclosure and am looking at screws... specifically, what sizes I should be using to assemble. The sinks have angle aluminum rails that connect everything. I was thinking 6-32 would suffice and be a fairly robust screw. Is it overkill? My chips use a 4-40 thread, and looking at that made me think 6-32 would be better.
I will be using machine screws and tapping the rails by hand. Ive read many tips on tapping so i feel confident in that, just not the sizes to use. Thanks in advance.
I will be using machine screws and tapping the rails by hand. Ive read many tips on tapping so i feel confident in that, just not the sizes to use. Thanks in advance.
I have used 6-32 and 8-32 as general-purpose hardware in a lot of "structural" applications. 4-40 is pretty much limited to securing parts or connectors to chassis, etc.
Where fasteners show, I think button-head cap screws look sexy but there are also many kinds of plated plain washers, and finishing washers, that dress up the fasteners' appearance.
Where fasteners show, I think button-head cap screws look sexy but there are also many kinds of plated plain washers, and finishing washers, that dress up the fasteners' appearance.
The #4 size is much more difficult to tap reliably. I use #10 hardware mostly, unless it won't fit the parts involved.
Yeah, the smaller pitches are harder to tap reliably by hand, and a royal pain if the screws snap off when over-torqued. I used M4 and M6 with black anodized button head cap screws on my last build, which was TubeLab Simple PP power amp. Particularly when your primary skill-set is woodworking, the coverage of the button head is tolerant of less than surgical precision of hand drilled & tapped holes.
For #4 in anything more challenging than about 1/8" aluminum I won't even attempt hand-tapping of a hole created by a hand-held drill.
Ideally the workpiece goes on the drill press table, the proper tap drill installs the hole, and then the same drill press spindle starts the first few threads with the tap - while disturbing the relationships between drill press spindle/table/workpiece as little as possible. I wrote up a much more detailed explanation of this process and posted here on DIYAudio some time back if you want to go looking for it.
The last tap I broke was an 8-32, about 1/2" into a steel standoff I was trying to enlarge from 6-32 to 8-32. The one before that was 1/4-20, during an entirely free-hand drill-and-tap task on a tubular steel trailer frame.
Dale
How would I go about this on a typical cheap/hobby quality drill press? Turn the spindle by hand I take it, but how?
Even a cheap hobby drill press will be an order of magnitude more accurate, and more repeatable, than what you can get with hand-held tools.
That's correct. Position the chuck key so the "handle" of the chuck key is roughly parallel to the table (and, therefore, perpendicular to the spindle axis). The chuck key handle is long enough to give you leverage for turning the tap.
If your drill press has belt-drive from the motor to the spindle, release the belt tension so the spindle turns freely while you get the tap started. If for no other reason, it increases the safety factor. More to the point, it reduces the torque needed to turn the spindle, and it helps you "feel" the cutting action of the tap. With a little practice you'll know when the tap has securely started the thread, and sense when it's time to back up the chuck by a quarter turn to break off the chip formed at the tap's cutting point.
Dale
That's correct. Position the chuck key so the "handle" of the chuck key is roughly parallel to the table (and, therefore, perpendicular to the spindle axis). The chuck key handle is long enough to give you leverage for turning the tap.
If your drill press has belt-drive from the motor to the spindle, release the belt tension so the spindle turns freely while you get the tap started. If for no other reason, it increases the safety factor. More to the point, it reduces the torque needed to turn the spindle, and it helps you "feel" the cutting action of the tap. With a little practice you'll know when the tap has securely started the thread, and sense when it's time to back up the chuck by a quarter turn to break off the chip formed at the tap's cutting point.
Dale
My biggest concern for me is whether or not I can get away buying all one size of screw for the majority of my build. I know I will need a few different ones here and there, but for affixing the 1/2" and 3/4" extrusions (1/8" thick), I was thinking of maybe some 3/8" length screws would work as the heatsinks arent that thick, so 1/4" may be all the space I have to work with.
Given the length and their structural requirement I am considering 8-32 screws, which would give me a bit more bite, and the tap is a little less fragile.
Dale, the way you describe it is how I was taught to tap by my high school teacher. Always pulling random bits of his teachings out when working in the shop today. Amazing which teachers you truly the most learn from... usually the ones that don't take themselves too seriously and make learning fun.
... if only someone had talked me into learning a trade instead of Uni 😛
Given the length and their structural requirement I am considering 8-32 screws, which would give me a bit more bite, and the tap is a little less fragile.
Dale, the way you describe it is how I was taught to tap by my high school teacher. Always pulling random bits of his teachings out when working in the shop today. Amazing which teachers you truly the most learn from... usually the ones that don't take themselves too seriously and make learning fun.
... if only someone had talked me into learning a trade instead of Uni 😛
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