Screw size for Parallax robots [SOLVED]
David Betz
Posts: 14,511
What size screws does Parallax use for their ActivityBot? I'd like to order some additional screws and I want to make sure I order the same size. I'm thinking they are #4 40 screws but the pictures of those that I find on Amazon look larger than the ones in my ActivityBot. What size does Parallax use?
Comments
I've never understood the imperial screw numbering, the numbers don't seem to have any meaning of themselves.
That's the size I used to hold the servos on the bot I assembled. Currently he's using a BOE as his brains. Next up, is the PAB design. POF (Point Of Fact) I think the frame was intended for an activity bot design.
Yes understanding the regular standard for machine screws takes time. It took me two whole semesters in high school to understand the whole business behind them. However I find understanding the Metric standard for the screws used by the bots who surface wearing directly an Arduino for the same purpose difficult.
EDIT: Or of you want it really snug for the top holes, say, then a 3 mm drill bit. And for tapping, use a 2.5 mm drill bit.
-Phil
Then there are the tap drill sizes. No advantage there for metric. It's still an exercise in consulting a chart and finding the correct number or letter drill.
-Phil
For tapping metric, it's simply M3 - 0.5 pitch = 2.5 mm drill bit. Another example, M4 x 0.7 pitch is 4 - 0.7 = 3.3 mm drill bit. Easy as.
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And there the mascot offers, "What this world needs is more sleep!", he said sleepily.
UNC means Unified National Coarse and UNF means Unified National Fine.
Does this by chance have what you need?
https://www.parallax.com/product/570-35000
-Phil
That's basically what I posted, I didn't go into that kind of detail, because that same teacher then did not either.
And it is not even a either or, try to put a Gate Opener on a Gate. Gate is imperial, Opener uses metric, lock uses both.
Last week I opened my 220 piece craftsmen set the wrong way around and ended up with about 190 pieces on the floor.
Getting the metric ones back in was easy, they are simply ordered by ascending numbers. The imperial ones - well - might still be in wrong order where the ffff belongs 9/16 or 5/56 this is literally nuts.
Same goes for weights. There is no L no B or no S in the word pound. Ounce does not contain an Z, the list goes on and on. Wire diameters in gauges, alike bullets the diameter is how many balls one can make out of one pound of lead.
Really?
I had to buy gravel for my drive way, I expected a question for cubic inch or cubic foot, but no I was asked how many YARDS I would need. Yards.
Try to work on ANY American car and you will have a mix of imperial and metric, because outside of the US nobody uses imperial so everything not made in the US is metric.
Mike
By the way, the designation #4-40 refers to the hole diameter and the thread pitch, so this would be a #4 hole (that the fastener passes through, not a tap) and 40 threads per inch.
0.1 mm steps is available as singles at least. The common small drill sets go in steps of 0.5 mm at the low end and bigger steps at the larger sizes usually. I've never shopped for any "craftsman" set.
My only major peeve with the UNC/UNF system is with #10 machine screws. I can't count the number of times I've gone to the hardware store to get, say, some 10-32s, and find a 10-24 in the assortment once I get home that was wrongly binned. Drives me nuts!
-Phil
The selection includes zinc-plated steel and stainless steel screws, bolts, and nuts, steel bolts and nuts in various hardness grades, T-nuts, coupling nuts, socket cap screws, jam nuts, lock washers, and a host of other fastener styles. They also carry metric drill bits, taps and dies in another part of the store.
The "imperial" section, of course, is much larger, comprising two entire aisles, floor-to-barely-within-reach. It includes screws ranging down to #0 on up in plated steel, stainless steel, bronze, brass, and colored finishes, in multiple hardness grades. And to top it off, this cornucopia is only a few blocks from my house (handy for plumbing jobs that require, on average, three trips to the store
Of course, their stuff is not cheap. My brother, who was in the hardware biz for decades, said that fasteners have the highest markup of any products in the store. So for bulk purchases that I can wait to receive, I order online from McMaster-Carr or microfasteners.com. But for onsie-twosies, the local store can't be beat. I'm pretty sure they even put Lowes and Home Depot to shame.
-Phil
No surprise there. The imperial UNC and UNF nuts and bolts available are generally of very good quality and consistency.
Are those mixed-thread #10 screws from China?
Last time I ordered screws from McMaster-Carr a number of years ago they were made in Taiwan.
-Phil
For numbered screw series, the major diameter = 0.060 + num * 0.013. So a #4 screw diameter is 0.112. (0.060 + 4*0.013)
-Russ