Society of Robots - Robot Forum
Mechanics and Construction => Mechanics and Construction => Topic started by: MaltiK on February 22, 2009, 02:15:55 PM
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Ok, the wood I am using is plywood I believe,
I want a screw that is less than or equal to 1.5 cm in length,
and the thickness must be less than or equal to .3 cm
and the head can be a tad greater than .3 cm
and philips head
Also any recommendations for a very strong screw for plywood that is my specifications?
And any tips for drilling. (IE, should i just drill a hole and just place the screw? any good ratios?)
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www.fastenal.com (http://www.fastenal.com) is a good place to start for screws and connectors of many sorts. There's a fastenal storefront in almost every town with, or near, a factory of any sort.
Are you trying to mount something to the plywood, or screw two sheets of plywood together? Does it have to be philips head?
Try here to start
http://www.fastenal.com/web/products.ex?N=999600071+1199944792+1199909027&Nty=0 (http://www.fastenal.com/web/products.ex?N=999600071+1199944792+1199909027&Nty=0)
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Its an L Bracket connecting two pieces of plywood.
Also, I searched "Thread Size" for a chart of some sort, but no luck, how do I find the thickness of the screw, as well as diameter numbers
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http://www.engineersedge.com/screw_threads_chart.htm (http://www.engineersedge.com/screw_threads_chart.htm) has a really good chart of sizes. Sorry, I meant to put that in earlier. It's all in inches, so you'll have to either correct/convert or just go with anything under 0.125 inches (1/8 inch). Keep an eye on the 'major diameter', that's the diameter of the screw and the threads. The 'minor diameter' is the body of the screw, not counting the threads. You'll probably want to go with a #4 screw. For the brackets, you'll also want to have a head diameter closer to 5 or 6 mm.
#4 screws are tiny, diameter-wise, so if you can step up to #6, it might be better. #6's can be found at your local mega-hardware store.
Going deeper, there are also T-nuts that take a larger screw diameter (1/4-20 is a commonly available threading for them) that you would drill a larger diameter through-hole, put the t-nut on the back and when you screw the pieces together, the t-nut is pulled partially into the pre-drilled hole. This might be a much better way to support the two pieces of plywood. It's how I've put a lot of (non-robotic) wood together. http://www.fastenal.com/web/products.ex?now=1&N=999600087&Nty=0 (http://www.fastenal.com/web/products.ex?now=1&N=999600087&Nty=0)
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http://www.engineersedge.com/screw_threads_chart.htm (http://www.engineersedge.com/screw_threads_chart.htm) has a really good chart of sizes. Sorry, I meant to put that in earlier. It's all in inches, so you'll have to either correct/convert or just go with anything under 0.125 inches (1/8 inch). Keep an eye on the 'major diameter', that's the diameter of the screw and the threads. The 'minor diameter' is the body of the screw, not counting the threads. You'll probably want to go with a #4 screw. For the brackets, you'll also want to have a head diameter closer to 5 or 6 mm.
#4 screws are tiny, diameter-wise, so if you can step up to #6, it might be better. #6's can be found at your local mega-hardware store.
Going deeper, there are also T-nuts that take a larger screw diameter (1/4-20 is a commonly available threading for them) that you would drill a larger diameter through-hole, put the t-nut on the back and when you screw the pieces together, the t-nut is pulled partially into the pre-drilled hole. This might be a much better way to support the two pieces of plywood. It's how I've put a lot of (non-robotic) wood together. http://www.fastenal.com/web/products.ex?now=1&N=999600087&Nty=0 (http://www.fastenal.com/web/products.ex?now=1&N=999600087&Nty=0)
Thanks for the help, I dont think I will go with the T-Nut, I am trying a simpler approach, and am a very amateur carpenter, I think I am gonna go with #4, thanks mate!
http://www.fastenal.com/web/products/detail.ex?sku=30028
EDIT: I am still struggling with the "thread size" I don't think you mentioned it, like 22 and 15
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mcmaster.com has a really nice screw search