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Mechanics and Construction => Mechanics and Construction => Topic started by: ROBOT420 on April 23, 2013, 10:40:57 AM

Title: Purple flake bot! I need suggestions on mounting components please.
Post by: ROBOT420 on April 23, 2013, 10:40:57 AM
http://s1362.photobucket.com/user/420photo420/media/20130327_190829_zps55588f8b.mp4.html?sort=3&o=1 (http://s1362.photobucket.com/user/420photo420/media/20130327_190829_zps55588f8b.mp4.html?sort=3&o=1)

http://s1362.photobucket.com/user/420photo420/media/20130405_140416_zps02c15b01.mp4.html?sort=3&o=3 (http://s1362.photobucket.com/user/420photo420/media/20130405_140416_zps02c15b01.mp4.html?sort=3&o=3)

So I am have started final assembly and the self tapping screws that I was gona use are not cutting it on this metal as it used to be a wheelchair and is quite strong. I have lots of power supplies, relays, LEDs, ect to mout on there, and hot glue seems pretty cheap-ish. Any advice? Thanks!
Title: Re: Purple flake bot! I need suggestions on mounting components please.
Post by: jwatte on April 23, 2013, 11:56:52 AM
Self tapping screws only work on plastic and aluminum, and perhaps very thin sheet metal in mild steel.

To do mounting using bolts in thick steel or alloy/stainless steel, I would drill holes and tap them, or I would drill through holes (clearance holes) and use a nut and lock washer on the other end.

Btw: Very sparkly purple color you got there. Good job!
Title: Re: Purple flake bot! I need suggestions on mounting components please.
Post by: jkerns on April 23, 2013, 11:58:04 AM
Drill and tap the holes and use machine screws.
Title: Re: Purple flake bot! I need suggestions on mounting components please.
Post by: ROBOT420 on April 23, 2013, 12:08:08 PM
Thanks for the reply! I have never had much luck with metal bits (at all). What is a good brand of drill bit that I can get from Lowes or Advanced auto? Also do I run it in Forward for penetration, or in reverse to remove metal shavings from the hole? 
Title: Re: Purple flake bot! I need suggestions on mounting components please.
Post by: jkerns on April 23, 2013, 12:19:22 PM
Any would work. I suspect that Advanced Auto will have the tap you need.  If you can't find number drills you can usually get away with the closest fractional drill. For example, for a 10/24 thread you want a number 25 drill, but 5/32" will be close enough.
Title: Re: Purple flake bot! I need suggestions on mounting components please.
Post by: ROBOT420 on April 23, 2013, 06:53:18 PM
Got em, and some rubber washers too. More pics to follow, trying to get my duel car horns with chrome grills mounted and working right now.
Title: Re: Purple flake bot! I need suggestions on mounting components please.
Post by: jwatte on April 23, 2013, 08:01:01 PM
For metal drilling, I prefer M42 cobalt drills. They can cut into stainless even, and dull a lot slower than regular high speed steel bits (coated or not.)
In general, you can drill up to 2 times the diameter of the drill before you need to retract to clear chips/swarf, and then keep drilling. You'll want a drill press or mill for good results; hand drilling in steel has never worked out for me.
I get my drill bits from drillbitwarehouse.com which has nice quality cobalt drill bits at reasonable prices, and only a $35 minimum order: http://drillbitwarehouse.com/home?page=shop.browse&category_id=6 (http://drillbitwarehouse.com/home?page=shop.browse&category_id=6)
For tapping, you have to cut a small amount (half a turn to a turn) and then back up to clear chips; repeat. You also have to have a very steady hand (or drill press that you crank manually) and use some kind of cutting fluid. Safe-Tap, WD-40, and 5/20 motor oil all work alright; WD-40 is a little light, and the motor oil is a little heavy.
Title: Re: Purple flake bot! I need suggestions on mounting components please.
Post by: Duane Degn on April 24, 2013, 05:44:43 AM
I second the drill press advice. Harbor Freight sells some cheap presses. I'm sure a more expensive press would be better and a cheap one but a cheap one sure beats not having one at all.

When cutting threads into hard metal (steel), it's recommended to start the cut with a tapper tap. This has a less aggressive cutting surface to make it easier to begin the threads. This is then followed with a plug (or second) tap. A bottoming tap is then used to cut the final threads if your cutting threads into a blind hole.

Here's a set of three taps I found at Amazon.

http://www.amazon.com/Irwin-Tools-2738--Piece-Set/dp/B003K15ERU/ref=sr_1_7?ie=UTF8&qid=1366802730&sr=8-7&keywords=three+piece+tap+set (http://www.amazon.com/Irwin-Tools-2738--Piece-Set/dp/B003K15ERU/ref=sr_1_7?ie=UTF8&qid=1366802730&sr=8-7&keywords=three+piece+tap+set)
Title: Re: Purple flake bot! I need suggestions on mounting components please.
Post by: jwatte on April 24, 2013, 12:26:02 PM
If you hand tap, you absolutely need to start with the taper tap!

If you use a drill press for holding/alignment, and turn it by hand, you can get away with starting straight on the plug tap, as you will have a perfectly straight start. This is also useful for cutting threads on the outside of round stock, I've recently learned.
Title: Re: Purple flake bot! I need suggestions on mounting components please.
Post by: ROBOT420 on April 30, 2013, 11:41:23 AM
Phase one is done.

http://s1362.photobucket.com/user/420photo420/media/20130429_123146_zpsae19c0c5.mp4.html (http://s1362.photobucket.com/user/420photo420/media/20130429_123146_zpsae19c0c5.mp4.html)


The relays and such are now screwed to the steel with 2 washers and 1 rubber washer on each screw as spacers and shock absorbsion. Next, to wire 'em up and add more goodies.