Hello,
Our team is looking at buying Steel 1/2" HEX stock at least 1ft long. We want the stock to hold a decent tolerance so we are able to run it through our bearings without difficulty.
Online or on store
(We are located in Los Angeles, California
Thank you
See you at the competitions!
MsMaster or MSC Direct
McMaster-Carr sells a 4130 chromoly .500 hex.
But from a lot of experince it’s usually .005-.007in undersized. So it fits everything very easily but is a bit loose in the .500± .001 hex bearings that come from AM/Vex.
Basically beyond that your opition is to make it. Which isn’t horribly hard with a turntable on a mill or a some kinda of 4th axis CNC.
If all you need to do is small sections, like the ends of a shaft, https://www.amazon.com/5C-HXCB-5C-Collet-Block-Closer/dp/B0007Q1Q46/ make this super easy and cheap to do on a manual mill. Just buy the hex 5c collet block and the appropriate sized 5c collet for your stock. Mill a flat on the first ‘face’ of the hex, the rotate the collet block in your vice and take the same cut. Repeat a bunch and you end up with a passable hex. The bores of these sorts of blocks seem to run pretty true to the hex; it won’t be perfect, but probably close enough for most FRC applications. It’ll definitely be a lot easier/faster to setup then a dividing head.
In this same situation, where you are making hex out of round stock, it is cheaper still to use a piece of churro extrusion (or other hex stock with a threaded hole in the center) as a jig. I’ve done this by turning the end of the round shaft to the appropriate size for threading it to fit the existing hex jig. Then, with proper spacers underneath (I used machining parallels) you can use the flats of the jig to rotate the shaft precisely 60° between cuts, which leaves you with a nearly perfect hex segment if the depth of your final cut is correct.
Your local store will probably store undersized steel hex, so that can work. If the hex arrives oversized, draw filing will take it down to length fairly quickly (<20 minutes for a long length IME).
OnlineMetals is good, SpeedyMetals is good. The latter is usually cheaper.
3946 bought a piece of 1018 from onlinemetals.com earlier this month, and it is sized perfectly for shaft.
Why does it have to be steel?
McMaster has steel hex bar stock. Here are a couple of examples.
Why, indeed. :ahh:
Well, ‘stronger’ and ‘steel’ are two different things, as are ‘stiffer’ or ‘we want to weld to it’ or [insert another reason for a material change]. There are alternativesto steel that are significantly stronger than other aluminum alloys teams might have chosen to use.
No one has said what they started with or why they want to change it, but it’d be a real bummer to go through the effort of replacing a 7075 T6 ThunderHex shaft (75ksi YS) with a 1018 or 1215 steel hex shaft (54ksi or 60ksi YS) expecting that the steel shaft would be stronger.