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Metal Making a Keyway Broach bushing.

Metal
jcdammeyer

jcdammeyer

John
Premium Member
I need to make an 8mm bushing for broach A type 2mm and 3mm key slots. Looking in my junk bin of steel and even my other stock I find I don't have any 7/16" or 1/2" steel stock. Or else it's lost in the mess somewhere. Don't want to turn down 5/8" although I guess I could.
Anyway, if I was going to buy a length of 1/2" stock what type is a good idea to buy?
CRS? HRS? Leaded? Some other alloy?
I'm not going to bother knurling the top from the example STP file I found on line but the OD is about 10.5mm so I could start with 7/16" or 1/2"
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So if I buy 4' to 8' of material what would be the ideal material for these types of things?
 

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Tom O said:
I don’t think it really matters the bushing just holds it in place and after the 1 pass you are using steel shims .
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Just wondering if I should spring for leaded steel as it tends to be easier to machine but cheapest is probably HRS which as I recall is also easier to machine than CRS because of the stresses in CRS.
I usually just use whatever junk I have hanging around or have received as scrap from someone. In this case 4" of 1/2" you'd think I'd have in a box or can but not. And I could turn down some thicker scrap that I do have.
 
You may want to ask the cost of a full length piece, might be the most economical way to go unless their full length is 20'.

I was going to buy two 10' lengths of 1 1/4 HSS and that was going to cost around $115ish. A full length at 24' was,,,,,,, drumroll ,,,,,, $85.
I ended up buying the full length and they cut it into two 10' pieces and I have a 4' piece left over for something else.

If you only need a short piece a tire iron from the junk yard would be a buck or two and they are usually 1/2" dia.
 
jcdammeyer said:
Just wondering if I should spring for leaded steel as it tends to be easier to machine but cheapest is probably HRS which as I recall is also easier to machine than CRS because of the stresses in CRS.
I usually just use whatever junk I have hanging around or have received as scrap from someone. In this case 4" of 1/2" you'd think I'd have in a box or can but not. And I could turn down some thicker scrap that I do have.
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I likely have some 1/2" for you.
 
Don't use cold rolled. Machining the OD is fine, but as soon as you go to mill the slot it might warp on you.

I have this love/hate relationship with CR steel!!
 
thestelster said:
Don't use cold rolled. Machining the OD is fine, but as soon as you go to mill the slot it might warp on you.

I have this love/hate relationship with CR steel!!
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Thanks for the feedback. And yes, 3mm cutters are fragile so I don't need them snapping for some unknown reason.
 
I know I’m cheap, so my initial thought is why not just grab a 1/2” Grade 2 or better bolt? And cut the slot with a slitting saw and then open up to size?
 
whydontu said:
I know I’m cheap, so my initial thought is why not just grab a 1/2” Grade 2 or better bolt? And cut the slot with a slitting saw and then open up to size?
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That's not cheap that's frugal. ;)
Don't have a 1/2" grade 2 bolt hanging around at the moment either. Although if I dug deep enough I suppose I could.
Mostly the problem is I can't go into stores until I test negative. And overall there is no rush because until the 2mm A type broach arrives I can postpone cutting the 3mm keyways.
 
I'd buy whatever you want to have on hand for the next project, I don't think it matters much what you use for a broaching bushing. I've made them out of mystery metal before.
 
I honestly didn't think the 3D printed guide would work but amazingly it did. Not sure if the keyway is up to 'real' metalworkers standards. Probably not.
 
jcdammeyer said:
I honestly didn't think the 3D printed guide would work but amazingly it did. Not sure if the keyway is up to 'real' metalworkers standards. Probably not.
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I think people including me underestimate what 3D printed parts are capable of. A friend of mine needed a headstock gear for his large by our standards Mazak clone lathe. He had a friend of his 3D print one and it worked great.
 
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