Metal Making a Keyway Broach bushing.

[jcdammeyer]

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"

So if I buy 4' to 8' of material what would be the ideal material for these types of things?

 

[Tom O]

I don’t think it really matters the bushing just holds it in place and after the 1 pass you are using steel shims .

 

[jcdammeyer]

I don’t think it really matters the bushing just holds it in place and after the 1 pass you are using steel shims .

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.

 

[YotaBota]

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.

 

[DavidR8]

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.

I likely have some 1/2" for you.

 

[jcdammeyer]

I likely have some 1/2" for you.

Thanks. At the moment I'm not up to, nor is it likely safe, to being in the machine shop. Still testing positive for COVID so all I can do is watch TV and muck around on the computer.

 

[thestelster]

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!!

 

[jcdammeyer]

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!!

Thanks for the feedback. And yes, 3mm cutters are fragile so I don't need them snapping for some unknown reason.

 

[DavidR8]

Thanks. At the moment I'm not up to, nor is it likely safe, to being in the machine shop. Still testing positive for COVID so all I can do is watch TV and muck around on the computer.

I hear you. Let me know when/if you want it
Be well!

 

[whydontu]

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?

 

[jcdammeyer]

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?

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.

 

[DPittman]

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.

 

[jcdammeyer]

Yes, I'm not sure what I used to make the ones on the right in this photo. I do know it was PLA for the 3D printed one. The the 3 on the left are purchased ones..

 

[trevj]

I'm of the opinion that about any easy to cut metal will do, including aluminum or brass.

If an Aluminum bushing wears out in your lifetime, it means that buying a decent hardened one might be a good idea, 'cause you are actually using it a lot!

 

[jcdammeyer]

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.

 

[Upnorth]

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.

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.