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Best steel for arbors if not heat treating?

Trboatworks

Trboatworks

Diamond
Joined
Oct 23, 2010
Location
Maryland- USA
I want to make a arbor for a odd sized face mill I have & am looking for a material which can be used in machinable form and not hardened.

The design is typical- say 3/4" shaft for collet work in mill, 1-1/2" base for the face mill body, 5/8" bore and keys milled in sides of arbor to index.
I can harden the keys and lap to good fit post hardening with what I have here- (a torch).

Thanks all
 
aerodark said:
Chromoly (4130/4340) in a prehardened condition (28-32 Rc) seems like a great choice to me.
Click to expand...

Thanks- can I cut that on a manual lathe?
I am seeing that some 4340 I recently worked with was Rockwell c27 and was no problem.
This was cold drawn and the size I need for this part is offered my McMaster in hot rolled.

Edit- reading the below I see that the material I purchased from McMaster was prehard..
 
I have made similar tools with 4140 pre hardened. It machines well on a manual lathe. You can purchase at McMaster carr. They carry many diameters and lengths.

Lost
 
4140HT is the standard material for such. Readily available in a wide variety of diameters. 4340HT is a little harder, and harder to machine, and less available than 4140HT. Both are perfectly machinable with a manual lathe.

If concerned about machinability, 1144SP is a reasonable alternative, not as hard or tough as 4x40HT, but far more machinable. It'll hold up to non-production use.

Forget the torch. There's no way you could evenly heat something with the thermal mass of an arbor to a known temp well enough to deterministically HT.

Regards.

Mike
 
LaSalle Stressproof, Fatigue Proof or E.T.D. 150 in ascending order of tensile strength...Stressproof is 100,000 PSI minimum yield point, much crisper to machine and more dimensionally stable than any form of 4140, assuming you're gonna mill a keyway in one side.
 
I second the motion on ETD-150. It's really lovely stuff for this sort of application. It machines nicely, and doesn't move around due to residual stresses. It's not cheap, but the cost is worth it for me, for arbors and similar non-production tooling.
 
I made an arbor for acorn dies from some 8620 simply because it was in my scrap box in the right size. Has been used a lot and shows no wear. I didn't harden it, but I have case-hardened pins from it and its a treat to work with.

It machines and welds nicely. Seems not to rust too quickly either.

I have absolutely no idea if this is an "acceptable" material by manufacturing standards.
 
i use prehard 4340 frequently .i get drops from ag. augers and shafts . it machines nice with cermet inserts, but can be drilled at-40-50sfm or so
with hss drills. its only `rc 35-40 , so it isn't too tough to work with , but makes great tooling .
 
I would second the motion on the 4140 pre heat treated ( usually around 30 rc). Stuff machines better than 1018 cr. better surface finish and better chip formation.
Use the hot roll. There is less stress in the material.
 
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