EN24T and a question on helical gear cutting

[Tinbasherdan]

first up, anyone with experience of en24T? specifically machining prior to heat treating. im going to be remaking an input shaft/gear for my landy as i dont rate the off the shelf option, its a toss up between 19 and 24 at the moment but in any case....

how much does 24 tend to move when being heat treated? is it wise to leave a few thou to be ground down later or does it not really matter? it has two bearing lands which need to be reasonably spot on to prevent the bearings spinning on the shaft.

and secondly, is anyone on here capable of doing helical gear cutting? i have no idea how to measure pitch of a helical gear so best i could do is send the original gear

cheers
dan

 

[ronan]

The "T" means its already heat treated. I think it can be nitrided for a harder surface though.

 

[Tinbasherdan]

The "T" means its already heat treated. I think it can be nitrided for a harder surface though.

i presumed the gear and splines would require case hardening or nitriding, just classed it as heat treating!

 

[TechnicAl]

En24T is heat treated.......quenched and tempered....its a through hardening steel so the core isnt any different or softer....so theres no need to heat treat after machining.......its not easy to machine though and needs to be kept cool or you can crack it

 

[ronan]

I think EN36 is prefered for gears, you machine the gear and have it case hardened, nitrided i presume.

See the three pictures i posted here

https://www.mig-welding.co.uk/forum...ere-do-you-buy-your-steel.93081/#post-1374119

 

[ronan]

En24T is heat treated.......quenched and tempered....its a through hardening steel so the core isnt any different or softer....so theres no need to heat treat after machining.......its not easy to machine though and needs to be kept cool or you can crack it

Yes i have milled it, it wasn't fun, but it can be done. Carbide tooling would speed things up.

 

[ronan]

http://www.norbro.co.uk/gear-cutting.html

 

[Tinbasherdan]

I think EN36 is prefered for gears, you machine the gear and have it case hardened, nitrided i presume.

See the three pictures i posted here

https://www.mig-welding.co.uk/forum...ere-do-you-buy-your-steel.93081/#post-1374119

machinerys handbook lists 4340 (en24t) as suitable for gears, nitrided for extra wear resistance, thats why i chose it.

cheers for the link ronan, i had seen them but was hoping a forumite might have the capability and fancy a challenge

 

[ronan]

machinerys handbook lists 4340 (en24t) as suitable for gears, nitrided for extra wear resistance, thats why i chose it.

cheers for the link ronan, i had seen them but was hoping a forumite might have the capability and fancy a challenge

Maybe Hood or Scott ? They do a lot of machining work. You are lucky as there seem to be still a lot of machine shops in your general area. There is no one near me with any capabilities to do serious machining work anymore.

 

[Hood]

I made my lathe turret from EN24T and I didn't think it was particularly difficult to machine. Yes it seemed tougher than some but it machined beautifully.
Couple of videos.
First is the clamping wedges, machine an angled face and then cut the vee grooves.

Machining the face.

Doing the wedge holes etc on the periphery.

 

[awemawson]

Hood that is an amazing tool changer, what make / model is the Cnc mill?

 

[Hood]

Chiron FZ12S from late 1980's

 

[graffian]

I just so happen to have a gear design book in front of me, I skipped most of it and looked at the pictures;-)

From my experience of though hardened gears I would go with case hardened, the old boxes I have had
with though hardened gears all have a lot of tooth wear. I was going to use EN36 or EN39 for some timing
gears.

There is someone on a landy forum[Zoltan] who makes gears, think it's new cluster for minis he makes. But he would
probably know a bit about gears.

 

[Johnnybravo]

En24t machines lovely. Nice and hard so you get a decent finish. Give me a piece of that anyday as opposed to snotty en3b. En19 also machines nicely,as does en40b. Carbide tooling and a sturdy machine and it’s a pleasure to machine.