Lathe advice needed!

[finyuk2005]

Hi there
Finally gotten round to wiring up my new to me, but definitely not new, lathe,
Its a Henry Broadbent, no idea of model, or age or anything else really!

Seems to work quite well, no horrible gearbox noises but i dont know anything about lathes,
Haven't quite fully worked out the power feed part yet, dont think it has it on the cross slide.

First job with it was a simple chamfer, ready for welding the tops back on a pair of broken trailer rams,
Pretty awful surface finish, possibly wrong tool angle, or wrong tool altogether! Also, it was pretty hard stuff

My next job i started today is a tapered flange for a new turbo for my van, I am using a chunk of what i think is possibly duplex stainless, got from a scrap yard years ago,
It seemed hard as hell when i was cutting a chunk off with a 9 inch grinder.

It started out surprisingly well, even leaving a reasonably nice surface finish, but then it just seemed to burn up the hss tool bit, I dont think i got it that drastically hot, but i read that duplex work hardens pretty quickly so thats possibly what has happened.

Any advice on how to save it?
Is it possible with hss as thats all i have just now,
Or do anyone have any suggestions for a carbide insert tool and holder that might work better? I did have a look at inserts but ended up baffled by the million different ones available!!

cheers!

 

[finyuk2005]

trying to upload a few pictures, but they are still too big even after compressing them,
any decent, free dropbox style things anymore?

 

[Barking Mat]

Stainless is hard as hell.

Did you use cutting lube / oil.

Could be the cutting speed ?

 

[finyuk2005]

Stainless is hard as hell.

Did you use cutting lube / oil.

Could be the cutting speed ?

Yeah i thought it was going to be, but for the first while it actually seemed to go quite easy,
used plenty of oil,
it might have been the speed, possibly a bit high, any idea what kind of rpm should be on a 3" diameter stainless part?
I will need to check what speed i was at when i go back out after tea

 

[Barking Mat]

Yeah i thought it was going to be, but for the first while it actually seemed to go quite easy,
used plenty of oil,
it might have been the speed, possibly a bit high, any idea what kind of rpm should be on a 3" diameter stainless part?
I will need to check what speed i was at when i go back out after tea

No, I can't help with speeds, it's a bit hit and miss for me.

I use a carbide insert tool, never had too much success with stainless and HSS.

But I'm no expert.

 

[finyuk2005]

No, I can't help with speeds, it's a bit hit and miss for me.

I use a carbide insert tool, never had too much success with stainless and HSS.

But I'm no expert.

Any hints on what inserts to go for? any kinda, get me started type sets i could look into?

 

[Barking Mat]

Any hints on what inserts to go for? any kinda, get me started type sets i could look into?

What size is the tool holder on your lathe ?

There's someone on here who is king at finding bargain lathe tools.

Possibly @Kram ???

My memory is vague.

 

[Domdom]

it might have been the speed, possibly a bit high, any idea what kind of rpm should be on a 3" diameter stainless part?

With HSS tools you want about 30 surface metres per minute. With TCT tips you can go up to 90 ish
For a 3 inch diameter part that equates to either 120 rpm or 360 rpm. Nearest number to those is close enough.

 

[finyuk2005]

With HSS tools you want about 30 surface metres per minute. With TCT tips you can go up to 90 ish
For a 3 inch diameter part that equates to either 120 rpm or 360 rpm. Nearest number to those is close enough.

ah nice one! thanks
I was on 220rpm so probably a bit on the fast side!

 

[finyuk2005]

What size is the tool holder on your lathe ?

There's someone on here who is king at finding bargain lathe tools.

Possibly @Kram ???

My memory is vague.

the tool holder has a gap of about 35mm

 

[finyuk2005]

well lads, by some fluke i managed to grind a tool okayish and slowed the rpm right down to 50rpm,
and i am managing to make chips.... well, more curls actually, need to figure out how to grind a chip breaker in there,
Making as good a surface finish as i can expect from using the compound with a vice grip as a handle.. need to make something a bit better ha ha!

 

[Kram]

Cobalt HSS is very common for lathe tools and adequate for stainless. You may need to hone the edge more often than steels. Important thing is to take reasonable thickness chips. If the chips are too thin it will rub and burn the edge.

What size lathe is it? If its one that can be shifted by a single person will generally want low depth of cut/light finishing type carbide intended for steel/general use

Ccmt0602 and dcmt0702 are the two styles I use most, to choose from.

 

[finyuk2005]

Cobalt HSS is very common for lathe tools and adequate for stainless. You may need to hone the edge more often than steels. Important thing is to take reasonable thickness chips. If the chips are too thin it will rub and burn the edge.

What size lathe is it? If its one that can be shifted by a single person will generally want low depth of cut/light finishing type carbide intended for steel/general use

Ccmt0602 and dcmt0702 are the two styles I use most, to choose from.

I am getting a much better finish now that im getting a bit more confident and digging a bit deeper!!
Almost took too much off as i was having fun!

Its a nice big lathe, from what little i can find online i think it could be 2.5 to 3 tonne,
It was certainly a challenge getting it in the hanger, next door neighbors manitou managed to lift it just off the trailer to let me pull the trailer out.... then it locked him out and wouldnt even let him lower it down... was just slightly hairy! He managed to fool it by working the ignition on and off and holding the over ride button untill it let him lower it down!!

 

[Kram]

Oh nice, we need some pictures. If the forum doesnt like them, try https://postimages.org/

As for inserts, You may want the bigger, more durable negative rake types like this.

https://www.amazon.co.uk/Korloy-1-06-013236-Double-Turning-Holder/dp/B077XVZ2HW/