Using faceplates

[gbus]

Hi all, I worked in a machine shop for about 6 months as a trainee. Long story short I couldn't commute 100 miles each way to justify the job.
Whilst I was in this work I never used a faceplate. I have some faceplates that I got with my lathe when I bought it years ago. I have no idea how to use them, or why I'd use them. I'm assuming it's for items that aren't round?
Anyone able to give me a bit more info on them?
Here's the plates I have.

 

[darkzero]

A 6" vise is overkill for a RF45 style mill. A 4" is more appropiate for that size mill & IMO 5" max. I have a 5" GMT vise on my PM45 & it's slightly too big. Not enough Y axis travel to make use of the 5" full capacity. Better to save your money rather than getting something too big & most importantly the weight. I take my vise of the table quite often, a 6" is still light enough for me to be carried by hand but I'm glad I have a 5". I also have a 4" vise as well. I prefer the 5" though.

But those GMT 6" Premium vises are pretty nice. I'd love to have one but don't need one on my current mill. But if you plan on upgrading to a full size knee mill in the future than the 6" will be perfect.


Here's what the 5" looks like on my mill.



I couldn't even complete this cut without my bellows & DRO scale getting in the way. Not enough Y travel & the 5" vise is not even maxed out.



Here's what a 6" vise looks like on another PM45 (gt40's)
View attachment 253544

 

[darkzero]

Oh, BTW, with the drive plates you posted, you would use straight lathe dogs as opposed to bent lathe dogs like the ones I pictured.

The slugs on your drive plates on the opposite end of the post are likely to be counterweights.

Here's a photo of a straight lathe dog from the net. This would resemble more closely your setup with your drive plates.

 

[Wreck™Wreck]

A 6" vise is overkill for a RF45 style mill. A 4" is more appropiate for that size mill & IMO 5" max. I have a 5" GMT vise on my PM45 & it's slightly too big. Not enough Y axis travel to make use of the 5" full capacity. Better to save your money rather than getting something too big & most importantly the weight. I take my vise of the table quite often, a 6" is still light enough for me to be carried by hand but I'm glad I have a 5". I also have a 4" vise as well. I prefer the 5" though.

But those GMT 6" Premium vises are pretty nice. I'd love to have one but don't need one on my current mill. But if you plan on upgrading to a full size knee mill in the future than the 6" will be perfect.


Here's what the 5" looks like on my mill.



I couldn't even complete this cut without my bellows & DRO scale getting in the way. Not enough Y travel & the 5" vise is not even maxed out.



Here's what a 6" vise looks like on another PM45 (gt40's)
View attachment 253544

 

[gbus]

Thanks for the reply. Every day is a school day!
Is the only benefit using drive plates with a lathe dog over a using a chuck, that you don't need to re-centre the job if you take it out for inspection?
I've turned some long work-pieces before, but it was generally using a chuck (be it 3 or 4 jaw). I was under pain of death, not to take the job out of the lathe until I knew it was done. Made that mistake once or twice.

 

[woodchucker]

No not just removing, you can use mild steel dead centers, and turn them true b4 inserting the part. You are now guaranteed dead true turning.

I also use taper mandrels which I don't think were mentioned. Sometimes you need to bore a hole, then turn the out side dead concentric to the hole. One way to do this is to use a taper mandrel, press the part onto the mandrel (it locks on due to the taper) and turn the outside to dead on concentric with the hole. The mandrels are precision ground.