VMC round part workholding

Howdy, first post here, and I'm relatively inexperienced in running a VMC, so bear with me.

I'm needing to run a batch of parts here in the near future out of ductile iron bar stock. The material is going to be about 3.250 thick bandsaw cut and cast finish 15.750 diameter. I'll need to machine all sides. I'm looking for the setup to be fast and repeatable. I have in mind to use two lathe chucks bolted down to the table, and have two parts going at once, machining opposite sides so every time the doors close and the program is started it essentially runs a complete part, just not on the same piece. every time the doors open I pull a finished piece out, and put a piece of raw material in, while flipping the half finished part to the other chuck.

My biggest concern with this is getting iron chips in the chuck scrolls.

Anyone have any imput<

If you are forced to use scroll chucks about the only kind of good option you have is to use soft jaws and machine them such that the body of the jaw is fully within the chuck body, and the scroll is never exposed. It won't keep it all out. The chuck will get full of coolant and wash the grease out in any case.

If it's a large batch of parts and you have some headroom for tooling, self contained pneumatic chucks designed for the purpose are a much better bet.

I use scroll chucks on the mill all the time, but only if it's one or two parts. More than that I will set up one of the pneumatic chucks instead.

Shop I worked at a long time ago had a couple of Atlas chucks made for mounting to a mill table. They worked great and I don’t recall any big issues with chips.

We cut sheet steel covers to fit closely around the jaws and cover up the center hole and slots. Quick and cheap is to jam blue wiper towels in the slots.

Car lane makes special clamps for that purpose I think called edge clamps check them out
Don


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Considered using Versa-Grips?

I keep using 3-jaw chucks on the table and it works out okay, but the Versa-Grips are way easier to clean up afterwards and have less part interference.

Are you concerned because iron dust has a reputation for being abrasive?

It's nothing like the dust from an abrasive cutoff wheel, or the grit from diamond dressing a grinding wheel. Plus, it's ductile iron, which is less crumbly/dusty than gray iron.

I would be very surprised if it had any impact at all on the long term accuracy or reliability of your scroll chucks.

I'll look into pneumatic chucks and see where that leads me.

I forgot to mention that part of the reason I'd like to use self centering chucks is that I have a huge list of round stock work for this machine, a couple chucks permanently on the table and modeled as such seem like they could be a huge time saver vs a clamping system. Another reason is that for this job, which is not at all a one time thing, I need to finish the part slightly bigger than the raw material suppliers guaranteed clean up diameter, so a self centering way of workholding is going to help my chance of getting my OD cleaned up vs most other types of clamping that I'm aware of.
I really could make use of a good turning center with live tooling, but I bought this VMC well tooled with a 4th axis for such a deal that I can't justify not using it for this type of work where I can, while letting it contribute to a turning center fund.

Yes, I'm concerned about the abrasive chips chips wearing out the scroll and just jamming up in general.

I have thought about making sheet metal covers to keep the majority of the chips out.

Can you get pie jaws for that chuck?

GYBAT said:

Howdy, first post here, and I'm relatively inexperienced in running a VMC, so bear with me.

I'm needing to run a batch of parts here in the near future out of ductile iron bar stock. The material is going to be about 3.250 thick bandsaw cut and cast finish 15.750 diameter. I'll need to machine all sides. I'm looking for the setup to be fast and repeatable. I have in mind to use two lathe chucks bolted down to the table, and have two parts going at once, machining opposite sides so every time the doors close and the program is started it essentially runs a complete part, just not on the same piece. every time the doors open I pull a finished piece out, and put a piece of raw material in, while flipping the half finished part to the other chuck.

My biggest concern with this is getting iron chips in the chuck scrolls.

Anyone have any imput<

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Keep them clean, or they will rust up. Do not let chips sit overnight.