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Why ER40 chuck and not 3 of 4jaw?

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Suzuki4evr

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#1
Quick question. Why would you rather use an ER40 chuck on the lathe than a 3 or 4jaw scroll chuck. I know it has exact collets for certain sizes,but that is not something the other chucks can't do. I am asking because of ignorance about it and have always used 3 and 4jaws on the lathe except on the mill of course ER32 collet chucks are great. Please shine some light on this for me. Thanks

Michael
 

plunger

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#2
Would it not give repeatable accuracy compared to a 3 jaw?
 

higgite

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#3
Ask yourself why you say ER collet chucks are great for holding cutting tools on a mill. Same answers apply to holding work pieces on a lathe.

Tom
 

BaronJ

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#4
Hi Michael,

There is the answer to your question ! If your work piece can go into a collet then you will get repeatable accuracy, You will get the same accuracy from a four jaw, however the collet won't be able to handle the wide range of sizes that the four jaws can.

Or the shapes for that matter.
 

Suzuki4evr

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#5
Would it not give repeatable accuracy compared to a 3 jaw?
Good to see another SA guy on here,welcome plunger. I guess you have a point.
 

Ken from ontario

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#6
I use Er32 chuck when turning smaller diameter ,short length workpieces, also on occasions when protecting the finish (screws/threaded rods etc.) is important.
 

ttabbal

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#7
Collets are more repeatable. You can get similar results with a 4 jaw independent, but you have to dial it in every time you move the work.

They don't mar finished surfaces.

You can work in closer to the chuck, safely use gravers etc..

Can be used to hold tooling in the mill and/or milling attachment.

Down side is you need to watch the diameter and make sure you are within the clamping range. And most normal chucks can hold larger parts. Independent chucks can handle odd shapes as well.

Just another tool, better for some operations, worse for some. If you aren't wanting to use them for their advantages, no need to buy them for most hobby guys. There isn't much you can do with them you can't do on a normal chuck. They do make some things easier and safer though. I decided to get them for gravers, which I have yet to make, and milling tool holding, which they work great for. I also like the added speed flipping parts around and being able to clamp finished surfaces. For small parts, the ER40 chuck is usually installed on my lathe. But I don't hesitate to swap when the 3 or 4 jaw is a better fit.
 

T Bredehoft

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#8
One of my products is an aluminum tube 3/8 in diameter with a .035 wall. When threading these, a 3 jaw chuck dimples the tube, an ER collet, on the other hand, does not.
 

Bob Korves

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#9
Why not both chucks and collets? That all have uses for which they shine.
 

mikey

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#10
The answer to your question is found above but can be summarized like this: You can use an ER chuck to hold most parts but you especially need it on thin walled, finished or threaded parts to minimize damage to them. A 3 jaw chuck is otherwise faster and accurate enough for first operation turning. A 4 jaw independent chuck is potentially more accurate but takes longer to dial in.

An ER-40 (vs an ER-32) simply allows you to clamp bigger stuff, up to an inch OD.

As to accuracy, it really depends on how accurate your spindle is, how accurate the chuck/collet/nut assembly is when sitting on that spindle and finally, how accurate your part is. If you're going to use nominal/rough stock then an ER collet offers few advantages, speed not being one of them (5C is faster). If you are working with ground or an already turned part then an ER collet is a good choice ... in other words, second operation work.

I have 6 high-end jawed chucks, two ER chucks and one magnetic chuck for my lathe. The most used, by far, is a good 3 jaw chuck. The least used are the magnetic and ER chucks.
 

plunger

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#13
Thanks Michael. Yes ,being a S African hobby machinest can be a lonely business
Good to see another SA guy on here,welcome plunger. I guess you have a point.
 

Tozguy

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#14
Not anymore now that you are here.
 

Briney Eye

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#16
Quick question. Why would you rather use an ER40 chuck on the lathe than a 3 or 4jaw scroll chuck. I know it has exact collets for certain sizes,but that is not something the other chucks can't do. I am asking because of ignorance about it and have always used 3 and 4jaws on the lathe except on the mill of course ER32 collet chucks are great. Please shine some light on this for me. Thanks

Michael
My very first project after getting a lathe was turning the backplate for an ER-40 chuck. It has less than two tenths runout, and is my most-used accessory. It's quick, obviates the need to indicate, and works great for holding a wide range of work, but especially for small parts and tubing. I only mount a chuck if I have to hold something over an inch. I ground the jaws on my 3-jaw, and the ER-40 chuck still has a fraction of the runout for anything it will grip.
 

plunger

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#17
It was one of my first projects too.I made a er 50 collet chuck but bought the nut.I had a bash at making a collet as well
 
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Suzuki4evr

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#18
It was one of my first projects too.I made a er 50 collet chuck but bought the nut.I had a bash at making a collet as well
This on my to do list now. It's a very long list I must add.
 
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