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ER40 collet chuck sizes.

I believe your looking at the diameter of the chuck. I also believe in unicorns so I could be mistaken.

The "fine adjustment" lets you correct for any variation in the spindle and dial in as close to 0 runout as you need to be.

I've got the Precision Mathews set tru and I'm not sure I really need it but it was on sale.
 
JustaDB said:
And what about these "fine adjustment" models: https://www.shars.com/5-er40-zero-set-fine-adjustment-collet-chuck
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Looks like 4 opposing set screws that adjust on (I presume) a dedicated adapter plate which has a matching undersized male boss that fits this recess. You can see the holes in the shadows (red circles). I would check that the appropriate adapter plate comes with the kit/price, but I suspect it would vary by what spindle style you have.
 

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To clarify @YotaBota : different backing plate diameters. I got one for my 7x16 with a 3" backing plate that was already machined to match the spindle locating boss and a 4" to mount on my 4" RT – both ER32 in my case.
 
JustaDB said:
There must be a reason to offer different sizes though
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I took you too literal.

As @ChazzC notes chuck size depends on the application. Lathes have differing size spindles, spindle holes and mounting requirements as do RT's. Pick the size that fits best for lathe or RT.

@JustaDB - I can't remember, what lathe do you have? You'll get lot's of opinions/recommendations for the machine you have.
 
@justasdb I ordered imperial collets and now regret it. I should have bought the metric ones, the whole set 2mm to 24mm, but that ship has sailed.

why?

Because with the metric ones you can clamp ANY size not matter what the diameter. The collets have an adjustment range of just over 1mm - the imperial collets have gaps, and I've needed to hold items in those gaps. Murphy, right?
 
I'm confused. Both metric and imperial collets have a range of sizes that they can hold. whether measured in mm or anything else
 
mbond said:
I'm confused. Both metric and imperial collets have a range of sizes that they can hold. whether measured in mm or anything else
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IF you buy a set in 1mm increments, all the ranges overlap. (slightly > 1mm clamping range.)
When you buy an imperial set, some of the sizes are close together, and other sizes have gaps larger than 1mm. My collet set has 18 pieces and has 3 ranges that are spaced > 1mm apart. so there are 3 sizes I cannot clamp. Because the imperial collets want even imperial sizes I cannot buy the collets to fill the gaps.

Hence: buy the metric ones, and use a chart/calculator to chuck your imperial sizes.

[update] I have considered buying the 6 metric collets I would need to fill the gaps. Buying individual collets makes those 6 collets cost almost as much as buying a whole set of metric collets. sigh.
 
Dabbler said:
IF you buy a set in 1mm increments, all the ranges overlap. (slightly > 1mm clamping range.)
When you buy an imperial set, some of the sizes are close together, and other sizes have gaps larger than 1mm. My collet set has 18 pieces and has 3 ranges that are spaced > 1mm apart. so there are 3 sizes I cannot clamp. Because the imperial collets want even imperial sizes I cannot buy the collets to fill the gaps.

Hence: buy the metric ones, and use a chart/calculator to chuck your imperial sizes.

[update] I have considered buying the 6 metric collets I would need to fill the gaps. Buying individual collets makes those 6 collets cost almost as much as buying a whole set of metric collets. sigh.
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I kinda disagree. ER collets where originally designed to hold standardized tools. So if you will be using Imperial sized tooling, you should have an Imperial size collet. If you use metric sized tooling, you should use a metric collet. The fact that ER collets have a range of adustment is just a huge bonus.

Case in point...if I put a 1/4" endmill into a 1/4" collet, it take a 1/4 turn of the handle to fully tighten the collet. When I remove the endmill, the collet will still grips onto the endmill with very light resistance.

If I use a metric collet, 7mm, to clamp the 1/4" end mill, it takes 2 full rotations of the collet nut to properly tighten it. When I remove the endmill, sometimes, the collet is so tightly jammed into the collet chuck taper, that when I unscrew the collet nut, I have to hold onto the endmill so it doesn't shoot out the collet, and you can hear the collet jump out and hit the nut.

I originally bought a full kit for my milling machine. The advert stated from 1/8"-1" (3mm-26mm), but they were really a metric set. And it worked for years, though I was annoyed with the looseness of the Imperial tools in the metric collet. I ended up buying several in-between sizes.

Eventually, I decided to just get several Imperial sized collets for the tooling I used most.
 

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thestelster said:
I kinda disagree. ER collets where originally designed to hold standardized tools. So if you will be using Imperial sized tooling, you should have an Imperial size collet. If you use metric sized tooling, you should use a metric collet. The fact that ER collets have a range of adustment is just a huge bonus.

Case in point...if I put a 1/4" endmill into a 1/4" collet, it take a 1/4 turn of the handle to fully tighten the collet. When I remove the endmill, the collet will still grips onto the endmill with very light resistance.
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Same experience have ER11 on my 3018(toy) CNC router. I did buy an imperial ¼” collet for the occasional times I can use a larger endmill. The 1/8” tooling I use is actually 3mm so metric is fine.

For my R8 mill I have a set of imperial collets and at least 1 metric 10mm collet to fit a specific endmill. I might have a 6mm R8 as well. You never know whether an aliexpress order is actually imperial or is just close.:)
 
thestelster said:
Eventually, I decided to just get several Imperial sized collets for the tooling I used most.
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I really agree with everything you said. I *almost never* use ER collets for tooling. I use ER collets in the lathe for workholding. I believe the original question was asking based on work holding, but if I am mistaken, I'm sorry.

In the milling machine, for holding the standard end mills, etc ABSOLUTELY get the native measurement set - if you use mm milling cutters, then get a mm set, if you use imperial cutters, the you should get the imperial set.

I do have a ER adapter for my mill I have yet to put an end mill into it, as I have all the R8 sizes I need.
 
Dabbler said:
I really agree with everything you said. I *almost never* use ER collets for tooling. I use ER collets in the lathe for workholding. I believe the original question was asking based on work holding, but if I am mistaken, I'm sorry.

In the milling machine, for holding the standard end mills, etc ABSOLUTELY get the native measurement set - if you use mm milling cutters, then get a mm set, if you use imperial cutters, the you should get the imperial set.

I do have a ER adapter for my mill I have yet to put an end mill into it, as I have all the R8 sizes I need.
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Big yes: when I first got my mill I picked up a set of end mill holders, and then R8 collets. When I started getting metric end mills (easier to find small metric end mills) I got a set of metric R8 collets. The ER32/R8 holder was a just in case since I had the ER32 collets.

I then got ER16 & 25 collet holders since I had those collets as well: these I have used for tooling to get linger reach than you can using R8 collets.

I also have an MT2/ER16 holder so I can use use end mills in the lathe tail stock.

Sometimes I thing I have more stuff than @mmcmdl (range of tooling, not quantities).
 
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