EOC-25/syoz-25 collet holder.

[jemin]

Hello everyone,
I bought a set of collets(7 total) and a collet holder off ebay for $70. The collet holder was suppose to be R8 shank to ER-32 collet holder. Turns out it is a R8 to EOC-25 holder. The guy selling it said he didn't know much about the holder because he was selling it for his dad. I did some searching online and the EOC-25 collets are good for milling but expensive. The intention I bought the set was because I want to settle on one kind of collets for my mill(RongFu 20 clone) and for the lathe(Atlas TH-42). My lathe spindle is a MT3 so I was hoping that if I bought a MT3 shank ER-32 holder, I'd be set. But it didn't turn out that way. So now I have 2 choice. Either sell the EOC-25 set and buy a brand new R8 to ER-32 set or find a R8 to EOC-25 holder(which seems like it is really hard to come by if they make them). Not even sure if they even make those. I also have some MT3 collets and some 3c collets which I intend to sell eventually. Because I lack the experience and knowledge, I am not sure which route to take and was hoping you guys can share your thoughts. I also found out that the EOC-25 collets are more expensive than the ER-32 collets. I am doing this for hobby and not doing any professional work but would love to find out the pros and cons or EOC-25 vs ER-32.

Thank you,
-jemin.

 

[ChazzC]

Return the purchase as not as described (eBay guarantee will cover any costs) and get either ER32 or if you have a larger mill/lathe ER40 collets & holder/chuck/blocks. ER collets will grip a 1mm range so either inch or metric will work.

 

[jemin]

Thank you @ChazzC. Appreciate your input. I will looking into the ER-32 set my mind was set on originally.

 

[pontiac428]

If it isn't ER, 5C, or R8, it's SCRAP!

 

[Red96]

One thing to keep in mind when you go shopping for a set of ER collets... The grip range of an ER collet is from nominal to minus 0.040". (0.040" = 1mm, roughly) That being said, you'll get more utility from a metric set than you will from a fractional set. Since the metric set will have collets in 1mm increments they give you the ability to grip any diameter within the range of the collet set. If you purchase a fractional set, each collet size jumps by 1/16", or roughly 0.062 but the grip range is only good to -0.040", there's going to be sizes that you can not grip with the fractional set while staying within the grip range of a single collet. So, say you want to put a piece of 0.197" (5mm) dia material into a fractional collet. The 1/4" collet can grip material from 0.0250 (nominal) to 0.0210 (nominal minus .040"). If you tried to gronk the collet down on the 0.197" material it would ruin the collet.

I made the mistake of initially investing in a fractional set, only for the light bulb to come on regarding grip range after the fact. Once in a while I'm pestered with that reality when I can not use a collet when I'd like to for an occasional oddball diameter that falls outside of the fractional sets' grip ranges. A metric set is on my seemingly never-ending list of stuff I "need".

Edit: FWIW, I personally would recommend ER40 collets, as they go up to 1"/25mm. ER32 collets can only go up to 3/4"/20mm, which you may find to be limiting. YMMV

 

[ChazzC]

One thing to keep in mind when you go shopping for a set of ER collets... The grip range of an ER collet is from nominal to minus 0.040". (0.040" = 1mm, roughly) That being said, you'll get more utility from a metric set than you will from a fractional set. Since the metric set will have collets in 1mm increments they give you the ability to grip any diameter within the range of the collet set. If you purchase a fractional set, each collet size jumps by 1/16", or roughly 0.062 but the grip range is only good to -0.040", there's going to be sizes that you can not grip with the fractional set while staying within the grip range of a single collet. So, say you want to put a piece of 0.197" (5mm) dia material into a fractional collet. The 1/4" collet can grip material from 0.0250 (nominal) to 0.0210 (nominal minus .040"). If you tried to gronk the collet down on the 0.197" material it would ruin the collet.

I made the mistake of initially investing in a fractional set, only for the light bulb to come on regarding grip range after the fact. Once in a while I'm pestered with that reality when I can not use a collet when I'd like to for an occasional oddball diameter that falls outside of the fractional sets' grip ranges. A metric set is on my seemingly never-ending list of stuff I "need".

Edit: FWIW, I personally would recommend ER40 collets, as they go up to 1"/25mm. ER32 collets can only go up to 3/4"/20mm, which you may find to be limiting. YMMV

Agree that metric collets will give more flexibility (pun intended).

While not as accurate and don’t have the full clamping range, you can get 21, 22, 23, 24 & 25mm ER32 collets on eBay. I’ll post photos (and I can find them current links) when I dig them out.

EDIT:

eBay still lists them from the same Seller. Stated TIR is 0.0006" (interesting for metric collets, but . . .). My medium-priced, 3 — 20mm set has a stated TIR of 0.008mm (0.0003"). I've never checked either, but I think it is reasonable to assume that the oversize collets may not hold as close a tolerance as standard collets (my investigation into small ER32 collets [<3mm] shows they are twice the TIR of 3 – 20). Here are mine (sorry, I forgot that the 24mm is in use):


Typically use these in a Collet Chuck on my 7x16 Mini-Lathe with a ball-bearing nut.

Oh, thanks to you I am now looking at getting 1mm, 1.5mm & 2mm collets!

 

[jemin]

One thing to keep in mind when you go shopping for a set of ER collets... The grip range of an ER collet is from nominal to minus 0.040". (0.040" = 1mm, roughly) That being said, you'll get more utility from a metric set than you will from a fractional set. Since the metric set will have collets in 1mm increments they give you the ability to grip any diameter within the range of the collet set. If you purchase a fractional set, each collet size jumps by 1/16", or roughly 0.062 but the grip range is only good to -0.040", there's going to be sizes that you can not grip with the fractional set while staying within the grip range of a single collet. So, say you want to put a piece of 0.197" (5mm) dia material into a fractional collet. The 1/4" collet can grip material from 0.0250 (nominal) to 0.0210 (nominal minus .040"). If you tried to gronk the collet down on the 0.197" material it would ruin the collet.

I made the mistake of initially investing in a fractional set, only for the light bulb to come on regarding grip range after the fact. Once in a while I'm pestered with that reality when I can not use a collet when I'd like to for an occasional oddball diameter that falls outside of the fractional sets' grip ranges. A metric set is on my seemingly never-ending list of stuff I "need".

Edit: FWIW, I personally would recommend ER40 collets, as they go up to 1"/25mm. ER32 collets can only go up to 3/4"/20mm, which you may find to be limiting. YMMV

Wow. Thank you so much for the detailed reply and for the advice on buying the collets. Really appreciate this community.

 

[Red96]

Thanks to David P Best. He has a very interesting write-up about collet types and the pros and cons of each. https://www.hobby-machinist.com/attachments/about-r8-er-and-5c-collets-pdf.478593/

Also Joe Pi has a good vid on YT explaining the clamping range differences between 5C and ER type collets.

 

[jemin]

Agree that metric collets will give more flexibility (pun intended).

While not as accurate and don’t have the full clamping range, you can get 21, 22, 23, 24 & 25mm ER32 collets on eBay. I’ll post photos (and I can find them current links) when I dig them out.

EDIT:

eBay still lists them from the same Seller. Stated TIR is 0.0006" (interesting for metric collets, but . . .). My medium-priced, 3 — 20mm set has a stated TIR of 0.008mm (0.0003"). I've never checked either, but I think it is reasonable to assume that the oversize collets may not hold as close a tolerance as standard collets (my investigation into small ER32 collets [<3mm] shows they are twice the TIR of 3 – 20). Here are mine (sorry, I forgot that the 24mm is in use):

View attachment 481522
Typically use these in a Collet Chuck on my 7x16 Mini-Lathe with a ball-bearing nut.

Oh, thanks to you I am now looking at getting 1mm, 1.5mm & 2mm collets!

Thank you for the pics. You guys are great.

 

[jemin]

Thanks to David P Best. He has a very interesting write-up about collet types and the pros and cons of each. https://www.hobby-machinist.com/attachments/about-r8-er-and-5c-collets-pdf.478593/

Also Joe Pi has a good vid on YT explaining the clamping range differences between 5C and ER type collets.

Thank you. I will def. Check out the guide and the YT video as well.