# What Does UM & RU Mean?



## darkzero (Feb 15, 2014)

For ER collet nuts & wrenches, I see them referred to as UM or RU. Seems like the appropriate wrench is compatible with both types but what does they mean?

I'm looking to buy another ER wrench but it's not so common so I want to make sure I get the right one.


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## Bill Gruby (Feb 16, 2014)

To be quite honest I have never heard of UM or RU? Maybe this will help you decide.

http://www.arceurotrade.co.uk/Catalogue/Collets/ER-Collet-Nuts-Wrenches-and-Spanners

 "Billy G"


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## darkzero (Feb 17, 2014)

Thanks Bill, great page but it does not help much. The size I want is not even listed there & they call the different types of nuts & wrenches differently too. I'll just go ahead an order the one I found & hope for the best.


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## george wilson (Feb 17, 2014)

UM means like,"Um,is this wrench going to fit?". RU means R U going to fit this collet?


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## Ray C (Feb 17, 2014)

george wilson said:


> UM means like,"Um,is this wrench going to fit?". RU means R U going to fit this collet?



Yep, I'm going with George on this one...


Ray


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## darkzero (Feb 18, 2014)

george wilson said:


> UM means like,"Um,is this wrench going to fit?". RU means R U going to fit this collet?



:roflmao:


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## Bill Gruby (Feb 18, 2014)

Could you tell me where you saw these suffixes on the wrenches? I have talked to several vendors of ER Collets and they don't know what they are or mean.

 "Billy G"


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## schor (Feb 18, 2014)

Seems that UM/RD are used interchangably. So chances are your going to be ok if your looking for a UM type.


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## darkzero (Feb 18, 2014)

Bill Gruby said:


> Could you tell me where you saw these suffixes on the wrenches? I have talked to several vendors of ER Collets and they don't know what they are or mean.
> 
> "Billy G"



As schor posted, I see that designation for the style wrench shown in his pic. I also see that style wrench called an E type. I see nuts with the UM designation engraved on them & I see some with the RU engraved on them but never both which is consistent when I see the designations listed as UM or RU. Thanks for checking Bill.

This is the one I ended up ordering made by Techniks.


*Part                       No.**Description**Nut Type**Length                       (mm)**Width                       (mm)*04613ER 16-E wrenchUM or RU16055

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I have 2 ER40 E-type wrenches. One fits my Bison ER40 fine, both do not fit my Lyndex ER40 BB nuts. The other one that did not fit my Bison, I filed it to fit my Lyndex ER40 nuts. I just scored a Lyndex ER16 extension that has the ball bearing nut also & is what I need it for. ER16 usually come in the mini type or hex type. My ER16 R8 is a mini type so I need another wrench for the Lyndex. I could always use the hook type wrench but I don't like them.


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