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Selecting Tool Holders

Shazam

Plastic
Joined
Jun 23, 2018
How do you chose which tool holder to get? If you can get a ER50 with a hole for say a 3mm or 1/8in tool, how is that different to an ER8 collet holding the same 3mm or 1/8in tool?

Also, how do you know that cramming the largest tool for a given collet WAS a bad idea? Say you take an ER20 collet and then cram the largest 13mm tool in there. They designed the system in a way that it should all work right? I mean if it fits, it should work? No?
 
Great question. The outside diameter of an ER50 is just over 3" diameter. So holding an 1/8 tool is just clumsy and not recommended. For first coolant is going to have a hard time getting to that tool since the outside diameter is so large.
2nd, most of the time for 1/8 tooling you will be spinning over 4,000 to even 12,000 rpms. I would not want to be next to an ER50 tool holder at such a high rpm. Thats a lot of mass spinning that high.
3rd, using an unessesarily large tool holder is using just wasting energy and coolant. Larger diameter tooling whips and mists coolant much more that smaller diameter tooling. Hope this helps.
 
Normally for us max endmill size in a give holder goes something like this:
TG100 3/4-1" carbide or indexables
ER-25 5/8(uncommon tool)-1/2
ER-20 3/8
ER16 1/4-5/16
ER11 1/4 down

Drills, taps, reamers etc are a bit more flexible but commonly end up in ER20 or down.
 
No, physical clearance can often be an issue.

I often make small parts, and find myself using a Techniks "Slim Fit" holder (like the one pictured below) quite often. Not only does it make getting coolant to the cutter very easy, but since small end mills are typically run at high rpm, a holder like this does not "sling" coolant hardly at all. Additionally (and probably the main reason), it allows getting into very tight spots that even something like an ER-16 wouldn't allow.

Techniks slimfit.jpg
 
The first thing would do is not use ER holders for end milling.

My rule of thumb for ER has always been to only end mills that are 60% of the maximum collet size available. For example, ER16 goes up to 7/16". 60% of that is roughly .28", so the biggest end mill I would ever put in an ER16 is a 1/4". Not necessary to do this for drills (up to a point), but a lot of people's fails with ER come from running tools at or near the maximum available collet size.

But the thing is; steep taper collets are better, and Frank @ Maritool has done an amazing job making SK holders/collets available at prices that sorta blow junky old ER out of the water. With SK, I'm happy to go up to 80% of the maximum collet size all day long (so a 1/2" tool in an SK16 holder is just fine).

A step up from that is Big Kaiser's Mega collets, designed with zero collapse to hold spesific end mill sizes. There, I am happy to go to 100% of the collet's maximum available sizes given how amazing the grip is.
 
Robin Renzetti has a good short clip on his Instagram page discussing this topic. The jist is that using the smallest collet available to hold your specific tool is likely going to offer the best grip because tool shank length tends to be proportionate to shank diameter and you get to use more of the collets working length this way.

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Thanks gkoenig, will have to dig into grip strength of ER collets some more.

Cole2534, I couldn't find the video on Robin's instagram page, too many videos, I went through the list a few times, but just based on image alone, I couldn't find the video in question, but I guess it talks about ER collet grip strength. So will have to look into that!

EDIT: NM found his video, right at the top! :)
 
Last edited:
Thanks gkoenig, will have to dig into grip strength of ER collets some more.

Cole2534, I couldn't find the video on Robin's instagram page, too many videos, I went through the list a few times, but just based on image alone, I couldn't find the video in question, but I guess it talks about ER collet grip strength. So will have to look into that!
See if this works- Robin Renzetti on Instagram: “PSA

#practitioner_of_the_mechanical_arts #dontleavewellenoughalone #thinkoutsidethebox #instamachinist #instatoolmaker #colletwhisperer”


Sent from my SM-G973U using Tapatalk
 
The first thing would do is not use ER holders for end milling.

My rule of thumb for ER has always been to only end mills that are 60% of the maximum collet size available. For example, ER16 goes up to 7/16". 60% of that is roughly .28", so the biggest end mill I would ever put in an ER16 is a 1/4". Not necessary to do this for drills (up to a point), but a lot of people's fails with ER come from running tools at or near the maximum available collet size.

But the thing is; steep taper collets are better, and Frank @ Maritool has done an amazing job making SK holders/collets available at prices that sorta blow junky old ER out of the water. With SK, I'm happy to go up to 80% of the maximum collet size all day long (so a 1/2" tool in an SK16 holder is just fine).

A step up from that is Big Kaiser's Mega collets, designed with zero collapse to hold spesific end mill sizes. There, I am happy to go to 100% of the collet's maximum available sizes given how amazing the grip is.

I agree with this. er's suck for bigger endmills. yeah I still use them in a pinch, dont like them though. I get vibration and chatter with 1/2" and 3/8 collets compared to the tg and sk's.
side lock holders work best for me, but sometimes I need more endmill holders and stuck with er's in a pinch. I use the bigger ers if the nut doesn't interfere with the parts.

Thanks for the tip on the sk holders from maritool .
 
The first thing would do is not use ER holders for end milling.

My rule of thumb for ER has always been to only end mills that are 60% of the maximum collet size available. For example, ER16 goes up to 7/16". 60% of that is roughly .28", so the biggest end mill I would ever put in an ER16 is a 1/4". Not necessary to do this for drills (up to a point), but a lot of people's fails with ER come from running tools at or near the maximum available collet size.

But the thing is; steep taper collets are better, and Frank @ Maritool has done an amazing job making SK holders/collets available at prices that sorta blow junky old ER out of the water. With SK, I'm happy to go up to 80% of the maximum collet size all day long (so a 1/2" tool in an SK16 holder is just fine).

A step up from that is Big Kaiser's Mega collets, designed with zero collapse to hold spesific end mill sizes. There, I am happy to go to 100% of the collet's maximum available sizes given how amazing the grip is.

Drills and taps. The large collapse range and low cost makes them ideal for that work.

I use ER collets every day for end mills. They work perfectly fine, and yes, I do have plenty of other high and low end means of holding them for comparison.

I do not like to use the collapse range of er collets. For drills, yes, but not for anything else. High precision ER collets do not even have a collapse range - nominal diameter only.

I often wonder how many of you guys that have problems with them are actually unknowingly using them in their collapse range - collets made to metric nominals and badged with inch sizes. Idk if anyone is making them like that, but it wouldn't surprise me in the slightest.
 
ER collets are perfectly fine for endmills. Not all end mill operations are full hoging or roughing. Finishing a side wall, profiling, 3-d profiling are perfect applications for ER collets. I use ER32 collet chucks for slotting with a 1/2 and 5/8 rougher in alloy steel all day for years. Never had a tool slip.
 
I used to have issues with tool pullout on heavy cuts with ER collets. I picked up the Techniks torque wrench and a handful of adapters for my toolholders, started torquing them to spec, and have not had an issue since even on some pretty aggressive cuts. 100ft-lbs for an ER32 may seem excessive, but it does the job and hasn't given me any trouble in the year and a half I have been doing it this way.
 
Most are unaware of how much you have to tighten an ER collet, it's a lot. I think that's why so many have issues with slipage.

Torque Specifications Chart for Collet Nuts and Tool Holders

Am I reading that right? For a given ER collet, if the tool shank is over 2mm, use the torque figure in the left column, if it's under 2mm, use the right column? So I.D. is inner diameter of the collet i.e. its bore?

I'm getting the bore thingy from this link:

BuildYourCNC - 1/4" ER11 Collet for Spindles

Click on the last image with the 3 view drawing of the collet and you get a description of what each of the dimensions is called.
 








 
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