MT3 Collet holder, or MT3 --> ER32 collet holder

[Jwest7788]

Alex helped me to finally remove the MT3 Jacobs chuck from my minim mill, so I can finally shop for a proper collet set for it.

I have run into a question though. Should I get a set of MT3 collets, like:

(Image from: http://www.toolstop[dot]co[dot]uk)

Or a MT3 Spindle Er32 Collet chuck, like:

(Image from https://www.rc-machines[dot]com)


I know I will lose some Z range with the ER32 set, but also get a wider range of collets for the same price.

How big is the convenience different when changing between the two?
--> I have a suspicion that it's about the same anyways...


What do you guys think?


JW

 

[PeterT]

Some pros & cons to mull
COLLETS
- generally smaller tightening range, 1/32"step is considered minimum progression set without over-springing undersized shanks. Ideally 1/64" but more moola
- may not lend itself to imperial vs. metric shanks (hint: there are a lot of decent cutters available offshore that are metric so ideally you would want a metric set)
- more headroom with collet
- (I think) better gripping power with collet but if you are hogging you really should use bill holders with set screw & flats on end mills

ER
- generally accommodates wider clamping range
- can keep ER shank in mill & just change collet/nut with different tool changes, maybe faster & less disturbance to setup unscrewing drawbar etc. Kind of machine specific though
- less head room, more spinning mass
- accuracy is now dependent a few things - shank + ER seat + ER collet + clamping force. ER requires decent torque on the nut to achieve rated accuracy. Its not hard to do with wrench, but most people under-torque even though the shank is securely held
- ER collets might lend itself to lathe use & other holding fixtures like mill clamps, rotary table if that's a factor

In both cases specs can be deceiving depending on the supplier

 

[Dabbler]

I have to add that even if you try hard, clamping on MT3 collets is quite variable. If you can zero your ER holder with decent clamping force then your ER collets will all have similar concentricity. For most milling jobs, this is nitpicking. The ER should be more convenient...

 

[Bofobo]

i use the same style as the MT3 shown but in R8. i gained the height required for some larger cutting heads with the gas assist and long travel kit from M.L.M.S.com. it gives enough clearance to really do nothing bigger than you did before but the MT3 collets do, (bonus is the long travel kit will allow you to mill at table height with the ER) keep in mind also that tool changing becomes harder the larger the work piece with the ER holder, include other tool lengths and consider drill bit lengths

i would not mind a set of ER myself but between kms and the included R8 holders i have a fair base selection ... could make some 4140 MT3 ....

 

[Johnwa]

I'm gradually accumulating a set of endmill holders. I do have a set of R8 collets but the holders just seem easier to work with.

Josh could also spend more $ and get an R8 conversion kit from little machine shop.