DIY collet chuck questions

[strantor]

I'm pondering making a DIY ER40 collet chuck for my logan 9" lathe with 1.5" X 8tpi spindle. I have MT3 taper inside the spindle but I'd rather leave that open and use the external threads.

I'm looking at some designs on the net, and seems like I have the right size chunks of metal to make something happen, but it's all aluminum. Is it OK to make the collet chuck out of aluminum?

Does anybody have the dimensions of the ER40 collets? I don't have any to look at.

Thank you.

 

[strantor]

How important is this groove?

They show the collet snapping into the groove, but is this necessary?

All the DIY collet chucks I'm coming across, they chose to purchase a collet nut instead of fabricating one; is this because of this groove being hard to machine?

 

[omni_dilletante]

The groove is critical as it pulls the collet out of the taper as you loosen the nut.

I am not sure how hard it is to machine, I am still building up the nerve to start machining my ER40 chuck. But it is basically a hole cut off center. So if you could cut the groove on the lathe with a smaller hole you have managed to complete the most complicated part.

The nut does have metric threads. My lathe does not cut metric threads so I am faced with the choice of making my own nut, or finding a metric thread cutting late to cut the threads on my chuck.

How important is this groove?
View attachment 78841
They show the collet snapping into the groove, but is this necessary?

All the DIY collet chucks I'm coming across, they chose to purchase a collet nut instead of fabricating one; is this because of this groove being hard to machine?

 

[strantor]

Could I not make something simpler like one of the two below, with standard threads? I understand the collet would be wedged inside, but that could be ejected by drilling a hole in the side like a jacobs chuck eject hole.

 

[Don B]

I am not sure how hard it is to machine, I am still building up the nerve to start machining my ER40 chuck. But it is basically a hole cut off center. So if you could cut the groove on the lathe with a smaller hole you have managed to complete the most complicated part.

The extraction ring will not be hard to produce especially if the nut is started on a 4 jaw, you would just offset the 4 jaw with your dial gage and finish the bore, the hardest part with the nut will be visibility when cutting the taper, and measuring the taper to obtain the correct seating position of the ER collet (i.e. To ensure the collet is pinched on the taper of the nut rather than the extraction ring) hope that's clear..! Sorry I've not found a diagram with dimensions yet but I'll keep looking, the bigest one I have is an ER32 so I'm not able to measure one.

 

[Baithog]

Are you sure you can't cut 1.5mm threads? Some smart guy around here just might be able to give you a work around if you tell us what lathe you have. It may end up easier than fabricating a nut.

I have read accounts of hobby machinists making ER chucks from aluminum, so it should work for light use. Getting a piece of steel or cast iron might be a better idea if you plan to do a lot of collet work.

Try this link for ER dimensions http://www.takayama-shoji.co.jp/rego/pdf/13_technical_information.pdf

 

[12bolts]

Hi Strantor
I corrected my post in the other thread.
This is what I was referring to. http://www.hobby-machinist.com/showthread.php?t=8079&highlight=collet?

Cheers Phil

 

[strantor]

Hi Strantor
I corrected my post in the other thread.
This is what I was referring to. http://www.hobby-machinist.com/showthread.php?t=8079&highlight=collet?

Cheers Phil

Thanks, I saw that. That chuck is quite awesome, but a little more than I want to bite off right now... or at any point in the foreseeable future (maybe after I retire). I am considering simpler designs; something like this is what I have in mind:

http://www.tallgrasstools.com/ER-32ColletKit.html

 

[GK1918]

Could I not make something simpler like one of the two below, with standard threads? I understand the collet would be wedged inside, but that could be ejected by drilling a hole in the side like a jacobs chuck eject hole.

View attachment 78842

Your first photo is very similar to my 3CH I do have the ring 'snap ring' but I dont use it and it is no big deal I just unloosen and a couple of light
taps side the end mill and it drops right out. like this holder I machined

sam

 

[strantor]

Your first photo is very similar to my 3CH I do have the ring 'snap ring' but I dont use it and it is no big deal I just unloosen and a couple of light
taps side the end mill and it drops right out. like this holder I machined

sam

Yes sir, that's what I have planned to get me by for now, but who knows; maybe it'll get me by forever? All I need for now is endmill holding, so your design should get me through, but for the future I'd like to have the versatility of collets.

Do you have separate sleeves to into that body for different sized end mills, or do you have a separate body for each size of end mill? that threads onto the exterior spindle threads, correct?