ER Collets and holders....Breaking the code.

[Terrywerm]

FWIW here's the video that perked my interested in collets to begin with.

http://www.youtube.com/watch?v=smKWlrjxXag

I started a similar thread because I didn't think my questions had much to do with the ER system since I'm not so sure I am looking to embark on all that would be entailed to build an ER holder for my threaded spindle nose. It was suggested that I bring my questions (if I still had any) here. I'm still not sure how much I'd use either the MT4s I'm considering buying or a more extensive ER system, which looks like I'd have to build...

Two of the things that perturb me the most about internet forums are: 1) questions that get answered with questions and 2) accusations that "you just haven't read enough be fore you posted"... None the less I suppose that working on building an ER holder could solve my concerns of protecting my threaded spindle nose, assuming I used the spindle thread system as the mount, but then the economy of a $100 ebay purchase goes out the window.

So I'll ask a different way, does anyone have any extensive experience running an older lathe collet system with a draw bar? If so does the draw bar lock somehow? or was it's function just to pull the drawn collet tight - then relax? For that matter since I still haven't purchased my first milling machine, how do collet draws work on a milling machine like is being offered by Rbeckett? Do they maintain tension the entire time?

I saw your thread elsewhere and meant to come back to it with some photos and answers for you. Working on that right now, so take a look there in a little while.

 

[NoShopSkills]

Thanks guys;

David, the lathe is a 1956 Sheldon L-46. Outside of the spindle & threads is in nearly perfect condition. Since this whole idea of running collets just hatched, I'll need to make a more thorough inspection of the MT4 taper, but I vaguely remember just running a shop rag with some solvent through it as I cleaned it prior to reassembly. Pretty sure it is smooth and undamaged.

The opposite end of the spindle however is dinged up a little bit where it sticks our of the gear guard door. Looks like someone once used either a hammer or a pipe wrench on it to attempt to achieve something that better shop practices couldn't...

 

[David Kirtley]

If you are going to be using them to hold end mills or drills, the MT4 collets are just the ticket. If you are looking to put stock in the collet, the 5C or ER series are more appropriate. With a larger bore, the 5C make a lot of sense as they have a larger capacity than the ER collets. Since you have the room, a collet chuck would be the easiest. The closer is a piece of tubing that has an internal thread to match the collets that you put through the spindle but still can pass things through the tube. It will tighten against the outboard end of the spindle to tighten and hold the collet closed while turning.

Turning a collet chuck is not be that big of a deal which is probably why you don't see as many of them to buy. One end is threaded to match your spindle, there is a bore the outside diameter of the collet and the taper on the end to close it. There is one more pin that keeps the collet from rotating. Tubalcain (mrpete222 on youtube) just did a video the other day replacing the pin on a collet holder or something similar. Again, watch doubleboost build one on youtube. The process would be the same for a 5C except for adding a pin and the dimensions would be different. Since it will be turned in place on your actual lathe, in effect, the runout would be negligible.

J.R. Beall sells some ER32 holders for threaded spindles that are reasonably priced but I don't see that he has any as large as the 1-3/4x8tpi that you mentioned in the other thread. His max out at 1-1/4x8tpi. I bought my cheap one for my wood lathe at Penn State Industries.

The different collet types have some advantages (and disadvantages) The ER series clamp parallel rather than just compressing on one end and they have a wider clamping range. The ER collets are self ejecting. They don't have as large of capacity as the 5C. There are lots more fixtures available for 5C collets than ER collets. There are 5C collets made to hold hex and square stock.

If my lathe were large enough, I would have gone for the 5C collets. I am happy with the ER32.