5c Collets...

[Florian]

Hi Paolo

Is it that you don't guide the collets cone with anything but the threads?
I think that can be a reason for some imprecision.

I would try to make the cone and the actual "body" of the chuck as one piece because this would help avoiding any runout. Especially if you screw the pre-machined chuck to the spindle and then make the fit for the collet shaft(important!!) and also the cone.

You should be able to push the collets into the spindle but tey need to pinch slightly. Just like a push fit.

I have seen a chuck here on the board which uses 5c collets and where the collet carrier is made of one piece:
http://www.homemodelenginemachinist.com/index.php?topic=3870.15

Florian

 

[steamer]

Looking great Paolo....keep at it.

Have you checked the run out of the cone on the chuck?

Collets have run-out too!....the chuck is the one you should care about at this point.....you can't do anything about the collet itself...it is what it is.

Dave

 

[Paolo]

Hi my friends....
Found the origin of the run out!!! the Tread of collet is a little bit out of center due to a different lathe used for doing it!!!
Just removed the bad tread and prepared a new collet!! Same procedure for the other one!!!! Florian nice suggestion maybe I'll ask to joeby the drawings...His collet chuck seams very handy than mine!! The MLA-21 is very expensive for my pocket.
Dear reggie
My opinion is based on the literature!! It said the collet are most precise than chuck...and in some case is better lose time for changing the chucks instead losing the pieces as I did a lot of times due at precision lack!!
Best regards
Paolo

 

[Paolo]

shred
I tryed also to use the 3MC on my lathe spindle with draw bar...sometimes is quite difficult to remove the parts from spindle...I had to use the hammer!!! Is that the motif of my new challenge!!!
Thanks
Best regards Paolo

 

[Paolo]

Hello My friends...
I sold my Fervi, as You know, and waiting for the new....Maybe tomorrow it will be at door...I'm not surrender on doing my own collet chuck...I prepared some modification at my project using the advertise received from some of you...!! Sure I'll...but last week I received that... ;D

and just finished that...

I hope soon to post a pics of My own collet chuck and the project in plans section...!!

 

[arnoldb]

Paolo, GO FOR IT!

It is REALLY useful to have a collet chuck for the lathe!

Regards, Arnold

 

[Paolo]

Hi Arnold...
Thanks for supporting me...much better having two..one from China..another one home made.... :big: :big:
Best Regards
Paolo

 

[Blogwitch]

Paolo,

You will find that even though you require a lot more 5C collets to do the same job as say an ER32, 5C is a lot more versatile in what it can do, and available items that they can be used in. There is a plethora of different mountings for 5C.

One main difference is the thru collet fitting. Invariably, with a 5C chuck, you can feed right thru your spindle, wheres with ER, it is usually blocked off if using a standard MT mounted ER collet chuck.

I have fitted a few of these 'cheapo' 5C chucks now, and not one has ever run true. The only real cure is NOT to make it like a Griptru with adjusting screws. That is just moving the problem from one place to another, and also produces a less rigid chuck, plus leaving yourself open to losing accuracy once again, if it decides to go on the move after a bit of heavy machining.

You have basic lathe grinding facilities already. So the way to cure runout in ALL these far eastern chucks is to mount the chuck with a normal backplate, and regrind the nose taper back to true, it is then done once and for all.
The worst of the ones I have come across had 0.008" TIR, and even though I ground it back to true, I never really liked the closing action of the internal gears (it was of the type that had a circumferential split running thru the key holes, rather than being assembled from the rear), and was recently dumped for use as scrap metal, and a new one fitted and ground up, and that is now perfect, with zero runout using a range of different sized collets.

Blogs

 

[steamer]

Blogs,

I have a Bison 5C and it's spot on. .....it cost a good bit more thant the Cheapo's....but it's worth it.

I bought it originally for my 10" Atlas, but the new owner didn't want to part with any more cash so it stayed behind

I then was left with a 5C chuck with a 1 1/2 -8 thread with a new 2 1/4-8 spindle!

Well, I also had a clapped out 3 jaw that came with the new lathe, and backing plate fit the register very nicely.

Knowing that the chuck was dead on, and any and all run-out was likely to come from my collets ( .0005" max typically from Lyndex collets and more from the far east collets) I decided to make my Bison adjust true, using the the two existing backing plates as a start.

I am glad I did, as I can now dial in a rogue collet to a fair the well. I have not had any slip to date but I rarely take heavy roughing cuts with a collet chuck .

Additionally I added 24 index holes for light milling or for use with my filing rest

4 of those holes have clocking screws. 3 8mm bolts lock the chuck in and she has never moved on me...knock on wood.

http://i164.photobucket.com/albums/u27/mcandrew1894/P1010194.jpg


http://i164.photobucket.com/albums/u27/mcandrew1894/P1020140.jpg

Dave

 

[Paolo]

Hi...
I don't know how mine works...I received my lathe just yesterday...I have to rework the backplate for housing it...I'll let you know!!!
Paolo

 

[Blogwitch]

Dave,

When you get to the good quality chucks then they are like comparing chalk to cheese, you are paying for the quality of manufacture, as you well know to your cost.

These cheap far eastern ones are abysmal at times. In fact, when I stripped down the one I discarded, I was surprised the internal collet tightening nut turned at all. They look real nice with their ground finish, but that is only cosmetic. All the assembled parts had no semblance to being either accurately or well made. In fact one of the bevel gear holding pins looked very similar to a piece of cut off 3" nail. Thrown together and given a quick bling job on the outside.

If you are really interested, I will retrieve the parts, and show you how badly it was made.


Blogs

 

[steamer]

Dave,

When you get to the good quality chucks then they are like comparing chalk to cheese, you are paying for the quality of manufacture, as you well know to your cost.
[quote author=Blogwitch link=topic=5376.msg67279#msg67279

Agreed....but it's worth it sometime to buy a good tool.....

[quote author=Blogwitch link=topic=5376.msg67279#msg67279
These cheap far eastern ones are abysmal at times. In fact, when I stripped down the one I discarded, I was surprised the internal collet tightening nut turned at all. They look real nice with their ground finish, but that is only cosmetic. All the assembled parts had no semblance to being either accurately or well made. In fact one of the bevel gear holding pins looked very similar to a piece of cut off 3" nail. Thrown together and given a quick bling job on the outside.

If you are really interested, I will retrieve the parts, and show you how badly it was made.
[quote author=Blogwitch link=topic=5376.msg67279#msg67279

Not Required Blogs.....I believe you
I was just pointing out that I have not had any issue with mine moving around on the adjust true mounting....at least not in the last two years or so.

 

[Blogwitch]

Dave,

I think you have picked up the wrong meaning of what I was saying.

With a good quality one, as you have, a griptru is feasible as you would required very little offset, if any, to get it running true. Say one or two thou at the most.

Whereas with these cheapos being so far out, you have to go back to basics, get them as rigid as you can, and grind back the noses. Because they are so far out, if you tried to put them on a griptru mounting to bring them into running true, they would be way out of balance from the very beginning.

In fact, the worst one actually came with a machined D1-4 mount built in, so couldn't have been fitted onto a griptru if I wanted to.

The three pics below show what had to be done. The first was on strip down and finding out how badly it was made, the second regrinding it back to true and the third was checking at the end.

With my latest one, I fitted a standard chuck to a backplate, and had to regrind the nose again.

What happens to all those people who think they have a good chuck, but don't have the facilities to check or to put it right?

John

 

[steamer]

Hi Blogs,

Oh I agree, if caught there, your approach is not only recommended, but required.

And like a machine tool manufacturer, your chuck will now have an error only as large as the error in the spindle it was ground on.

Dave