5c Collet Holder Rack System

[RJSakowski]

I have used 5c collets with a lever collet closer and repeatable was with in a couple tenths. With a scroll chuck if you are using ground stock it should still be less than .001

This is only true if you have consistent diameters. For every .001" in reduced diameter, the collet is drawn in further by about .003".

 

[mksj]

The Y axis is based on my DRO reading change of the carriage, or longitudinal change, but Bob is correct that on the lathe this is technically the Z axis on the lathe (sorry neophyte hare). In any case, the 5C collet chuck draws in the piece by about 0.004" per 1/4 turn in the unit I have. If you are holding stock that is slightly under the collet size (between the 1/64th increment), there can be a bit of a variation in the final key position with repeat use. Sometimes you might torque a little more or less with these types of chucks. So it is fairly easy to be off a few thousandth in the longitudinal position of repeat pieces using a collet stop that threads into the back of the 5C collet with this type of chuck. I was making a number of duplicate parts, and noticed some variation in the lengths. A collet closure system would be expected to be more repeatable, since the applied pressure/set point is more repeatable. An ER system I find is more secure with a wider clamping area and has a wider diameter clamping envelope for a given collet size. As I have only used this on the mill, I can't comment as to better/worse on a lathe, but I expect it to hold rods better. On more than one occasion, I have had a rod twist when cutting threads with a 5C collet. Just some observations with the 5C collets.

 

[RJSakowski]

A 5C collet, like an R8 collet, has a single pivot point as the collet closes down. For undersized stock the collet grasps first and hardest at the end, gradually drawing down as the collet is tightened.

An ER collet and other double angle type collets have two pivot points which allows the collet to close uniformly along its length. If piece of stock approaching the lower limits of the closing diameter is mounted in a 5C collet, this single point grip is noticeable if you pull the stock from side to side. Additionally, the collet is only gripping at the three points where the slits are located.

I suspect the the OP has seen this and is why he has amassed the large collet collection he has.

 

[wrat]

Z is always the axis in line with the spindle, on any machine. You can certainly call them anything you want in your shop, just please don't try to confuse us...
http://yarchive.net/metal/axis_naming.html

Sounds like that might not require much.

But you did, after all, provide a link and everything, to a blogger that agrees with you. So while I should doubtless bow out in the face of such all-inclusive expertise, I'll just allow you to explain that to the likes of Boeing -- not that they'd listen to you or your blogger-friend. Of course, I have a difficult problem there because it's not exactly *my* shop, either.

So sure, attack me all you want. But notice i prefaced it on my experience; and shy away from obtuse generalities like "always". You may have inspected every machine in the world, but i have not, so using words like "always" is something i avoid.

When you get up to integrating and programming 5, 6, and 9 axis machines, you be sure to come set me straight. I'll probably need it by then.

Wrat
.

 

[Bob Korves]

No attack from _this_ end, Wrat. Just trying to communicate in a common language...

 

[planeflyer21]

That's a great rack setup for your collets.

Plenty of room for adding hex 5Cs too.

 

[toolroom]

Very smart thinking, and very professional. Great job!

 

[machman2k]

It would seem to me that if you use a "spindle stop" (which locks into the spindle) and not a "collet stop" (which locks into the collet itself), you would have no more creep problems. Easy solution, and besides, it works with most other chucks ( 3 jaw, 4 jaw, etc.) as well.

Reference the following post:
Lathe Headstock Work Stop G0602

 

[mksj]

In theory a spindle stop should work, but it would be difficult get it to fit into the different sized collet and there may be some flex to the rod. There are work arounds using a collet stops, just not as accurate for repeat work as I found out. A collet closer I would expect to be more repeatable.

 

[kingmt01]

I didn't know locating a part inside of the chuck would be z ether. Altho each axis can be referenced to different depending on your perspective they do have a common way of looking at them. so I'd think when locating a part it would be referenced the same way as the machines axis. So in locating the tool on the x axis wouldn't it seem logical to locate the part from the same prospective?

I always assumed that when your talking about a lathe the axis was referring to locating the work from the tools prospective. Is this not correct? If so logically z would be the tools height wouldn't it?