Oversize aluminum bar

[moonlight machine]

Doing a little 5C collet job, 1" 6061 T6 easy peasy, right, not so fast. Service Center metals gives you more for your money! The 1" I got is actually 1.008 to 1.010 so needless to say it will not go in a 1" 5C collet. what a giant PITA!

 

[rcoope]

What you need there is a 65/64 collet. Or maybe a 26mm collet and squish a bit. Honestly I don't find 1.008" surprising at all for 6061 round bar, but yes a PITA.
Edit: I posted this to be funny of course but McMaster, which never laughs or fails us, sells 1 1/64" 5C collets for $28: https://www.mcmaster.com/5c-collets/5c-collets-7/size~1-1-64/ That's 1.0156" so should work great. They sell 26mm too but that's more like 1.023".

 

[Garwood]

Doing a little 5C collet job, 1" 6061 T6 easy peasy, right, not so fast. Service Center metals gives you more for your money! The 1" I got is actually 1.008 to 1.010 so needless to say it will not go in a 1" 5C collet. what a giant PITA!

My salesman have always told me when metal prices are up the mills stuff the tolerance. When they're down they give the bare minimum. It's always been true from what I've seen.

 

[ponderingjunkman]

The oversize stuff has not been very round either!

 

[Milland]

Extruded rod is shite. We hates it, we does...

 

[Mtndew]

What you need there is a 65/64 collet.

How about a 1-1/64" collet?

 

[projectnut]

I've noticed the same thing over the last year or so. I use a relatively small amount of 6061 T6 but noticed about a year or so ago the dimensions were at the high end, often .006 to '008 oversize. At first, I thought maybe I'd gotten some odd metric size. Now when I go to the suppliers, I take along a set of calipers to do a quick check. Almost all 6061 round and flat stock has been slightly oversize. It seems to be specific to aluminum as the steel alloys are all right on the money.

 

[Cole2534]

It seems to be specific to aluminum as the steel alloys are all right on the money.

A result of the manufacturing process, extrusion vs drawing perhaps?

 

[WizardOfBoz]

Are you billed by the pound? If so, that is a PITA: you pay an extra 1.6 percent for each length, AND you have to turn it down to spec...

 

[FredC]

I think Hardinge charges the same for a 1.009 collet as a 1 inch collet. The odd collet may be ticket another day.

Years ago we had a long running job where the part was turned very close to 14mm. We saved time and money by buying 6061 extruded stock and having it sent to a centerless grinder for straitening and grinding. Paid the same for the finished material as the 9/16 we had used and did not have to turn it to size. Sometimes extruded stock is the answer to the question.

 

[jims]

eBay has 5c emergency collet for $11.03 with free shipping.
I keep 4 or 5 blank emergency collets in stock for special size
stock.

 

[moonlight machine]

Just what I want to do make a special collet instead of the parts. Pays well though, no wait it is for free. yah I like that, no wait I hate that.

 

[Mud]

I've honed collets to size in that situation.

 

[Cole2534]

eBay has 5c emergency collet for $11.03 with free shipping.
I keep 4 or 5 blank emergency collets in stock for special size
stock.

Never had great luck with those, but Im pretty sure it's operator error.

Much rather use soft jaws.

 

[FredC]

Never had great luck with those, but Im pretty sure it's operator error.

Much rather use soft jaws.

I have had trouble with imported soft collets also. Even when bored with the provided 3mm pins they do not hardly expand when the closer is opened. Never had a single problem with the ones from Hardinge. The old shop foremen i worked for said that closing an emergency collet without a part in it ruined them, that has not been my experience the couple times I did that.

 

[Cole2534]

I have had trouble with imported soft collets also. Even when bored with the provided 3mm pins they do not hardly expand when the closer is opened. Never had a single problem with the ones from Hardinge. The old shop foremen i worked for said that closing an emergency collet without a part in it ruined them, that has not been my experience the couple times I did that.

That has been an issue as well as never getting a very good finish on the bore. I suspect it's the cheap collet I used

 

[jims]

I have had trouble with imported soft collets also. Even when bored with the provided 3mm pins they do not hardly expand when the closer is opened. Never had a single problem with the ones from Hardinge. The old shop foremen i worked for said that closing an emergency collet without a part in it ruined them, that has not been my experience the couple times I did that.

I have used hundreds of them in my 60 plus years of machining with no problems. I even kept different size sets of pins for when I wanted to rebore them smaller. An 1/8 inch set a metric set and another set turned a few thousands smaller.
We held the round rod end heads in them with the side cut out for the stems to hang out. Tens of thousands of them.
You need the extended emergency collets from Hardinge to do this. Hardinge makes extended ones that stick from spindle from spindle 1/2 or 1 inch out.
Hardinge also stocks 5c collets in .001 increments.
lf the import collets don’t exspand enough buy them from Hardinge.

 

[FredC]

jims,
I had a job where the 1/2 extension emergency collets would rust and mar the acrylic disks we were drilling. I had Hardinge make me 7 or 8 of them from a 416 heat treated bar that I sent them. They heat treated the collets again. They worked fine and the plastic caused no corrosion in the collets after that. They did not even seem to blink an eye on that request. I got the impression they did stuff like that all the time.
One thing I have started to do is mark the collets after I bore them. Used to leave an extra part in them so I would know what they were bored for, but sometimes the part and collet would get separated.

 

[50BMG DUDE]

jims,
I had a job where the 1/2 extension emergency collets would rust and mar the acrylic disks we were drilling. I had Hardinge make me 7 or 8 of them from a 416 heat treated bar that I sent them. They heat treated the collets again. They worked fine and the plastic caused no corrosion in the collets after that. They did not even seem to blink an eye on that request. I got the impression they did stuff like that all the time.
One thing I have started to do is mark the collets after I bore them. Used to leave an extra part in them so I would know what they were bored for, but sometimes the part and collet would get separated.

That's a great idea! - I have collets kicking around that I know I made for some special dohickey a while ago.So I re-use or re-purpose only to wind up needing to make the original part, like the next week. THAT's what that collet was for... Especially expandables

 

[jims]

I have used hundreds them in my 60 plus years of machining with no problems. I even kept different size sets of pins for when I wanted to rebore them smaller. An 1/8 inch set a metric set and another set turned a few thousands smaller.
We held the round rod end heads in them with the side cut out for the stems to hang out. Tens of thousands of them.
You need the extended emergency collets from Hardinge to do this. Hardinge makes extended ones that stick from spindle from spindle 1/2 or 1 inch out.
Hardinge also stocks 5c collets in .001 increments.

That's a great idea! - I have collets kicking around that I know I made for some special dohickey a while ago.So I re-use or re-purpose only to wind up needing to make the original part, like the next week. THAT's what that collet was for... Especially expandables

Hardinge makes some great collets but they are pricey , I know they make brass 5c emergency collets . I think I would have asked them to make extended 1/2 inch nose emergency brass collets for that application. Years ago I had them make a special
index plate for a Hardinge indexing fixture and it cost a bunch.

Also on a different note I have taken 5c collets that have sprung tight and opened them up a bit by inserting a tapered punch in them and leaving them sit overnight. It doesn’t always work but is worth a try and costs nothing.