Author Topic: Lathe collets.  (Read 5254 times)

Online Jo

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Re: Lathe collets.
« Reply #30 on: March 23, 2018, 10:34:00 AM »
The yellow set is the 21 ones. The one in the blue box came from Jason. As he never admits to buying from from anyone but Ketan I am assuming it is an Arc EURO one.

Jo
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Offline Jasonb

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Re: Lathe collets.
« Reply #31 on: March 23, 2018, 01:28:40 PM »
yes the one in the Blue box came from ARC though I seldom actually buy anything from them I do have a lot of their products, mostly gifts (friends & family) plus the items for the long term SX2.7 test.

Funny enough I swapped a few e-mails and had a long phone conversation with Ketan a couple of months ago when the hardness of another item cropped up. I tried a file on the one I had and it did not skid over the surface but certainly required more effort to remove metal than just plain mild steel. I tried the same file on a product from elsewhere and it did skid off. Without a hardness tester it is difficult to be accurate but the level or hardness can vary. From a bit of searching about on the net it would seem that an expensive name brand maker hardens these parts to about 5Rc more than the factory Ketan gets his items from so still hardened but just not quite a s much. It is also more than likely than another factory may harden to an even lesser degree and by taking pot luck with one of the bargain priced suppliers direct from China you may get lucky or you may not.

He will also tell you that many of these very cheap suppliers buy in stock from assorted factories that may have been rejected due to not meeting the level of quality required or just made in a factory that only makes to a low spec. They then box them all up in matching plastic boxes and sell as sets which probably explains the font and slot differences.

As Stuart says you get what you pay for - bargain bucket direct unseen you may be lucky you may not. Mid priced far eastern items made to a more consistant spec which costs the supplier hence they cost more than the bargain ones but you will get a reasonable quality that will do for most of us and can return anything that is not right. Buy named brand and get very good quality at a price and you may end up paying for a level of accuracy that is above the ability of yourself and the rest of your workshop equipment and also more than is needed to make a steam or IC engine.

You see it in all hobbies where there are some that have to have the latest set of golf clubs, this years bike, fancy hand planes etc. but if you can't hit a ball straight or use a plane you won't get much of an advantage except for what is in your mind.

J

Offline Mcgyver

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Re: Lathe collets.
« Reply #32 on: March 24, 2018, 05:32:19 PM »
Jo and others preferring 5c over ER.....

I use 2J 5C 4C, W12, 10mm and 8mm.....all variations on a theme; longer body, 3 slits, drawn in from the back, but have never turned with ER collets.  There's a slight advantage in that shapes are available such as square, hex and pot chucks but they are seldom used, at least by me.  What do you see as the advantages?

Offline john mills

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Re: Lathe collets.
« Reply #33 on: March 25, 2018, 09:30:30 AM »
the difference is more to do with accuracy at the distance from the face of the collets er 25 the distance from collet is less than for a er 32  the 5 c  the distance should be much longer   for short parts the difference may not be noticeable .It is a while since i have seen the specifications it would be good to check.   

Online Stuart

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Re: Lathe collets.
« Reply #34 on: March 25, 2018, 09:42:00 AM »
this will make you think how you use ER collets

http://www.techniksusa.com/metal/torque_chart.htm


the line for ER 40 is why I stoped using them you need a bench fixture to get that on

for 5C its the chuck key or small wrench for the collet blocks

just my take on things


disclaimer I do use ER16 on a MT2 for the small cnc mill this is not a problem to torque up as I have a fixture to do it then they are measured to gauge line entered into the tool table and the in storage rack 10 off in all plus 4 6mm EM holders

Stuart
My aim is for a accurate part with a good finish

Online Jo

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Re: Lathe collets.
« Reply #35 on: March 25, 2018, 10:01:14 AM »
Collets like 5C have a single taper and can hold very short items - I have held and turned holding on a 1mm shoulder. Collets like ERs have a double taper and can close down much more than a single taper collet but if you attempt to hold something that is less than over the distance to the end of the front taper they close unevenly and the result is they "bell open" and do not hold the item  :ShakeHead:

The idea of a collet is that it holds evenly all the way round the item: the more you move away from this single size the more you are holding on a number of points rather than evenly on the entire surface. So a 1mm shoulder on a 5c collet is providing holding on 1mm x the circumference holding surface. On a ER if you stretch its capacity you are holding on 6 or 8 points on that 1mm surface - so do not be surprised that you have to use a lot more force on the nut to squeeze the collet onto your item to prevent it turning and galling.

Did I mention ERs are excellent tool holding collets :)

Jo
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Offline Jasonb

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Re: Lathe collets.
« Reply #36 on: March 25, 2018, 10:16:45 AM »
Though with an ER you do have a chance of holding any part even if it means closing right down and possibly making a plug for the back end, can't do that if you don't have the 5C size needed short of machining an emergency one or getting the 3-jaw out and cutting soft jaws.

Online Jo

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Re: Lathe collets.
« Reply #37 on: March 25, 2018, 11:46:39 AM »
You can always use a four jaw chuck. But on short stuff you still may have to make a pot chuck.


I thought the original question was about collets for the lathe  ::)

Jo
« Last Edit: March 25, 2018, 11:49:53 AM by Jo »
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Offline Jasonb

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Re: Lathe collets.
« Reply #38 on: March 25, 2018, 01:35:24 PM »

I thought the original question was about collets for the lathe  ::)

Jo

It was you that said they were good for tool holding :insane:

Online Jo

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Re: Lathe collets.
« Reply #39 on: March 25, 2018, 01:43:52 PM »
It was you that said they were good for tool holding :insane:

Yes holding tools in the tailstock, which is why we have ER chucks on a 2mt ;)

Jo
« Last Edit: March 25, 2018, 05:11:12 PM by Jo »
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Online Neil-Lickfold

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Re: Lathe collets.
« Reply #40 on: January 13, 2019, 03:26:50 AM »
ER collets will only hold a part true if the part fits for the whole length of collet length. When I hold short parts in an ER collet, I use a short  piece that is the same diameter I am holding, that supports the back of the collet so it can't collapse.
5C and R8 collets will hold a short piece quite well , as long as it is within a very small amount of the collet nominal dimension.
There is a really big difference in quality and concentricity with all collets, and unless you buy the precision series of collets, the rest  are all a gamble.

Offline galland

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Re: Lathe collets.
« Reply #41 on: January 13, 2019, 01:59:45 PM »
I regularly hold parts in er collets that are under 1/8th of an inch long with out problems but like Neil said you need more support farther back in the collet. I typically slide in a faced piece of bar that is .001 smaller diameter than the piece I am working on.     Gary

Online steamer

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Re: Lathe collets.
« Reply #42 on: January 13, 2019, 05:20:05 PM »
ER collets will only hold a part true if the part fits for the whole length of collet length. When I hold short parts in an ER collet, I use a short  piece that is the same diameter I am holding, that supports the back of the collet so it can't collapse.
5C and R8 collets will hold a short piece quite well , as long as it is within a very small amount of the collet nominal dimension.
There is a really big difference in quality and concentricity with all collets, and unless you buy the precision series of collets, the rest  are all a gamble.

Neils comments are correct.    ER collets were originally designed to hold cutter shanks only.   Draw in collets like 5C, 3C, 8 and 10 mm    W12 and W20 have a fairly small size range.     3C and 5C have about a 0.007" range where you should use them for good accuracy.   The object going into the collet should be round, and not as cast, or Cold Rolled, or anything else not otherwise round.   

3C, 5C and 8mm or in my shop.  My Clausing is the only one that has a ER25 in it.   

Dave
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Offline RMO

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Re: Lathe collets.
« Reply #43 on: January 13, 2019, 07:29:56 PM »
About 18 months ago I picked up a set of collets in a lot of surplus tooling, inthe pictures they looked like 5C, but when I went to pick them up, it turned out they were huge.  About 5 inches tall, 2-1/4 inches in diameter at the widest point.  Turns out they were 215 collets mahe by Hardinge.  So I ended up with a set of 26 collets with no chuck.  Yesterday I finally received a chuck to fit them.  Now if I am ever going to need to turn something an 1 and 3/4 in diameter, I am set.   :whoohoo:  Actually the set includes most common sizes from 1/8 on up to 1-3/4.  I have never used collets in a lathe before, looking forward to figuring it all out.

Mike