R8 Collets

Let us what know you find Dabbler. After doing more research on r8 collet quality, the one piece r8 collets are more precise, less run out, leading to longer tool life.
It appears that companies like Hardinge, Crawford, etc..had two lines of r8 collets and in regards to Crawford, their original run were machined from one piece of steel and as the company started to fold, they went with pressed in threads/staked, lower quality. I can see this in my Crawfords.

My 3/4" Crawford is one piece with a ground end, no stake mark on the keyway. Same with two of my Hardinge collets. Hardinge started making their BP mills in Taiwan and could have a Taiwan r8 collet line as well. Some later Crawfords tried to hide the pressed in threads but the stake marks give them away. The best r8 collets have no marks on the keyway. One piece of steel. If you don't care about the quality of your r8's, please disregard this thread. I don't own many r8 collets but the 10 or so that I Use, I want to be of good quality. Adding .0010 runout to the stack will make a difference in how long your end mills will last.
 
Got some unexpected locksmithing to do today. I'll get to the collets ASAP...
 
I can't say if one piece is better than a two piece with pressed in thread. The threaded portion has no affect on the runout tolerance, more the collet body and clamping fingers machining. I find the pressed in type collets to have nicer threads. All my (Asian) one piece R8 collets appear to have been cast and then machines, so far they have had the worse runout of all my collets. Another forum member did an extensive survey of the stated TIR, the manufacturer and where the R8 collets were made. After calling a number of collet manufactures it appears that most are now made in Asia these days. If you look at the listed maximum TIR for different brands, Lyndex and I believe Vertex is 0.0005" or better, I think Crawford states something like 0.0002" . I use the Crawford collets to setup my edge finders and the tip alignment is within 0.0001" on rotation. Really do not care how it is made, or for that matter the name as long as it works, but of course those with better finish and machining, usually these are the more expensive of the bunch. Used ones can be hit or miss, rare that someone is selling NOS at a realistic price.

I like the Crawford's, mine are very well made, but have gone up in price. If one is looking for a set without busting the bank, then I would go with a Vertex. In reality, the vast majority of end mills use standard sized shanks, so maybe 4 or 5 size collets will cover most everything (1/4, 3/8, 1/2, 3/4 and maybe 5/8). I also have both an ER32 system and a CNC chuck if I need to clamp some weird size. I rarely use my R8 collets, other than end mills larger than 1/2", otherwise I use my CNC chuck. An end mill lasts me a long time, I will break a tip long before it wears out. The TIR comes more into play for me when I am doing the DRO setup and defining the edges or centers with my edge finder.
 
Do your Crawfords have pressed/staked threads? I have Crawfords with both pressed and machined from one piece.
I'll check the TIR on these collets one day just out of curiosity. I like to use precision r8 collets for certain operations, like holding arbor shanks or
using carbide endmills., center finding, etc.. I buy the Hardinge r8's when they come up on Ebay, cheap. I just bought a 3/4" Hardinge r8 for $20 with the Hardinge tube, NOS, on a best offer deal. The seller wanted $45.00! I just wait and buy the sizes that I need. All I need is 5/16" to complete the set I use.
 
I wrote to Harding and they told me that their $45 r8 collets have a tir of .0005”
They went on to say that they don’t usually make two piece collets, whatever that means, and that they have a special accuracy r8 for $87 each.

My conclusion, thus far, is that not all collets, even from the manufacturers, are created equal. The only way to really know, is to check them yourself with a .0001” indicator. And, if your spindle, bearings, etc. are in good shape, you will have decent numbers.

My belabored point is, at least know what you’re paying for. Looks like Crawford, Lyndex , etc downgraded specs also. The CNC world is making this all mute. Old iron is on its way out.
 
EmilioG said:
I wrote to Harding and they told me that their $45 r8 collets have a tir of .0005”
Click to expand...

Just as a side note, this number by itself doesn't mean anything. You need to know the TIR and the gauge length to know if a collet is good or not.
 
That is true. I'm sure this is a mean average at about 2". Who knows. I'll just have to check my collets.
 
EmilioG said:
Do your Crawfords have pressed/staked threads? I have Crawfords with both pressed and machined from one piece.
Click to expand...
My Crawford R8 collets are staked, as seen in the first picture. I purchased them earlier this year from Rotagrip so assume they are the remains of newer stock, if I recall they were under $15 each at the time. They appear very well made and beefy. The runout is usually specified as worse case, they are much better then their guaranteed not to exceed specs. I use a Compac (215GA) 0.0001 indicator with a 0.0004" per evolution dial, so a very sensitive indicator. There are many factors that affect the TIR, not just the collet. What I am looking for is consistency when buying a number of collets (or a set), that the QA is such that you do not have some collets with a 0.001 or 0.002" runout like like the ones they replaced.
 
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Thanks. I just received my Ebay find, Hardinge high precision R8. It's made like no other Hardinge I've ever seen.
Black oxided on the inside with two "lands". Tools slide in like silk. I got it for $20 on a best offer. They didn't know what they had.
This is for my Criterion Boring head with 3/4" str. shank. (The Compac DI is the best. Which model do you have 214GA?)

So, it seems that Hardinge and Crawford made various level quality r8's. I have a Crawford r8 that is a one piece design, no stake mark on the keyway. As long as an R8 can be made accurately with a pressed in thread, I don't mind. See the last photos for Crawford R8's. Both are one piece but one has a nice ground finish. See>>> https://photos.app.goo.gl/7tavjP9yUfZWmMg83

4BE1B269-0D58-4253-A5EE-35213D8C6CD3.JPG9955BCD9-FC7B-4162-9110-67D722DAE291.JPGABA73524-E238-40E5-9B14-19992B656C88.JPGAD33D9E4-5A55-4E47-9E87-B0EDCAC7B0F2.JPGFD0C5216-4CC6-4AAF-952C-50D7E9F0CEAA.JPG
 
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