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View Full Version : Learned Something About R8's Today !!!



JoeLee
07-27-2012, 03:04 PM
Years ago I bought a set of Lyndex R8's, glad I bought them when I did. The set is 1/16" - 1" x 1/16's
I never used anything larger than the 3/4".
Last week at a yard sale I found a couple of brand new Niagara 7/8" double end mills.
Today I went to use one of them and guess what??????? they won't fit far enough up into the 7/8" collet to grab the center of the shank.
I have two choices, part them in half on the T&C grinder or sell them and look for some single ended ones. If I cut them in half there won't be more than 1" of shank to fit up into the collet and I'm afraid of the grip due to the flat that is ground into the center of the shank. I guess it would be OK if I'm careful as not to put too much of a side load against it. So, I'm wondering if that type and size end mill is just too big for my BP or if ther is another choice as far as tool holders.
PS...... I could grind the center down to 3/4" and then part them, that should get rid of most of the flat.

JL........................

Toolguy
07-27-2012, 03:26 PM
You use the R8 setscrew holders for those, the larger sizes stick out quite a bit below the spindle. I have used up to 1-1/4 many times and they work amazingly well on a Bridgeport sized mill. They can be used on smaller machines with light cuts and some caution.

KiddZimaHater
07-27-2012, 04:18 PM
Here's what ya need:
7/8 endmill holder RB for Bridgeport (http://www.ebay.com/itm/7-8-R8-End-Mill-Holders-Bridgeport-Holder-Milling-/390414394413?pt=BI_Tool_Work_Holding&hash=item5ae682e42d)

loose nut
07-27-2012, 04:19 PM
I bought some cheap (odd size sale) double end mills, had the same problem so I cut them in half with a zip wheel. Two for one sale.

Dr Stan
07-27-2012, 04:42 PM
Here's what ya need:
7/8 endmill holder RB for Bridgeport (http://www.ebay.com/itm/7-8-R8-End-Mill-Holders-Bridgeport-Holder-Milling-/390414394413?pt=BI_Tool_Work_Holding&hash=item5ae682e42d)

Those are intended for single end.

In general 5/8" and up double end mills do not fit well in collets and double end mills do not fit in end mill holders. I just had to cut a 1/2" double end mill in half so it would fit in an end mill holder.

JoeLee
07-27-2012, 06:15 PM
Well I'm aware of the set screw type holder, what do they call that??? Weldon shank???? I think. I have a couple of them for smaller dia. end mills, but I never really liked them because they tend to load the cutter to one side and make it run slightly eccentric. I should have been more specific about holders in my first post...... like are there any R8's that have a deeper bore??? Worst case senario, I'll make two out of one.

JL....................

lazlo
07-27-2012, 07:45 PM
The 7/8" R8 collet is sketchy -- it's just gripping by a really tiny portion of the front collet. The "authentic" Bridgeport R8 collets only went up to 3/4", IIRC.


Well I'm aware of the set screw type holder, what do they call that???

"Endmill holder"

Dr Stan
07-27-2012, 07:57 PM
like are there any R8's that have a deeper bore??? Worst case senario, I'll make two out of one.

I've never seen any deeper R8's and given the way they hold a cutting tool I don't see any advantage. Personally I think getting 2 out of 1 and then taking the shank down to 3/4" is your best bet.

ammcoman2
07-27-2012, 08:07 PM
I have a 60 degree dovetail cutter with a 7/8" shank that I use with an R8 collet. The Weldon flat is just barely covered and the cutter is out a fraction of a thou. I know I should get a decent 7/8" endmill holder but I rarely use this particuler cutter, and do take it easy when doing so (cutting one surface at a time). So far it hasn't "climbed" out of the collet. With all my other endmills I do use the proper endmill holder.

Geoff

gnm109
07-27-2012, 08:39 PM
I didn't even know that R8 collets were made in 7/8" diameter. I have a whole set of Weldon Shank type holders all the way up to 1-1/2". I have some sidecar parts that I make where I pluinge mill with an 1-1/2" roughing E.M. I wouldn't care to put much sideload on such a large tool, however.

If you don't want to cut the double ended E.M.'s you could get a W.S holder just for those.

justanengineer
07-28-2012, 01:53 AM
I didn't even know that R8 collets were made in 7/8" diameter.

They are actually made much larger than 7/8. My set goes up to 1 1/4" but the collet bore is then entirely below/outside the spindle.

I would suggest the OP check the end mill in the collet, without the collet in the mill. Ive seen several examples of homemade R8 drawbars that were overly long and would not allow some tooling to fit properly due to the drawbar taking up most of the room inside the collet.

gnm109
07-28-2012, 05:23 AM
They are actually made much larger than 7/8. My set goes up to 1 1/4" but the collet bore is then entirely below/outside the spindle.

I would suggest the OP check the end mill in the collet, without the collet in the mill. Ive seen several examples of homemade R8 drawbars that were overly long and would not allow some tooling to fit properly due to the drawbar taking up most of the room inside the collet.

That's really unusual. I've not seen any collets that extent below the spindle.

Paul Alciatore
07-28-2012, 05:30 AM
They are actually made much larger than 7/8. My set goes up to 1 1/4" but the collet bore is then entirely below/outside the spindle.

<snip>

I have a 7/8" one like that in my set and frankly I don't know what it would be good for. It seems to me that if you try to grip tight with it, the "jaws" would just flare outwards and be useless. Kind of the opposite of the better grip that a larger cutter would need. I have not used it and don't know if I ever will. I guess it lets them say that their sets go up to that size, but, in truth, it is worthless.

If I get any cutters with larger shanks, I will get the set screw type holders for them.

uncle pete
07-28-2012, 06:47 AM
I will admit that double ended end mills can and do work. They are and have been completely proven under industrial conditions. Call me anal or whatever, I do have a issue with clamping down hard enough on any double ended end mills exterior cutting surfaces hard enough to keep it from spinning within any collet, You have in fact hardened and precision ground surfaces on both the end mill and the internal collet that are or should be hardened and ground. In a perfect world with .0000000 tolerances? It can and would work. Clamp down on any double ended end mill with a precision collet? You would have hardened and ground internal surfaces on the collet and the external hardened and finely sharpened surfaces on a good end mill, Given the real world realities of nothing is ever perfect? A hardened ID along with a good end mills OD. That never seemed to me a great logical combination. I've yet to buy a double ended end mill, but it sure seems like a rather rinky dink way to save a few bucks while adding a hell of a lot of wear and tear to your collets and f%%king up those high cost precision sharpened end mill surfaces. An end mill or set screw Weldon shank type tool holder may be in fact the only tool holder that double ended endmills are designed for.

Possibly I don't understand or know what I should, and my thoughts aren't correct. Anyone care to correct me? 100% either way, it's extremely doubtful I'll ever buy any double ended end mills and take a chance on screwing up what Bison considers a pretty decent ER series for my collets. I even own a full set of Weldon type endmill holders. Fair enough you can score some endmills at a yard sale, but I'm not ever going to go out of my way at this point to find any double ended endmills.

Pete

JoeLee
07-28-2012, 09:31 AM
That's really unusual. I've not seen any collets that extent below the spindle.
My 1" Lyndex extends below the spindle, the 11/16" collet fits up in the spindle like all the smaller size ones do.

JL.............................

Doozer
07-28-2012, 11:22 AM
You can buy up to 2" end mills with a 3/4" shank.
You can buy up to 1" end mills with a 1/2" shank.
Do people not know this?
Open your catalogs.
--Doozer

becksmachine
07-28-2012, 01:03 PM
Well I'm aware of the set screw type holder, what do they call that??? Weldon shank???? I think. I have a couple of them for smaller dia. end mills, but I never really liked them because they tend to load the cutter to one side and make it run slightly eccentric. I should have been more specific about holders in my first post...... like are there any R8's that have a deeper bore??? Worst case senario, I'll make two out of one.

JL....................

One of the problems with this solution is that you will now have only half as much shank length, and part of that length is negated on one side by the remaining portion of the Weldon flat. This makes the bending forces all the more onerous.

Given that it is already a tenuous grip, large end mill, relatively flexible collet/Weldon holder, and lots of overhang, it should be obvious that this set up should be used with only the lightest cuts.

Dave

justanengineer
07-28-2012, 02:26 PM
I have a 7/8" one like that in my set and frankly I don't know what it would be good for. It seems to me that if you try to grip tight with it, the "jaws" would just flare outwards and be useless. Kind of the opposite of the better grip that a larger cutter would need. I have not used it and don't know if I ever will. I guess it lets them say that their sets go up to that size, but, in truth, it is worthless.


I havent had any issues with the few I have like that, but I also dont have the common issues of spinning cutters in the collet like others do so take my advice for what it is - good within reason I hope.

Black_Moons
07-28-2012, 03:08 PM
You can buy up to 2" end mills with a 3/4" shank.
You can buy up to 1" end mills with a 1/2" shank.
Do people not know this?
Open your catalogs.
--Doozer

Yea I don't get why people are buying these oddball sizes then worrying about collets and stuff.
Everyone else on earth with R8 just buys 3/4" reduced shank tooling. your machine is not rigid enough to be worth 1" shank and 3/4" reduced shank is very common because... R8.

loose nut
07-28-2012, 03:56 PM
Cost.

I can buy odd sized over stocked endmills, or used to be able to, from Wholesale tools, an example of which is 15/16' double endmill with a 7/8" shank for less then $2.00 then cut it in half and I have 2 endmills for under a buck each. I use these for light facing cuts only so the actual size doesn't matter. Since this is a hobby and not a business cost figures greatly into it. I have a limited hobby budget which is diminishing all the time and also I'm a cheap bugger.