R8 Drill Chuck + Screw?

This topic has 12 replies, 10 voices, and was last updated 27 January 2017 at 17:14 by Brian Oldford.

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27 January 2017 at 11:33 #18379
Martin Kyte
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@martinkyte99762
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27 January 2017 at 11:33 #280532
Martin Kyte
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@martinkyte99762
Hi Chaps

I bought a drill chuck for the Myford Mill at the show last week (R8 arbour + Keyed Chuck) and the chuck is just a taper fit with no retaining screw. I'm thinking I need to fit one. Any thoughts/things to bear in mind.?

regards Martin
27 January 2017 at 11:38 #280534
clogs
Participant
@clogs
Hi Martin.

providing we're talking about the taper fitting for the chuck to the mandril, make sure the taper and the hole is perfectly clean (no oil) and dry……..put them together with push and twist…thats it job done….some say a light tap to get them to seat together !!!!!!!!!!

clogs
27 January 2017 at 11:49 #280537
Emgee
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@emgee
Plus 1 for Clogs post as it is a DRILL chuck.

Emgee
27 January 2017 at 14:06 #280580
Robbo
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@robbo
Plus 2 for Clogs, drill chucks don't have a drawbar. If you do give it "a light tap" to seat it (I always do) use a soft mallet and make sure the jaws are withdrawn into the body before you hit it.
27 January 2017 at 14:59 #280592
Martin Kyte
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@martinkyte99762
Well I cannot say I'm overly convinced. I do get the point about self holding tapers and I'm sure it's going to be better once it's not slathered in oil like it is at the minute. What bothers me is the tap I give to the drawbar to remove the R8 taper and I cannot get images of the trotters and the chandelier out of my mind so i keep seeing the drill taper letting go instead of the R8. Silly I know because I agree with the theory and would not care on the lathe where the chuck is horizontal. Still I will clean it off and give it a go.

regards Martin
27 January 2017 at 15:42 #280603
HOWARDT
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@howardt
I have just swapped a B16 mount drill chuck over from a MT3 to an MT2, it has been on the MT3 for a year. The chuck was opened to its full extent so that I could put a rod up to the base of the B16 taper, gave a sharp tap and the taper released ( as expected). Then a quick wipe on the B16 with MT2, place it in the chuck, a quick tap on the bench with the MT2 small end, job done.

Always done it this way and never had anything come off. intact it is usually the other way round, trying to get the !!!! off.
27 January 2017 at 15:43 #280604
old Al
Participant
@oldal
Just remember its a DRILL chuck. Dont ever think you can take the lazy route and do a quicky milling job with the drill chuck holding a milling cutter
27 January 2017 at 16:11 #280610
Robbo
Participant
@robbo
Martin

It is a drilling chuck, the pressure on it is axial. The pressure on the drill pushes it into the taper.
27 January 2017 at 16:21 #280613
Anonymous
Posted by old Al on 27/01/2017 15:43:55:

Just remember its a DRILL chuck. Dont ever think you can take the lazy route and do a quicky milling job with the drill chuck holding a milling cutter

Oooopsie!

Andrew
27 January 2017 at 17:12 #280624
Spurry
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@spurry
Posted by old Al on 27/01/2017 15:43:55:

Just remember its a DRILL chuck. Dont ever think you can take the lazy route and do a quicky milling job with the drill chuck holding a milling cutter

Does using a slot milling cutter count? I have to admit to using them for small counterbores, on occasions. Would agree that using the cutter's side faces is not to be recommended, with a drill chuck.

Pete
27 January 2017 at 17:13 #280625
Tony Pratt 1
Participant
@tonypratt1
Never ever had a properly fitted chuck come off its arbor. A light tap on the draw bar top will free a R8 taper.

Tony
27 January 2017 at 17:14 #280626
Brian Oldford
Participant
@brianoldford70365
According to Wobblypedia "

R8

collets with R8 taper

This taper was designed by Bridgeport Machines, Inc. for use in its milling machines. R8 tapers are not self-holding, so they require a drawbar extending up through the spindle to the top of the machine to prevent loosening when lateral forces are encountered. They are also keyed (see image) to prevent rotation. The drawbar thread is typically ⁷⁄₁₆″–20 tpi (UNF). The angle of the cone is 16°51′ (16.85&deg with an OD of 1.25″ and a length of ¹⁵⁄₁₆″.^[13] (source, Bridgeport Manufacturer) The resultant inner diameter is slightly over ³¹⁄₃₂″.

Tools with an R8 taper are inserted directly into the machine's spindle. R8 collets are typically used to hold tooling with round shanks, although any shape can be held if the collet has the correct corresponding shape cut in it. The collets have a precision bore with axial compression slots for holding cutting tools and are threaded for the drawbar. The R8 system is commonly used with collets ranging in size from ¹⁄₈″ to ³⁄₄″ in diameter or tool holders with the same or slightly larger diameters. The collets or tool holders are placed directly into the spindle and the drawbar is tightened into the top of the collet or tool holder from above the spindle. Other tools such as drill chucks, fly cutters, indexable insert cutters, etc. may have an R-8 taper shank built into or added to the tool.

The R8 taper is commonly encountered on Bridgeport and similar turret mills from the USA, or on (very common) copies of these mills from elsewhere. The popularity is due in large part to the success of Bridgeport and other mills that were closely modeled after it and produced throughout much of the 20th century."
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