want2race
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| posted on 10/4/05 at 10:41 PM |
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How do you properly Tap tube?
I bouight some thick wall tube. Its 1/2 inch inside diameter and about 1inch OD.
I intend to tap it to accept a 5/8th inch rose joint / ball joint (call it what you wish)
So I bought a drill bit thinking I could just drill the tube to 37/64ths and then use a tap to go to 5/8ths but I keep snapping drill bits! Whats the
deal? What am I doing wrong?
Any help is appreciated!
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omega 24 v6
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| posted on 10/4/05 at 10:45 PM |
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best to do it on a lathe using the tail stock and a centre to keep the tap true. The drills are probably snapping cause they are snatching in the hole
and twisting your grip until they snap. You could try grinding a shallower point angle on the drill this might help.
[Edited on 10/4/05 by omega 24 v6]
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Hellfire
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| posted on 10/4/05 at 11:20 PM |
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Hi W2R,
As Omega says but regarding the drill I don't think it will have much effect on the 'grabbing' issue if you flatten the point
completely as the drill still retains the rake angle. IMHO your best bet would be to reduce the drill rake angle by taking the cutting edge to the
side of the grinding wheel face and putting an almost neutral cutting rake on the drill. This will prevent grabbing, though it will mean you have to
increase pressure to achieve the same effect. As you are only removing 0.078" (less than 2mm) you are only taking off a minimal amount so the
faster the speed and the lighter the feed the better the result will be. Alternatively you would be better 'reaming' it out.
Youi don't mention what material the tube is though if it is aluminium it will grab more than if it is steel. If it is aluminium, you could
always use paraffin to lubricate it (old machinist's trick) but be very weary of the fire hazard.
If you get stuck - this is a good place to look for tips on drilling. DRILL GRINDING
HELP
Good luck - HTH
[Edited on 10-4-05 by Hellfire]
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clbarclay
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| posted on 11/4/05 at 09:26 AM |
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If you have the lathe then you can try a center tool and lathe (not sure what the correct term is) the hole out to the correct size.
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MikeP
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| posted on 11/4/05 at 06:59 PM |
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You can buy tube that's already the correct ID for tapping. Many race shops have it, http://www.chassisshop.com/ have some in their
catalog under tubing.
It'll let you skip past breaking drill bits and move right into snapping taps instead  .
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want2race
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| posted on 11/4/05 at 07:03 PM |
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doesnt help since I already own the metal and it wasnt cheap!
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MikeP
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| posted on 11/4/05 at 08:41 PM |
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Yeah, I guess it doesn't, sorry. Threadable tube isn't cheap either  .
Of course if you factor in the cost of the broken drill bits and buying a lathe... 
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madman280
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 posted on 11/4/05 at 10:09 PM |
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You say you are using 5/8" rod ends. They generally have a fine thread so we're talking 5/8 18 TPI. If I recall correctly the tap drill
size should be 37/64" that should give something like 75% thread depth with is good. Getting there from 1/2" with a hand held drill
I'd be inclined to use the next larger drill I had from 1/2 then the next, little by little until you are at the right tap drill size. If you
try to enlarge the hole with a tap you WILL break it. If you have access to a lathe, which from the content of your message I'd assume not you
could do it in larger steps. So just take it slow and easy, a little at a time and lubricate things with oil at the very least and every so often back
the drill out to clear the chips out. They say you can pay in time or tools. Break the wrong one or buy the right one or take it slow. A drill that
size generally isn't too cheap.
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907
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| posted on 11/4/05 at 11:09 PM |
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As you have no lathe....
Cut to length and tack them to a plate, on end, and drill them on a pillar drill...
if you have one.
If not, please ignore this post.
Paul G
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