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Discussion Starter #1
well I took the rocker pin that I could barely get a 5mm bolt into(maybe 1-1 1/2 turns) and screwed a 5mm tap into it. I turned it maybe 5 or 6 at turns. After the first time I did it I tryed the 5mm bolt into it and not much difference. So I tryed again with the tap a few more turns than 5 or so. I took it back out but noticed a sliver of metal on the end. Almost like a thread came out with it. The 5mm bolt I can now get screwed in about 4-5 turns. So was that metal sliver that looked like a thread supposed to happen when you tap threads that are messed up? Or did I do something wrong and mess up threads and pull one of them out?
 

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You might have just cut a little more thread in there. Sorry I couldn't make sense of the first bit of your post.

If you are tapping a thread it will create slivers of some type, cleaning shouldn't bring much out but as I said if you went deeper than the original it will produce more swarf.

Just re-read the post.. are you sure the thread pitch was the same as the bolt?

Mal
 

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sounds like you did it just right. now you should be able to get the stuck rocker pin out, just make sure you thread the extractor bolt in all the way, and if it won't bottom out, get a longer one, then proceed extracting. be sure to lightly emory cloth the pin once removed and heavily grease it upon reinsertion.
 

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Discussion Starter #4
onespeedpaul said:
sounds like you did it just right. now you should be able to get the stuck rocker pin out, just make sure you thread the extractor bolt in all the way, and if it won't bottom out, get a longer one, then proceed extracting. be sure to lightly emory cloth the pin once removed and heavily grease it upon reinsertion.
Actually I could get the rocker pin out in the first place. But just barely could get that bolt on it because it barely threaded. So I wanted to make it easier for next time.

Even after doing the tapping the bolt won't go in even further than 5 turns or so. But some of the others won't either. But at least now it will go in more than 2. I'm just curious did I do it right or screw it up?
 

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Replace it I would not take the chance but that's just me.
 

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you did it right. :D

i mentioned the stuck rocker, because i recently had one stuck, and the slide-hammer tool only egaged 1-3 threads and ripped the threads of the screw. i chased the rocker pin threads, and got a longer screw for the slide hammer tool.
 

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Discussion Starter #7
onespeedpaul said:
you did it right. :D

i mentioned the stuck rocker, because i recently had one stuck, and the slide-hammer tool only egaged 1-3 threads and ripped the threads of the screw. i chased the rocker pin threads, and got a longer screw for the slide hammer tool.
Does chasing mean tapping? Same thing? You needed the longer screw because the first few threads were dead. So basically what I did was tear into the metal fixing bad threads, not tear out good threads?
 

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Chasing and taping are to different things. Taping is creating new threads in a bare hole, chasing is just cleaning out the hole of crap(old loctite, mashed threads, broke threads etc.) you are chasing yours to fix the damage you did. Sounds like yes you just fixed the bad threads ... if the screw threads in nicely now then you did a good job. Be very careful with taps as they are very brittle and can break very easy, then they are almost impossible to get out. It is best to thread a screw into a good shaft first to see how deep the threads are and then mark the tap so you no not to go to far, then gently go 1/2 to 3/4 turn in then 1/4 back out over and over untill the threads are all better. Turning the tap back cleans the crap out of the taps cutters and helps prevent the tap from getting stuck or broken. Don't use cutting fluids or lubes for chasing threads as they tend to build up the crap and cause problems (stuck taps), fluids/lube are for cutting new threads.

Tap/chasing 101
Hope this wasn't overkill
JD
 

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Discussion Starter #9
853MACHINE said:
Chasing and taping are to different things. Taping is creating new threads in a bare hole, chasing is just cleaning out the hole of crap(old loctite, mashed threads, broke threads etc.) you are chasing yours to fix the damage you did. Sounds like yes you just fixed the bad threads ... if the screw threads in nicely now then you did a good job. Be very careful with taps as they are very brittle and can break very easy, then they are almost impossible to get out. It is best to thread a screw into a good shaft first to see how deep the threads are and then mark the tap so you no not to go to far, then gently go 1/2 to 3/4 turn in then 1/4 back out over and over untill the threads are all better. Turning the tap back cleans the crap out of the taps cutters and helps prevent the tap from getting stuck or broken. Don't use cutting fluids or lubes for chasing threads as they tend to build up the crap and cause problems (stuck taps), fluids/lube are for cutting new threads.

Tap/chasing 101
Hope this wasn't overkill
JD
Wow thanks. I didn't know all this. I did "chase" it as far as I could have. But really there is no need as I just needed to be able to screw a bolt in 4-5 turns good so that in the future someone won't have a problem. The guy who gave me this tap said use WD-40 to lube but he probably didn't know I was chasing. I didn't know about going in a little and backing out. But makes sense.
 

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Discussion Starter #11
853MACHINE said:
This is just from personal experiance building aircraft piston engines(15 yrs+), I'm sure there is someone that will disagree with what I've written.


Hope it does you good though.

Why is it that there are more space engineers and aircraft engineers on a Ducati forum than on any other forum I go to? Meanwhile I work on freakin computers for a living and am not mechanically inclined. Definitely the wrong bike for me.
 

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Not so fast there !

"Chasing"....a vague and ambigous term....also means that a bottoming tap is used. A bottoming tap means that the cutting thread feature of the tap is of a constant diameter all the way to the bottom of the tap.

This is not the same as a normal tap which you would ask for !

If you do not do this, then the threads at the bottom of the hole will not be cut or chased to the same diameter as those in the upper area of the thread. You need the regular tap with it's tapered, incrementally greater thread cutting diameter to get things going and remain centered in the hole. Then the bottoming tap.

Make sense now ?

grendels_arm said:
Wow thanks. I didn't know all this. I did "chase" it as far as I could have. But really there is no need as I just needed to be able to screw a bolt in 4-5 turns good so that in the future someone won't have a problem. The guy who gave me this tap said use WD-40 to lube but he probably didn't know I was chasing. I didn't know about going in a little and backing out. But makes sense.
 

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Discussion Starter #13
bevel450 said:
"Chasing"....a vague and ambigous term....also means that a bottoming tap is used. A bottoming tap means that the cutting thread feature of the tap is of a constant diameter all the way to the bottom of the tap.

This is not the same as a normal tap which you would ask for !

If you do not do this, then the threads at the bottom of the hole will not be cut or chased to the same diameter as those in the upper area of the thread. You need the regular tap with it's tapered, incrementally greater thread cutting diameter to get things going and remain centered in the hole. Then the bottoming tap.

Make sense now ?

No not in the least. I went into True Value and asked for a 5mm tap. Got one. Used it on the hole. I can now get 4-5 turns. A sliver of metal did come out the second time through. No idea about anything else.

Do i need to do something more now?
 

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Sam-

I'll take a whack at answering your question. Ducatis tend to make "engineers and machinists" out of many of us due to the lousy quality control which the company had through the years up to the 999 era. That is a terribly sad thing to say, but rather true. The current era bikes are undoubtedly making more Ducati riders than Ducati mechanics, so what work needs to be done nearly always involves installation of an accessory.

( Oh...I forgot to add that it makes many of us far more fluent in the mysteries of electricity than we ever bargained for ! LOL )

Also, the bikes are both fascinating and relatively easy to work on, which probably both delights the mechanically fluent, and sucks the rest of us into some higher level of mechanical ability than we ever intended just out of self defense.

Sorry it is that way. The above is just one enthusiast's take on the issue and may partially explain why I have never been without a spare Duc in the household. And why I always have a spare bevel motor in a crate for disassembly, explanation and discourse to the girl friend dujour who just can't make much sense out of these neuroses of mine.

Lastly, is Springfield close to Manassas ? I was there over the weekend and thought to ring you up but ran out of time. Perhaps next time.


grendels_arm said:
Why is it that there are more space engineers and aircraft engineers on a Ducati forum than on any other forum I go to? Meanwhile I work on freakin computers for a living and am not mechanically inclined. Definitely the wrong bike for me.
 

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I don't know. A couple of the earlier responses seem to make sense, and I am leaning toward mals comment on having the right thread spec tap. Did you/can you confirm it is the same thread on both, other than "5mm" ? Coarse or fine or ???

Have re-read the responses and haven't heard anyone confirm the exact match so I am going to be conservative and assume the worst. I haven't messed with this particular problem on a Duc and am not speaking from first hand experience on this. Just a lot of general experience in tapping/chasing holes on bikes.

Does that help ? From what I hear, all of the responses here support what you are seeing there ( so far).

grendels_arm said:
No not in the least. I went into True Value and asked for a 5mm tap. Got one. Used it on the hole. I can now get 4-5 turns. A sliver of metal did come out the second time through. No idea about anything else. Do i need to do something more now?
 

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bottoming taps, and being a home machinist

+1 bevel450 for recognizing what is probably going on with these holes, and a bottoming tap required.

Unfortunately, not all engineers are good mechanics either. After a dept. lunch a couple years ago, a co-worker's car turned over but wouldn't start, and he asked if the battery was dead. This was an honors engineering graduate. But then again I am sure that engineer writes with far fewer typo's than I do. Sad but true.......
 

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I wouldn't worry too much about using a tap with the wrong thread pitch. The rocker pins are hardened and you probably would have broken off the tap had you used the wrong one. The small peice of metal you pulled out could have been a piece of thread from another bolt that was used to pull the pin out earlier. I have an A&P license, been a machinist for the last 7 years, and turned wrenches on a lot of different engines and so far from what I see all you have gotten is good advice!
 

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Discussion Starter #18
bevel450 said:
Sam-
Lastly, is Springfield close to Manassas ? I was there over the weekend and thought to ring you up but ran out of time. Perhaps next time.
Yep maybe 10 miles. My sister used to live there.
 

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Discussion Starter #19
bevel450 said:
I don't know. A couple of the earlier responses seem to make sense, and I am leaning toward mals comment on having the right thread spec tap. Did you/can you confirm it is the same thread on both, other than "5mm" ? Coarse or fine or ???

Have re-read the responses and haven't heard anyone confirm the exact match so I am going to be conservative and assume the worst. I haven't messed with this particular problem on a Duc and am not speaking from first hand experience on this. Just a lot of general experience in tapping/chasing holes on bikes.

Does that help ? From what I hear, all of the responses here support what you are seeing there ( so far).

I have no idea if it's coarse or not. There was only one 5mm they had and I think it was .8 or .08 I forget.

At this point I don't think it's worth messing with anymore I don't think.
 
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