>:(
Well, I'm in the midst of hoeing a hard row! Servicing a Penn International 50SW for my friend. Started to remove the reel mount from the frame, turned the first 8x32x7/16" screw about a 1/4 turn and the screw head fell off in my hand. Had better luck removing the two front screws. Started on the remaining screw, difficult to turn, did all the normal stuff with penetrants, heat and so forth with no luck. Finally, it too broke under too much pressure from yours truely. These screws are absolutely frozen and have to be removed by drilling them out. To make things worse, the screws seem to be made of the hardest stainless I've had to deal with.
I have a drill press (Min Speed about 500 RPM) and a set (actually several) of the cobalt drills and they will drill the stainless screws SLOWLY, but on my first attempt the drill bit bounced off the screw and went through the aluminum frame like it was butter.
I've tried several different things to no avail. Finally have a hole through the first screw, but not very straight.
Just wondered if this has happened to you. And if so, how did you resolve the issue.
Guess the question is "What is the best way to drill out a stainless steel screw?"
Any help would be greatly appreciated.
josa1
The BEST way is with a mill and stub bits and a very strong hold fast arrangement but I doubt you have access to that (mst don't.) With the bit wandering I'd bet you are using a regular length drill bit and possibly not pre-drilling with a smaller bit? This will probably have to be done in steps, small diameter short bit, small diameter long bit, medium short bit, etc. A lot of work but it is the best way to protect the frame. At the end of the day, the holes in the frame may be shot and then you are looking at tapping oversize holes.
Tough row to hoe.
The Man
Thanks Ron. I used to say in the Commercial Air Conditioning Industry that knowledge is expensive.
I am closely informed that the same is true with drilling these stainless screws. It's agonizing to know that there's only about 1/4" of the screw remaining in the frame.
I don't have access to the machine shop equipment/tools that you mention. So, I'll either have to make use with what I have or send the frame out to get the screw extracted.
A couple of things I've learned. Slower drill speed is better than faster. And, water is a better lubricant for stainless than drilling/tapping oil. Those from stuff I've watched on YouTube.
Thanks for your comments.
josa1
I have a blue point / snap on set # 1020 that i use . It has bushings that have steps in each bushing to aid you to center drill .
One side you drop in to the hole or flip it over to slide over a broken bolt .
You can use copper tube or small sockets as bushings ... or make a tape bushing on the drill bit .
That's a very nice set of tools there Joe. Something I could have used many times in the past.
Just too large for my needs.
I appreciate the ideas on centering the bit on the broken screw a lot. That was my first mistake, not getting the drill bit absolutely centered on the broken screw. Probably the most important first step in drilling out a broken screw!
Thanks a lot!
josa1
;D First step is to see if you are looking at a icicle or a flat top . So you can drill it ...
Whenever removing broken bolts and screws I always use left handed drill bits. Halt the time they will come loose while you drill them.
McMaster-Carr is a good source for left handed bits. Some auto parts stores carry them but they are not always high quality.
Hi pacrat,
I can assure you that these screws are so tightly bound that they may as well be welded to the frame. There is only a very short portion remaining in the hole in the frame. I could not budge them when the head was still attached to the screw, the frame was heated, the screw was heated and I used an impact driver to try to break them loose. The only remaining solution I can see is to totally drill out the remaining portions of the screws and retap the screw hole.
I appreciate your assistance and have put your helpful suggestions in my list of things to remember for future use.
Thanks!
josa1
been there......
i use a propane torch and blast it until it glows. the problem is that any plastic even remotely in contact will melt. you have to strip it down as much as possible. now i ALWAYS torch the soft brass clamp bolts in the old internationals. it's just not worth taking a chance anymore. :-\
Hi Alan,
Thanks a lot for your comments. And, I can sense, your understanding of the current predicament I find myself in.
I am always certain that the best way to loosen stuck parts is to heat them or the body around them. In this case, I am just concerned what that amount of heat would do to the gold anodizing on the reel body. The aluminum is such a good heat conductor that it's pretty much necessary to heat the whole reel body to obtain the required result. I have considered putting the part in the kitchen oven to evenly heat it to some predetermined temperature. I might yet do that.
Have you had the "opportunity" to apply that much torch heat to an anodized part? If so, what was the cosmetic result?
At the present time the minor damage I've done to the body is going to be covered by the rod mount, should I ever be lucky enough to remove the damaged screws and get to the point of reinstalling it!
Thanks again!
josa1
the anodizing will hold up. there might be a slight discoloration, but there is really no other choice. you could soak it in penetrating oil for months and get no results. you are stuck, literally, and i think that this is the best way out. and have patience while drilling.
It is hard to argue with the Boss!
The Man
I agree!
Thanks Alan!
josa1
This might come under the heading of "Stuff I Don't Want to Know About".
But....
Because I was wondering how hot I needed to get the aluminum reel body to cause it to grow enough to release its hold on the stainless steel screws, I learned a little something about the "coefficient of thermal expansion" this morning.
My first question was "What if the stainless grows more than the aluminum as it is heated?" Seems that would be a bad thing as to my uneducated mind that would make the screw more difficult to remove.
Coefficient of thermal expansion is defined as a product's fractional change in length divided by its rise in temperature.
Turns out the coefficient of expansion of the different aluminum products mentioned range from 11.9 to 13.1 for AN AVERAGE of 12.83.
The Coefficient of expansion of different stainless steel products range from 5.7 to 9.6 for AN AVERAGE OF 7.24.
So, in general the aluminum grows at a must faster rate than stainless. It then seems that if the reel body was heated to about 250-300 degrees Fahrenheit it should loosen the bond between it and the stainless screws.
:)
josa1
J will be along to comment shortly I'm certain.
The Man
it heats and then cools. the expansion and contraction will help to break the salt and corrosion that hold the busted screw shaft. you count on these differing expansion coefficients to break these corrosive bonds. or at least that's what i learned in pharmacy school!!! ;D ;D ;D
oh, and i don't hit the entire frame. i just hit the stud, or the hole that holds the stud!!!!
Quote from: Ron Jones on December 16, 2021, 07:18:49 PM
J will be along to comment shortly I'm certain.
The Man
You know me too well. "coefficient of thermal expansion" is like baiting a trap for this science fanboy :) .
But Alan already answered the question. If we wait for the parts to cool, they will return to the original size, so it has to be that we are using the heat to break off/up the corrosion crap (what actually is the composition of that white stuff ?) that is bonding the screw to the frame.
When the frame expands, everything on the frame temporarily gets larger, even the hole diameter. This should help detach the corrosion from the frame, screw, or both. But even if the screw expands first, we would get the same effect. If I had to make a bet, a sudden localized application of high heat (like a torch) will cause greater differential in expansion than more slowly and evenly heating everything in lockstep to a lower temp (like in an oven). But an oven might be good enough. Expansion is a function of temp and the coefficient of thermal expansion (more temp = more expansion). If the Al expands more than the stainless, the hole diameter will increase more than the screw diameter.
I would also be less inclined to bake my dinner in an oven that had been heating up Al parts that may have absorbed lubricants and corrosion cleaners. When preheating a "cleaned" Al part for powder coating, I have seen a lot of nasty stuff leach out.
Whether the heat from a torch also breaks down or weakens the corrosion structure itself is an interesting question.
But in the end, torchlng broken corroded bolts is a pretty common practice for all kinds of mechanical repair. And if it is Alan's preferred method, I would try it first, especially before trying to drill out a stainless screw, which would most likely result in me buying a new frame :)
It is tricky stuff to cut a deep hole in stainless with a small diameter drill without being able to accurately control the feed rate (this I have learned the hard way). Advice like using water as a lubricant seems kinda sketchy.
Hope this helps,
-J
If you used a penetrating oil first but it didn't break free, then it was time to bring out the torch. Even though it didn't work, the penetrating oil probably did some penetrating. So, you have the thermal expansion of the two metals and aluminum oxide impregnated with boiling/burning oil. I don't know.... but hold your breath.
Since you have a hole drilled through the stainless then it should come out with an EasyOut type of extractor
[For future reference]
There are folks who do this kind of stuff for a living.
The technology is called "EDM" (Electrical Discharge Machining).
It can remove the screw without damaging the finish or the threads.
A quick google showed, to my surprise, many portable options (and DIY EDM too!)
https://youtu.be/yUXJiPtWVrk?t=173
We have a couple EDM's where I work.
The precision of these is mind blowing.
The video was interesting to watch. Painfully slow, but interesting.
I have found that on the International reels if the rod clamp screws and reel seat screws feel like they are going to break I stop. I don't go any further. I've been through the same thing. Never again.
Well, as usual most questions raise other questions!
I've not had much chance to work on my project recently due to the holidays. But I'll get back on it soon. Guess maybe I'm just avoiding it a little bit.
After J's note that using water for a lubricant while drilling stainless steel was "sketchy", I watched this video.
https://www.youtube.com/watch?v=frc5BzLId58
What do you think?
Obviously, I'll keep working on these broken screws until I get them removed. I'll then post whatever misery I encountered as I did it.
Happy New Year!!
josa1
Saw this thread and thought I would chime in with some general advice/different strategies I have learned from a few too many attempts extracting broken screws and taps. I know many of you have been doing this far longer than me (and do not need my advice!), but I hope this is helpful to anyone approaching this problem for the first time in the future. Let me preface this by stating that anything I say should be pre-empted by advice from real machinists (of which there are more than a few on this board). I have just spent too many hours of my life battling this problem! Much of my experience is with broken taps and drill bits as opposed to screws, but the same general advice should apply.
In terms of removing stuck screws/broken taps and drill bits, in my experience there are a few main avenues you can take. (I'll refrain from commenting on strategies to loosen/un-seize the screw itself, as others have given better advice than I have on that front previously in this thread):
1) Using vise grips to grab the stuck screw to turn it (only works if you have some stuck screw left)
2) Shattering the screw/drill/tap with a punch and picking out the pieces
3) Drilling out the stuck screw
4) TIG welding a piece of stock to the screw
5) EDM-ing out the stuck screw
Here are some more details on my personal view on the pros and cons of each method:
1) Vise grips: requires that you still have something sticking up above the hole to grab onto with the vise grips. Best bet is to try to break the screw loose with all of the methods mentioned by Alan et al, then grab the screw with the vise grips and try to get it loose. Advantage is that it is the "safest" method in that it is not likely to damage the part, the fastest (if it works!) and is the easiest to do. Disadvantage is that it is basically the same as unscrewing the screw, and if that didn't work, this is not likely to work either. Works best if the issue is mainly due to stripping of the screw head not an underlying issue.
2) Shattering the stuck item:
General principle here is to hit the stuck item into smaller pieces with a punch, and extract them one at a time. Works much better with broken taps (which are often hard and brittle) than with screws. Good news is that this method is unlikely to damage the part but often doesn't work, especially with a screw instead of a tap.
3) Drilling out the stuck screw:
This method is probably the one that people use most commonly. As mentioned by Ron and others, this method can be annoying and time consuming but only requires machines you (likely) already have. Disadvantage is that it can result in damage to the part if done wrong.
If I were to attempt to drill out a stuck screw, here is the general workflow I would try:
1) Make sure the screw itself is flat before attempting to drill it out. Best tool to do this with is an end mill like this one (https://www.mscdirect.com/product/details/58559774). For stainless steel screws, I would recommend a carbide end mill. The key to this succeeding is to make sure the setup is extremely rigid. I would suggest using a vise if possible and clamping the vise to the table of your drill press after aligning the part with the drill chuck. If you don't have a drill press, I would advise not attempting this method.
If you are using a drill press (as opposed to a true milling machine), it is extra important to keep the setup rigid when flattening the top of the screw. Bring the table all the way up to the chuck, put the part in a vise, and use the shortest endmill possible for the job. Carbide in particular is very brittle and prone to breakage, but it is the most effective at machining hardened stainless steel items like screws.
2) Now that the remnants of the screw are flat, you will need to start the hole. It is critical to get this hole centered in the screw as best you can. If the hole is off-center, you will be unable to remove the entire screw via drilling without damaging the original threads. As Ron mentioned, best bet is to start with a small, stubby drill (like a center/spotting drill), and then slowly work your way up to the largest drill (should be the tap drill size for the screw size in question as listed in a standard drill and tap chart). Choosing cobalt steel drills will expedite the process, but you will need various sizes in likely both "screw machine" (short) and "jobber" (longer) lengths. Be careful to not drill beyond the bottom of the hole, or the part can be damaged. Left hand drilling can work as well (same general theory as the EZ-out) but unless you have done a lot to loosen the stuck screw I would not be optimistic that it would work.
3) Now that the screw remnants have been removed, you can begin to re-tap the hole. Extra care should be taken here, as if you happen to break the tap off you will be right back where you started, except this time with an even more difficult tap to extract! If you were not able to drill with the tap drill size, do not bother to attempt tapping, as you unfortunately won't be able to get it to work, since the tap will not be able to remove the material that goes beyond the depth of its threads. Choosing a good tap is key, as you will need a sharp tap to remove the (hard) threads of the old screw. I prefer high speed steel or cobalt taps with a spiral point (you will likely need both a "plug" and a "bottoming tap" to completely clear the hole if it is a blind hole).
- An aside: you can try an EZ-out/screw extractor to remove the screw after it has been partially drilled out. In my experience, this method is unfortunately not often successful if the screw is even marginally stuck. General strategy is to chuck up the EZ out and put the drill in reverse and bring the EZ out in contact with the hole drilled in the work (helps to gradually increase the pressure) and hope the screw comes out! If you are picking out a set of EZ-outs, get the one with the smallest EZouts they have. I have yet to find a good use for the huge EZ-outs present in most sets.
4) TIG welding a piece of hex stock to the screw:
This method works by attaching a proverbial handle to the broken screw by TIG welding on a piece of hex stock which can be gripped with a wrench and turned. Advantages of this method is that it is less likely to damage the part than drilling the screw out. The (somewhat obvious) disadvantage is that you need access to a TIG welder, and if all other "turn the screw out" methods failed, this one is not likely to have any better luck unless you've made drastic progress in loosening whatever caused it to stick in the first place.
5) EDM to remove the stuck screw
This method works by using Electric discharge machining to obliterate the offending material one bit at a time (likely using a custom electrode designed for the size of the screw).
- Advantages: Very likely to remove the stuck screw. If all the methods above sound exhausting, I would recommend this choice. For broken taps, this was our go-to method since it was the most robust and likely the fastest (I never want to see a #0-80 tap in my life again!)
-Disadvantages: Need to find a machine shop that does EDM (I do not have much experience with DIY EDM), can be expensive.
My thoughts on a few random topics from this thread:
Coolants for drilling/cutting Stainless steel:
Any cutting additive has two purposes: cooling the tool/work, and lubricating the cut. Commonly water soluble oils are used for this purpose (here is a link to an example: ). Generally, the water performs the cooling, while the oil provides the lubrication. Too much water and the bit will not cut right, while too much oil will just lead to overheating of the tools and smoking the oil. Best bet is to adjust the oil and water mix proportions on the fly to get the correct mix of both cooling and lubrication for your application. For stainless steel, I used to use coolants like this one marketed for "ferrous metals" (https://www.mscdirect.com/product/details/42963918), while for cutting aluminum, I would recommend Relton A9 cutting oil (https://www.mscdirect.com/product/details/62001292). For aluminum, more lubricating/less cooling will be needed as compared to stainless steel, as aluminum is a "sticker" metal with a lower melting point and is much more prone to fusing to cutting tools, particularly if the aluminum is of low quality (i.e. made from recycled soda cans).
Recovering from thread damage:
If there is any doubt as to the integrity of the threads, they should likely be re-tapped prior to use. Even the smallest burr in the threads can cause galling/cold welding of the screw to the part itself, particularly if the metals are identical. If re-tapping of the original threads does not repair them satisfactorily for use, a helicoil can be a good option to fix the part. The helicoils will take up much less room than any other type of threaded insert, and have the advantage that they will allow you to use the same size screws as the originals and are a better fit if there is a small rim on the frame you are trying to modify. The downside is that you will need specific helicoil size drills, multiple taps and potentially an installation tool. Here is a link to an example if you are interested in going this route (https://www.mscdirect.com/product/details/00060111, https://www.mcmaster.com/helicoil-taps/)
Great write up Ryan. Thank you. Bill
i recently had 3 broken screws in a daiwa sealine. the only difference is the screws were brass.
I was lucky that i had a small bit to get a grip on.
first of all i soaked the screws in WD40 overnight and cleaned any corrosion away with a brass bristle wire brush.
the next day I warmed the frame up with a hot aur gun and GENTLY tried to remove the broken stud. after a bit of perseverance and sweat i got them all out.
I then replaced the whole set with new stainless hex head screws but i coated the threads with grease before screwing them in.
I have an old time machinist with an affinity for a cold beer at 4:45, ten dollar bills, and some conversation.
A VERY valuable resource for certain!
josa1
I have reel bar that snapped the screws . Soaked it for a few days , now I have time to work on it .
Looking at it I did not see the capillary action .
(https://alantani.com/gallery/38/17471-071023174513-38323238.jpeg)
So now I heat it up with a torch , not to hot and dunk it in penetrating oil. I watch it boil until cool ,than repeat this posses several times . In this case it was 4 times
(https://alantani.com/gallery/38/17471-071023174515-383251685.jpeg)
This picture shows that one screw broke flush with bar and the other was standing a little proud .
Just enough to grab with forceps . It move a little and locked up again . Movement is good !
(https://alantani.com/gallery/38/17471-071023174517-38327990.jpeg)
I grabbed the dremmel with a cut off wheel and made slots in the screws . "Note were you want to make the cut " If you are worried about going past the screw and into the surrounding housing , pick a spot that will not show !!
(https://alantani.com/gallery/38/17471-071023174517-383272093.jpeg)
(https://alantani.com/gallery/38/17471-071023174519-38329236.jpeg)
The flush one with the slot did not want to move . So back to warming and dunking.
Finely got movement . The screw driver was slipping a little due to shallow slot , so I did a deeper cut . "Note A wore down cut off blade with less diameter would have been safer to just cut the screw with out worrying about the housing " (https://alantani.com/gallery/38/17471-071023174521-38331365.jpeg)
Take your time don`t force it , rock it back and forth it will come ....
(https://alantani.com/gallery/38/17471-071023174523-383351071.jpeg)
Quote from: josa1 on December 30, 2021, 06:04:20 PMWell, as usual most questions raise other questions!
I've not had much chance to work on my project recently due to the holidays. But I'll get back on it soon. Guess maybe I'm just avoiding it a little bit.
After J's note that using water for a lubricant while drilling stainless steel was "sketchy", I watched this video.
https://www.youtube.com/watch?v=frc5BzLId58
What do you think?
Obviously, I'll keep working on these broken screws until I get them removed. I'll then post whatever misery I encountered as I did it.
Happy New Year!!
josa1
So, I'll be that guy lol!
Did you ever have any luck fixing your reel?
Thanks for your inquiry and interest!
Yes, finally got the broken screws out.
After watching many videos I came to the conclusion that a drill would never work so I made a trip to McMaster Carr and purchased two plunge cutting end mills that are normally used in CNC machines.
I rigged a jig to hold the reel frame in the correct straight line position to the drill chuck which is no easy task as the holes in the reel frame holding the broken screws are drilled at an angle to the frame center line. I made certain that the end mill went through the drilled and tapped holes of the frame from which I had been able to remove the screws
I put the correct sized end mill into my drill press after setting the press to the lowest possible speed setting and SLOWLY lowered the end mill onto the broken screw. The end mill cut the stainless steel effortlessly. The end mill removed the screw remnants and left the threads in the frame intact. There was a tremendous amount of corrosion but was able to clean up the threads with a tap. Probably the best part of the operation is that the end mill centers on the drilled and tapped hole. If removing a broken screw with a drill bit you have to center the drill bit on the broken screw.
Was quite a project but I had fun doing it. It will be interesting to see how I do on the next broken stainless steel screw I run into. But best of all I learned a very valuable lesson....
DON'T BREAK SCREWS!
josa1