Suggestions For Loosening Frozen Machine Screws?

Free Republic ^ | 12 March 2017 | Windy

[Windflier]

The problem with dissimilar metals (steel bolt and aluminum block) is the galvanic action (corrosion) that tends to occur between dissimilar metals that can bond the two metals together. You need to achieve expansion and contraction to break that bond.

Noted. Thank you!

[Windflier]

A lot of others have recommended the home brew penetrating oil you suggested. I will probably go that route, and use some localized heat to break the corrosion bond.

Thanks.

[Windflier]

I don’t know why the designer would have specified self-tapping screws but that’s all I can think of as a possible cause.

The screws are standard machine thread, not self tapping. The consensus here, is that the cause of the problem is dissimilar metals, which has induced corrosion between the screws and the block.

[Windflier]

you have 2 very dissimilar metals. Steel and aluminum. They have different expansion rates. Maybe bring a little heat to bear. As they cool, break them loose.

Someone suggested using a soldering iron to localize the heat, and thus protect the adjacent neoprene feed rollers. That, plus a high grade penetrating oil, and patience, sounds like the key.

Thanks for your help.

[Windflier]

Repeated thermal cycling.

I assume that means heating, then cooling, and repeating as necessary?

[Windflier]

That’s a great idea for the next to last resort. I’m going to try lubricants and heat before taking it to the next level.

Thanks.

[Windflier]

Thanks for your help, Trebb. FR is a supermind.

[barmag25]

I have seen a hole tapped for course threads and then fine thread bolts forced in with an impact. And vice versa. Basically tapping as you go with force.

You might have to drill.

More than likely it doesn’t have Loctite on it when installed. Loctite would of prevented any corrosion enabling you to break it loose.

Loctite only increases the area of contact between the threads which is around 25% contact. Loctite increase that by filling in the gaps.

Drill it out and retap. Make sure the tap thread pattern match the new bolts you will use to reinstall.

I also remove stripped or bolts with broken heads all the time with left handed drill bits drilling counter clockwise right into the body of the bolt.

[Windflier]

PB B’laster. About $3-4 at any wal mart. It’s the best stuff I’ve ever seen for what you’re talking about.

A lot of folks here seem to like it. Many are saying that a homebrew 50/50 mix of acetone and transmission fluid is even better.

I may try both ;-)

[Windflier]

The three best chemicals are PB Blaster, PB Blaster, and PB Blaster.

Sounds like a pretty strong product endorsement ;-)

Actually, an electric heat gun will help a lot, too. Use a real heat gun, not a hair dryer. You can buy one from Harbor Freight for around ten bucks. The coefficient of thermal expansion of aluminum is nearly double that of steel, so a good warmup will expand the aluminum around the steel and help a lot.

I can do ten bucks for a heat gun. I'm reluctant to use my propane torch because of the nearby neoprene rollers.

Thanks!

[Windflier]

Call in a machinist. You don't appear to have the tools or experience right now to deal with this. Look over their shoulder and learn for next time.

No need for that, friend. I've been a tradesman for forty years, and have done a fair amount of wrenching in my days. I just never ran into a set of screws so tightly bound before.

This really ain't rocket science, and I'll probably have the whole assembly apart by tomorrow. In the meantime, my machine is still running on its other two drives. I'll get the third one back online by this weekend at the latest.

I do appreciate the concern and good advice.

[right way right]

I have seen loc-tite and or interference screws used in the type of application you describe. Manufacturers are more concerned with vibration loosening the parts than you being able to easily service. They want to sell you a new expensive part.
You may have to drill those heads off.
You may find a better quality allen bit socket somewhere too.

[HandyDandy]

Just looking at the picture of the bolt I have to say I have only seen that style of bolt used to attach a “plate” that is no thicker than the depth of the countersunk flank. Is what you are calling a “block” actually a thin plate?

[HandyDandy]

In other words, do those bolts pass through one part and get threaded into another?

[onona]

You got it. Careful you don’t ignite the loosening fluids.

[right way right]

Whooo man, just a little dose of PB Blaster smoking vapor will turn you green....right before you drop dead.

[Trod Upon]

Blue wrench is just slang for a torch flame. We don’t want to go there if possible :) Just give a little rap on the fastener head, like driving a nail. The object being to break the corrosion up slightly—really just kind of sending a shockwave through the assembly without deforming anything other than the corrosion. Do it after letting the Kroil work on it for a while If the fastener head is soft, like aluminum, take a little care not to mar it up. Just a sharp/quick, but still soft tap with the smallest ball peen you have. Good luck.

[FreedomStar3028]

So, what happened? Were you able to get them out or not?

[Windflier]

Botox may work for windflier? ;^}

I do have a few wrinkles. Might help me to get back my boyish good looks ;-)

[Windflier]

Good luck! Let us know what works.

I most definitely will, and I'll take pics to give all my good Freeper friends a better idea of what I was dealing with. Many thanks!