Help! How to loosen stuck steel screwed parts?
April 29, 2022 11:39 PM Subscribe
I have somehow screwed the large external shield on a commercial meat mincer tight to the mincing assembly, how do I get it apart?
The mincer is a Bizerba FW-N22. A hammer has been tried. An image is here. Can I put the screwed-on part into very hot water to loosen it? Any ideas to help me keep my job much appreciated!
The mincer is a Bizerba FW-N22. A hammer has been tried. An image is here. Can I put the screwed-on part into very hot water to loosen it? Any ideas to help me keep my job much appreciated!
Can you get more torque from a longer spanner handle, and are you sure you've not cross-threaded the bolts which will need you to cut them off?
posted by k3ninho at 12:14 AM on April 30, 2022
posted by k3ninho at 12:14 AM on April 30, 2022
Heat or increasing the amount of leverage are good first steps for removing stuck hardware.
posted by drezdn at 5:25 AM on April 30, 2022
posted by drezdn at 5:25 AM on April 30, 2022
Also squirt some WD-40 around the threads & let it soak in for an hour.
posted by rd45 at 5:27 AM on April 30, 2022 [1 favorite]
posted by rd45 at 5:27 AM on April 30, 2022 [1 favorite]
Penetrating oil will work better than WD-40 for this kind of situation. And yes - heat.
posted by leslies at 7:07 AM on April 30, 2022
posted by leslies at 7:07 AM on April 30, 2022
Sorry to be contrary but heating causes metal to expand. Very high heat such as a torch in stuck lug nuts is more about breaking the thing bonding the peices.
If you think it's just too tight freezing it overnight might actually help but in reality you need more torque which means longer handles. An oil filter tool (the belt kind) might help here.
posted by chasles at 8:37 AM on April 30, 2022 [1 favorite]
If you think it's just too tight freezing it overnight might actually help but in reality you need more torque which means longer handles. An oil filter tool (the belt kind) might help here.
posted by chasles at 8:37 AM on April 30, 2022 [1 favorite]
Have you taken it apart before? If not, make sure you’re not dealing with a left-handed thread.
posted by jamjam at 8:39 AM on April 30, 2022 [1 favorite]
posted by jamjam at 8:39 AM on April 30, 2022 [1 favorite]
Use an electric hair dryer on the big lobed nut to get it good and hot, and then try again using both hands and a potholder. Tap it with a hammer, lightly, in an unscrewing direction, all around, like you've already done. Find someone with bigger stronger hands, if possible. Lefty-loosen.
After washing the mincer parts with very hot water, wait for the parts to cool before reassembly, and reassemble only loosely.
posted by the Real Dan at 11:20 AM on April 30, 2022
After washing the mincer parts with very hot water, wait for the parts to cool before reassembly, and reassemble only loosely.
posted by the Real Dan at 11:20 AM on April 30, 2022
Strap wrench is definitely going to be the "real" solution on this one.
Everyone is right about temperature, including chasles. The ideal situation would be to chill the inner part to contract it and heat the outer part to expand it. Try freezing the assembly for a few hours, and then focusing your hair dryer on the outer edge of the outer part, ideally heating it while leaving the inner part cold. If nothing else, the temperature cycling itelf could break the parts free.
Footnote: you can do this procedure in reverse to press-fit a bearing into a housing without a hydraulic press. Put your case half in the oven and your bearing in the freezer, and the bearing drops right in after a couple hours!
posted by Krawczak at 11:39 AM on April 30, 2022 [2 favorites]
Everyone is right about temperature, including chasles. The ideal situation would be to chill the inner part to contract it and heat the outer part to expand it. Try freezing the assembly for a few hours, and then focusing your hair dryer on the outer edge of the outer part, ideally heating it while leaving the inner part cold. If nothing else, the temperature cycling itelf could break the parts free.
Footnote: you can do this procedure in reverse to press-fit a bearing into a housing without a hydraulic press. Put your case half in the oven and your bearing in the freezer, and the bearing drops right in after a couple hours!
posted by Krawczak at 11:39 AM on April 30, 2022 [2 favorites]
If you need to heat one part while freezing another, there exist "freeze sprays" that are intended to protect parts of electronics while soldering nearby parts. I've used them successfully to ever-so-slightly shrink part of a stuck lathe chuck, which seems like a similar application as here, and was much more convenient than putting something in the freezer.
So, heat the outer part, hit the inner part with the freezing spray a few times.
Make sure you get freezing spray aimed at industrial or electronic uses -- there now seem to be a variety of cosmetic freezing sprays that are not actually very cold and seem to talk about "cryotherapy" on their cans. The real stuff is dangerous and will give you frostbite in seconds.
As a mildly interesting aside, in most cases there isn't much of a thermal bond between a bolt and the "bolted part". In olden times a wizard with a blowtorch could melt a rivet out of a joint without affecting the rest of the structural parts (so that you could replace the rivet with a modern bolt). They still do this on some bridge repairs as it's easier than drilling out the rivet or spending your day with a pneumatic chipping hammer.
posted by aramaic at 12:16 PM on April 30, 2022 [1 favorite]
So, heat the outer part, hit the inner part with the freezing spray a few times.
Make sure you get freezing spray aimed at industrial or electronic uses -- there now seem to be a variety of cosmetic freezing sprays that are not actually very cold and seem to talk about "cryotherapy" on their cans. The real stuff is dangerous and will give you frostbite in seconds.
As a mildly interesting aside, in most cases there isn't much of a thermal bond between a bolt and the "bolted part". In olden times a wizard with a blowtorch could melt a rivet out of a joint without affecting the rest of the structural parts (so that you could replace the rivet with a modern bolt). They still do this on some bridge repairs as it's easier than drilling out the rivet or spending your day with a pneumatic chipping hammer.
posted by aramaic at 12:16 PM on April 30, 2022 [1 favorite]
My German language skills are not much, but I think according to this page in a manual I found it is indeed a right hand thread.
The accompanying photo shows that when viewed from the front, you loosen it by turning to the left.
Hope this helps.
posted by tronec at 4:27 PM on April 30, 2022 [1 favorite]
The accompanying photo shows that when viewed from the front, you loosen it by turning to the left.
Hope this helps.
posted by tronec at 4:27 PM on April 30, 2022 [1 favorite]
Response by poster: Thanks for all the answers, unfortunately I couldn't get any equipment during shift, the next guy came in and forced the machine so it broke. If you're in Berlin, come to the organic shop rhyming with Rio Tumpenny - we're experts!
posted by runincircles at 7:04 AM on May 1, 2022
posted by runincircles at 7:04 AM on May 1, 2022
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posted by mezzanayne at 11:51 PM on April 29, 2022 [1 favorite]