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What Type Of Washer To Reduce Friction Between Moving Meatal Parts

9803 Views 14 Replies 10 Participants Last post by  JIMMIEM
I'm fixing the metal arm on pull down attic stairs. The rivet that attaches the metal arm to the fixed metal frame plate has worn out. This allows the arm to go out of alignment and the spring to pop out of its travel path. I've drilled out the rivet and will use a lag screw to attach the arm to the plate and penetrate the wood frame and attic floor joist. The lag screw will hold the metal arm to the metal frame plate but the arm has to be able to pivot. I'm planning on sandwiching the metal arm between 2 washers....one washer between the arm and the lag screw head and the other between the arm and the metal frame plate.
What type of washers to use? Plastic? Nylon? Fiber?
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White or black nylon washers work great. They hold up better than the softer plastic ones do. Black nylon (delrin) is supposedly self lubricating.
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I'm 100% with Doug.
White or black nylon washers work great. They hold up better than the softer plastic ones do. Black nylon (delrin) is supposedly self lubricating.
Thank You!!!
Jim; if they're lag bolts, there's no mechanical advantage to cranking them down tightly.
Leaving a couple of thou clearance alone will greatly reduce the friction. The wear on the arm-holes, and bolt shanks where they contact, might be a concern?
Jim; if they're lag bolts, there's no mechanical advantage to cranking them down tightly.
Leaving a couple of thou clearance alone will greatly reduce the friction. The wear on the arm-holes, and bolt shanks where they contact, might be a concern?
I'll be using a 3/8" lag screw......#8 if they have it. I'm not sure of the gauge of the arm or mounting plate metal but they are not thin or flimsy. The manufacturer connects them with a rivet. I've contacted the manufacturer and this type of wear is not an uncommon problem. I've seen some on-line blogs and a lot of folks seem to have encountered the same problem. One blogger was going to use a hex bolt and nylock nut to make the connection....not a bad idea but the bolt head would not be accessable if the nut ever loosened....so I decided to go with a lag screw. I could buy an entire arm assembly from the manufacturer but I figured I'd try this quick and less expensive fix first. This is for attic pulldown stairs which get very little use.
Depends on often you use the stairway. Mine has been in the ceiling for a bit over 20 years and not worn out yet. I am, though.
If the stairway has worn out the original hardware already, go with metal washers and lightly coat them with Vaseline. The plastic will wear out.
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Using 2 or 3 metal washers works better than just one.
the lag is softer than the original rivet... it won't last either..
the lag is softer than the original rivet... it won't last either..
If it doesn't I can always buy the entire arm assembly from the manufacturer.
I had trouble with the real holder in a wire feed MIG welder. The wing nut would tighten itself against the spring that offered friction to keep the reel of wire from coasting during the starts and stops of the feeder. I tried several kinds of metal and plastic type washers. and all transferred enough friction to the wing nut that It would tighten. I finally has success with a grade 8 hardness washer. If nothing else works, try some of them.

Charley
If it doesn't I can always buy the entire arm assembly from the manufacturer.
Sometimes the ultimate solution is to replace the defective mechanism, if it is still available. If you are going to attempt repair, I agree with Doug on the nylon washer.
Sometimes the ultimate solution is to replace the defective mechanism, if it is still available. If you are going to attempt repair, I agree with Doug on the nylon washer.
When I realized what the problem was the first thing I did was call the manufacturer and was told that they sold a replacement for the worn out part. I did some internet searching and came across the blog concerning fixing rather than replacing the part. A lot of folks chimed in and all said they had success with the fix. I spent $3.00 for fixit hardware. If the fix doesn't hold up then I can always buy the part from the manufacturer. I was kind of surprised at the failure rate of this part. FWIW the stairs still function with the loose part and have been this way for several years. My neighbor has the same problem with his stairs. I told him that the manufacturer has the replacement part which I would install for him or, if he would like, I could do the same DIY fix that I am doing form my stairs. I'll do the DIY on my stairs first and if he likes the result I will do his stairs.
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I'm with John, go wit metal washers. Don't try to over think the problem, metal on metal will last for ever on something like attic stairs that are only puled down occasionally.
I'm with John, go wit metal washers. Don't try to over think the problem, metal on metal will last for ever on something like attic stairs that are only puled down occasionally.
I'm done thinking!!!!! It's time for doing!!!!!!
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