Pedestal mount repair?

[kstrayhorn]

2000 AlumaWeld 1440 Xpress
The bench has 3 pedestal mounts. The one I use has been loose, but it's been one of those "I'll fix it when it completely fails" kind of issues. Well today it did. I guess after years of torsional stress, the holes in the bench where the mount was fastened have become larger than the screws. Now the mount is not secured at all and can just be picked up and removed easily. Obviously this does not work when sitting on it. I figured I would just put some aluminum square tube or something under the bench and fasten it back down with toggle bolts, easy enough. But further inspection shows that limited access will not allow such a fix. So, any ideas? I'll post some pics of what we're looking at:

Mounting spot. The mount actually has two more holes (6 total), but the middle two were not used. Being in the middle, I don't believe just those two would hold it as it would only create a pivot point and cause the bench to warp.

None of the foam is removable. It is all attached to a larger block that occupies most all of the area under the bench.

 

[fishmonger]

Drill out the pedestal mount screw holes to a larger size and use larger screws or ...

Replace the mount and drill new holes in different locations than the original holes or ...

Get a piece of flat stock and cut a large hole in the center to accept the pedestal. Attach that to the bench with counter sunk holes and flat head screws or if it's larger than the mount you can use pan head screws. Place mount on the flat stock, drill new holes and screw it on.

 

[richg99]

(Edit)...you might want to find aluminum rivnuts.....

I've never used Rive-nuts, but that is what I'd be looking for. I'd also take the base and make a quarter turn on it so that you will be mounting into all new metal.

You will need some sort of a rivet gun to put them in....(edit)...not so, see below....

I am sure that you will hear from more experienced guys soon.

richg99

https://www.amazon.com/20Pcs-Steel-Rivnut-Insert-Nutsert/dp/B00W8YJ9SA/ref=sr_1_4?ie=UTF8&qid=1462449586&sr=8-4&keywords=riv+nut

 

[perchjerker]

rivnuts would work, I used them all the time in automotive prototype builds.

But you do need an installation tool, its a simple tool, not a gun. It screws into the rivnut once its in place and tighten it down, this expands the rivnut. But they do have guns also but Im sure it costs more

I don't know how much the tool costs, they were provided to use by our employer. I don't know if it would be worth it unless you were to use it all the time but it probably doesn't cost that much

 

[hildebrandr990]

You can also do rivnuts without a special tool just need a fully threaded bolt the size and thread as the rivnut and a nut and washer that fits the bolt just thread the nut onto the bolt until it touches the head of the bolt then put the washer on the bolt below the nut then tread the rivnut on the bolt insert the rivnut into the hole and use an wrench to hold the bolt while you tighten down the nut on the bolt until it stops compressing I will get you a picture asap

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[perchjerker]

You can also do rivnuts without a special tool just need a fully threaded bolt the size and thread as the rivnut and a nut and washer that fits the bolt just thread the nut onto the bolt until it touches the head of the bolt then put the washer on the bolt below the nut then tread the rivnut on the bolt insert the rivnut into the hole and use an wrench to hold the bolt while you tighten down the nut on the bolt until it stops compressing I will get you a picture asap

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now that you mention it that is true. Been a while since I have worked with them but that would work with a little imagination

 

[hildebrandr990]

Scratch what I said before it only works with the hex rivnuts completely forgot i was using hex rivnuts when I used that method

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[Johnny]

more fasteners

 

[richg99]

(Edit)..you might want to find Aluminum rivnuts.....

Here you go....Have to use metric bolts...but...so what.

I am not sure why it matters whether or not the rivnut is a hex head or regular. I think the tightening method described above would work on either style.

I was going to order some of the hexnuts, but have cancelled that order until the style question is clarified by others more knowledgeable than I about these items.

8 mm is .315 inches, is larger than a 1/4 and smaller than 3/8ths...right at 5/16ths according to my rough calculations. Please double check.


https://smile.amazon.com/M8x18mm-Insert-Rivets-Nutserts-Fasteners/dp/B015A3IBHA?ie=UTF8&keywords=hex%20rivnut&qid=1462454252&ref_=sr_1_2&sr=8-2

 

[richg99]

OK..I did some Googling..

EITHER kind of rivnut can be used. Serrated or hex....

This is one of a number of well-done YouTube videos on the subject.

richg99

https://www.youtube.com/watch?v=3Og-tHIR_0I

 

[richg99]

After doing my research, I ordered 25 of these ( for under $5.00..with slow shipping) just to have on hand. They are near 1/4 inch size; require no special tools; Aluminum; and would be a good thing to have in my tool box. I do have to get some Stainless steel bolts in 6 mm metric.

Every other 1/4 20 Aluminum rivnuts that I could find would cost a ton more, so having these as metric isn't too bad.

Just FYI... richg99

https://smile.amazon.com/Aluminum-Blind-Insert-Rivet-Rivnut/dp/B00NGK6W9O?ie=UTF8&psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00

 

[kstrayhorn]

Wow, thanks for all that input, and so quickly too!
Johnny, the mount only has 6 holes, so in your diagram only two would be in new metal and the other four would be in the already damaged holes. That might not be so bad if it was holding down opposite corners, but both would be in the middle and would be under a lot of front/back stress as the mount sits now or left/right if I rotated it 90°.
Rich, I had considered just rotating it 45° and drilling new holes. As a matter of fact I had already laid it out that way as a last resort if I didn't get anything here. I'm cautious to do that as it leaves the same problem from occurring again and being SOL after that, it would leave 4 holes for water to get in where it won't drain with gravity, and having one angled mount with the other two being straight would be bad for my OCD.
Looks like I'm going to explore rivet nuts.

Also, I'm going to peel off that old silicone, but I don't want to have to put new on if I don't have to. Is it necessary? I don't see any amount of water getting in there if the mount is fastened properly and if it's for noise, that's the least of my concerns on a 15+ year old beater like that.

Thanks guys.

 

[richg99]

Well, if you wish to use the old holes, then I'd buy larger rivnuts. You might have to drill out your plate, also. Stainless can be a PIA to drill.

I didn't see any silicone reference?

Good luck.

richg99

 

[perchjerker]

Well, if you wish to use the old holes, then I'd buy larger rivnuts. You might have to drill out your plate, also. Stainless can be a PIA to drill.

I didn't see any silicone reference?

Good luck.

richg99

there is silicone sealer around the hole in the bench. I imagine that was to keep water out of the floatation foam

I would scrape it off and use new.

cant hurt anything

 

[hildebrandr990]

I think if you can get the rivnut to hold in the metal the method I had posted would work I tried it after I posted it and couldn't get the rivnut to hold

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[richg99]

Hilde....two of the videos that I watched both warned about the rivnut moving. Each had a different way of keeping the rivnut in place.

The video that i LINKED was very specific about properly using a star shaped lock washer while working the bolt/nut combo. The other video showed a lever that the guy made???

It seemed to this old codger that a very accurate sized drill bit was necessary. Slightly too large a hole, and the rivnut would spin.
richg99

 

[perchjerker]

this is the style tool I used to use

worked real well

https://www.bernardiparts.com/Honda-Rivnut-Tool-8mm__LEML722M8.aspx

 

[richg99]

That is a bit expensive, especially if you only use it once or twice.

This is another youtube video that I thought did a good job of explaining the alternative method of installing rivnuts.... richg99

https://www.youtube.com/watch?v=AfQIYLSKGwI

 

[perchjerker]

That is a bit expensive, especially if you only use it once or twice.

This is another youtube video that I thought did a good job of explaining the alternative method of installing rivnuts.... richg99

https://www.youtube.com/watch?v=AfQIYLSKGwI

I know it is, just showing you what I used

personally I would not buy them as I have never needed them outside of the workplace.

without the proper tools its kind of a crapshoot

 

[kstrayhorn]

Really don't know how I didn't know about these things other than from this forum. Especially as I own a body shop and all... I watched the video and a couple others under the related suggestions. One had a standard rivet gun with a threaded head. Wonder if I could modify something on my gun to make that work... I figure I'll have to put the plate on the drill press as the holes are countersunk. I'll keep looking into it and see what happens. Guess I'll just learn to drive wrong handed until then