Question on bolting on large hole size 2

[Kurt114]

Hello, I need to install this piece of equipment (about 11kg) on a round face with 4 bolt holes (diameter 25 mm, diagonal distance between hole = 200mm). The equipment I have come with 4 off 15 mm holes, same diagonal distance 200mm. How do I bolt the two together given the large different hole sizes? Thank you.

 

[GregLocock]

Helicoil twinsert (maybe) or a threaded insert, basically a tube with internal and external threads.

https://en.wikipedia.org/wiki/Threaded_insert

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[Jboggs]

Or use a bolt that will fit through both holes with oversize washers that will cover the larger hole.

 

[Tmoose]

Are there any pilot diameters etc between the equipment and the "round face" intended to provide centering ?

 

[rb1957]

washers as suggested by Jboggs would do it.

Small thing to fuss is the unsupported washer (over the larger hole). Maybe make your own washer from 0.125" thk plate, and over size.

bigger thing (maybe) to fuss is the dishing of the washers (over the larger hole) as you tighten the screw. So you can help this by filling the space with a "spacer".
If you want to go to town over it, make the spacer slightly oversize and freeze fit into the hole, then drill the hole you need.

another day in paradise, or is paradise one day closer ?

 

[MintJulep]

Bushings.

 

[rb1957]

you can bush, but you have to make sure that the nut can transfer load to the surrounding structure (and is not sitting (only) on the bush (so over-sized washers).

another day in paradise, or is paradise one day closer ?

 

[GregLocock]

Or a stepped stud. you haven't said if either hole is threaded.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[SWComposites]

Or drill the equipment holes out to 25mm.

 

[Joe591]

What about taper head machine screws? I've checked and a M14 taper machine screw's head has an outer diameter of 27mm. If you put the taper head on the 25mm hole side there might be enough bite for it to hold. It could end up looking weird though so I won't blame you if you don't want to go with this option. Another option is using a washer with a normal size bolt. If you want to you can look into fender washers, they tend to be a bit bigger in outer diameter than normal flat washers. A normal M14 washer has a outer diameter of 28mm (as far as I can tell). A M14 fender washer has an outer diameter that is way bigger than that.

 

[Tmoose]

"Small" detail like what size fasteners you intend to use to secure the PoE have not been mentioned.
Similarly The loads the mounting screws are likely to encounter also have been given no thought, based on the OP.

Based on few words and no pictures // I think // the largest fastener that can be used off the shelf is M14.

If using an M14 Hex Head cap screw, the corners of the hex could drop right in the 25 mm hole. Even more important, the face on the underside of the screw head is likely to be about 22 mm Ø.
An M14 SHCS hed is about 21 mm Ø.
As suggested by others, this will relentlessly try to "cone" any washer used.
Similar to 00:20 here -

https://www.youtube.com/watch?v=EJMgz6ZG-2w

My hunch is you will need .25" thick set up washers or an even taller stack of hardened steel washers to permit the screw heads to clamp properly.

 

[BrianE22]

I've used these when I need a thick washer:

https://www.mcmaster.com/shaft-collars/shaft-collars/shaft-collars-6/shaft-mount-type~set-screw/