How to fix studs/bolts into wooden sheet and be sure they can't turn?

message from usenet on 14 May 2004

I have some large castors I want to fit onto a hen house. The floor
of the hen house is 12mm plywood and there is an edging of 50x25mm
timber round the edge below the floor.

The castors are on metal plates with four 10mm holes for fixing.

I could simply put bolts through the floor but I'd really prefer not
to as I'd like to preserve the smoothness of the floor as far as
possible to make it easy to clean etc. I'd also prefer to keep the
henhouse as low as possible on the wheels, thus I'd like to minimise
the thickness of anything I put below the floor to fix the castors
onto.

Countersunk bolts through the floor would be OK but, 1) I don't have
any and 2) I'm not really sure the 12mm ply would be string enough
with the countersinking as you wouldn't be able to use washers to
spread the load.

At present the best plan I can come up with is substantial chunks of
(say) 18mm plywood fixed under the corners of the floor (the
surrounding 25x50 will help) with 10mm bolts through in the right
positions to fit the castors. The heads of the bolts would be buried
in the 18mm ply (counterbore them) and you just use nuts to fix the
castors. The 18mm ply will spread the load and can be screwed/glued
to the 12mm floor.

However I fear the heads will turn when I one day want to remove the
castors.

Can anyone come up with any better ideas for fixing these castors?

Elessar replied to usenet on 14 May 2004

Round-headed coach bolts should be OK - no need to countersink and they
won't affect the smoothness of the floor too much.

usenet replied to Elessar on 14 May 2004

Yes, that is one possibility, only problem is that I'll need bolts
with thread right up to the head, or pretty close anyway.

mrcheerful replied to usenet on 14 May 2004

Use the extra pads screwed underneath, but use spiked nuts on the upper
surface of the pad, and use bolts through the castor up into the spike nuts.

mrcheerful

usenet replied to mrcheerful on 14 May 2004

Now that is a good idea, thanks!

Archived message: How to fix studs/bolts into wooden sheet and be sure they can't turn? (UK D-I-Y House Renovation)