CNC Machined Sign Hanger

[Keith Outten]

I decided to place this thread in the CNC Forum because what makes this one different is the hanger. The sign is pretty typical, it's CNC machined from Glacier White Corian and the text and other details were laser engraved then painted red.

The hanger was also CNC machined from Corian. The idea was to make a hanger that wouldn't need maintenance or would ever rust. The hole was machined to allow enough space to line the interior with double sided tape. Using double sided tape takes care of the thermal expansion difference between the steel pipe and the plastic hanger and at the same time keeps the hanger tight to the pipe outside diameter with very little tension from the stainless steel cap screws. The Corian was drilled on my bench mill and threaded to accept the cap screws.

[Mike Heidrick]

Loosk nice. Love the sign.

As for teh bracket, had you considered slotting for a thin stainless nut for the cap screw rather than threading it?

[Keith Outten]

Thanks Mike,

I did consider using a nut on the bracket instead of threading the Corian but I figured a student might have a pair of pliers but its unlikely they have a set of allen wrenches in their car. Signs are popular souvenirs for college students There must be a point system, if a sign has the name of a building on it is worth more points........
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[Ken Dolph]

Keith

Nice job as usual. I would suggest that you insert a Heli-Coil This will make your threads much more durable and less likely to strip.

[Keith Outten]

Thanks Ken,

I considered using a Heli-Coil but I figured that since there isn't any reason to remove the sign unless it was damaged threading into the Corian would be ok. The hanger doesn't put hardly any stress on the cap screws due to the double sided foam tape. My only concern with this design is the life span of the tape.

In the future if I have a situation that I have to install and remove a sign frequently I would definitely install a Heli-Coil with a little silicone adhesive. I have several more of these to build when my schedule lightens up a bit.
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[Ken Dolph]

Keith

I think that the tape, if it is 3M VHB will probably out last the rest of the installation. If the pipe is maintained and does not rust under the tape. There is the possibility that a vandal will use a screw driver to push out a bit of tape. Since it is a Command Adhesive it will release completely when stretched. I would use the thinnest appropriate tape to keep this from happening.

As to the Heli-Coils: They were demonstrated to me and explained by a Heli-Coil rep a few years ago. He torqued the head off a bolt, without stripping the treads, in a piece of Corian. He explained that The coils not only protect threads from repeated disassembly but "balance" the load on each thread.

When a bolt is tightened in a tapped only situation, 90% of the pressure is on the first thread continuing to tighten strips this thread and the process continues. With the balancing provided by the coil, if there are 10 engaged threads, there will only be 10% of the load on each thread. This effectively gives you 10 times the holding power of the joint.

That is why I recommended the Heli-Coil. You will be less likely to strip the threads on initial assembly. They can be torqued down more and will be stronger.

I think they are a better alternative to squirrels http://www.squirrels-uk.com/installation.htm in many other applications.

[james mcgrew]

i owned a half dozen college bars in five points (columbia sc) home of the USC gamecocks, i can tell you first hand if they want it they will get it, after all they are in the most ingenous education they will ever see in thier lives, (sorta goes down hill from there !)


once a groom to be whose bachelor party stole my statue of John Wayne (yes the Duke himself) off the bar on a friday night while we were packed to the gills,,, ( little did they know we always had everything on camera in the bar)

well the next day after we filed the ploice report, a limo followed by two police cars pulled up in front of the bar about 2 in the afternoon and out comes the groom getting on his knees to beg my forgiveness as he returned one of my most valuable possesions, the police had left it up to me as to whether to finnish the arrest as they picked him up in front of the church moments before he was to wed !!

i told him we were all good and then said be careful on the walk you are about to take, as he got into the limo he closed the door then reopened it and said, "something tells me i might want to listen to you" i waved and said "GOOD LUCK"