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  #1  
Old 06-15-2018, 05:37 PM
jbiddle jbiddle is offline
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Default HDU questions

I want to make a few outdoor signs for friends. Turns out there is a WENSCO about 10 miles from me and they carry HDU. They have:

SignFoam IV
15# and 18#
Corafoam
15# and 20#

They stock 4' x 8' sheets in 1/2", 3/4", 1", 1-1/2", and 2" sizes.

1. What is the typical thickness of a single and double-sided sign (assume about 24" x 30" signs)?

2. Does the thickness depend on the size of the sign, depth you want to cut, or other factors?

2. How do you decide on which density to use?

3. Is either Signfoam IV or Corafoam better?


Thanks,
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  #2  
Old 06-15-2018, 06:46 PM
Bob Walters Bob Walters is offline
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Quote:
Originally Posted by jbiddle View Post
I want to make a few outdoor signs for friends. Turns out there is a WENSCO about 10 miles from me and they carry HDU. They have:

SignFoam IV
15# and 18#
Corafoam
15# and 20#

They stock 4' x 8' sheets in 1/2", 3/4", 1", 1-1/2", and 2" sizes.

1. What is the typical thickness of a single and double-sided sign (assume about 24" x 30" signs)?

2. Does the thickness depend on the size of the sign, depth you want to cut, or other factors?

2. How do you decide on which density to use?

3. Is either Signfoam IV or Corafoam better?


Thanks,
I love my Corafoam, cuts awesome.
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  #3  
Old 06-15-2018, 07:40 PM
Jim_in_PA Jim_in_PA is offline
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My understanding is that the Corafoam (Duma) is a slightly better product than the Signfoam product...there was commentary to that effect in a recent thread here. The weight was also covered...15 lb is great for "most" work and the 20 lb can serve when you need a little extra something.

I've been playing with HDU myself and really like it. (I had the good fortune to be able to fill the back of my Grand Cherokee with a lot of scrap from a friend's place in Richmond on the way north from central Florida recently) I almost never want to make a "wooden" sign after working with the foam! I like the Duma better than the Coastal product that I've been playing with...the latter seems a lot coarser.

It cuts beautifully, has no grain so bit choice is less critical and also...cuts quietly. I mean, my cyclone moving air through the dust hood is louder than the act of cutting the HDU quiet. And I like that.
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  #4  
Old 06-15-2018, 08:37 PM
BradyWatson BradyWatson is offline
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The Great Seal was done in 18# Corofoam by Duna (previously Dunaboard)

-B
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  #5  
Old 06-15-2018, 11:08 PM
jbiddle jbiddle is offline
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So, is the density choice dependent on the quality output you want? That Great Seal is as good as it gets. How would it have been different using either 15# or 20# instead of 18#? I'm trying to wrap my head about the differences in densities.
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  #6  
Old 06-16-2018, 08:10 AM
Jim_in_PA Jim_in_PA is offline
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Someone can correct me, but the higher the density, the smaller the cells and that bodes well for increasing detail. BTW, you can feel the weight difference even on small pieces...
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Non CNC stuff...

SCM/Minimax - slider/JP/BS
Festool "a good collection"
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  #7  
Old 06-16-2018, 08:55 AM
BradyWatson BradyWatson is offline
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Quote:
Originally Posted by Jim_in_PA View Post
Someone can correct me, but the higher the density, the smaller the cells and that bodes well for increasing detail. BTW, you can feel the weight difference even on small pieces...
Correct.

When these, or any other polyurethane material is made, the density is regulated via controlled back pressure. They essentially throttle the expansion via vent holes by either the number of holes or diameter, to regulate the pressure in the mold. Just like rattle-can insulation foam, it expands out of any cracks or holes. By increasing pressure, air bubbles are pushed smaller into suspension/compressed and the density is increased.

When there isn't anything to restrict the expansion, the air bubbles expand as far as they can. More air = less density & in turn a lighter panel (including more voids in the panel as well). Think of those InstaPak expanding foam bags for shipping - same thing...

So in terms of CNC, the density chosen is a function of how much detail it needs to hold, what kind of finishing system you are going to use and how much weight (if applicable) can it be. For the Seal, there was no way to get real cast bronze on that facade...so the HDU could be pulled up the scaffold by a few guys without too much trouble. I'll let the 'sign guys' give you tips on density as it relates to signage.

-B
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  #8  
Old 06-27-2018, 06:26 PM
jbiddle jbiddle is offline
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There's a local Craigslist ad for 45# density OBO Modulan Polyurethane Tooling Board. They have a 2' x 2' x 4" chunk of it listed for $50. They claim it's $180 new. Is it usable, worthwhile, and priced right?
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  #9  
Old 06-27-2018, 07:48 PM
Jim_in_PA Jim_in_PA is offline
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45 pound sounds like it will be like a rock!

I wonder if that's even the same stuff as typical sign foam.
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Jim Becker

SR-44 (2018), 1.7kw spindle, Performance Premium, USB, Keypad, T-Slot table (y-axis configuration), WinCNC, VCarve Pro

Non CNC stuff...

SCM/Minimax - slider/JP/BS
Festool "a good collection"
Stubby - lathe
Oneida Cyclone
more...

Retired from full time work in the telecom industry 9/2017
Commission work for equestrian tack storage and other custom furniture and cabinetry
Located Bucks County PA
http://bvww.us
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  #10  
Old 06-27-2018, 08:44 PM
BradyWatson BradyWatson is offline
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That's good stuff. It's very similar to Butterboard but I think it is less porous. Machines like a dream and great for mold master models or anything else that needs to be tight grained or homogeneous without voids. $50 is a steal.
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