Cutting Kingboard

[bleeth]

Just got done cutting a sample sign out of colorcore and looks like the prospect may go for it. For the full size project I'll be using a v-bit for some lettering and mill end for the rest. The cuts were nice and smooth but there was a lot of "hair" left that needed hand clean up. For one or two signs I might be able to live with it but this is for a realtor and if he orders I'll need to cut over a hundred of these two sided!! So the question is-Anyone have any tips on avoiding hairy edges?

Dave

[billp]

Dave,
I have "cheated" on some of these in the past, but it takes an extra pass. I would "Z-zero"my machine (after drawing up my V carving file of course), and then I would RAISE the Z axis a small amount and re-zero it at the new location (.01" should work). Then I run the file. After doing so I lower the Z to it's original Z-zero location and run the file again. On the second pass I would knock off any edge fuzz. Benefit of the second pass is that you can run it VERY fast since you are really only skimming over a previously cut surface.
And if one had to do a LOT of these as you have mentioned you could probably build both passes into the same file. Yes it's more time, but it's time the machine is spending, not YOU and a piece of sandpaper...

[bleeth]

Bill:
Those were the lines along which I was thinking and I was hoping for confirmation. Too many hours with sandpaper and/or scrapers defeats the profitability but an extra 5 minutes per sign on the machine is meaningless.
It's clear that that would work for the v-bit work but how about the end mill? Or would I run my first end mill passes leaving an allowance and then "clean up" to full width.
By the way, that stuff is so soft I ran all at high spin and ips. (18k and 2.5) How does that compare to your experience?

[billp]

Dave,
Kind of hard to tell since I don't really know what the signs look like, but I can't see why it wouldn't work with an end mill as well. Caveat here is that if you are "hogging out" a background this is the area where if things CAN go wrong, they will. ANY miscrepancy in height will show in a hog out, and of course it's also the worst part of a sign to have to sand by hand due to it's larger surface area.
If you are just profiling letters, it shouldn't be any different than the V carving setup.
I usually cut almost everything at slower speeds than 18,000 (almost 99% of what I do is between 10-12,000 k). It seems to clear chips easier, with less chance of melting back on itself. And depending on the actual file you could probably bump up the machine speed a bit as well. I haven't cut anything faster than 3.5"(except foam of course...), but I'll bet in the softer stuff it wouldn't be any problem..

[bleeth]

Bill:
Center v-carved and outer border and other lettering with millend. Final size 18w X 24h with a phone # at the bottom in black surface with white core. Since the end mill work ends up thin (around 1/4") you can see why I don't want to be hand detailing!!


4766

[billp]

Dave,
Now I see. I think your idea of an "allowance"is probably the safest way to go.
Next thought would be; instead of having to do a bit change between the V carving, and, end mill letters on EACH sign,maybe you could begin by carving ALL of your end mill versions first. THEN go back, and do ALL of your V carving . This would probably mean zeroing off of the area you have hogged out in the first end mill run, and then going through the two step V carving process. If you were holding these pieces down with some sort of a vacuum jig your heights should stay constant...
Now that I've re-read your initial post the "two sided" nature of these might also be problematic however unless you had TWO jigs; one for cutting the first side (where your back side would still be flat), and one for cutting that back side ( where you would now have a "flange" around your edges). I'm not sure if your material is thick enough ( how thick is it anyway?) to resist flexing after the first side is cut away. Perhaps on your second jig you could place a strip of some material under the center area where you'd be V carving to minimize that flex. Then use the flange area as your vacuum hole location to keep it all in place.
I know this all sounds convoluted, but as you well know when you are doing as many parts as this job requires it does pay to put some thought/time into rigging up the right hold down fixtures. Maybe someone else has ideas on this?

[jsfrost]

A beginner's 2 cents, but by thinking I'm learning.
Can we get much the same effect by running the file with a Z multiplier of say .98 (assuming a max V carve depth of .5), then re-running at Z multiplier of 1?
And given the size of the run, is it worth some hand edits to eliminate unneeded roughing steps from the cleanup pass, especially in the V carve?

Jim

[bleeth]

Bill: I can get 12 signs out of one sheet and was planning on using the 3/4" colorcore. So far I am definitely planning to do all the lettering and then cut the sheet. Each sign also will have two holes for hanging and I can always drill these first and then put some screws in. I'll be keeping my cutting depth max around 5/16 on the v and 1/4 on the end mill work. Flexing should be at a minimum. With the cost per sheet at $300 I really don't want to screw one up. If I'm pulling vacuum on the whole table then the letter voids shouldn't be a problem on the back side.

[t_fiddler]

I have found a power washer will remove most of the "fuzzies"
Also a bit with a little flat bottom helps a great deal

Thanks
Tom

[btk]

Tom,

I am not sure exactly how the Scaling factor works in SB, however, in some other programs when a NC file contains both positive and negative Z values, you may run into trouble if you try to use "Scaling" to create an offset. In the case of a 0.98 Scaling, the negative Z values will become larger (i.e. -0.5--> -0.49) and Positive Z values will become Smaller (i.e. +0.5-->+0.49).

However you have to confirm that SB Scaling Command does not make some sort of appropriate adjustment (I know that some other programs that do not).

You wrote in your post "(assuming a maxium depth of 0.5)", assuming that you may be talking about relative depths and zeroing on the top of your material in which case I beleive you would have all positive z-values then 0.98 Z scaling factor would create the desired effect.

I will try to use Scaling factor later and confirm that it does not make and special adjustments.

Brian

[dmdraper]

If you can get by without an end mill, try using a two-fluted down cut spiral bit for the non v-carved letters. Also, I found that v-bits vary quite a bit in quality of cut. I use the 60 degree three-fluted laser point bit made by CMT in plexi with good results.

[jhicks]

I appreciate the input on this Color core and have plans to try some but heard it was a bit pricey. Its obviously better than painting but is the final sign competitive enough for realtors? Can you give me some idea what this sign would sell for? Seems to me it would be perfect for construction/ home builders as well.
Appreciate any guidance you are willing to provide.
Thanks

[bleeth]

It, like any carved sign, is going to cost the customers more per issue than the prices available for simple vinyl or screenprinted items. Perceived value is between the supplier and end user. The company I pursued it with deals only in very high end properties and so it is being suggested as both an image enhancer, as well as a practical item that stands up to the elements. They are still "thinking about it". I think they choked!!
As a supplier to many contractors over the years I have generally found them extremely cheap in spending for millwork, furniture, and display items. Considering the bulldozing and running over that their site signs take it is understandable. The hottest market seems to be golf courses!

[davidallen]

Dave,

Can you 'simulate' color core by using layers of laminate? maybe over corrugated plastic?

da

[bleeth]

David: Laminating or fusing plastics together always creates a challange without industrial specific machinery. It seems to me the extreme thinness of the wall and the uneveness of the surface would eliminate corrugated as a candidate.
Without a solid consistant core carving at variable depth as in V letters would be eliminated and you would be left with only single depth cutting as well. You could probably work out a system to use one of the solid color laminates over colored acrylic but it seems like a small bang for a big headache.

Dave

[jhicks]

Selling the "added value" is always the challenge. Dale Kerr tells us the national average for HDU single sided signs runs in the $100.00 / sq ft area before exotic guilding etc.
So far that number has worked for me but I dont have them knocking the door down yet.
I've heard from a local vinyl guy he starts the discussion at $75.00/ sq ft + design time at $65.00/hr so to me the $25.00 per Sq premium is a no brainer but for some reason the Chicago HDU distributors dont seem to sell that much. There is a vinly guy on every corner so maybe thats the reason but if the Color core could get between HDU and vinly, it seems like the benefits greatly outweigh the premium.
Guess thats why we have to design it, buy it, SELL it, make it and deliver it. Should be some extra value somewhere in there. Guess I need to make samples and get my sales hat back on to find out.