Help on feed rates for foam

Discussion/questions about software used with your CNC Shark and programming issues

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NewAgent45
Posts: 230
Joined: Sun Sep 08, 2013 8:29 am
Location: Edgewater, Florida, USA

Help on feed rates for foam

Post by NewAgent45 »

I’m working on a project with several firsts!
First Sign like project
First Tiling project (2 tiles X 18"x X 17"y for a total 34"y)
First time with foam material (Common Dow Chem. 2 inch thick blue board)
First time using the Create Texture Vector Tool for Wood grain background

I’m pleased with my carving results and plan to repeat on the other side to make the sign two sided.
I’m not satisfied with the carving time and thing there is room for improvement even after making several toolpath adjustments. I have noticed that this material cuts real easy.

Here are my current settings for the slowest part of the job. I’m cutting a pocket ½ inch deep between the text and border so there is a lot of material to remove. I’m using a 1/4 inch diameter end-mill. A larger diameter bit I would lose detail.
Current Tool Settings are:
Tool” 0.25” 2-Flute Up-cut carbide endmill
Cut depth: 0.5”
Pass depth: 0.125” for 4 passes. Not sure if we could increase pass depth without sacrificing quality.
Stepover: 0.1 (40%) I think I may be able to increase this as I’m adding a separate texturing step to the bottom of the pocket to achieve a woodgrain effect. Any advice would be welcomed!
Spindle speed: 20,000 RPM
Feed rate: 250 ipm. Doesn’t the controller limit this to about 200 max?
Plunge rate 100 ipm
Tool path takes about 4 hours to complete.
So far this foam has taken all my more aggressive moves but I don’t want to mess-up what looks like a good job so-far.

I’ll ad a picture of the sign when finished.

Thanks in advance for your comments.
Have a great day!
.. Rod

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meb
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Location: Nevada, Texas

Re: Help on feed rates for foam

Post by meb »

When you calculate your tool path you can choose to use a large area clearance tool to clear most of the waste then use the smaller bit to clear the remainder. This will generate 2 toolpaths, one for the larger tool and one for the 1/4" bit.

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NewAgent45
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Location: Edgewater, Florida, USA

Re: Help on feed rates for foam

Post by NewAgent45 »

MEB,

Using a large area clearance tool sounds like a good idea and I should be considering it for other work. I do have a 5/16 inch Endmill I could use for that.

I am concerned that the larger tool might "tear out" the foam and will have to try it on a scrap first.

I completed carving on the two sided sign shown in the attached picture yesterday. Now I just need to paint it I plain to prime and apply a brown color to look like wood and will use an airless sprayer for the latex paint. After that dries I will use a small roller to apply black latex to the face of the letters.

I also cut a 3/4 inch dado in the edge of the 2 inch thick foam on the table saw and made a simple frame to finish the edges. The frame pieces have a tee piece that engages the dado and adds a lot of strength. This sign will be portable and used to hang on a bar mounted above one side of a canopy. I plan to use this for craft shows. A lot of craft shows in Florida are outdoor events.
CGT Sign 3.jpg
CGT Sign 4.jpg
I learned a lot on this project with out generating any scraps.

Have a great weekend!

... Rod

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NewAgent45
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Location: Edgewater, Florida, USA

Re: Completed sign

Post by NewAgent45 »

I think my sign turned out better than expected in spite of all the first time operations. I should point out one quality issue with the common foam board used. There are marks in the face that are obviously caused by the manufacturing process. If you look closely you will see this. It is especially noticeable in large uncarved areas. One though to eliminate this would be to machine the entire face as a first step. I'm not sure the material will hold up to a large surface planning bit. For my sign this is not a big issue because of the rustic design. Good excuse anyway!




Have a great day!
... Rod

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NewAgent45
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Joined: Sun Sep 08, 2013 8:29 am
Location: Edgewater, Florida, USA

Re: Completed sign

Post by NewAgent45 »

Sorry! Forgot the attachment!
CGT Sign 5.jpg

TAW
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Joined: Tue Oct 20, 2015 10:50 am

Re: Help on feed rates for foam

Post by TAW »

very nice job= was this the heavy duty foam that will support 250 lbs per sq?

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NewAgent45
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Joined: Sun Sep 08, 2013 8:29 am
Location: Edgewater, Florida, USA

Re: Help on feed rates for foam

Post by NewAgent45 »

TAW:

The foam used is common variety found in home centers Dow Blue Board with square edge. I look on the Website and I think it is Styrofoam Deckmate 2" x 4' x 8' 25 psi. I was originally looking at professional grade sign board and found it to be costly. What could I loose by trying this. A sheet of this 2" material is about $50. So the cost for this 18 X 34 inch sign was about $7.

As mentioned in the original post I reinforced the sign by cutting a dado in the center if the edge all the way around and the wood frame is keyed into the dado.

I also noted that there are some surface anomalies in the blue board. I ignored them and didn't think it was a problem because of the rustic nature of my sign. I plant to try a surface planning bit (1 1/4") and see it this stuff will stand up to surface planning.

I also noted an issue with the texturing I did on this sign. I just designed a sign for a customer and was able to solve this problem. This new customer saw my sign on my booth at an event last Saturday and decided to order a sign.

This new sign is 2" x 15" x 24" and I'm attaching a screen capture from the simulation.
Camp Run - A - Muck Sign - Simulated Image.jpg
Are you doing any projects on foam board?

.... Rod

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NewAgent45
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Joined: Sun Sep 08, 2013 8:29 am
Location: Edgewater, Florida, USA

Re: Christmas Decor

Post by NewAgent45 »

I thought I would add this project here as it shows the results of several results/improvements to the my sign board process.

First! To eliminate anomalies found in the surface of common foam board we sanded all surfaces of the blank piece of foam board with a random orbital sander with 80 grit sandpaper. We saw no need to use finer grit for the project. We were surprised the light sanding technique worked so well. Since this sign is one sided this improvement shows up most on the backside where I used the wood grain texture it also show in the front side frame border.

We created separate offset vectors to use for creating the wood grain texture. This eliminated the texturing problems described in my earlier posts.

We wanted to make the 3D Santa very high relief and cut the model almost 1 inch deep With the boundary pocket being slightly deeper. We created the arched banner for the test/curves to sit on and the test is approximately 3/8 tall.

We plan to add a strip of white LED lights glued to the inside border frame to illuminate the sign. The LED strip is on order. I'm not sure if I will like this lighting effect or not. We will eliminate it if we don't like it.

Here are my pictures!
Santa 2.jpg
Santa 3.jpg
Have a great day!

... Rod

altalenahome
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Re: Help on feed rates for foam

Post by altalenahome »

These Christmas decor ideas are worth trying. Interior decoration are great way to enchant your guests.

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