Experimenting with STL slices and pierce carvings on both sides......

[zan29]

I've been trying for a while now to carve both sides PIERCED in order to be able to carve the back of a slice from the STL importer.
I had to figure a way that the tabs would not be cut off while carving the front and finally found a way to do it.
With this technique you can carve hallow vases and intricate pieces that can't be done just by carving the front of the slice.
I'm starting test #3 today by slicing horizontally instead.
Here are the results of my first 2 tests.

76587Test #1 front of board with a half vase.
76588Test #1 back of board
76590test #1 results
76591test#2
76592test #2

[bergerud]

The STL importer will output double sided carves of slices. I thought slicing up something like a vase into double sided carvings was what the STL importer was made for. Can you explain what the problem is. Why do you need to pierce both sides in such a way that it takes out the tabs?

[zan29]

The STL importer does output both sides of a slice but in order to carve a slice on both sides and have the exact shape and size, both sides have to be pierced. I have this santa claus head that I was hoping to carve but with the way it's shaped, I was always missing part of the beard. I knew some slices had to be pierced both sides in order to get the full beard. If you look at the vase, you would not be able to get the inside results if you only carve your slices on one side....both slices have to be carved to make one piece. Gosh I knew I was going to have problems explaining this.

[oscarl48]

Suzanne,

What a cool experiment. Can't wait to see the follow on efforts.

Oscar

[bergerud]

I realize both sides of slices have to be carved. What I do not get is the need for piercing. Maybe you could post an example sometime which shows the problem the piercing fixes.

[zan29]

I should have taken pictures. If you don't pierce on both sides than your slices will not fit together properly. It all depends what you're slicing, some pieces dot not require the piercing on both sides just like the CW video. I wanted my vase to have the same shape both inside and out so piercing on both sides was required. Like I said in my previous post, the santa head I wish to carve requires it otherwise part of the beard will be missing. The front will look OK but not the back of the head. On this one I'll probably have to carve pierced on both sides for just 1 or 2 slices.

Slicing a four legged animal is probably the best example I can give. Try carving the inside of the legs and have a full 3d figure.
That's probably what I'll try to do for test#3.

[bergerud]

As far as I know, piercing just drops the pattern down until the lowest part is 0.008 below the bottom of the board. I only use it on flat, carve regions made from offset outlines to make sure the pattern gets out out all around. (Pierced does not work if the boundary of the pattern is not planer.) I do not see any magic in using pierced. It is the same as setting the depth to 0.758 instead of 0.750. If you use pierced from both sides, your pattern looses 0.016 in thickness. Somehow that helps?

Edit: Are you using bit optimization best and small draft?

[zan29]

Well there's only so much I can say Dan. I do not use pierce, I set my slices to .750. I did not use a draft but a feather on the outline and optimized every piece and outline and carve at best since it was only a test.
Like I said try carving a four legged one without loosing any details and without piercing your pieces or some of them of both sides.

[zan29]

What do you mean by (Pierced does not work if the boundary of the pattern is not planer.)??



As far as I know, piercing just drops the pattern down until the lowest part is 0.008 below the bottom of the board. I only use it on flat, carve regions made from offset outlines to make sure the pattern gets out out all around. (Pierced does not work if the boundary of the pattern is not planer.) I do not see any magic in using pierced. It is the same as setting the depth to 0.758 instead of 0.750. If you use pierced from both sides, your pattern looses 0.016 in thickness. Somehow that helps?

Edit: Are you using bit optimization best and small draft?

[bergerud]

What do you mean by (Pierced does not work if the boundary of the pattern is not planer.)??


The idea of pierced is to make a pattern "cut itself out". If you apply pierced to a pattern whose boundary is not planer, like a potato chip with floor feather off, only part of the boundary will cut through. (Floor feather will make the boundary planer.) The thing is, pierced just lowers the pattern by 0.008. It does not really change the pattern. The pattern has to have a planer boundary at the bottom of the board and then pierced just adds a little to the depth to overkill and make sure it cuts through.

I hope that makes sense.

What you said about piercing changing your patterns for the better made me curious. Since I do not see piercing really changing anything, I thought maybe something else was going on. (I tried slicing up a pig and the inside of the legs seemed ok to me with or without piercing.)

[zan29]

I agree piercing is not always required but for the vase I had to do it on both sides for the smallest piece. If you could send me a picture of some sort to show me what you mean exactly. I'm still not quite sure.
All I can say is that the option of being able to pierce on both sides gave me a whole new world to explore. So many things I wanted to carve but couldn't since I was missing some details.

[bergerud]

Here is an example of what piercing and flooring do to a pattern. The left side shows the tops of the patterns and the right side shows what the underneath looks like. The base pattern is 1/2" deep and the board is 3/4" thick. Floor feather drops the boundary to the bottom (but not through). Piercing drops the patten to the bottom + 0.008. (Note only parts of the pattern that were at 1/2" cut through.) Floor feather and piercing drops the pattern and the boundary to the bottom + 0.008.

This is all I see happening. Patterns and pattern boundaries changing in depth. If anything, pattern details would be lost. 0.008" of the pattern drops off of the bottom.

(Sorry but the mpc is 3.0.)

[zan29]

Ok now I get it, thanks Dan. Anyway, I'm just glad my little technique is working so far. Trying out another project today to see what are my possibilities and how far I can take this.

[papawbummie]

I am using rotary jig and I have created a flat area. I have been trying to carve a pocket on the flat area one inch deep but I cant get the pocket to carve straight. They carve slanted I need them to be straight like a flat board Is there a way to do that Thanks Bert

[SteveNelson46]

Can you post the .mpc?

[bergerud]

I am using rotary jig and I have created a flat area. I have been trying to carve a pocket on the flat area one inch deep but I cant get the pocket to carve straight. They carve slanted I need them to be straight like a flat board Is there a way to do that Thanks Bert

Not possible on the rortary. Just think, the bit always points toward the center line. What you want to do would be like trying to under cut on a flat board.

[papawbummie]

Thanks I did not think it would unless it would do the same adjustment is does to create the flat Maybe they will do a upgrade. Be nice to make a mortise Thanks again Bert

[bergerud]

I worked today on slicing up a vase. It has been awhile since I have used the STL importer to to make slices. I had forgotten, it is not that easy. Making a 3d hollow object from slices requires some trickery.

I worked for awhile on this.

1. Notice that I only used pierce on outlines and offsets. Not on the patterns as pierce drops patterns into the board.

2. I made zero height masks to stop the machine from carving the mating surfaces of the parts. It is much better to have the original planed board surfaces for gluing than a skim carved surface. (A carve region has to be all at zero for the machine to jump over it. Patterns with parts at zero get those zero parts skim carved.) (I use to use a touch shim to stop the bit from skim carving the surface.) I made the masks in the PE. Simply lower the pattern until only the flat top surface is left. Some patterns needed the holes filled as well.

3. I used outline carve regions on the back side to hog out the interior of the vase. One does not have to do this. One could jump over the large blocks of wood and save the bit. I think the finishing would then take more effort. I do not trust the bit would make it through. The vertical sides of the blocks would also require using feather. (Hide the hog outlines to see the blocks.)

4. I used alignment pins in the STL so that I could easily align the parts and their masks using the snap grid. The pin holes are all covered in the end by small circular masks.

I have not carved it. I do not know if it was worth all the effort. Anyone want to give it a try?

[zan29]

What do you mean by using mask Dan? You're too technical for me ........:D
I started to carve a crown, again pierced on both sides (the outline only) but my cut motor gave up after the back was done.
You could carve the inside totally but to do so, you're tabs have to be aligned on both sides so they don't get carved out.
The height of the tabs has to be set at .25" but of course a lot of sanding is involved.
Here's test #4, a door knocker. Every piece had to be pierced on both sides except for the back plate.
The pieces don't fit very well since I sliced at .625 and my board was .6875.....silly me!
It's very rough looking since I didn't waste any time sanding off the tabs completely.
766717667276673

[bergerud]

Have you noticed that the top surface of the board, which will become the glue joint, gets carved? What was a nice planed surface gets roughed up by the carving bit. The smooth surface gets skimmed off. I like glue joints to disappear as well as the slice to actually be 3/4" thick. The mask is a 0.00 depth carve region which protects the gluing surface from being carved. With the mask on top of the slice, the carving bit will "jump" over the top surface.

I still do not understand your piercing thing. I hope you can post an example.

[zan29]

It seems we can't understand each other....LOL
The horse is an example. I should have taken pictures before gluing it together.
You would have been able to see both sides of each piece that are carved.

If you look at the ears, front and back are carved.
When you slice your object and end up with details on both side of the slice, this is when I pierce on both sides. In order to have the true slice (thickness, width and length) it has to be done that way.
I've tried not piercing the back of the slice and it does not work. The slice doesn't fit properly.

I normally use 3/4" but it's cheap pine I bought at homedepot for testing only.

I only pierce the outline and set my pieces to the same thickness as my board.

The mask is a great trick, thanks for sharing, I was not aware of that.

Here's my door knocker so you can have a look.