Chair seat carving: Probe or Aspire?

[jTr]

See photo. This is the best I've been able to produce using Sketchup. Hopefully detail is plain enough to show why I'm wanting for better results. (Ripples, curled type of irregularities along edge) I do have a carved model on hand done with my old fashioned methods, but need to digitize and utilize the bot now.
Thoughts:
1 - Try the digitizing probe and hope for better results than my Sketchup file? (used curviloft plugin - very helpful, but maybe I just need another approach)
2 - Invest in Aspire, as I understand it is much easier to generate organic shapes than in Sketchup? (Hard pill to swallow, as this is the first true 3D carving I've needed to do since I got my bot 18 months ago)
3 - Will digitizing with probe be worthwhile if I don't have optimal software to clean/smooth the file?
Appears that Partworks 3D is dedicated to vectoring only(?)

Any advice appreciated.

Thanks!
Jeff

[coryatjohn]

It appears to be a rather complex shape. Aspire is quite good at modeling such things but there is a steep learning curve so if you just need that one thing, it might be a good idea to hire it out.

[dana_swift]

For making chair seats, or organic shapes its hard to beat the combination of Sculptris and Aspire.

Sculptris is a free down load-

http://pixologic.com/sculptris/

What makes sculptris so good, is it will work on an axis of symmetry and for people its just so easy to do. The learning curve for sculptris is very low, most people at FabLabTulsa seem to pick it up in about ten minutes.

First figure out how to move a model from sculptris to aspire. Then work on the actual shape you want.

If you have Partworks 3D, that works also, but now there are three steps in the process: Sculptris->PW3D->PW2D then cut.

Hope that helps-

D

[gerryv]

You might want to contact Brady Watson at http://www.ibild.com Scanning and Shopbot are his specialty.

[Ajcoholic]

Having done several different chair seats in the past year and a bit... I wouldnt want to do it without Aspire.

I can go from an idea to a part in literally minutes now. And, I can adjust dimensions and sculpt the seat differently to adjust to various tastes of my customers.

AJC

PS I have posted a number of threads of some of the chairs I have done. Currently I am working on two more sets of 8 (one in walnut one in birch) and some various stools. All with carved/sculpted seats via Aspire.

http://i83.photobucket.com/albums/j307/ajcoholic/IMG_0975_zps8da61c7d.jpg (http://s83.photobucket.com/user/ajcoholic/media/IMG_0975_zps8da61c7d.jpg.html)

http://i83.photobucket.com/albums/j307/ajcoholic/IMG_1125_zps3195e849.jpg (http://s83.photobucket.com/user/ajcoholic/media/IMG_1125_zps3195e849.jpg.html)

http://i83.photobucket.com/albums/j307/ajcoholic/IMG_1030.jpg (http://s83.photobucket.com/user/ajcoholic/media/IMG_1030.jpg.html)

http://i83.photobucket.com/albums/j307/ajcoholic/IMG_0146.jpg (http://s83.photobucket.com/user/ajcoholic/media/IMG_0146.jpg.html)

[Ajcoholic]

Jeff,
If you have one seat to copy - you could always get the seat digitized and then use it. However, with the file in Aspire - it is very easy to change the carve shape (flatter bottomed or spherical), the depth & width, the depth of the carve, etc.

It is one of the main reasons I bought my Shopbot to begin with, as I do a fair bit of chair making and hand carving seats is time consuming, and as you know if you do it - to get a set of 6 or 8 identical is difficult.

WIth the Onsrud 5/8" diameter two flute ball end spiral I use, and a 10% stepover, I can carve a seat in about 20 minutes and just a little sanding is all that is needed to get it done.`

[Ajcoholic]

And while you are at it, carving a complex 3D shape like the backs on those walnut low backs, is EASY. Both sides, curved in two planes. Aspire makes it easy!

AJC

[Burkhardt]

As it happens I am working right now on a seat surface. This is however not for a chair but for the sit-on top of a Cajon drum, see below. If that is any help for you I will be happy to send you an the .stl file. The blank is 12"x12"x1.5" but in your CAM you could scale it to size, e.g. for a bigger butt or less deeply shaped. The .stl is actually carved out to a constant wall thickness from below but that is optional.

It looks almost like what you need, however the Cajon requires to sit with legs spread which is maybe not really what you want for a chair :)

https://lh3.googleusercontent.com/-dDd_ZIcVSHQ/UdDOXX1F7_I/AAAAAAAAEEw/Wv1rkDN76y0/s1024/SeatSaddle.jpg

This was modeled using IronCad.

[Burkhardt]

O.K., never mind....I made the model a little more chair-friendly and increased to 16"x16":

https://lh3.googleusercontent.com/-htxFOEjmjys/UdDXzz0TYGI/AAAAAAAAEFA/T7d9CHPUw-4/s1024/SeatSurf.jpg

[myxpykalix]

Jeff,
Do a search here, over on vectric site, and cnczone as i have seen a number of chair seat models guys have made that they posted and shared.
Some looked like Andrew's chair seat in terms of shape.

[jTr]

Wow - great work guys!
Andrew -
Have reviewed / admired those very designs - kept thinking a bit more practice in Sketchup would get me there, but this type of work is not one of it's strengths.
Since enjoying Denver shopbot camp last week and seeing Randy Johnson's work and magazine articles, it's clear that Aspire is the soul mate to the shopbot if you need to generate more organic 3D shapes. Flip op's are not far down on the list of 3D work I have in mind, as noted regarding chair backs.

Would love to short-term scan and run, but upon closer inspection, wood movement issues have crept into my original sample seat, so accuracy is compromised.

Eventually will need the program power to morph for other styles I've done.
Another of my designs to eventually digitize:

[Joe Porter]

Jeff, if you look at the Vectric Forum, rscrawford (Russell) has just about done a tutorial on chair seats with Aspire. Recently, Angie, (Zeeway), also on Vectric Forum, has done a Maloof style chair seat. Also, in the latest issue of "Popular Woodworking Magazine", Mario Rodriquez has done an article and video on making a really good looking chair seat with a table saw jig and no computer of CNC at all. Hope this helps...joe

[jTr]

Joe,
Thanks - I'll check into those. Trying to get away from old method, which involved a special router base that rode in a set of cradles oriented in the X/Y position that incorporated concave curves for "Z" movement. (Sounds like I could use a cnc, eh?)
Worked pretty well , but was very dangerous and needed an elevated level of clean up. Re-worked my Sketchup model a bit, since I've delved this far into it. Looks like eliminating the curvature at the edges got rid of the weird warping. Looks more like a potato chip, but Partworks 3D is handling it just fine. Next Step: test carve into pink insulation board.

Here's the Sketchup shot of splines, then rendered / processed using Curviloft plug in, followed by the partworks 3D preview. Only trouble I'm having with Partworks is the cutout - unable to get the cutout to reach through material - seems it won't exceed cut plane setting - why tool change and re-zero to travel a path 90% completed by carving process(?) I'll simply release at the band saw and begin sanding, unless someone knows the key to cut beneath the carving's cut plane...

[myxpykalix]

One way you could go about this is to just model one half of it with your curves and then mirror it over to the other half:confused:

[jTr]

Jack - that's how I generated the lines visible in first photo, so things are looking uniform.

jeff

[ssflyer]

Jeff,

Did you render the "other design" in Sketchup? Looks way better than my renderings. :D I agree that Scuptris may be the way to go here, if you aren't ready for Aspire.

[jTr]

Ron -
That was "rendered" by trial and error, modifying and utilizing my old handheld router trestle, and a special swinging jig mounted on my old Woodrat to gently roll the front edge in lieu of the traditional pommel.

Now that I'm addicted to digital woodworking, I'm aching for the ability to get those old concepts digitized and continue developing them in that format. Though a committed Sketchup user, I think you're right - Sculptris looks quite impressive, but think Aspire will prove essential for the long haul.

[ssflyer]

Jeff,

Pretty amazing when the original can look like the rendering! :o Sorry I missed that! These days, I'm just so used to seeing renderings, instead of photos! I've use Keyshot rendering engine with Alibre, and it is so realistic...

Anyway - I agree. You don't need renderings - you need product. Aspire is the way to go. Keep in mind, however, that a program like Scupltris, can still effectively enhance your workflow, particularly when doing organic shapes.

[ssflyer]

BTW, while it was a good paying job, doing 10 reproductions of gargoyle and lion head corbels, to match damged pieces on a 18th century wainscoting, they took about 3.5 hours apiece to scan with a probe - and they were only about 2" x 3.5", but with a lot of detail so really small stepover wite the smallest probe tip.

[myxpykalix]

Ron,
I could swear i have seen a picture of a 3d model somewhere on the net of that exact corbel, so someone has made that into a 3d file somewhere...but then again i could be imagining it but i don't think so...:confused:

[ssflyer]

Hi Jack,

I've posted it several times, on both this and Vectric's forum. I didn't model it, I probed it and the corresponding gargoyle, then cut several of each... Damn maybe we're both getting old! :eek:

I have, however seen similar - I think Osboune has one close...

The picture I posted was the original - came from wainscotings imported from Belgium, reputed to be from the 1700's

[blackhawk]

Andrew - I really like the shape of your chair seats. Could you show some screen shots of how you setup your vectors and share a little of your methodology? I assume that you are using a two rail sweep. or sweeps.

Thanks

[scottp55]

Off topic Andrew, But LOVE the Walnut backs of those chairs:)

[Brian Harnett]

For making chair seats, or organic shapes its hard to beat the combination of Sculptris and Aspire.

Sculptris is a free down load-

http://pixologic.com/sculptris/

What makes sculptris so good, is it will work on an axis of symmetry and for people its just so easy to do. The learning curve for sculptris is very low, most people at FabLabTulsa seem to pick it up in about ten minutes.

First figure out how to move a model from sculptris to aspire. Then work on the actual shape you want.

If you have Partworks 3D, that works also, but now there are three steps in the process: Sculptris->PW3D->PW2D then cut.

Hope that helps-

D

Dana, Thanks for the link I will be playing with this, seems nicer than the few free 3d programs I have used.

[Ajcoholic]

Andrew - I really like the shape of your chair seats. Could you show some screen shots of how you setup your vectors and share a little of your methodology? I assume that you are using a two rail sweep. or sweeps.

Thanks

Yes I do two, 2 rail sweeps (one for each side - then join them up).

I have to do the screen shots on my work computer... will try and get it done some time this week. Sorry I'm not as quick as usual,currently, as life is just crazy with a sick dog and 8 week old baby at home these days... :eek:

Do you want to see shots of the aspire stuff I am assuming? I can walk you through how I do my seats. Its just one way, but its the way I figured it out when I started in early 2012, and they way I continue to do it as it works great.

[blackhawk]

Andrew - No problem, sometime this week is more than fine. Yes, I use Aspire and it would be great if you could walk me through your method.

I have tried a few things with only one sweep, but can't quite figure out what I need to do with using two sweeps.

Thanks

[blackhawk]

Andrew - I am still interested in your method. If you could still help out, it would be greatly appreciated.

[Ajcoholic]

Andrew - I am still interested in your method. If you could still help out, it would be greatly appreciated.

Sorry I completely forgot. Will do in the near future... Might not be until the weekend.

[Ajcoholic]

OK I did this today... excuse the cell phone pics of my computer screen, but I do not know how to get a screen shot on my new PC.

Before I begin, please for the Aspire pros out there, be kind. I dont mind some constructive critical comments - this method really works well for me and is quick to perform and modify, etc. But I know there might be better ways as well. I was asked to show how I do it, and here it is...

Basically the steps I perform are as follows:

-Draw the chair seat outer profile
-create a line that will be the center raised portion, up from the center front edge. experimenting with length will show what works best. 1/4 to 1/3 the overall carve depth front to back, is a good place to start
-draw 1/2 the outer profile of the carve, I use a short line drawn from the rear down, to start and carry the curve past the front edge, then trim.
-create a curve/arc bewteen the front center and outer edge of the curve - set the depth somewhere comfortable. for a seat thickness of 1.75" I often do a carve depth/height of .75 to .875".
-do a two rail sweep with the outer curve, and the short center line as the rails, both in the same direction, and the arc you created as the profile. I set it to vary the depth with the separation and set the height max to your arc height.
-once swept, I simply mirror both the 3D shape, and the outer profile/curve.
-I manipulate the two sides so there is no space bewteen them (simply zoom in and use the arrow keys to move them so they are touching)
-draw in the lower front line connecting the curves, and join to get a boundary around the whole shape.
-create the tool path using both 3D sides and the outer profile.

Here are a series of photos. It really does work!

[Ajcoholic]

http://i83.photobucket.com/albums/j307/ajcoholic/IMG_0022_zps9960976c.jpg (http://s83.photobucket.com/user/ajcoholic/media/IMG_0022_zps9960976c.jpg.html)

http://i83.photobucket.com/albums/j307/ajcoholic/IMG_0023_zpsc0242769.jpg (http://s83.photobucket.com/user/ajcoholic/media/IMG_0023_zpsc0242769.jpg.html)

http://i83.photobucket.com/albums/j307/ajcoholic/IMG_0024_zps7527c449.jpg (http://s83.photobucket.com/user/ajcoholic/media/IMG_0024_zps7527c449.jpg.html)

http://i83.photobucket.com/albums/j307/ajcoholic/IMG_0025_zpsa03754f9.jpg (http://s83.photobucket.com/user/ajcoholic/media/IMG_0025_zpsa03754f9.jpg.html)

[Ajcoholic]

http://i83.photobucket.com/albums/j307/ajcoholic/IMG_0026_zps371073a4.jpg (http://s83.photobucket.com/user/ajcoholic/media/IMG_0026_zps371073a4.jpg.html)

http://i83.photobucket.com/albums/j307/ajcoholic/IMG_0027_zpsea806745.jpg (http://s83.photobucket.com/user/ajcoholic/media/IMG_0027_zpsea806745.jpg.html)

http://i83.photobucket.com/albums/j307/ajcoholic/IMG_0028_zps551bcfa6.jpg (http://s83.photobucket.com/user/ajcoholic/media/IMG_0028_zps551bcfa6.jpg.html)

http://i83.photobucket.com/albums/j307/ajcoholic/IMG_0029_zpsc2100517.jpg (http://s83.photobucket.com/user/ajcoholic/media/IMG_0029_zpsc2100517.jpg.html)

[Ajcoholic]

http://i83.photobucket.com/albums/j307/ajcoholic/IMG_0030_zps8fdb65a2.jpg (http://s83.photobucket.com/user/ajcoholic/media/IMG_0030_zps8fdb65a2.jpg.html)

http://i83.photobucket.com/albums/j307/ajcoholic/IMG_0032_zps4ae27806.jpg (http://s83.photobucket.com/user/ajcoholic/media/IMG_0032_zps4ae27806.jpg.html)

http://i83.photobucket.com/albums/j307/ajcoholic/IMG_0033_zps88b5a4e8.jpg (http://s83.photobucket.com/user/ajcoholic/media/IMG_0033_zps88b5a4e8.jpg.html)

http://i83.photobucket.com/albums/j307/ajcoholic/IMG_0034_zps4decbf88.jpg (http://s83.photobucket.com/user/ajcoholic/media/IMG_0034_zps4decbf88.jpg.html)

[Ajcoholic]

Here is a better shot of the finished rendering.

http://i83.photobucket.com/albums/j307/ajcoholic/sampleseatfile_zps10a70867.png (http://s83.photobucket.com/user/ajcoholic/media/sampleseatfile_zps10a70867.png.html)

If I am doing a set of seats I usually trial cut one in a blank of poplar or something cheap, and sit in it to make sure the proportions are correct. After a few seats you can usually get pretty good just on the screen.

One thing, with the sweep, the carve gets deeper in the rear section where your butt sits, and shallower in the narrower section where your thigh is, and deeper again at the front edge. Just like you want it to be.

I also sometimes round off the front section with more 3D manipulation, but generally find it faster to just pass a roundover bit with a hand held router (with the base sitting on the front edge of the seat, while clamped vertically in a bench vise).

[Ajcoholic]

And usually, with my 5/8" Onsrud spiral carbide ball end mill, and a stepover of 5% to 7%, I can forgo the roughing pass and just carve the seat going back and forth starting at the rear and working side to side, and ending along the front edge. That way you start with a very light cut and get progressively deeper.

Just hit it with a 120 grit disk in a random orbital and you are good to go!

[Ajcoholic]

Andrew - I am still interested in your method. If you could still help out, it would be greatly appreciated.

Brad did this help you at all?

[blackhawk]

Andrew - Yes, I think that I have it. Great write up! I read your post twice through and in about 15 minutes created one of my own. Take a look below and see if it looks OK to you.