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Optimal Cutting with minimum scrap - iPad app

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Blog entry by SmartCutter posted 11-02-2011 12:31 PM 9251 reads 2 times favorited 18 comments Add to Favorites Watch

I recently finished working on a cutting algorithm app for the iPad and iPhone called Smart Cutter, and wanted to share the app with every one hoping get some feedback from carpenters and wood workers.

Smart Cutter finds the maximum number of small pieces cut from a larger sheet of paper with minimum scrap. It employs a state of the art algorithm to generate the maximum number of small pieces cut from a larger sheet of paper, wood, cloth or any other material, with minimum waste. Whether you are a a carpenter wanting to cut pieces of plywood from a larger sheet, a tailor wanting to saw smaller pieces of cloth from a larger size piece, a photographer printing multiple photos on graphics paper and looking for the best print layout, or even a metal or glass sheet cutting worker, Smart Cutter will generate for you the optimal cutting diagram which utilizes every square inch from your original sheet, minimizing your material scrap

Here is a video about it: http://www.youtube.com/watch?v=A8_mrmqaBXk

The app can be downloaded from the Apple Store, more info here: http://www.smartcutterapp.com

Smart Cutter can help you with your work anywhere as long as you have your iPhone or iPad device handy. It also allows you to take a snapshot of the generated diagram and save it to your photo album in your mobile device. This can help you review different project layouts you’ve generated in your iPhone or iPad at later point

Everyone please share with me whether something like this would help you as a carpenter in your shop, and any ideas you have in mind that you think would make it more helpful.

-- Get Optimal Cuts from your iPad - Carpenter Pro: http://goo.gl/U6FVJ



18 comments so far

View grantlairdjr's profile

grantlairdjr

31 posts in 1248 days


#1 posted 11-02-2011 12:52 PM

Android version?

-- Grant Laird Jr - Garland, Texas

View SmartCutter's profile

SmartCutter

24 posts in 1055 days


#2 posted 11-02-2011 12:56 PM

Android version is planned for early 2012.

-- Get Optimal Cuts from your iPad - Carpenter Pro: http://goo.gl/U6FVJ

View tazray's profile

tazray

32 posts in 1057 days


#3 posted 11-02-2011 01:46 PM

does it allow for the kerf

View PeteMoss's profile

PeteMoss

207 posts in 2128 days


#4 posted 11-02-2011 02:27 PM

That looks like a pretty neat ap. My concerns for it from a woodworking perspective are Tarzray mentioned, the kerf would have to be allowed for, also is that most of the time woodworkers are not trying to get the maximum number of same sized cutting from a sheet, but rather have different sized cuttings coming from that sheet. I suppose it does happen from time to time though. The other issue peculiar to wood is that it has grain direction. So a piece cut vertically is not the same as a piece cut horizontally. Normally that has to be be taken into consideration when laying out parts.

-- "Never measure......cut as many times as necessary." - PeteMoss

View SmartCutter's profile

SmartCutter

24 posts in 1055 days


#5 posted 11-02-2011 02:27 PM

What would it need to support kerf? Do you think adding a tolerance to the small sheet dimensions would help do that?

-- Get Optimal Cuts from your iPad - Carpenter Pro: http://goo.gl/U6FVJ

View SmartCutter's profile

SmartCutter

24 posts in 1055 days


#6 posted 11-02-2011 02:33 PM

Thanks PeteMoss for your feedback. Points are well taken. As far as cutting durection, I would assume putting a small piece rotation constraint on the algorithm should take care of the grain direction issue, is that correct?

-- Get Optimal Cuts from your iPad - Carpenter Pro: http://goo.gl/U6FVJ

View PeteMoss's profile

PeteMoss

207 posts in 2128 days


#7 posted 11-02-2011 04:35 PM

Yeah, I think for cutting direction, if there were a simple checkbox or something to lock rotation that would do it.

-- "Never measure......cut as many times as necessary." - PeteMoss

View Raspar's profile

Raspar

246 posts in 1806 days


#8 posted 11-02-2011 05:19 PM

Again been said but grain direction could be important. Also as what i would like to see is multiple size pieces. Most of my cutting is different sizes and grain direction. This is a awesome app but could better with a few tweaks.

-- Have thy tools ready. God will find thee work.

View SmartCutter's profile

SmartCutter

24 posts in 1055 days


#9 posted 11-02-2011 07:13 PM

Thanks for the tips, I’m considering all these options in the next app I’m working on.

One question though about kerf, what would help allow for kerf? Would allowing to specifiy a tolerance to the width and height values of each small piece do the trick for kerf?

-- Get Optimal Cuts from your iPad - Carpenter Pro: http://goo.gl/U6FVJ

View Raspar's profile

Raspar

246 posts in 1806 days


#10 posted 11-02-2011 08:04 PM

I would add in a cut thickness…

-- Have thy tools ready. God will find thee work.

View Jeremy Greiner's profile

Jeremy Greiner

568 posts in 1430 days


#11 posted 11-02-2011 09:21 PM

It’s great to see other programming woodworkers out there. Taking into account saw blade kerf is very important for these types of programs.

A full kerf saw blade is usually 1/8’’ thick, or 0.125’’ a thin kerf blade I believe is 0.100’’ but don’t quote me on that, blades can get thinner still but those are some pretty crazy thin blades. Here’s an example of why taking into account saw kerf is important

Say you have a 12’’ by 12’’ board that you want 1’’ by 12’’ strips from. Simple math says “hey I can get 12 strips from this board” but that’s not the case because the sawblade eats away a little bit of waste wood making the cut. This wood ends up on the floor, dust collector or in your neighbor’s back yard etc..

To get 1’’ strips for a 12’’ with a full kerf blade you would get 10 strips. 10’’ goes to the boards .. 10/8 or 1 and 1/4’’ goes to sawdust waste from making the cuts, and you’d be left with 3/4’’ of a board left so you couldn’t get another full inch out.

Modifying your algorithm should be very easy, all you have to do is add the kerf size to the height and width .. and then do your calculations. If you want extra accuracy, you can check to see if the final waste piece is thick enough to fit another piece in it, since the cut has already been made, you won’t lose the extra kerf amount.

I hope this helps if you have any questions feel free to let me know ^^

-jeremy

-- Easy to use end grain cutting board designer: http://www.1024studios.com/cuttingboard.html

View dakremer's profile

dakremer

2455 posts in 1749 days


#12 posted 11-02-2011 11:36 PM

what a cool app. I’d agree there needs to be Kerf included into the layout – without that kerf included it is pretty inaccurate for a woodworker.

for you next version, you might consider being able to add more than one size of shape to be cut from your larger sheet. Say you have a 4’X8’ sheet and you want as many 22”X30” AND 15”X10” as possible. Another idea would having a little drawer for odd shapes like L’s or triangles or whatever….

I’m not a programmer so dont know how easy all of this would be to do – it looks like you have a good start though! Thanks for sharing

-- Hey you dang woodchucks, quit chucking my wood!!!!

View crank49's profile

crank49

3434 posts in 1629 days


#13 posted 11-03-2011 02:31 AM

I rarely need to cut only one size smaller piece from the large sheet. A cutting layout tool should allow any number each of any number of different shapes. And, it has to allow kerf losses.

Many commercial programs for doing this have two main functions. For instance, working with long linear shapes to be cut into shorter pieces – or – cutting random shape pieces from a larger sheet. The ones I have worked with were for cutting steel, but the same thing applies to wood. A person might need to cut 15 different length pieces from six 1×6 boards, 8 feet long. OR you might need 6 different shapes cut from a 48×96 x 3/4” sheet of plywood. Its important to include a number of pieces of stock and let the program optomize which pieces come from which sheet or length of stock. To keep track of all this you must be able to assign a name or part number to each piece.

In the commercial world of cutting metals the program also figures the weight of the cut pieces and the weight of the scrap and kerf loss. This is because metals are usually bought and sold by weight. Not so important for a wood worker, but you said you wanted this to be useful for multiple materials.

By the way, you only add 1/2 the kerf to each piece cut. In the example by Jeremy above for instance, if you add 1/8” kerf all around the piece then you are adding 1/4” to the width, and the calculation will not be correct for number of pieces coming from a 12” piece of stock.

-- Michael :-{| “If you tell a big enough lie and tell it frequently enough, it will be believed.” ― A H

View SmartCutter's profile

SmartCutter

24 posts in 1055 days


#14 posted 11-03-2011 08:47 AM

Thanks Jeremy for explaining the kerf allowance for me, your example was very clear and well written.

crank49, I assume that it is safe to assume no kerf is needed at the edges of the big sheet since it has finished sides, correct? Given this, I would put all the kerf to the bottom right of each small sheet instead of the middle, so Jeremy’s suggestion of adding all kerf to the height & width is valid. Each top-left sheet would have all kerf put to the bottom-right, which should allow for cutting the next sheet.

Fitting multi-size pieces is rather a complicated process and I do believe it is classified an “NP-Hard” problem in the world of math jargon, which in plain English means there is no one optimal algorithm that can get you to an optimal solution, but it seems like a fun challenge to do.

What’s even a more challenge is dakremer & crank49 requests to fit different small shapes like polygons or L shapes… this is an even harder problem to program, and will surely keep me busy for a while… let’s see what I can come up with in the next few weeks :)

-- Get Optimal Cuts from your iPad - Carpenter Pro: http://goo.gl/U6FVJ

View OttawaP's profile

OttawaP

89 posts in 2384 days


#15 posted 11-03-2011 02:19 PM

If you want the real thing check out Cutlist software. Lots of good ideas that could be adapted for a smaller version like this.

-- Paul

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