New Machine Build- 16' x 5.5' Fabric Cutter/Plotter

[Pyronaught]

This isn’t a router, but this seems to be the only thread for DIY machines so I’m putting it here…

I just got done building this 16 ft x 5.5 ft fabric cutting machine which is a tangential cutter that has both a cutting tool and pen on the same tool head for doing both operations without needing tool changes. This is my first CNC machine and was a lot of fun so I plan to build a mill next summer. It might have made more sense to start with the mill, but the fabric cutter is actually a simpler machine that requires less precision and lower cost components, so it was a better choice for a first time builder I think. The down side is that there seems to be no information anywhere on building fabric cutters, as not many people appear to be building their own. While router and mill plans are all over the place, fabric cutters are nowhere to be seen. Perhaps this is due to the fact that the CNC hobby is 99% guys, and most guys do not sew! I have to admit I catch a lot of crap for even owning a sewing machine, so I just want to state up front that my only purpose for sewing is to make hot air balloons, not dresses. I use one type of fabric, one gauge of thread and only know how to sew one type of seem used for making balloons. So THAT, my friends, is why there is a sewing machine in my man cave. And it’s not some plastic betty homemaker Jo Ann special, it’s an industrial double needle, all metal Japanese Juki built like an engine block, so yeah… just wanted to clear that up

Because of the large size of this table, it was necessary to find the absolute lowest cost option for rails and sliders, which turned out to be makerslide from inventables.com. Speed is a higher priority than precision with a fabric cutter, so the aluminum 80/20 type construction was ideal. I looked at a lot of options for how to build a machine this large without breaking the bank and makerslide was the optimal solution. Not only is this the most economical way of building a large format fabric cutter, it is also one of the most light-weight and expandable designs. The machine shown here uses 43 linear feet of makerslide.

Another criteria for a fabric cutter is the ability to expand the length of the X-axis later on if you need more length. The primary reason I built this cutter is for cutting large fabric panels used for making hot air balloons. The 16 ft X axis would handle most balloons, but if someone were going to make sails, ultralights or paragliders then a longer table might be needed. The table can be expanded in 4ft increments by building more table segments and then adding more rail. Chain drive was chosen for the X axis so that the chain can be easily lengthened by splicing onto it. Timing belts would require replacing the whole belts with longer ones. Gear racks can be expanded by adding more rack segments, but they are very expensive and would have busted the budget.

I’ve noticed a lot of chain drive machines just leave the chain hanging on the X-axis, which requires an excessive amount of tension on the chain to pull out the sag. For a shorter X-axis this might not be an issue, but the longer the table gets the more weight of chain you have to try and pull the sag out of. So what I did was use a chain gutter to support the chain for the full length of the table. The ¾” aluminum channel you can buy at hardware stores works great. With the chain gutter holding the weight of the chain, you are free to apply only the amount of tension required to remove play, thus putting less load on the motor bearings. I was worried that the chain might make a lot of noise rattling around in the metal channels, but it really doesn’t.

Another complication that arose from having such a long X axis was cable management. Originally I was going to use the catenary wire festoon method of running the cables, which is where you have a tight steel cable from which loops of wire are strung such that they can expand or compress as they slide on the wire. This turned out to be a more difficult method with several disadvantages over drag chains, such as entanglement issues, requiring longer over twice as much wire, bunching up at one end and just doesn’t look clean. It seems to be a fairly standard way of cable management for commercial fabric cutters, but I just didn’t have any luck with it. I went with a long drag chain instead, using a support shelf to prevent sagging issues as described here:

http://www.cnczone.com/forums/diy_cn...ong_spans.html

Like most fabric cutters, the entire table surface is a vacuum table. Rather than using commercial blower motors that cost over $300 each, I used two 5HP Rigid shop vacs under the table costing $80 each. This saved a good bit of money and works just fine. Not only that, when I need to clean off the table I can pull one of the shop vacs out and use it to clean the table. I will mainly be using this for cutting coated ripstop nylon, which air can not pass through so the vacuum table holds it down quite well.

Unlike the DIY vacuum tables you might have seen built for router table drag knifes, a fabric cutting vacuum table must have very small holes—otherwise the fabric will get sucked into the hole and produce a dip which the knife will fail to cut. The holes in this table are 1/16” diameter with 3” spacing, drilled through 3/16” hard board. Each panel has a 16 x 22 hole grid and is sealed so that airflow does not occur between adjacent panels. This allows you to power only the panels you need for a given job rather than the entire table. So that was 1408 holes that had to be drilled for my four panel table, and since my machine has no Z axis or spindle, these had to be drilled by hand. It wasn’t as bad as it sounds though.

Because of the light weight of the gantry and even lighter weight of the tool head, I can easily run rapids at 1300 IPM or more. Rigidity is not as much of an issue here since there is no heavy spindle with side forces acting on it the way there is with a router. The levelness of the table does not matter much either, since the tool head is pneumatically actuated and will hold the tool to the table regardless of any dips or peaks in the table surface (as long as they are within the range of the cylinder stroke). The air pressure is independently adjustable for the pen and cutter, both of which use springs for return. The cutter head was heavy enough that I had to add an additional external spring because the internal spring in the pneumatic cylinder wasn’t enough to bring it back up.

In the videos below I am using a hot-knife cutter which I built from an 80W soldering iron. This cutter has tangential cutting capability, so there is a blade rotation motor that keeps the blade tangent to the cutting line as it goes. For drag knife you just wouldn't use this motor, but for hot knife and wheel cutters you would need it. Currently all I have made is the hot knife, since that is the main thing I need, but other knife types could be made and inserted into the tool shaft in place of the hot knife. The ideas is to build each tool type into a 7/8” O.D. cylinder that slides into the holding tube. The hot knife is actually the most challenging option since you have heat dissipation issues. I could not use normal ball bearings on the tool shaft because the high temps would break down the grease and melt any plastic bearing seals. I went with graphite impregnated sleeve bearings for this, and still need to add a muffin fan that blows air through the gear box. Without the air flow, the heat transfer will slowly heat up the entire tool head and eventually overheat the blade angle motor.

I did have to write a custom post-processing program that takes g-code generated for 3-axes machines and converts it into what a 2 axis fabric cutter needs. This mostly consisted of stripping out Z axis data and inserting the knife/pen up and down macros at the proper places, and also calculating what the knife angle needs to be based on the X,Y data and setting the A axis motor to that value. When A axis angle changes are below a certain threshold, the tool head stays on the table. For larger angle changes, the tool head comes off the table so that it does not twist the fabric when turning. Because the hot knife has a power cord to it, the program also insures that it does not ever turn beyond 360 degrees in order to keep the cord from getting entangled. Another feature I built into the post processor is the ability to automatically add registration lines at regular intervals around the entire cutting perimeter. Registration lines are reference marks that are used to keep two pieces of fabric aligned when sewing them together, since a sewing machine actually pulls one piece more than the other and you must continuously struggle to keep both pieces in synch. Rather than having to include these lines in the original CAD files, my program will automatically generate the g-code for perfectly spaced lines based on the geometry of the patterns and add them into the final output file.

The remaining work left to do is build a computer console with joystick and other buttons running through an i-pac, and build a screenset for Mach which is specific to fabric cutting. Total build time for this machine was about three months and material costs were about $3K, which also includes a small air compressor to run the pneumatics. A commercial machine this size would run you about $30K, so that is quite a bit of savings!

Here’s some video of the first tests:






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[Bl@ckrat]

really awesome !!

would love to see more detail on your rotating cutter ...
if i had a clue ... i would try to make a cutting head to cut carbon fiber out ... but i dont so i will stick to doing it by hand ;-S

[Pyronaught]

I think just a standard wheel type rolling cutter would be able to cut carbon fiber cloth. Would probably have to increase the pressure a bit, but I bet it would work. Currently I'm using 40 PSI on the head, and most of that is to overcome the return spring. I can go as high as 100 psi.

Here's a commercial machine cutting carbon fiber with a wheel type cutter:

[Pyronaught]

Here's another video of carbon fiber cutting with more information in the comments area. Apparently you can't just cut that stuff dry or it will fall apart, so they are pre-impregnating it with resin before cutting it I guess. That's got to get messy! Check out how fast their cutter is though, WOW! Then there's that odd looking router making the molds at the beginning that is also moving at a very fast feed rate. They actually built that one themselves and it is being run on Mach.

[CarveOne]

Pre-impregnating carbon cloth or uni-fiber keeps it from buckling and sliding around. The solid material can be cut faster and with better accuracy. Lay a sheet of 6 mil polyethylene plastic or waxed paper on a smooth flat surface. Lightly spray the plastic sheet or waxed paper with 3M77 spray contact adhesive first, flip it over and lay it on the flat surface then smooth it out by hand or a roller. Lay the sheet of carbon material on top of the plastic or paper and roll on a thin coat of slow cure epoxy to saturate the carbon material and lay a sheet of Plexiglas on the carbon material, add weights on top of the Plexiglas, let it cure overnight. It isn't so messy when done correctly. The carbon will peel up from the plastic or wax paper easily. Try it on a small piece first. You can make your own carbon fiber plate or the DIY equivalent of Dragon Plate this way.

Rough handling of small pieces of carbon cloth will cause it to fall apart, and short strands where cloth is cut to sharp points (like star shapes) will fall apart. Carbon fibers in your lungs and hands is not good for you.

[grawley]

Really nice machine. Great low price.

My background is that I used to manufacture similar machines, but much larger for the carpet industry (12 foot x 16 foot standard). Our knife was ultrasonic.

A few questions and tips from experience. For the shop vacs, we once delivered them to a buyer (actually for removal of dust while operating the machine). But, our buyer ran them all day so they broke and, of course they are under warranty, but after taking them back twice to Home Depot, they were informed that the shop vac was not rated for continuous use. However, it looks like your balloon work is periodic use so should be no problem.

For the vacuum tables, do you have any information on the panel thickness, in order to prevent sagging over time? Not sure if sagging is the right description, but the vacuum applies a force and will be pulling on the panels.

For the knife blades, anything on how long they last? It looks like you are going into plywood. We used to set a sharpening time for the blade, so that after so many cut inches then the machine would pause the job and return to the home position for hand sharpening (every 2000 inches). We found the blade cost could be high for customers and spent a lot of time sourcing the right blades and ordering them in high quantities to reduce the costs.

Did you consider the pizza wheel? At the Industrial Fabrics trade show, the guys selling the balloon cutting machines typically use pizza wheels.

Sometimes the panels are fabricated from fiberglass, but the best thing I saw was a re-sealing skin placed overtop the rigid structure. This skin would not be damaged by the knife and the knife would stay sharper longer.

Again, great looking machine, and like the budget.

[Khalid]

nice machine and thank you for sharing. What software you are using for Gcode generation. Really love to watch the posted video. Regards

[Pyronaught]

Ultrasonic knife would be an interesting option. Right now I'm using only hot knife for two basic reasons: 1) it seals the edges of the fabric so that it doesn't fray and 2) it does not damage the table surface so I don't have to bother with a secondary disposable surface. Also it never needs to be sharpened, which is nice. The down side is the limited feed rate though, and the tendency to burn the table when the feed rate drops during a curve. The pizza wheel type cutters can be blazing fast, but like you say you need a special cutting mat under them which can get expensive. I saw one machine that actually had the blade sharpener built into the tool head and it would stop at regular intervals and sharpen the blade on its own!

Back to ultrasonic though... I never thought of using that for cutting. I've seen it used for bonding and have considered using it for that purpose. Does there need to be any special surface when cutting with ultrasonic? Would it damage the heat tempered hardboard surface like what I'm using? One application I have planned for this machine is building RC blimps, which are typically built from aluminized nylon or polyurethane films which are thermally welded together. I looked at a Sonobond machine a few years ago for doing this but they are very expensive ($25K for one that doesn't look much different than an industrial sewing machine). They do make perfect welds though. I could not tell if both the top and bottom pieces forming the seams involved the ultrasonic vibration or if it was only the top roller. If only the top roller vibrates, then perhaps one of the cheaper hand-held ultrasonic tools could be modified and adapted to the machine

[Pyronaught]

nice machine and thank you for sharing. What software you are using for Gcode generation. Really love to watch the posted video. Regards

I start by importing DXF files of the patterns into CamBam, then let CamBam generate the G-code. I use the "engrave" tool for the tool paths, then define one tool for the pen and one for the knife. Then the g-code output from CamBam is processed by a separate program I wrote which creates the final g-code for the fabric cutter. I wrote this in c# because I'm a programmer by trade and I can crank out a little windows utility like this a lot faster than trying to learn some limited scripting language such as typically required to write built-in post processors in these CAM programs. I think CamBam can call external processors anyway so I should be able to auto-run my program from within CamBam too, I just haven't got around to it. I've attached a screen shot of what the program looks like below.

[Pyronaught]

Today I'm working on the computer console for the machine. I've spent a lot of time looking at the various options for this and looking at other people's designs. Since this machine operates in a pretty clean environment, with no dust, chips or oil getting flung around, I did not bother with a washable keyboard or sealed case. Also since my controller is using a smooth stepper, the speed of the PC is also not a big concern. So I'm using a light-weight low cost laptop ($300 Toshiba) mounted diagonally in a minimalist console, with a cordless Logitech k400 keyboard sitting on top. This keyboard has a mouse pad built into it, so there is no need to have a mouse or trackball located anywhere else. The button/joystick console uses an I-pac keyboard emulator and the E-stop button is also located here so that the controller can be stored under the table. The button layout includes the standard set of shuttle buttons (rewind, play, pause and stop) and then five special function buttons. If I need more than five functions later on I'll just add a shift button to give double functions to these five buttons, increasing the function count to 10. This light-weight console is mounted on a pipe swivel at the corner which is the Home position.

[Khalid]

Thanks for sharing your program GUI shot. Programming is fun i also love it

[Pyronaught]

I got the control console done and posted the build notes for that as a separate thread, since it was generic enough to be used on pretty much any CNC machine and not just a fabric cutter:

http://www.cnczone.com/forums/diy_cn...ml#post1356902

[Pyronaught]

Added a heat roller tool for heat sealing plastic films. Here's a 36" diameter foil balloon I made as a first test

[Pyronaught]

Because lots of time would be saved by being able to do sealing and cutting operations in addition to pen plotting within one operation, I had to redesign the tool head to have three tools instead of two. I also improved the overall design of the tool head to eliminate some play that the last design had. The new design uses pistons operating through a rotating sleeve instead of pushing the entire gear box up and down. This made the tool being moved a lot lighter, thus eliminating the need for additional return springs and freeing up more pressure to be used applied to the tool instead of being applied to overcoming return springs. Both the heat wheel and the cutting wheel are tangential tools, but since only one of them will ever be on the table at a time I geared them both together so that only one motor/axis/controller is needed to rotate both of them.

[amseam]

Very impressed with your system!

I have an older plotter/cutter that I'm looking to modify. How do you feel that the makerslide would hold up in longer span. (my existing table is 6' x 32') looking to go to 7' wide x 40' long?

Are you using a digitizer?

Thank You

[koss2j]

Hey Pyronaught Great Machine! I have a need to build a fabric cutter of similar dimensions and the costs for units in Australia are 3 times that of commercial units in America.
The table and the hardware to carry the cutter I can build, as we already have a 2 metre x 10 metre table, but can you please help me with sourcing the correct cutting head or indeed some help with building one. I only need a pizza cutter wheel and a pen for cutting PVC fabric.
The software then to run this will be a bit of a challenge and maybe you might be able to point me in the right direction there too.
Any help will be greatly appreciated.

[Bl@ckrat]

bump

hows the machine running ?

[msandford]

This is quite an impressive machine! I am looking at building something like this myself. I have a few questions:

1. stepper size and rating
2. chain (looks like ANSI 35 but I can't really tell)
3. it looks like a 9 tooth drive sprocket, is that right?

The answers to these questions would be really helpful to be able to roughly replicate the gantry setup you've got. I'm looking at doing a rotary cutter so the 1300ipm rapids you talked about are really desirable.

I can see how you got the Y rails parallel, use precisely cut t-slot sections and perhaps no adjustment is necessary. But how did you ensure that your X rails were parallel? It seems like being really careful on the woodworking part can only get you so far. I saw that you used aluminum angle to mount the makerslide to the table. Did you just drill oversized holes so you could slide things around and use an 8ft level to align all the sections to one another? Does the lack of aggressive gusseting on the gantry riser help with the parallel tolerance issue? What I mean is that it looks like it could flex a bit which would mean that instead of needing to be parallel to a few thou you could get away with a 0.020 or 0.030 and still be OK.

Thanks for any help you can give!

[cyclotron]

Pyro,

Great project! It actually inspired me to build my own CNC fabric cutter (I make super light hiking gear as a hobby) . Mine is built from some salvaged Isel slides and 80/20 drops. I'm attaching some pics of my build below. I have some questions about your post processor and sent you a PM. Cheers!

[Pyronaught]

bump

hows the machine running ?

I've been using the machine to build blimps and flying saucers recently. Here's some pics.