Automatic Hot Knife Cutting Machine for Narrow Goods Design

[Mael Eòin Tactical]

Hey everyone, so while stitching part time i have also been at university studying electronic and electrical engineering, currently in my final year which means Honours Project dissertation woo.

For my dissertation i am designing and building a automatic cutting machine for webbing etc. The features as of writing this is as follows:
Automatic feeding of up to 5" wide material/materials
steady Temperature controlled Hot knife cutting
user selectable cutting temperature
Accurate Cutting to specified lengths (currently increments of 5mm)
Quantity of cuts to 9999
Easy user interface
Cut from user provided file ( see Below)

as well as the above the aim is to make it as small and also as cheap as possible without jeopardizing function or durability.

The final features is to allow the user to create a simple file that has all the cuts for a product place it on a USB, insert into the machine and be able to cut the lengths on the file to the quantity inputted on the machine. this was with a product with multiple lengths in mind like a chest rig to make setting up a production run of cutting simpler and as the files will be incredible tiny

i was wondering if there is any features you guys like or would like in an automatic cutter or any considerations to take into account, If any of you are interested in the progress i can keep you all updated.

Thanks in advance for any input

[dropshort]

The ability to cut from a profile will be a great feature.

Not sure on the mechanical issues involved but would there be a way to cut cord as well as webbing?

[BergspitzeCustoms]

Have seen some cutters have issues with elastic.  A setting to adjust tension on the feeder to feed stretchy/non-stretchy materials reliably?

I love seeing DIY projects like this, even when there is a commercially available option.  Please keep us updated!

[Mael Eòin Tactical]

Cord shouldn’t  be an issue, currently my thought is to have a roller with a spring to apply pressure with a motorised roller underneath for the actually feeding, two motorised feeders would be ideal but currently to cut cost and also over all side that is the basic concept still early doors so could change.

BergspitzeCustoms, thanks for mentioning that I had been so focused on the actually build and programming of the machine that the fact of elastic stretches hadnt crossed my mind haha I think it should be fine but won’t know until initial function testing, by any chance do you know what causes the fault with the big cutters at yours

and yeah I am the same diy stuff is always interesting, would love to buy a shieffield cutter but the cost and size was a big killer for me at the moment plus needed to come up with something for the dissertation haha

Thanks for the responses guys 

[Fouinard]

If you intend on using and arduino or a raspberry to control the lengths it could be awesome to ditch the usb part and be able to use some kind of web interface (hosted on the controller) and access it via wifi, so you can configure all your cuts on a computer or even from a smartphone.
To reduce the fumes you should set a temperature not too high, that melt but not burn the nylon. The temperature will drop each time you cut something and you'll need some kind of filtering on your temperature sensor values to prevent overshoot since your blade will have some thermal inertia.
Also you would need some guides to prevent the webbing (or anything) to go sideways, and if the feed rate is rather high and your roll is on a stand you'll need to limit the rotation of the roll or your webbing will continue to unroll.

[Mael Eòin Tactical]

If you intend on using and arduino or a raspberry to control the lengths it could be awesome to ditch the usb part and be able to use some kind of web interface (hosted on the controller) and access it via wifi, so you can configure all your cuts on a computer or even from a smartphone.

Great suggestion, i did originally want to have an app/interface on the pc and i will still work on it after completion of my dissertation. The reason for the usb was a time thing, i have till april to complete the full machine + the report + my other coursework while sewing.

For the Microcontroller at this point in time i will be designing my own board using an atmel chip, i have been advised by my supervisor (PHD assigned to keep each of us on track) to design a system to the specs required and if a after market board such as an arduino if it also meets the same specs and is cheaper to construct then i will be allowed to use them, so far i think the Arduino Micro is looking like it will be perfect possibly lacking on RAM, ideally somthing like the MKR1000 which already has a wifi chip would be great.

To reduce the fumes you should set a temperature not too high, that melt but not burn the nylon. The temperature will drop each time you cut something and you'll need some kind of filtering on your temperature sensor values to prevent overshoot since your blade will have some thermal inertia.

agreed, for the temperature control it is what i am focusing on the most at the moment, i have pretty much finalised the feeding, cutting and electronics but the hot knife temp control i have revised 4 times now to make it more accurate and efficient.

The temperature will be controllable by the user but the default will be the ideal setup for melting mil-w-17337 and A-a-55301 webbing, still waiting on texcel and mmi getting back to me to see if they have more detailed specs for there narrow goods to make research a little easier.

Also you would need some guides to prevent the webbing (or anything) to go sideways, and if the feed rate is rather high and your roll is on a stand you'll need to limit the rotation of the roll or your webbing will continue to unroll.

my plan was to always have the guides A to always provide a 90 degree cut and B also means for example you want to cut 1" webbing you can set up multiple rolls and just add more guides so they all feed at 90 to the blade.

Thank you for the response Fouinard


as an addition to the control via wifi my goal seperatly to the dissertation was to have the device communicate with an excel file (what i use to keep stock count) and automatically reduce the stock count as it cuts, i will do it after completion as nothing beats not having to manually reduce stock

[sodjer]

Hey nick ,if you find you need ally angle ,box section or item profile give me a shout  Davy

[SunriseTacticalGear]

I had a chance to look at my Sheffield webbing cutter and the heat is set to 600 degrees C which works great for webbing, including 2” Scuba.
One thing I noticed is that there is a spring loaded hold down bar that comes down first to hold the webbing, then releases after the cut. I think it keeps the webbing from sticking to the blade.
Food for thought.
Scott

[Mael Eòin Tactical]

I had a chance to look at my Sheffield webbing cutter and the heat is set to 600 degrees C which works great for webbing, including 2” Scuba.

Thats very very useful thanks, by any chance do you have a spec sheet for your cutter,

One thing I noticed is that there is a spring loaded hold down bar that comes down first to hold the webbing, then releases after the cut. I think it keeps the webbing from sticking to the blade.

which side of the cut is this on i have something similar on the "roll" side acting as both pressure for feeding and also just keeping it flat in general, i am making my first enclosure prototype  as i am hoping the design will have the cut piece fall away from the blade once cut. hope that made sense haha

thanks for the reply, very useful

[SunriseTacticalGear]

I’m out of the shop this week, but as I recall the hold down bar is located between the blade and the drive roller.
One more thing to consider is an “auto retract” function that pulls the webbing back, away from the heat of the blade after a batch cut. This keeps the webbing from melting while parked between batches.
Scott

[@less@ndro]

thumb up for this project. Is something that I was also thinking to do, I talked a lot of times with Fouinard about it.

I was thinking to use bluetooth instead of wifi or usb but once that the machine is done is easy to adjust it. My biggest problem was to create the support for the blade, now I have the 3d printer and this would be easier.

If you need help you can ask for coding and some electronic, I felt in love for Arduino some time ago and I pretty good with it.

I can assure you that a an Arduino Uno r3 has enough ram to do everything this machine needs to do. You can't believe how incredible are 2kb of ram if well used.

Are you going to release it open source / hardware?

[Mael Eòin Tactical]

thumb up for this project. Is something that I was also thinking to do, I talked a lot of times with Fouinard about it.

I was thinking to use bluetooth instead of wifi or usb but once that the machine is done is easy to adjust it. My biggest problem was to create the support for the blade, now I have the 3d printer and this would be easier.

If you need help you can ask for coding and some electronic, I felt in love for Arduino some time ago and I pretty good with it.

I can assure you that a an Arduino Uno r3 has enough ram to do everything this machine needs to do. You can't believe how incredible are 2kb of ram if well used.

Are you going to release it open source / hardware?

currently i am using an Atmega8 chip for the blade temperature control (will scale down once i decide which thermocouple to use, Thinking ATtiny85 or ATtiny10 if i can minimize the circuit a little more) and an Atmega328P chip as the main brain, i think that chip is what is in the arduino uno and nano, i won't be using the arduino ide as it has a few limitations that using the Atmel IDE doesn't.

still unsure if i will have the time to add wifi but personally i think wifi would be more beneficial than Bluetooth as it
 means a computer could also have software to interact

Depending on how my test results i may release it but will happily help you out if you need a hand on any design elements, my university has talked about possibly patenting a element of the system so unfortunately i wouldn't be allowed to give out that element as they will own the patent (god damn university),

thanks for the input @less@ndro

I’m out of the shop this week, but as I recall the hold down bar is located between the blade and the drive roller.
One more thing to consider is an “auto retract” function that pulls the webbing back, away from the heat of the blade after a batch cut. This keeps the webbing from melting while parked between batches.
Scott

Thanks man, and does the blade sit in the down position after a batch? would love to have a chat if you had the time

[sodjer]

I have been watching this article with interest ,at present I am cutting 2 inch straps by the hundred and it tedious.
I also just bought a cheapo Chinese laser cutter ( to learn with ) when setting it up I cut through a 40 mm piece of webbing and it cut it quick and nice ( and square ) would it be possible to make a strap cutter using one of these machines .
The y axis to cut across and the x Axis to run the feed rollers

[Mael Eòin Tactical]

I have been watching this article with interest ,at present I am cutting 2 inch straps by the hundred and it tedious.
I also just bought a cheapo Chinese laser cutter ( to learn with ) when setting it up I cut through a 40 mm piece of webbing and it cut it quick and nice ( and square ) would it be possible to make a strap cutter using one of these machines .
The y axis to cut across and the x Axis to run the feed rollers

cheers mate

it could be done with a laser but once you get with heavier webbing it would need multiple passes or slower passes which would then become slow compared to the hotknife. not sure how the laser would handle elastic or cordage either.

with a laser you are looking at roughly the same power requirement than the hot knife too which means the circuit wouldn't need much changed but then there is the added cost of the extra motor.

for a standalone machine with a goal of a small form factor and sub £500 (the goal anyway) i think a laser would add too much cost and also would increase the size quite a bit

the principle is definitely something that should be considered

i had thought of a machine using the same basic principles as a as you had said for cutting fabric where you feed to roll x amount of distance then cut, but as far as i could think of it could only be useful for per Metre(yard) fabric stores or for squaring off material after a batch or product run

i could definitely help modify a laser if that is something you wish, wouldn't take too much work i don't think,

[@less@ndro]

thumb up for this project. Is something that I was also thinking to do, I talked a lot of times with Fouinard about it.

I was thinking to use bluetooth instead of wifi or usb but once that the machine is done is easy to adjust it. My biggest problem was to create the support for the blade, now I have the 3d printer and this would be easier.

If you need help you can ask for coding and some electronic, I felt in love for Arduino some time ago and I pretty good with it.

I can assure you that a an Arduino Uno r3 has enough ram to do everything this machine needs to do. You can't believe how incredible are 2kb of ram if well used.

Are you going to release it open source / hardware?

currently i am using an Atmega8 chip for the blade temperature control (will scale down once i decide which thermocouple to use, Thinking ATtiny85 or ATtiny10 if i can minimize the circuit a little more) and an Atmega328P chip as the main brain, i think that chip is what is in the arduino uno and nano, i won't be using the arduino ide as it has a few limitations that using the Atmel IDE doesn't.

still unsure if i will have the time to add wifi but personally i think wifi would be more beneficial than Bluetooth as it
 means a computer could also have software to interact

Depending on how my test results i may release it but will happily help you out if you need a hand on any design elements, my university has talked about possibly patenting a element of the system so unfortunately i wouldn't be allowed to give out that element as they will own the patent (god damn university),

thanks for the input @less@ndro

I’m out of the shop this week, but as I recall the hold down bar is located between the blade and the drive roller.
One more thing to consider is an “auto retract” function that pulls the webbing back, away from the heat of the blade after a batch cut. This keeps the webbing from melting while parked between batches.
Scott

Thanks man, and does the blade sit in the down position after a batch? would love to have a chat if you had the time

yes, atmega 328p is the same of Arduino Uno. One of them should be enough for all the machine. I'm developing a project that has much more calculations involved and the Arduino is working well.

Can I ask you which limitations did you find withe the Arduino IDE? I know that the Atmel IDE is more powerful but actually I had never found any limitation with the Arduino IDE.

thanks.