The foam-cutter – a full description

Our proces of building the foam-cutter has been a stabile process, where we have adjusted the design continuously.

We have some overall criterias and specifications for the final construction. We want to summarize them on this blog-post, to get a clear view on what our construction is capable of, and what advanteges it holds.

How does it work?: The construction is familiar to a so called T-bot, except from the fact that it has two individual belts. We achieve the linear lead in the x-and y-axis by having to sleighs made of acrylic material. The sleighs are fastened with the belts and goes along both the horisontal and vertical aluprofile. The first motors is fastened to the horisontal aluprofile and the second motor is fastened to the acrylic-sleighs. This leads the second sleighs up along the y-axis and leads the hanger and wire. The wire is fastened to the hanger by two aluminiumpipes and twisted around two screws. The hanger is made of tree and that’s how we avoid electric leading from the wire.

The plate, on which the foam-pieces will be cu,t is ply-wood and the foam is stuck to the plate by nails. The plate itself is being screwed on the aluminium-profiles.

The design: The criterias for the final construction are as follows:

1. The construction has to consist of a few components as possible (simple construction).

2. It has to be easy to seperate and collect again (the components are joined in a few places).

3. The weight should be low, which means that a man of average size will be able to carry it by himself.

4. The area, of which the foam is being cut, has to be maximized – of course in collaboration with the weight and simplicity.

Our final construction has a design that fully meets the criterias listed above. It’s able to cut big pieces, it has a weight of 6,9 kg (included the PSU and all other electronic components). It’s easy to seperate because it consists of few components and therefore has a simple design.

Materials: We wanted to mostly use standardcomponents in order to make it as easy for us as possible to obtain the parts, and also to make sure that the final construction wouldn’t be too expensive. We have used the 4 m. of aluminium, which was availiable from the beginning. The plate is made of ply-wood and the hanger is likewise out of tree. The components we had to make specially are the sleighs and some of the mountings. We made these out of acrylic material by lasercutting. All other components like screws, ball bearings and fittings are all standard.

Own experiments: Regarding the tests, we have made multiple. We had a lot of trouble figuring out how the GRBL-configurations of the geometries should be done. We tried several times to change the the speed alternating, depending on which geometry we were cutting. We eventually figured how we should fix the different files and that’s how we got our final results.  The pictures below illustrates how different results we got from changing specifications on different letters, such as the size and the speed.

In the end we figured that it was the belts that was a little too loose, and furthermore the gear on the motor was very loose and almost about to fall off, if it wasn’t for the belts that held it in place. After we tightened the gear, the running went way better for all the different geometries.

The letter A - we had some trouble with the speed of the running, and at a point, the wire stopped for a few seconds before it started running again. Why this happened is still a mystery to us.

The letter A – we had some trouble with the speed of the running, and at a point, the wire stopped for a few seconds before it started running again. Why this happened is still a mystery to us.

The fact that the wire holds still for a few seconds has a huge impact on the final form - some of the foam is melted away and makes holes in the geometry.

The fact that the wire holds still for a few seconds has a huge impact on the final form – some of the foam is melted away and makes holes in the geometry.

The letter E is smaller than the letter A, and it went way better. The wire didn't stop during the running, and the letter was cut in a nice shape.

The letter E is smaller than the letter A, and it went way better. The wire didn’t stop during the running, and the letter was cut in a nice shape.

Further work: If we had the opportunity for further work, then we would adjust different elements. First of all, we would fixate the hanger even more, to make sure that it wont vibrate when the construction is running. So far, the hanger can be affected when we run on a high speed, and start to vibrate. This affects our precision. If we improve the fixation, we can might prevent the vibrations.

Furthermore we might be able to optimize even more on the number of components and reduce it even more. Hereof will the weight also be minimized a bit more.

En tanke om “The foam-cutter – a full description

  1. Pingback: Inkscape and GRBL | m3ch47r0n1cs

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