Boundary Box Pricing for SLS

Boundary Box Pricing is the default and most common pricing method for SLS 3D printing. With this method, you are essentially paying for a rectilinear box volume of space that we price at 11p per cm³. The major benefit of boundary box pricing is the potential for massive savings by nesting multiple parts into a single file.

The Boundary Box Volume of a 3D File is your file's length x width x height. We use this value as the basis for quoting SLS parts. It's often referred to as XYZ pricing. Your file can be uploaded in any orientation and we will calculate the minimum boundary box volume for the most economical price.

As parts must be separated from each other by 1.0 mm when printed, we include 0.5 mm of space around each piece when calculating the boundary box volume.

The workings below show how we calculate the basic unit price for SLS prints.

X = Part length (mm)

Y = Part width (mm)

Z = Part height (mm)

SLS unit price = (X+1) x (Y+1) x (Z+1) x 0.00011

We multiply the boundary box volume by 0.00011 as we charge 11p per cubic centimetre for Boundary Box Pricing with SLS 3D Printing.

Low-Density Pricing for SLS

Low-density pricing is an estimate of the true volume of material used when printing your part.

The majority of SLS 3D printing costs is the PA12 nylon powder material. However, contrary to what you might expect, the amount of material required to print a single object is not equivalent to its volume. An SLS machine fills its entire build chamber with nylon powder every run. Some of this powder is fused to make solid 3D printed parts. The remainder of the powder becomes lower quality due to the high temperatures of the build process and must be mixed with fresh powder to be reused. 3D files with a small volume can still require an enormous amount of space. Larger boundary box files are more expensive to produce as a lot of powder is needed. However, a more economical price is achievable if other small parts fill the space around these large, sparse parts. Therefore, we check to see if parts contain space to nest other small files within their boundary box. The space is determined to be useable if a 50 mm part can be printed within the boundary of your file and then separated. 3D files must have a single body to qualify for low-density pricing, nested files will be priced using boundary box pricing.

The surface of your 3D file is expanded by 3.0 mm and the volume of the new offset file is recorded. We use this value to calculate the offset price of SLS parts. The pricing method is referred to as Low-density pricing.

The workings below show how we calculate the base unit price for SLS prints using Low-density pricing.

1. Offset surface by 3.0 mm

2. Record offset volume in mm³ = (OFF volume)

3. Low-density price = (OFF volume) x (0.0003)

We multiply the offset volume by 0.0003 as we charge 30p per cubic centimetre for Low-density pricing with SLS 3D printing.

1. Minimise the boundary box volume of the part. Unless the model is perfectly spherical, the orientation of a 3D file will affect the boundary box volume. The most simple trick to save money with SLS printing is to change the orientation of the part to minimise the boundary box volume. You can see this in most 3D file editors such as Netfabb or Meshmixer.

2. 3D Nesting is a technique of grouping multiple parts together into a single file to reduce their combined boundary box volume. This technique typically saves around 30% on cost; however, it can save much, much more. It's by far the best technique for reducing the cost of quotes in additive manufacturing. Read the full article on 3D Nesting for more information about how to save money with SLS 3D Printing.

Material Pricing for MJF

The surface of your 3D file is offset by 3.0 mm, and the new file's volume is recorded. We use this value as the basis for quoting MJF parts. The pricing is referred to as Material pricing as it is an estimate of the true volume of material used when printing MJF parts.

The workings below show how we calculate the base unit price for MJF prints using material pricing.

1. Offset surface by 3.0 mm

2. Record offset volume in cm³ = (OFF volume)

3. MJF OFF price = (OFF volume) x (0.2)

We multiply the offset volume by 0.2 as we charge 20p per cubic centimetre for material pricing with MJF 3D printing. MJF material pricing is cheaper than SLS low-density pricing but more expensive than SLS boundary box pricing. Therefore, the most affordable printing method is dependent on the geometry of your 3D file.

Why is this pricing structure used for MJF 3D Printing?

MJF 3D printing uses detail and fusing agents to fuse PA12 nylon powder material into 3D printed parts. An MJF 5210 3D printer fills its entire build chamber with nylon powder for every print run. Some of the powder is fused to produce solid 3D printed parts. Most of the unfused powder that surrounds the parts can be recycled and used for the next print run. However, the unfused powder close to the surface of the parts is degraded by the high temperatures of the fusing process. The small amount of powder within 3 mm of the part is collected and can not be reused for 3D printing.

The cost of an MJF 3D print is determined by the amount of volume it takes up, plus 3 mm, within the MJF build chamber.

What is additional Pricing for Finishes? 

We charge in addition to the original price a percentage markup of 10% for black dye. Therefore a part quoted to be £10 in natural white SLS will be £11.00 in the black dye finish.

Why is this pricing structure used for Black Dye Finish for SLS?

Specialist liquid dye for PA12 Nylon is our highest cost, coupled with equipment investment we are required to charge extra for this finish to cover our costs.

What?!? Is it free? 

Yes! We have no additional charge for Vibro-Polishing your SLS orders. While there is a cost involved in this process, we want our customers to have smooth SLS plastic parts without breaking the bank. Use both Vibro-polishing and black dye finishes to receive smooth black plastic parts in PA12 Nylon.

Why is Vibro-polishing free?

Vibro polished SLS parts are smoother, pick-up less dirt and in our opinion have an overall better look and finish. We offer Vibro-polishing free of charge as the costs are low and we want to deliver products that have a premium finish every time. We recommend vibratory polishing for any part that fits the criteria.

1. Spruing (SLS & MJF) is a technique of joining parts together to make them one component. Our system notes separate bodies in an STL file and will apply the minimum part cost for each. If you join these parts together with a small rod of 1.5mm diameter or more, you can avoid the minimum part cost for SLS & MJF.

2. Quantity! The minimum price per part is still affected by our volume price breaks; therefore, you can get a cheaper minimum part cost by adding more numbers of the same file. See the table above for more details.

What is the minimum charge for using 3D People’s 3D Printing Service? 

Our minimum order cost of £30 + VAT applies to any 3D Printing order placed with our service. The minimum charge is for the whole order and not per part, and therefore if your order is below the minimum charge, we suggest adding more quantity of your pieces to make up the difference. This price does not include costs for shipping.

Why is there a minimum order cost for 3D Printing? 

The minimum order cost is there due to the time it takes to process an order. Each order involves set-up, sorting, finishing and packaging by 3D People technicians. Therefore each order has a minimum time spent working on it.

Before proceeding with a batch production run of 3D printed parts, we recommend ordering a sample print to verify the manufacturing process is suitable for your application.

We offer refunds for the sampling cost after receiving a batch order. Refundable samples apply to orders that exceed a value of £1000. To claim the refund, email us with the order details, and we will refund the cost of your sample.

- The lead time for orders that include multiple technologies will be the length of the longest lead time within the order.

- Lead times are in working days. That is Monday to Friday excluding UK bank / public holidays and weekends.

- The cut off time for 3D Printing orders is at 2 PM on a working day.

- Orders placed before 2 PM on a working day start from the same day.

- Orders placed after 2 PM start from the next working day.

The count down displays the time remaining until the next order cut off.