Custom CNC bowl from walnut

This custom cnc project turned out nicely for a customer who wanted a wooden salad bowl unlike any other. The material is laminated walnut finished with polymerized orange oil polish. Size is approximately 15.5″ x 13″ x 5″.

cnc bowl complete

Suction elbow pipe sections

We have been contracted to complete a series of different suction elbow patterns. Each one has a different configuration, inside diameter, flange size, hand hole clean out position, etc. We develop the models and pattern designs from drawings with input from the customer. Pictured below are the first two in what we hope will be a long series of orders.

Suction elbow 1 pattern with clean out cover and half core box Suction elbow 1 detail Suction elbow 1 core box detail

Suction elbow 2 pattern Suction elbow 2 core boxes

Mooring bollard pattern

This is the largest pattern we have made in our shop so far. It is for a bollard similar to the example pictured below for mooring heavy ships at port. We developed the 3d model and pattern design from a customer supplied drawing. The pattern has an integral flask, a modular core box to accommodate the gating system. The image below shows the gating system (green) incorporated into the pattern. We also verified dimensional accuracy and alignment position with the FARO Arm. Dimensions are 75″ x 52″ x 19″ for the cope and drag boxes, overall pattern weight was 1200 lbs.

bollard Bollard pattern 75 x 52 inches and core box Bollard pattern modular core box

Bollard pattern with sprue detail

bollard gating form

Bollard pattern dimensional verification with CMM

Ingersoll-Rand loose vane impeller pattern

This is a loose vane pattern for an open style Ingersoll-Rand impeller.

loose vane impeller pattern - top viewLoose vane impeller patternThe master vane was CNC machined to ensure accuracy to the original part, as well as a perfect fit in the hub. Duplicates are cast poly-urethane.

CNC machined master vane 1CNC machined master vane Here is the worn OEM part from which the pattern was reverse engineered:

Ingersoll-Rand OEM impeller

And the finished part:

open impeller casting

 

Stuffing box and repeller patterns – Finished parts

This is the final post chronicling the reverse engineering, pattern development, casting and machining of a repeller and stuffing box for an Allis Chalmers slurry pump.

Here are the damaged OEM parts which we used for reverse engineering.

Allis Chalmers repeller and stuffing box

Allis Chalmers OEM parts

The pattern we developed for the stuffing box is a match plate configuration – which makes for simple molding at the foundry. This helps guarantee a good product while reducing the cost of the casting.

stuffing box pattern cope side

Cope side of the stuffing box pattern

stuffing box pattern drag side

Drag side of the stuffing box pattern

And here are the final products:

stuffing box finish machined

Top view of finished stuffing box

stuffing box and repeller finish machined

Back side of the stuffing box and the mating repeller

3d Printing: Lost PLA Investment Casting

As mentioned in MAKE: click here

make_project

We are always looking for new and innovative ways to meet our customers casting needs. Recently we conducted a successful beta test of a lost PLA investment casting in stainless steel. Others have tried this approach with aluminum, but we haven’t seen another example in stainless, here’s how we did it:

Background

This particular impeller proved difficult to cast from conventional sand tooling. The objective was to prove that we could produce a high quality investment casting without investing in expensive tooling. Below is a picture of the troublesome sand pattern we were trying to replace.

conventional_segmental core_sand_pattern

3d Printer

Our 3d printer uses a renewable bio-plastic (a polyester derived from corn to be precise) called PLA. We hypothesized that a scale model impeller in PLA could be used like the wax conventionally used in the investment casting process. Our main considerations were:

  1. Dimensional accuracy and model rigidity. PLA is remarkably strong and our prints are typically accurate to plus-or-minus 0.005”.
  2. Chemical and mechanical properties of PLA. PLA burns quite well and does not contain any nasty chemical or compounds that might cause emissions concerns during burn-out. The hollow structure of the model means that heat expansion of the plastic does not risk cracking the investment mould. PLA is water resistant, so the application of water-based ceramic slurry is not a problem either.

The photo below shows the finished PLA model. Note it was printed in two parts and  merged with glue.

3d_printed_PLA_impeller_for_investment_casting.jpg

Image showing the internal structure of the print, which is 90% air:

pla_impeller_internal_structure_90percent _air.jpg

Investment Casting

You can read more about investment casting here.

Our friends are Precise Castings were kind enough to help us with this experiment. The photos below show our model encased in a ceramic shell, and the furnace used the burn the PLA out of the shell prior to casting.

lost-PLA_investment_mould.jpg

PLA_burn_out_of_investment_mould.jpg

Finished Product

The finished product in ANSI 316 (CF8M) stainless steel was an excellent casting which could easily be finished with minimal machining. The cost of this test proved to be significantly lower than the same part cast in sand.

finished_casting_from_3d_printed_impeller_model.jpg

Thoughts on the Process

We conclude that lost-PLA is a viable prototype or small scale production technique. We look forward to using it for our customers in the near future.

If this looks like something you could use, or you want to learn more about our experiences with the process, please contact us for more information.

Retail display bust prototype

This is a unique and challenging project to make a high-end retail display bust. Here are some shots, including the design process, of a prototype bust we made from Ontario hard maple for Stacklab. Click here for more information.

Challenges

  • Impeccable surface finishes typically require very fine finishing passes, which translate to long machining time and high costs for the customer.
  • Wood is an inconsistent product which requires special attention during machining.
  • Machining such a complex shape requires special fixturing and multiple orientations.
Finished bust front

CNC made maple bust – front

CNC maple bust - back

CNC made maple bust – back

How we did it…

We began by analyzing the part for tool access given certain fixturing choices, and designed tool paths around our findings.

We decided to machine the part in two distinct orientations but completed both roughing and finishing tool paths for the first orientation before moving to the second orientation.

Maple bust - side one machining access

Green indicates tool access for the first machining passes

Maple bust tool-path simulation

Tool-path simulation

To deal with the difficulties of working with wood, we exploited the huge spindle speeds achievable on our machine along with custom designed tooling. We achieved a consistent surface finish regardless of grain orientation and knots.

Roughing tool paths

Roughing tool paths