Markforged 3D printer to the rescue – The story of fixing a spa pool
In August 2013, I purchased a new spa pool that was about half the comparable price of a well-known brand. That should be a great big warning as to what I was going to have to put up with as soon as the warranty expired.
- The recirculating pump failed to run – turned out that the output relay failed so I chose a spare one.
- The same failure again but this time it blew a hole through the PCB.
- Repaired that with copper wire and that ran for a while.
- PCB failed again so completely replaced all the electrical and electronics with a good brand. Been good ever since.
- The first recirculating pump seals failed so I replaced them and it was good for another 6 months.
- Replaced the pump with the same model pump. The mounting holes were different but the height was OK. Good for 2 years.
- Bought a different brand pump as a replacement thinking it would be different. Turn out that only the motor is different with different mounting holes.
This is when I thought I have access to a Markforged 3D Printer so I’ll make a replacement mounting plate for it.
Designing new mounting plate
The mounting points on the failed pump are part of the motor casting. The pump impeller cut a hole through the scroll and separated into 2 pieces. The seal also failed.
The new pump had a removable black plastic base plate that was too high with the mounting holes in a different location.
The Markforged Mark Two was setup with Onyx and Carbon Fibre which would have been ideal.
- Tough Nylon would have been too flexible so some continuous fibre was required.
- The Kevlar would have done but we had some Fibreglass that I wanted to try.
In Eiger, I made all the appropriate settings and added fibre in 4 layers – bottom, middle of the bottom part, through the highest stress area on the vee area and again at the top.
In the image below, you can see the concentric fibres around the perimeter and isotopic on the others. The isotropic layers alternate angles for more even strength properties.
The 3D print started out looking 100% but then the support structure started to lift off the bed. What to do? I let it run and was impressed with the final outcome.
What I should have done is ‘Use Brim’ in Eiger so that the support structure has a decent surface to stick to. I think the small heat build-up during the print caused enough load to peal the frail supports from the bed.
To my tremendous satisfaction, the 3D printed part fitted perfectly.
The cold water filling the spa is only 11℃ so it will be a few hours to get it up to 38℃.