Computer controlled machining

For this week assignments we had to complete these tasks :

Linked to the group assignment page
Documented how you designed your object (something big)
Documented how you made your CAM-toolpath
Documented how you made something BIG (Machine setup, fixing, testing joints, adjusting feeds & speeds)
Described problems and how you fixed them
Included your design files and ‘hero shot’ photos of the final object

Group assignments

This week I trained Sylvain to use the shopbot. I’ve been using this machine for a long time now, but that doesn’t meen I never do mistakes so I’ll train a bit myself too. First, I help him to design a test file to train him on Fusion 360 with the CAM module.

After design a short linear toolpath, we move to the shopbot room to wear safety equipment. We had :

Safety glasses
Ear protection
Fashion Covid19 mask (Actually it also protect from sawdust a bit)
No gloves unless for carrying heavy wood plancks
Safety shoes

There is a line on the floor That when musn’t cross when the machine’s started.

We’ve seen how to set up the tool, using the wrench near the machine.

I showed how to zero the Z axis as well as the X/Y axis. We trained to move the origin of the program using the VCare Shopbot sofware. And we also tried the procedure of starting the spindle.

After manipulation training, we check the to-do list. Each program is relatively similar and we have a very few action to do. Nevertheless a short to-do list is great to avoid mistakes and oversight.

So here is the process :

If it will, move the screws !

Before starting the machines, we always print to-do list to be sure to not forget any operation.

Oh, yeah and just for fun… While doing the training Sylvain mounts the tool, but unfortunately I didn’t check if it was tightened enough… The mill has gone deeper than the desired depth but still I was pretty inspressed how far It went !

I’ve already calculated and tested a lot of speeds and feeds profile in the past. And I created a file to automatically calculate the Fusion360 parameter using a Google spreadsheet file. If you want to use it please click the button below.

Be sure to test any parameter on your own machine even if it’s a shopbot. The settings are tuned for our machines, they may differ a lot. Good luck :)

Shopbot Calculation tool

The file also contain an Auto diagnostics routine to find why a job might fail. If you find that useful please let me know !

In Fusion 360 make sure you’re using the Shopbot post-processor (Not Shopbot ISO).

Piano stand

I designed a piano stand for our fresh new 88 keys digital piano. We always dreamed about having a piano at home but I’m affraid about cheap piano stand. I want to be sure that the piano remain safe for years.

I began by sketching the side profile of the stand using Fusion 360. The top of the stand has to have the size profile as the Piano bottom in order to match perfectly. I use a ruler and my caliper the measure the piano feet profile and began to had lines in Fusion.

I finally got this side panel :

Then I copied this panel 1,6 meter away and added planks between them. One plancks will support the instrument (at the top of the stand). The two others will ensure strong stability to the stand. The bottom planks will ensure that the two side panels remain fixed.

I started a rendering in Fusion to show the result to my loved musician to have her feedback. As she was really happy with the result I started to program the CNC using fusion Manufacturing module.

Before generating the milling program we have to setup the Fusion 360 Manufacture environment. To do so I imported all the parts of the Piano stands In a new design to lay them flat.

I also sketched a rectangle of 2.5 meter by 1.25 meter representing the wood panel I’ll be using. The stand will be made of plywood.

Then I setup the milling configuration. By right cliking on the Setups folder in the navigation tree you can create a new configuration. As I created a sketch before, Fusion360 automatically detect the size of my stock. I just checked that the thickness is correct in the second tabs. I used the 2D Contour function and the 2D Pocket function to make my Milling programm.

Here is the settings I used :

Settings	2D Pocket	2D Countour
Spindle speed	18 000 RPM	18 000 RPM
Cutting speed	340 m/min	340 m/min
Feedrate	3240 mm/min	3240 mm/min
Lead-In feedrate	1950 mm/min	1950 mm/min
Lead-Out feedrate	1950 mm/min	1950 mm/min
Plunging feedrate	1620 mm/min	1620 mm/min
Pass depth	3 mm	3mm

I used a Diamond shaped 6mm Endmill to cutout the parts. The nominal spindle speed is arround 180000rpm. I created a calculation sheets when I was at Waag during my 2020 internship abroad.

You can check this sheet by clicking here :

Shopbot Calculation tool

I filled the operation parameters using the calculation sheets and saved the program using the Shoptbot post-processor (Not Shopbot ISO). Before starting the machines, I made a to-do list to be sure to not forget any operation.

Here is the process :

Clean the shopbot
Place your stock wood
Screw the stock to the shopbot (On the edges)
Check if the program will hit the screw

If it will, move the screws !

After the stock setup I finally mount the diamond endmil on the shopbot

After setting up the toolhead, It’s time to make it move ! First wee need to move the toolhead above a clean falt area. To do that, we used the remote control box in Shopbot Tools.

Then we clicked on Zero Z axis.

The Shopbot asked for us to set up the Z metal plate. We placed the metal plate just below the tool and the aligator clip on the metal part of the toolhead.

Don’t forget to clamp the copper clamp to the aluminum part of the mill carriage.