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Week 7. Computer Controlled Machining

Hero Shot

This week we were introduced with one of the furniture making machine which is present in our lab and the name of the machine is Shopbot machine. As I am quite familiar and used to with Shop bot machine because I have been using this machine quite oftenly in the Lab whenever there are some client works or for giving trainings to those individuals who are interested in learning how to operate the machine. Eventhough I am comfortable with running the machine confidently but due to time constraints and also as we were four in numbers who will be operating the machine simultaneously to make something big for this week’s assignment. I was quite nervous and anxious what to design and start milling using Shopbot machine.

Group Assignment:

  • Complete your lab’s safety training.

  • Test runout, alignment, fixturing, speeds, feeds, materials and toolpaths for your machine.

  • Document your work to the group work page and reflect on your individual page what you learned.

Link to the group assignment is here

Key takeaways from this week:

  • Always wear Personal Protective Equipments while operating the machine.

  • Never leave machine unattended, atleast one person should be all the time with machine while in operation.

  • Make sure that the job piece on the sacrificial layer is properly mounted and fixtured using the clamps.

  • Always carry the control pendant with you while operating the machine because we should be always ready to press the emergency button if incase there are some abnormalities with machine.

  • Always make sure to give tabs while cutting something big and consider the wood thickness while making your design.

  • While generating tool path for your design never forget to add passes in the parameters.

Individual Assignment:

  • Make (design + mill + assemble) something big.

This week I had design a simple three layer flower stand which is quite bigger in size and for that I had used fusion 360 to design as I am used to it and familiar in using fusion 360.

My rough sketch of design

Before I started machining my design in Shopbot, I explored some of the important fundamentals which are essential while we proceed further with Shopbot which are:

  • Difference between Endmills and Drill bit

A drill bit is designed to bore straight down into the material – metal, plastic, or wood whereas an end mill is designed for sideways cutting. The two cannot be interchanged.

End mills are mainly used for milling and can sometimes be applied for drilling, while drill bits can only be used for drilling

  • What is Climb and Conventional Cutting?

The cutting tool rotates “up” in conventional milling, in climb milling the cutting edge rotates “down” resulting in the cutting tool climbing or pulling into the workpiece.

climb milling tends to pull the workpiece towards the operator as it cuts downwards, conventional milling does it in the opposite direction. Therefore, it offers machinists greater control, translating to greater stability. Compared to down milling, there is no excessive vibration in conventional milling

  • Difference between Upcut and Downcut.

Upcut bits have upward flutes, throwing chips up and out of the cut. While downcut bits have downward flutes, pushing chips down into the cut.

Disclaimer: The above three comparison has been abstracted from google for the reference purpose only

Design process using Fusion 360**

I opened the fusion 360 and started creating sketch by giving the required dimensions that I am going to do machining. I kept length as 300mm, width as 300mm and offset at a distance of 10mm inside.

After that I had added the slots and for that I had kept slots length as 60mm and its width as 12mm as we are going to use 12mm thickness white particle board for machining.

Then Clicked on add sketch on the tool bar and selected one of the plane.

I created rectangle which is my side support bar for the flower stand and extruded.

Next I extruded the tab length of side support bar for 12mm and selected on create new component from the dialog box.

Then I selected on bodies and created different components from them

I used the combine option and joined some of the bodies together.

After that I clicked on assemble option and joint the components together.

I selected on the plane of smaller component and created project on those tabs.

Next I clicked on the extrude option and extruded my third component by giving its dimension as 300mm.

I selected on one side of my third component and then selected on rectangular pattern inorder to create tabs.

I created three tabs and then extruded in opposite direction by selecting the cut as operation from the dialog box.

Then after that I followed the same steps which are mentioned above for creating different components for my design.

Finally after modelling all the components and by assembling them together, I was able to make my design look alike with what I had sketched roughly before I actually started designing using fusion 360.

I started laying out my components individually and exported the 2d files which I will be using in Shopbot machine while machining my design.

Next I compiled all the components together and transfered it to drive and went towards Shopbot for machining.

Steps to follow while machining using Shopbot

  • Procedure to put on the machine

When opening the Shopbot Interface a window will come up reminding you to press the reset button. Pressing this button allows the Shopbot to figure out where it is in 3D space. Press the reset button on the control switch to the left of the computer. After pressing the reset button click “Ok”.

Shopbot Control Software

Shopbot Control software allows us to do calibration of the machine and let us upload our saved file so that we can do machining of our design.

After that I opened the Shopbot Control software from the monitor.

And I set the origin of X and Y to zero

Followed by that I also set Z position to zero but before that I kept the alluminium plate on the work piece and the alligator clip on the top of spindle.

After that I clicked on Ok and the Z axis position will be set to zero.

Since for the Shopbot we are using V-carve so I opened the V-carve and clicked on create new file option and set the length, breadth and thickness of material.

After that I imported the design files by selecting all of the them one by one in V-carve.

I had given the dog bone fillet by keeping the radius as 3mm.

Next I kept offset value as 0.25mm because if I don’t offset, than my joints won’t be fitting smoothly so for that I had offset my design.

Next what I did was, I had provided the value of cut depth by selecting the type of endmill that I am dealing with and selecting it from the lists.

After that I had set the number of passes for which I had followed the steps mentioned below

Then I selected entire slots from the design and kept its machine vector as Inside which means machine will cut from inside and then calculated its path.

I selected the outer boundary and kept its machine vector as Outside which means machine will cut from outside and then calculated its path and I also had given tabs for them which will hold them while we are machining our job piece.

After I finished calculating the toolpaths for my designs, next I saved the file by selecting one of the location in disk.

Next I opened the Shopbot Control software, clicked on Cut part selected the saved design and opened the design and gave start command.

As soon as I clicked on Start option a warning dialog box appeared out so we should never click on Ok on that instead first press on the Start button on the control switch then only click on OK on the monitor to start the machine perform its operation.

After that machine will start machining and I stayed near the machine by monitoring and by inspecting the machine during operation.

Finally after finished machining my design I removed them and started assembling together and it came like this

Files for the week

This week I had a great time learning and at the same time machining using Shopbot machine and not only that it was also good oppurtunity to showcase our talent in designing and making something big with our own designs.