Lessons learned while making the parts for our drive train prototype

We need a jig system that quickly mount 1x 2 square tubing so we know the exact origin.

Wood in the tubing works great at prevent the tubing from being pushed in.

Cut tubing 2 inches longer and have a file to drill a test hole in the extra part at both ends. Easy way to determine if your tubing is lined up.

Our settings worked beautifully for sheet aluminum but it took forever. Our 2nd piece we cut the time in half but chips were a problem. Test different speeds to get a faster but clean result. Ensure space to scree down the sheet every inch near the edge will help reduce chatter.

Always ensure holes are 1/16″ bigger in CAD to avoid issues with fit. Experiment!

The challenges of cutting square tubing

The side tube has taken a very long time to make. The biggest challenge is we don’t have a good jig – making sure everything is straight takes a huge amount of time. The actual cutting doesn’t take long but this piece requires cuts on all four sides and the positioning has to be within 1/32″ for every hole. We are investigating jig systems for the future. The bonus is we know how to use some machining tools to check for accuracy.

The other aspect we encountered was we needed to adjust in the plans. Some of the holes are for a 3/8″ bolt. We needed to go back and add 0.01″ to the diameter to ensure the bolt could fit easily. Details!

Students are working well. Electronics is well done, roborio is imaged, motor controllers are configured, wheels are assembled, bolts and nuts are all picked up. Grade 10 class is starting their Linux assignment.

Milling square tubing

Material: 1″x2″ rectangular tubing
Thickness: 0.095″ (approximately 3/32″)

From the video: 6061 aluminum – 3/16″ thick

Concepts

  • Chip thickness – controlled by feed rates and spindle rpm. Faster you go the thicker the chip.
  • SFM – surface feet per minute – how fast the edge of the tool is going along the material
  • Bit deflection – if you cut too deep the bit deflects
  • Maximum depth of cut per pass – wood you can go 2x the tool diameter. Plastic the maximum depth of cut is the tool diameter. Aluminum – the maximum depth of cut is 1/2 the tool diameter. So a 3/16″ tool cutting 3/16″ thick aluminum will require two passes – a rough pass (conventional cut) and a finish pass (climb cut).
  • Lubricate the cut – make sure we use cutting fluid!
  • 60ipm at 14k rpm with a 0.1″ DOC i
  • Plunge is at 30ipm
Aluminum chips
Chips

Tools

O Flute

O flute
O flute
CNC Bits

1/8″D x 1/2″ L Up-Cut
1/8″D x 1/2″ L Down-Cut
3/16″D x 1/2″ Down-Cut
3/16″D x 1/2″L Up-Cut
1/4″D x 5/8″L Down-Cut
1/4″D x 5/8″L Up-Cut
1/4″D x 3/4″L Up-Cut
1/4″D x 1-1/4″L Up-Cut

Safety

PPE – Safety glasses, hearing protection

dust collection system to handle chips

Square Tubing for the S and T Drive Train – another day in our build blog

Square tubing

After work yesterday I picked up the square tubing we ordered from Reynolds Wm & Sons Metal Fabricators Ltd. This is a local company that have been wonderful to our team. They mentor for the team and have been incredibly helpful.

The robot frame will be made of aluminum – it is a very strong but light material. For this frame we are using 1″x2″ tubing – it comes in lengths of 24′ so we had it cut in half to ensure we could easily get around corners! The thickness is 0.095″ and it has square corners. This is thinner than we usually use. Our goal is to determine how durable the thinner material will be. It will be considerably lighter which can be very valuable for complex mechanisms.

Horizontal Bandsaw

Students will be cutting the metal to the sizes we need using the horizontal bandsaw. They are working through the safety lessons to learn how to use it properly.

One of the parts

This is one of the parts. For these drawings we are only worried about the proper lengths for cutting. When we are ready to drill holes we will do a more detailed drawing with the measurements.

Introducing the build blog for the S&T Drive train

Last spring Sam Topps designed a new drive train for first robotics. Sam was the lead designer for team 4152. The S&T Drive train is a combination of sheet and tube. The design features a number of things that we are interested in doing. We are making a sample version to test it.

Today we inventoried the parts we have. There are a few things on order. We are making sure we have what we need.