CNC Machining Bearing Blocks

[Gregor]

Originally Posted by Richard Wallace

Thanks for the link, Cory. I knew these existed but had forgotten where to look. Pretty sure I first saw them on one of your team's robots many seasons ago.

Two questions not immediately addressed at the WCP link (since my iPad doesn't run CAD): (1) what is the material? and (2) do these blocks accept FR8 bearings?

Here's the equivalent VEXPro page, which is more detailed.

http://www.vexrobotics.com/vexpro/we...gblocks-g.html

[R.C.]

Originally Posted by Richard Wallace

Thanks for the link, Cory. I knew these existed but had forgotten where to look. Pretty sure I first saw them on one of your team's robots many seasons ago.

Two questions not immediately addressed at the WCP link (since my iPad doesn't run CAD): (1) what is the material? and (2) do these blocks accept FR8 bearings?

Both the bearing blocks and versablocks are 6061-T6 and they both accept fr8 style bearings and hex bearings.

[Richard Wallace]

Originally Posted by R.C.

Both the bearing blocks and versablocks are 6061-T6 and they both accept fr8 style bearings and hex bearings.

Thanks, R.C.

Ordered a set to play with.

[waialua359]

Originally Posted by Cory

Do you have a reason for not buying these?

That's the best bang for the buck you're gonna get. If you want to learn to use your mill to the fullest extent of its capabilities, that makes sense. But this might be a problem to throw money at.

My first reaction was what Cory has mentioned.
Is this a learning exercise opportunity or you just need these?
I can see making it, if alternatives werent available, but these days, you have lots of other options which are much cheaper and less time consuming.
When we used bearing blocks in the past, our program made them as a learning experience for students and aesthetic reasons.
These days, we dont even use bearing blocks at all for our drivetrain.

[Joe G.]

Why are so many people in this thread so hostile towards the idea of a team making these themselves? It's clear that they have the resources and valid motivation to do so, a plan to schedule production so that it does not come at the expense of other things, and are seeking the knowledge to back these resources up.

In the past few years, after my team acquired decent manufacturing resources, it became quite rare for us to purchase something that we could make ourselves in a reasonable time frame. It's not just about providing students with a learning opportunity either. Cost was by far our most limiting factor; 1687 robots were always built on tiny budgets, but we acquired enough manufacturing ability and dedicated students/mentors to work around this and build quality robots. We also liked having to learn how to produce as much of our robot as possible inhouse. This meant we were less at the mercy of vendor availability and lead times if something broke or needed to be changed last minute (which saved us more than a few times), and gave us the ability and confidence to design in slight variants to parts we could have gotten COTs, when it was beneficial to our design. In many places, this actually saved us lots of time, since we did not have to spend time designing to fit the dimensions of COTs parts.

I know that these bearing blocks are a pretty standardized item, but I can definitely see why a team would like to save money in their fabrication, and maintain freedom to modify them as it suits their design.

Buy a man six bearing blocks, he'll have a sweet west coast drive next season. Teach a man to fixture properly on his CNC machine...


In regards to the original question, this may be of use.

[techhelpbb]

I think it is admirable to have interest in making something yourself.
Hence I side-stepped the issue of 'working smarter' until now because it expands the topic beyond where I think it was asked to go.

One should consider that merely having CNC experience and CNC access does not mean that the job will be as efficient as possible.

One might not have the correct tools for that CNC machine and therefore the job might take longer or buying the tools might drive the cost of a job way up.

CNC machine tools are full of consumables in the form of coolant, tools and sometimes fixturing and all those should be considered in the costs.

One might not have the experience to operate the machine themselves and are therefore burning a mentor or donor's time to make these items. If you are asking for someone to give you time, materials, possibly tools and labor it can quickly become very much not in their interest to make something they could more cost effectively buy.

I certainly will not discourage the adventure of learning but there are important lessons in efficiency to be had here.

I would be interested to know how long it takes teams to perform this manufacturing process that have done it themselves. In the past I helped Team 11 make much less complicated bearing mounts and it took a few hours to turn 6 of them out. In that case these parts needed to be custom as it was an after thought and the design was not made with these commercial alternatives in mind.

Brainstorming here - I would love to see a gallery that shows some of these CNC jobs and some simple details like the time and expendables needed to make them. I think it might help those learning set expectations more effectively.

[Mk.32]

Originally Posted by magnets

We're making an offseason drive base, and we'd like to make our own bearing blocks on our CNC mill, but I can't think of a good way to hold down these parts for machining.

Does anybody have a clever way to make these parts?

What kind of mill do you have?

The cost of materials, tooling and then machine time (that does "cost" something) versus $20 a piece from vex is sometimes hard to justify.

It's quite a bit of material removal as well.

[magnets]

Originally Posted by Mk.32

What kind of mill do you have?

The cost of materials, tooling and then machine time (that does "cost" something) versus $20 a piece from vex is sometimes hard to justify.

It's quite a bit of material removal as well.

2 robots with 6 wheels is 12 of the $20 bearing blocks, or $240.

Aluminum for all the bearing blocks is under $40, and I don't expect to purchase any new tooling for this. That's a savings of $200, or the price of one drive gearbox.

We're still not sure how much money we'll have by the start of build season, but every dollar counts!

[Chadfrom308]

What I would do is turn most of it, then use a mill to cut the flange and drill the holes. You could use round stock and probably cut less off. Also, you could order a long bar of aluminum rather than small pieces and keep turning them.

For turning you would need a good contouring tool (at work, we use all ISCAR tooling) and then a good boring/ID tool. Then slap it on a mill and cut the rest with a drill and an end mill. Then as a bonus, chamfer it because chamfered things look nice!

And if you have the big bucks and have a really nice lathe with a live tooling, then you can do it all on the lathe

Originally Posted by Chadfrom308

And if you have the big bucks and have a really nice lathe with a live tooling, then you can do it all on the lathe

If you have the big bucks it would make more sense to just buy them and save yourself from having the spend time machining bearing blocks.

[Mk.32]

Originally Posted by Andrew Lawrence

If you have the big bucks it would make more sense to just buy them and save yourself from having the spend time machining bearing blocks.

Yes... but if you already have the $80,000+ Lathe/Tooling and I would "hope" the experience to take full advantage of it, it would be a trivial part to make. Heck you go into production and sell them at the same price as vex almost....

Personally I've made the same design before, I would just machine them from billet on a tormach in two operations... basically start with a hunk of alum in the vice and then machine all of one side. Make some soft jaws (alum jaws bolted into the vice so I can machine a profile them to grab circle parts) and then flip them over and face off the otherside/other operations.

Good practice probably, especially if you haven't done parts this complicated before.

[Gray Adams]

Originally Posted by Mk.32

Yes... but if you already have the $80,000+ Lathe/Tooling and I would "hope" the experience to take full advantage of it, it would be a trivial part to make. Heck you go into production and sell them at the same price as vex almost....

Personally I've made the same design before, I would just machine them from billet on a tormach in two operations... basically start with a hunk of alum in the vice and then machine all of one side. Make some soft jaws (alum jaws bolted into the vice so I can machine a profile them to grab circle parts) and then flip them over and face off the otherside/other operations.

Good practice probably, especially if you haven't done parts this complicated before.

Definitely what I would do. Given that its FRC, you could easily get away with circular interpolation and not even reaming the bearing pocket, though a 1.125" reamer is a pretty good investment. It's easily worth the cost of doing it yourself if you're doing 4 or more, especially when you consider student time to be as cheap as it is.