Custom West-Coast Design Feedback

[daliberator]

Originally Posted by highlander

I understand your want for structural stability, but from my experience going aluminum is fine (even 16th inch). My team ran a WCD with 1/16th thick aluminum 6061 2x1 extrusion, and a 1/16th sheet metal belly pan, and it we had no structural issues.

Thanks for the reply!
That was one of my hardest decisions for this build. I went for steel in the end mostly because this "bot" will not have any kind of superstructure, so I just wanted to weigh it down more. Do you think I went a little bit overboard with the supports then?

Thanks,
daliberator

[asid61]

Steel is not worth it usually in FRC robots. I would only use it for weight, like on flywheels.
1/8" 6061 aluminum is super strong for a WCD. Lots of teams even use 1/16" 6061 for their robots.
Keep in mind steel takes much longer to machine than aluminum, so it's easier on the machinist if you just stick with aluminum over steel. If you need the weight, add some plates, but I don't think you'll need it.

Why do you need weight?

I think you should take a look at the WCP/VEXPro Versa Chassis.

[Gregor]

Originally Posted by Andrew Lawrence

I think you should take a look at the WCP/VEXPro Versa Chassis.

Why's that?

[highlander]

Originally Posted by Gregor

Why's that?

I'm going to assume it is the typical spiel of "look at/buy COTS options" before making your own. I don't mean to be a cynic here, but you learn a lot more from making and failing with your own than buying one off the shelf. Granted, for the first couple of iterations of the design, the COTS option would likely perform better, but it's not about the goal, it's about the journey.

During the season, the Vexpro option would be my top choice, but since this is an offseason project, I would fully recommend working on your own.

Originally Posted by highlander

I'm going to assume it is the typical spiel of "look at/buy COTS options" before making your own. I don't mean to be a cynic here, but you learn a lot more from making and failing with your own than buying one off the shelf. Granted, for the first couple of iterations of the design, the COTS option would likely perform better, but it's not about the goal, it's about the journey.

During the season, the Vexpro option would be my top choice, but since this is an offseason project, I would fully recommend working on your own.

Remember the VersaChassis isn't a perfectly functioning west coast drive in a box shipped to your front door already assembled ready to drive out of the box, or a kit with parts you put together from an instruction booklet. It's still a custom drivetrain. You design the dimensions. You choose where the holes are made and you drill them. You machine most everything and put it all together. The Versachassis components are in no way different from regular custom WCD components. The aluminum tubing is aluminum tubing. The bearing blocks are bearing blocks. The transmission is a transmission. The gussets are gussets. The difference is these parts are strategically designed to involve minimal required machinework to have a functional drive, and provide a lot more tolerance to mistakes. I think in an offseason drivetrain where your goal is to learn and test ideas, the added tolerance, the minimal required machining, and the seamless integration of allowable iteration is not only a great asset, but an achievable goal that those building their first west coast drives should strive for.

The drive enables low resource teams to build a competitive drivetrain, and high resource teams to spend less time on their drive system so they can focus on their scoring mechanismms. It allows teams doing their first west coast drive to iterate with a large tolerance window, and for the teams making their tenth west coast drive, it offers a simple, reliable system that is functionally equivalent to what is already used in west coast drives, readily available as a COTS resource.

[asid61]

Originally Posted by Andrew Lawrence

Remember the VersaChassis isn't a perfectly functioning west coast drive in a box shipped to your front door already assembled ready to drive out of the box, or a kit with parts you put together from an instruction booklet. It's still a custom drivetrain. You design the dimensions. You choose where the holes are made and you drill them. You machine most everything and put it all together. The Versachassis components are in no way different from regular custom WCD components. The aluminum tubing is aluminum tubing. The bearing blocks are bearing blocks. The transmission is a transmission. The gussets are gussets. The difference is these parts are strategically designed to involve minimal required machinework to have a functional drive, and provide a lot more tolerance to mistakes. I think in an offseason drivetrain where your goal is to learn and test ideas, the added tolerance, the minimal required machining, and the seamless integration of allowable iteration is not only a great asset, but an achievable goal that those building their first west coast drives should strive for.

The drive enables low resource teams to build a competitive drivetrain, and high resource teams to spend less time on their drive system so they can focus on their scoring mechanismms. It allows teams doing their first west coast drive to iterate with a large tolerance window, and for the teams making their tenth west coast drive, it offers a simple, reliable system that is functionally equivalent to what is already used in west coast drives, readily available as a COTS resource.

I totally agree with your reasons, but IMO it's a better experience to design a chassis and use as many stock vex parts like bearings blocks than to just order all the parts and bolt it together. Designing 2x1 was a (cough) memorable (cough) experience for myself.
I guess it depends on what the OP feels is "too stock" and what is not. Personal experience says to design for modularity (have different gearbox mounting hole patterns) and use stock parts (like vex bearing blocks) without sacrificing learning (make your own WCD 2x1 with slots).

Originally Posted by asid61

I totally agree with your reasons, but IMO it's a better experience to design a chassis and use as many stock vex parts like bearings blocks than to just order all the parts and bolt it together. Designing 2x1 was a (cough) memorable (cough) experience for myself.
I guess it depends on what the OP feels is "too stock" and what is not. Personal experience says to design for modularity (have different gearbox mounting hole patterns) and use stock parts (like vex bearing blocks) without sacrificing learning (make your own WCD 2x1 with slots).

But you don't just bolt it together. You design it all. That's kinda the point of what I just wrote.

I believe there is a misunderstanding here - in what ways is buying stock aluminum 2x1 and machining your own slots and holes and adding gearboxes and gussets any different from the Versachassis?

[asid61]

Originally Posted by Andrew Lawrence

But you don't just bolt it together. You design it all. That's kinda the point of what I just wrote.

I believe there is a misunderstanding here - in what ways is buying stock aluminum 2x1 and machining your own slots and holes and adding gearboxes and gussets any different from the Versachassis?

Oh, ok. I wasn't quite sure what you meant.

Anyway,
buying the stock and cutting it yourself is different from just using versachassis, because you actually have to design in different chassis elements such as slots and mounting holes. This is good practice. The more custom work you can do in the offseason, the better for when COTS parts are not available or don't exist. Anything new has to be done in the offseason or it has a much higher chance of not working/ failing.
Anybody can take the versachassis and use it during the season, but the offseason should be used for custom parts and designs. There's little reason to just build a versachassis instead of actually inputting custom work somewhere into the equation; that can be accomplished during build.
Yes, it is less effort and more effective to use a versachassis, but doing a custom build makes good use of the time available.

Originally Posted by asid61

Oh, ok. I wasn't quite sure what you meant.

Anyway,
buying the stock and cutting it yourself is different from just using versachassis, because you actually have to design in different chassis elements such as slots and mounting holes. This is good practice. The more custom work you can do in the offseason, the better for when COTS parts are not available or don't exist. Anything new has to be done in the offseason or it has a much higher chance of not working/ failing.
Anybody can take the versachassis and use it during the season, but the offseason should be used for custom parts and designs. There's little reason to just build a versachassis instead of actually inputting custom work somewhere into the equation; that can be accomplished during build.
Yes, it is less effort and more effective to use a versachassis, but doing a custom build makes good use of the time available.

You have to put slots and mounting holes on the versa chassis yourself. Otherwise they're not there. And regardless, you still design it all in CAD.

[roystur44]

IMHO steel is a acceptable material for making a robot drive train. I like it because it will keep the weight down low to improve your COG. Steel is appx 3 times heavier than alum but designed correctly can be much stronger/ less costly in the same size package.

Steel is much cheaper in terms of cost/lbs vs alum. CRS and stainless sheet is readily available from material suppliers. Steel can be easily spotwelded and mig welded. Welding steel is much easier than welding alum. Laser cutting light guage steel is significantly faster than cutting the same thickness aluminum.

Here's some stats you can use for you analysis
Cost/lbs of Cold roll sheet sheet is appx. .55/lbs
Cost of Alum 5052 is appx 2.00/lbs
density of steel is .29 lbs/sqft alum .098 for alum.

Take a look at using .036 or .048 CRS for your sheet stock and using .065" thin wall 2x1 , 1x1 tube.

Here's a website of a company that can laser cut tubes. Think of designing tab and notches to click together your frame and use the sheet metal as gussets and brackets


http://www.tubeservice.com/index.html

[asid61]

Originally Posted by roystur44

IMHO steel is a acceptable material for making a robot drive train. I like it because it will keep the weight down low to improve your COG. Steel is appx 3 times heavier than alum but designed correctly can be much stronger/ less costly in the same size package.

Steel is much cheaper in terms of cost/lbs vs alum. CRS and stainless sheet is readily available from material suppliers. Steel can be easily spotwelded and mig welded. Welding steel is much easier than welding alum. Laser cutting light guage steel is significantly faster than cutting the same thickness aluminum.

Here's some stats you can use for you analysis
Cost/lbs of Cold roll sheet sheet is appx. .55/lbs
Cost of Alum 5052 is appx 2.00/lbs
density of steel is .29 lbs/sqft alum .098 for alum.

Take a look at using .036 or .048 CRS for your sheet stock and using .065" thin wall 2x1 , 1x1 tube.

Here's a website of a company that can laser cut tubes. Think of designing tab and notches to click together your frame and use the sheet metal as gussets and brackets


http://www.tubeservice.com/index.html

I would use 6061, not 5052 for a cost analysis unless it is a sheet metal chassis. 6061 is cheaper and stronger, but harder to bend.

[daliberator]

Originally Posted by roystur44

IMHO steel is a acceptable material for making a robot drive train. I like it because it will keep the weight down low to improve your COG. Steel is appx 3 times heavier than alum but designed correctly can be much stronger/ less costly in the same size package.

Steel is much cheaper in terms of cost/lbs vs alum. CRS and stainless sheet is readily available from material suppliers. Steel can be easily spotwelded and mig welded. Welding steel is much easier than welding alum. Laser cutting light guage steel is significantly faster than cutting the same thickness aluminum.

Here's some stats you can use for you analysis
Cost/lbs of Cold roll sheet sheet is appx. .55/lbs
Cost of Alum 5052 is appx 2.00/lbs
density of steel is .29 lbs/sqft alum .098 for alum.

Take a look at using .036 or .048 CRS for your sheet stock and using .065" thin wall 2x1 , 1x1 tube.

Here's a website of a company that can laser cut tubes. Think of designing tab and notches to click together your frame and use the sheet metal as gussets and brackets


http://www.tubeservice.com/index.html

Thanks for replying!
This is main reason I wanted to go with steel in the first place; we don't have a massive budget and I wanted to incorporate some welding into the project.

Thanks,
daliberator

[AdamHeard]

Originally Posted by asid61

Oh, ok. I wasn't quite sure what you meant.

Anyway,
buying the stock and cutting it yourself is different from just using versachassis, because you actually have to design in different chassis elements such as slots and mounting holes. This is good practice. The more custom work you can do in the offseason, the better for when COTS parts are not available or don't exist. Anything new has to be done in the offseason or it has a much higher chance of not working/ failing.
Anybody can take the versachassis and use it during the season, but the offseason should be used for custom parts and designs. There's little reason to just build a versachassis instead of actually inputting custom work somewhere into the equation; that can be accomplished during build.
Yes, it is less effort and more effective to use a versachassis, but doing a custom build makes good use of the time available.

This is entirely your opinion, and not fact.

My above post explains my reasoning, and the same logic holds true for offseasons. Teams might get much more out of dedicating their resources to arms, elevators, etc. than drives.

It's certainly true that for some teams the reverse exists (or they have plenty of resources) and they can go custom and not negatively impact overall learning.

Each team has a unique circumstance, and it's unfair to imply that teams are doing things right or wrong in this capacity.

[asid61]

Originally Posted by AdamHeard

This is entirely your opinion, and not fact.

My above post explains my reasoning, and the same logic holds true for offseasons. Teams might get much more out of dedicating their resources to arms, elevators, etc. than drives.

It's certainly true that for some teams the reverse exists (or they have plenty of resources) and they can go custom and not negatively impact overall learning.

Each team has a unique circumstance, and it's unfair to imply that teams are doing things right or wrong in this capacity.

In all fairness, many things said here are opinions. Very little that I say myself is "fact" and I (try) not assert myself that way. I should probably hack that into my signature so I remember.

I'm not saying anybody is doing things right or wrong, I'm sorry if I came off that way.

My apologies, I wasn't considering making things other than drivetrains (I'm a drivetrain freak) so totally, arms and elevators are cool too. Especially given that we've had so many ball games, having a usable elevator design would be nice to have.

I'm not sure how resources factor into this specific instance; I am assuming the OP has resources to build a WCD?