Uses of a Machine Shop and Equipment

[Joe G.]

Originally Posted by carpedav000

I am assuming that they don't have a laser/water jet cutting sponsor and that they only have access to what they have in shop.

I think the broader point that RC and Chris are making is that while a mill can perform precision cuts in sheet material, it is not the correct tool to do large scale "sheet metal" work in the conventional sense, and that with this resource set, a predominantly sheet metal robot would be a poor choice. The CNC mill works much better with a fabrication approach centered around extrusions, small gussets, thick, heavily pocketed plates, and complex parts milled from solid than a series of thin sheet parts, especially since you don't mention having a precision brake to do bends either.

[R.C.]

Originally Posted by Alan Anderson

Lasers and waterjet cutters are not on the list of available machines.

I understand that but in no way does a cnc mill beautifully makes sheet metal parts...

Also why would you recommend the cnc mill to make sheet metal parts if a brake isn't on the list? I guess you can make just flat parts but at that point you might well just buy the gussets from vexpro or other vendors.

I feel the team here needs to understand what machines they got and how to combine their machining capabilities with cots components. We have both a cnc mill and router in house. We rarely produce true sheet metal parts (bent) due to the fact we can't consistently bend the parts.

[Bennett548]

I would suggest you stay away from the surface grinder. They are used to make high precision flat surfaces, and they are easy to mess up if you don't have proper training. Machine shops don't like it when you mess up their machines.

On a related note, make sure you know exactly how to use these tools and get training before you use them. All of these tools have the potential to damage themselves and the operator if used incorrectly.

[jman4747]

1st find a good junk yard.

You can make just about anything you need for FRC on those tools but you will need stock. Something you will be doing a lot in future will be to weigh time making custom parts vs buying them. If you can get good raw material for free (hence the junk yard) it cuts down on the material costs and assuming labor is free you end up with a ~free part. If you do get a good relationship with a junk yard you should get comfortable with using steel. It's usually easier to find for free.

This goes into the main point that the more raw materials you can get donated from anywhere the more ~free parts you can make, especially simple things.


2nd get designing.

When you have custom capabilities like this it can be easier in the beginning to design things that are hard to assemble and sometimes impossible. The best way to avoid doing this in the middle of build season is to start practicing now. A good way to start may be to try to re-design your current robot with these tools in mind.


3rd Take a look.

Ask to sit in on the tools being used for as long as you can. It will give you a better understanding of what the limitations are and what kind of designs cost more time.


4th Ask an expert

First obviously the machinists who man the shop. But don't forget the people designing things that get made in there. They will be a great resource in getting to know how to design for the tools.

Remember that the biggest cost to you will likely be time from now on if you can get donations.

Try to design things that don't require the CNC. This I've found can help with machining time and will make you more resilient in case something you were depending on is not available right when you need it.

[Joe G.]

Originally Posted by jman4747

1st find a good junk yard.

You can make just about anything you need for FRC on those tools but you will need stock. Something you will be doing a lot in future will be to weigh time making custom parts vs buying them. If you can get good raw material for free (hence the junk yard) it cuts down on the material costs and assuming labor is free you end up with a ~free part. If you do get a good relationship with a junk yard you should get comfortable with using steel. It's usually easier to find for free.

This goes into the main point that the more raw materials you can get donated from anywhere the more ~free parts you can make, especially simple things.

A better bet is probably to approach local metals and plastics distributors. Junk yards are unpredictable at best in what they'll have, just do to their nature, and you generally won't know too many specifics on the exact alloys you'll be getting, important information for all parts of the fabrication process. Material distributors, on the other hand, are in the business of knowing exactly what their product is and how to use it. Look for places that offer custom cutting -- these companies generally end up with scrap cutoffs which are generally too small to be easily sold, but suit the needs of FRC perfectly. The easiest donation to get is something that would've been thrown away otherwise.

[Monochron]

Originally Posted by R.C.

I understand that but in no way does a cnc mill beautifully makes sheet metal parts...

Also why would you recommend the cnc mill to make sheet metal parts if a brake isn't on the list? I guess you can make just flat parts but at that point you might well just buy the gussets from vexpro or other vendors.

I feel the team here needs to understand what machines they got and how to combine their machining capabilities with cots components. We have both a cnc mill and router in house. We rarely produce true sheet metal parts (bent) due to the fact we can't consistently bend the parts.

Would smaller (say roughly 1' x 1') sheet metal parts be appropriate for a CNC mill? Something like a side support on a manipulator or shooter? I ask because our team may be building a shooter during the offseason and we were hoping to use a CNC mill to cut a structure out of sheet metal.

[R.C.]

Originally Posted by Monochron

Would smaller (say roughly 1' x 1') sheet metal parts be appropriate for a CNC mill? Something like a side support on a manipulator or shooter? I ask because our team may be building a shooter during the offseason and we were hoping to use a CNC mill to cut a structure out of sheet metal.

You could, the machine can do it , all I'm saying is it shouldn't be the workhorse for sheet stuff. Ex: Our Router should not be used as a mill and vice versa.

Also the sheet can be any size you want, that's dependent on your bed travel. Without knowing your machine and setup I can't give you a good answer.

On the same note, you should just find a local guy and work with them to help you cut your sheet. Who knows they might do it free and help with the robot build season. Quick google: http://www.yellowpages.com/research-...er-jet-cutting

Unsure if any of those are in range.

[jman4747]

Originally Posted by Joe G.

The easiest donation to get is something that would've been thrown away otherwise.

The yard I go to doesn't deal with any plastic.

I once walked out of there with a 4'x4' sheet of 1/8" thick polycarbonate. I mentioned junk yards because there are easier to approach for donations usually.

The other side is you need to check often and stockpile for it to be effective.

[asid61]

We own a nice Bridgeport mill equipped with a DRO and what technically qualifies as a metal lathe.
I run the mill almost exclusively. I made pretty much every single machined part on our robot this year excepting the hex axles (which were done in the lathe). It can cut things to within 0.001" of the size you want it to be, provided care is taken and a competent person is running the machine. It can also drill holes in the location you want them to within 0.001".
To my team the mill is far more valuable than the lathe, because the lathe is a really bad one that breaks easily. Generally though, a lathe is very good for spacers and modifications to anything that goes on a shaft. A CNC mill can do a great many things. Getting a nice CAM program for your CAD program could be useful, depending on the situation.

We use the drill press and bandsaw to make gussets for riveting things together on our chassis. Just bandsaw to the right profile, sand it all to make it look nice, and then we drill the holes in the right locations.

We use a chop saw to cut aluminum. It functions somewhat like a cold saw. I believe there are cold saw blades with the right tooth geometry sold for cutting aluminum, but generally a horizontal bandsaw will do you just as well.

Surface grinders are for making surfaces in steel shiny and flat. They can also grind something down accurately to within 0.0001" height. Steel is far less common than aluminum in FRC (for machined parts, at least) so I doubt you'll ever find a use for a surface grinder, unless you want to make jigs or something.

If your university offers courses on machining, have new students take them. They are fantastic resources.

EDIT: Not my team, but an eample of what can be done on a CNC mill (or a manual mill if one is skilled enough): https://lh5.googleusercontent.com/-M...480/13%2B-%2B1

[Mr. Mike]

Welcome to FIRST and Chief Delphi

The collage will more than likely require anyone using the equipment to go through a training/safety program. Start now so you can make some practice parts during the off season.

Instead of pictures contact another team and visit them. This way you can see firsthand what can be done. Per the FIRST web site team 1370 is only 25 miles from Dover.
Team 1370
MIDDLETOWN HIGH SCHOOL
Middletown, DE 19709 USA
I tried the link to their web site but it looks like it has been hijacked. I was able to find them on face book and you can email them from there.

Mr. Mike

[protoserge]

Originally Posted by Monochron

Would smaller (say roughly 1' x 1') sheet metal parts be appropriate for a CNC mill? Something like a side support on a manipulator or shooter? I ask because our team may be building a shooter during the offseason and we were hoping to use a CNC mill to cut a structure out of sheet metal.

You won't learn anything without trying. I would focus on the best method of workholding. This is where I see the most issues. Plan out the workholding and keep it safe. What thickness material do you plan on using? You definitely want to take light cuts to avoid digging into the sheet. I think this is the most risk of a good part yield.


OP,

Your machine shop access sounds great! You will find out how to use the machines in due time. Since you are a rookie team, I would suggest starting with a KoP or Vex Drive base and focus your energy on game piece manipulation (don't forget to consider active intake of game pieces) and scoring.

A simple example I can think of is an active intake wheel for a tote. You could:

1. start with a box tube,
2. drill a hole for a bushing (drill press or mill, depending on accuracy required),
3. press the bushing in (shop press/arbor press),
4. turn down an aluminum shaft to the appropriate length,
5. mill a keyway or broach a keyway (or use a hex shaft that could be turned round to fit in the bushing),
6. mount a drive pulley with a key,
7. drill holes in the end of each end of the shaft to mount machine screws to hold it all together (lathe),
8. machine a motor mount bracket (mill),
9. drill mounting points on the box tube for the motor mount bracket (mill),
10. become amazed at what you can do with such a shop!

The surface grinder is something I don't think you'll ever use, but if you needed something flatter to within a few tenths (0.000[x] inches) that would be your tool.

[Andrew Y.]

Non technical comment/question. Are your mentors non engineering mentors?

[RoboChair]

Originally Posted by R.C.

You could, the machine can do it , all I'm saying is it shouldn't be the workhorse for sheet stuff. Ex: Our Router should not be used as a mill and vice versa.

Also the sheet can be any size you want, that's dependent on your bed travel. Without knowing your machine and setup I can't give you a good answer.

On the same note, you should just find a local guy and work with them to help you cut your sheet. Who knows they might do it free and help with the robot build season. Quick google: http://www.yellowpages.com/research-...er-jet-cutting

Unsure if any of those are in range.

A mill is perfectly able to handle sheet if approached right, about half of all the sheet gussets on out robot were made on a CNC Router(and is by far one of the least stiff machines ever). It just takes some doing. A water jet or laser would be best but some times we need a part NOW.

[FrankJ]

Originally Posted by R.C.

Why would you use cnc mills for sheet metal fabrication? Cnc lasers/routers and water jets are way more suitable for sheet metal fabrication.

You'd rather use the cnc mill for stuff like tubing and solid milled parts.

One of our sponsors has a large CNC mill. We don't have convenient access to a router, water jet, laser. The mill does fine even if it is a bit of overkill.

We got a small CNC in our shop last season. It is currently more of a learning tool, but is has great potential.

I would love to have a sheet metal break. Ones that can form 1/8 sheet are hard to come buy.

[Monochron]

Originally Posted by stinglikeabee

You won't learn anything without trying. I would focus on the best method of workholding. This is where I see the most issues. Plan out the workholding and keep it safe. What thickness material do you plan on using? You definitely want to take light cuts to avoid digging into the sheet. I think this is the most risk of a good part yield.

We don't have a CNC machine of any type, we have a company who vaguely offered us help manufacturing who has a CNC Mill. I'm hoping they will be willing to include us a bit in the manufacturing process or at least let our students observe.