Integrated WCD "Warp drive" chassis

[mman1506]

Originally Posted by Mr. Lim

We use hold-down setup clamps, step blocks, studs and t-nuts. Similar to this set found on McMaster: http://www.mcmaster.com/#fixture-clamps/=mc62a5

The top of our router's table has t-slots running down the length.

In between the t-slots, the top surface has black Sintra strips glued to the surface. These came with our router, and we replace them around once a year. When we replace the strips, we face them down with the router to make sure the working surface is level.

Whenever we cut a part on the router, the cutter goes through the part, and barely scratches the surface of the Sintra strips beneath. This does leave scratch marks on the Sintra, but not enough to warrant replacing them more than once a year.

In hindsight, a vacuum hold-down table would've been a nice addition, but we've been able to do without. Cutting COMPLETELY THROUGH plate is easy. Cutting partially through thinner plate is an issue, because the middle section tends to lift off the surface of the table when clamped using the hardware above.

Thanks, is there any advantage using the sintra over wood and other plastics?

[Mr. Lim]

Originally Posted by mman1506

Thanks, is there any advantage using the sintra over wood and other plastics?

Yes. Because our router has a Unist mister on it, the coolant it sprays could absorb into wood. Depending on the wood you use, it could maybe even cause it to swell? I'm not 100% sure as I've never let coolant sit around on wood to see if this happens, but I would be concerned.

Over other plastics - yes - it turns out Sintra can be had for quite cheap, and we've started using it for some of our in-class projects and prototypes. Its surface properties are grippy enough to provide a nice clamping surface.

Now we don't see the Sintra as a "sacrificial material" as we barely scratch the surface of it when we cut parts. As I mentioned before, these strips last us about a year before they get scratched up badly enough to be replaced.

If you were considering using it for a true sacrificial material, where you're trashing the Sintra sheet every time you cut parts, then it's probably not going to be very cost-effective.

[CENTURION]

Originally Posted by Mr. Lim

Yes. Because our router has a Unist mister on it, the coolant it sprays could absorb into wood. Depending on the wood you use, it could maybe even cause it to swell? I'm not 100% sure as I've never let coolant sit around on wood to see if this happens, but I would be concerned.

Over other plastics - yes - it turns out Sintra can be had for quite cheap, and we've started using it for some of our in-class projects and prototypes. Its surface properties are grippy enough to provide a nice clamping surface.

Now we don't see the Sintra as a "sacrificial material" as we barely scratch the surface of it when we cut parts. As I mentioned before, these strips last us about a year before they get scratched up badly enough to be replaced.

If you were considering using it for a true sacrificial material, where you're trashing the Sintra sheet every time you cut parts, then it's probably not going to be very cost-effective.

IIRC, a good hardwood impregnated with oil actually gets harder and stronger, but I'm no carpenter.

[mman1506]

Originally Posted by Mr. Lim

Yes. Because our router has a Unist mister on it, the coolant it sprays could absorb into wood. Depending on the wood you use, it could maybe even cause it to swell? I'm not 100% sure as I've never let coolant sit around on wood to see if this happens, but I would be concerned.

Over other plastics - yes - it turns out Sintra can be had for quite cheap, and we've started using it for some of our in-class projects and prototypes. Its surface properties are grippy enough to provide a nice clamping surface.

Now we don't see the Sintra as a "sacrificial material" as we barely scratch the surface of it when we cut parts. As I mentioned before, these strips last us about a year before they get scratched up badly enough to be replaced.

If you were considering using it for a true sacrificial material, where you're trashing the Sintra sheet every time you cut parts, then it's probably not going to be very cost-effective.

Wow, I never thought about that. Are "brute force" coolant pump would destroy the wood. I'll have to see if I can get my hands on some sintra.

[DampRobot]

Originally Posted by Mr. Lim

Depending on the wood you use, it could maybe even cause it to swell?.

We've definitely had this issue. Especially with very long pieces (eg long tubing), if the piece is being clamped with MDF underneath, swelling from absorbed coolent can cause some misalignment in the part. Plywood is even worse; because it isn't informally packed like MDF, it doesn't swell evenly and is very often not flat to begin with.

I can't remember any specific issues with sacrificial backing swelling, but I'm pretty sure we've had issues with it in the past. Don't read this the wrong way, coolant (especially mist coolant) is awesome, just swelling in the MDF backing can sometimes mess up milled parts.

Also, that film of MDF dust and coolant mixed together that forms after a long day of milling is really gross...

[sgreco]

Kind of reminds me of some 233 drivetrains of the past.

http://www.chiefdelphi.com/media/photos/33366

http://www.chiefdelphi.com/media/photos/31472

(The second one doesn't have wheels, but you can see from the bearings where they'd go).

[mman1506]

I've been a little busy lately but here is the latest update:

I've modified the modules to the plate design with 4 wheels. It is properly dead spaced now (Thanks, that saved me a lot of headache). Unfortunately there is not a lot of room for spacers but hopefully the addition of a tire will add some rigidity. I could always add some plasma cut spacers if strength becomes a issue.

We also learned how to use our bridgeport CNC with CAM software. Are last team "wave" didn't like using any computerized tools. Now we just have to buy endmills that aren't 0.02" off (It might have been a non standard endmill but we rarely buy those)

If someone is interested I will post the CAD files here.

[CENTURION]

Very nice! Looks like it will be a lot easier to work with the chains now.

I assume you're going to be adding some lightening in there?

Also, why can't you add more spacers in there? It looks like there's plenty of room

[Bdf809]

This design is actually very similar to our chassis layout this year and the one we used in 2011, except that we drove the center wheel of the chassis and had chain running from that to front and back.

You can see an exploded view here:

http://www.youtube.com/watch?v=uIpXitkiu7U

[mman1506]

Originally Posted by CENTURION

Very nice! Looks like it will be a lot easier to work with the chains now.

I assume you're going to be adding some lightening in there?

Also, why can't you add more spacers in there? It looks like there's plenty of room

Yup, I'm waiting for are team to decide on a standard lightening pattern.

You're right, now that a look at it there's a bunch of space.