Greyscale Racing MRCG

SuperFly · Post by **SuperFly** » Sat May 26, 2007 2:00 pm

Yes, that helps a lot. While I've built up plenty of 1:28 cars, I've always used stock or modified stock electronics. I was just checking out the guts on my Micro-T thinking about how they are about half the price of mini-z guts.

color0 · Post by **color0** » Sun May 27, 2007 1:44 am

Heh, that's what I thought too, and then I went around a bunch of forums and infosites looking up reviews on the Micro-T. Evidently the guts are good, so I look forward to building the first test cars.

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Just letting everyone know that the RM version of the MRCG chassis will most likely not make it to the shelves, at least not in the first release. The MM design is more economical, so far more popular, and my machinist friend is worried that we don't have that much time to be making two versions.

If interest in the RM suddenly shoots up I will try to convince my friend otherwise, but tentatively, MRCG will be released only as an MM chassis.

color0 · Post by **color0** » Fri Jul 20, 2007 6:52 pm

First post in the thread updated... yes it has been a while.

I bought a CNC mill, have all the materials and tooling needed to go, CNC software and CAM software I have (just need official licenses), and basically the only thing missing is the mill. Prototypes are finally in sight.

ynad · Post by **ynad** » Sun Jul 22, 2007 12:10 pm

color0 · Post by **color0** » Wed Aug 22, 2007 12:39 am

Updates, finally.

The CNC stuff has finally come, after multiple threats on my part to file an eBay dispute. I got the CNC mill working, and ran a test program through it. Seems to work well, although I won't be able to see the tolerances until I build some prototype parts. At any rate, the thing IS working at least, so I can finally legitimately say I'm on my way to getting this chassis produced for those interested.

color0 · Post by **color0** » Sat Sep 08, 2007 5:27 pm

First batch of G10 prototype parts! The cut quality is no good, but it's mainly because I used a ruined endmill to cut with. The holes will be countersunk later, no worries.

I plan to get these parts made correctly before moving on to the fancy 4-axis work, so check back for updates.

sidewinder · Post by **sidewinder** » Sat Sep 08, 2007 6:06 pm

OUT-FREAKING-RAGIOUS!

Dangerous Dave · Post by **Dangerous Dave** » Sun Sep 09, 2007 11:42 am

nice work

If you have some breakages, a few more radiused corners might be more durable

color0 · Post by **color0** » Sun Sep 09, 2007 7:40 pm

I can try it, I've been reading up on what differences it makes, seems that it has to do with heat production? I haven't broken my endmill yet, but thanks Dave.

Dangerous Dave · Post by **Dangerous Dave** » Sun Sep 09, 2007 9:17 pm

I actually meant breakages of the chassis components when testing, sorry.

Just to reduce the stress concentrations. May not be necessary anyway

SuperFly · Post by **SuperFly** » Sun Sep 09, 2007 10:44 pm

Dangerous Dave wrote:I actually meant breakages of the chassis components when testing, sorry.

Just to reduce the stress concentrations. May not be necessary anyway

I know radiused corners improve the strength of plywood cutouts quite a bit, and they tend to give it a much more "finished" look.

color0 · Post by **color0** » Mon Sep 10, 2007 2:14 am

Ah, understood; yes, the corners right now are all .5mm radius (i.e. the 1mm endmill just goes in and out). I will most likely change that, and some other specs as well later. This IS the prototyping stage after all.

Any ideas on fixturing? I have some scrap pine board I used to build the mill enclosure, not sure how to make it flat enough to mount the G10 on? I could also mill some Delrin blanks to the correct thickness, drill and tap holes, and support the parts that way.

Thanks for your help guys!

color0 · Post by **color0** » Sun Oct 07, 2007 5:34 pm

I was using the wrong units! D'oh. I have the feed rates right this time, and edge quality is much better, though the cutting bit didn't go deep enough to separate the pieces entirely from the stock. (It turns out that this plate of fiberglass is slightly thicker than 1/32".)

If you look closely at the picture, you'll notice there are two "kinds" of edges. I was playing around with the settings and found that really slow speeds (6mm/min) are really good but take forever, slightly higher speeds (15-30mm/min) are terrible, and the proper speed (150mm/min) nets nearly perfect cuts (check the outside edges of the flex plates).

So that's my update. Since I have a 3-day weekend I should be able to do some more work on the fiberglass and get that all sorted out and perfect. The Delrin and aluminum parts may have to wait since I still need some screws to mount my micro vise to the rotary table. Rest assured I will get this done as fast as I possibly can!

color0 · Post by **color0** » Fri Oct 12, 2007 12:49 am

Ok, I've got good and bad news.

Good news first: edge quality is perfect on the longer cuts.
Bad news: edge quality on the countersinks has gone down.
Worse news: the mill seems to jam up right around this one spot of travel. I have no idea where to look for the cure; the mill is freshly lubed up with WD-40 and the rails are clean. Yet there's a slight grinding noise and sometimes the whole thing just jams while the CNC control software believes it's still going.

Check Exhibit A:

Murdoch · Post by **Murdoch** » Fri Oct 12, 2007 1:42 am

color0 wrote: Worse news: the mill seems to jam up right around this one spot of travel. I have no idea where to look for the cure; the mill is freshly lubed up with WD-40 and the rails are clean. Yet there's a slight grinding noise and sometimes the whole thing just jams while the CNC control software believes it's still going.

check your rails for debris such as small specks of metal. If you can't find any from a visual inspection, they're probably underneath somewhere.

which means you're either pulling apart the rails or running a swab through.

Also, there may be debris somewhere on the gears inside. check those aswell.

You ever thought of using dry lube instead of WD40?