micRo V1, Inactive archive; see micRo V2 for current info. Options

[ddillard]

Sigh. We had it set up to run a job on 1/2" alum billet and exactly when we tried to start the job we accidentally shorted the Z motor leads and smoked the driver! I almost cried, but having worked for >20 hours, we were too spent to fix the situation.

Ouch that has to suck. I thought the breakouts would prevent issues like that from happening.

[brainchild]

Ooooh, can you try sinking it's teeth into a bit of aluminum and some steel for us? I wanna see some more swarf!

I actually had a vid of Robin cutting some alum but I deliriously deleted it by accident. It cuts great!

[brainchild]

Ouch that has to suck. I thought the breakouts would prevent issues like that from happening.

We kept having this annoying glitch on the Z that caused the Z to suddenly reverse. We had the wiring apart and loose at the motor while testing. We found the problem, replaced the bad wire, then blew up the Z.

[Alex Chally]

Sigh. We had it set up to run a job on 1/2" alum billet and exactly when we tried to start the job we accidentally shorted the Z motor leads and smoked the driver! I almost cried, but after working for >20 hours, we were too spent to fix the situation.

I am looking forward to seeing this thing in real action. Any idea on how long until you guys start shipping those out to us, the grateful peasantry?

[answerguru]

Those spindle combos look great! Minus the genius of Chinese miss-translation, of course. On the plus side, the foot pedal could provide a nice base for mounting a servo to control the motor speed...

I'm actually aiming for a digital speed control myself.

[geeky]

What in the frack do you do at work?

I work at a tissue bank. The tool I was referring to is also a corded rotary tool, used for cranial surgery and other bone cutting jobs. I operate the bone grinder.

That button on the foot pedal thing is pretty funny. At least it works and can be modified to be controlled by EMC, which is pretty awesome. >20 hour days... wow. You guys are working hard and I really appreciate it.

[Narwhal]

I'm reminded of the time I was programming for arcade machines. We had our "affiliates" in Taiwan building and painting the fiberglass bodies for this new Star Wars Starfighter game. They did a really amazing job and spent weeks building the jet engine and seat pods. Painted them in a beautiful yellow and shiny silver. The really looked slick, except for a few problems....

They wrapped them in plastic sheet, put them all in a single wooden crate on top of each other, then mailed them to us without letting the paint dry.

Re-purposed foot pedals works fine for me.

[brainchild]

Ahem, calling German trolls. Here's some cut cheese!





I'll throw in pix while the vids upload. Here's the rig; you can see the spindle motor is just sitting there...seems fine, but I did oil the shaft with turbine oil, and I greased the tang on the drive.

 therig.JPG ( 440.6K ) Number of downloads: 25






Nearly done!

 nearlydone.JPG ( 679.59K ) Number of downloads: 17




Heheh!

 micRoplaque1.JPG ( 711.83K ) Number of downloads: 18


 micRoplaqueclose.JPG ( 603.46K ) Number of downloads: 22





Cheers!

[svalebror]

Grand! I can't wait!

[mas3773]

Nice, I fully expected it to be able to pull it off nicely, but seeing it actually happen was a treat. That should put the cheese troll back under the bridge.

Say, do you have any idea on what the depth of the cuts were and about what RPM you were running on the spindle? I'm planning on doing a bit of aluminum and that would help. I do have to say though that I am a little disappointed, I went with a Harbor Freight grinder for mine which I bought a long time back and upgraded to ABEC9 bearings...but it's AC [i]not[/t] DC like yours. It would've been cool to have EMC handle it all, but oh well.

I take it after the redesign that the spindles and motor mounts will be shipping this week? Not wanting to push, I've just been waiting on ordering the milling bits and don't want to get everything set then not have them in hand.

A big cheers as well. That piece, though not requiring much precision, signifies that micRo is only a little G-code away from proving the construction of the Rogr parts from the little brother. Job well done guys.

[-soapy-]

Dudes, you are the dudes! I'm sitting here at a few minutes to midnight with a big smile on my face. Those videos are brilliant, the machine is brilliant, and it's creators are also, clearly, brilliant. And I'm getting one. :-) I've also got a new desktop image, possibly even better than a walrus with a bucket, of a little machine with it's self-made nametag. :-D

That reminds me, I've got to do the $100 check-it-works thing.

Next: The spirograph design in aluminium.

[brainchild]

Nice, I fully expected it to be able to pull it off nicely, but seeing it actually happen was a treat. That should put the cheese troll back under the bridge.

Say, do you have any idea on what the depth of the cuts were and about what RPM you were running on the spindle? I'm planning on doing a bit of aluminum and that would help. I do have to say though that I am a little disappointed, I went with a Harbor Freight grinder for mine which I bought a long time back and upgraded to ABEC9 bearings...but it's AC [i]not[/t] DC like yours. It would've been cool to have EMC handle it all, but oh well.

I take it after the redesign that the spindles and motor mounts will be shipping this week? Not wanting to push, I've just been waiting on ordering the milling bits and don't want to get everything set then not have them in hand.

A big cheers as well. That piece, though not requiring much precision, signifies that micRo is only a little G-code away from proving the construction of the Rogr parts from the little brother. Job well done guys.

Depth was .01"/pass and we tested up to 18 IPM.

I want to do a little testing on a new spindle mount; but by week's end is almost certain.

Precision: the piece we ran is remarkably accurate; Robin and I were quite impressed.

[rturner]

Each pass was .01" at between ~9IPM (nursing it in the beginning) and 18IPM, spindle speed was set at maximum, though we have to confirm with a tach what that speed truly is.

The spindles happen to be a happy accident, since they're SCR rated brushed DC motors, a range of controls can be used... as simple as a logic-level relay and bridge rectifier up to an elaborate spindle speed control system... I think we'll have to do some testing to confirm the limits though...

edit:

DOH! Grayson beats me to the reply once again.

spindle mounts:
The mounts seen in the video were sort of test mounts.... Some of that design has to be totally scrapped (mainly, the clamp was designed very late at night with the primary consideration being the fasteners we had sitting around... to not so great results.), but a better design should be ready within another test or two.

accuracy:
The most pleasantly surprising part of this was seeing that the finish of the cuts was... Really good. Usually getting a surface finish like that takes a bit of trial and error, but, really it produced as good of a finish as anything I've seen fresh off the knee-mill or any other bot... This is indicative of the fact that with reasonable cuts, there's very little deflection within the system. As a side note, there seemed to be no lost steps either.

[brainchild]

Each pass was .01" at between ~9IPM (nursing it in the beginning) and 18IPM, spindle speed was set at maximum, though we have to confirm with a tach what that speed truly is.

The spindles happen to be a happy accident, since they're SCR rated brushed DC motors, a range of controls can be used... as simple as a logic-level relay and bridge rectifier up to an elaborate spindle speed control system... I think we'll have to do some testing to confirm the limits though...

The spindle can def go faster; the motor barely got warm.

Dudes, you are the dudes! I'm sitting here at a few minutes to midnight with a big smile on my face. Those videos are brilliant, the machine is brilliant, and it's creators are also, clearly, brilliant. And I'm getting one. :-) I've also got a new desktop image, possibly even better than a walrus with a bucket, of a little machine with it's self-made nametag. :-D

That reminds me, I've got to do the $100 check-it-works thing.

Next: The spirograph design in aluminium.

Cheers

[Hirudin]

That is way cool! Did you do the whole thing without coolant, air, or vacuuming up the chips?

Hopefully these videos will put a fork in the whole micRo-roni and cheese trolling.

[rturner]

We did give it a couple squirts of oil towards the bottom of the parting cut, and yes, chip was vacuumed/blown a few times, but mostly so that we could see the progress it was making (you'd be surprised how much chip there is stuck in a block of aluminum). Using a sharp carbide bit makes cooling mostly sort of a non-issue, it doesn't absolutely need a cutting fluid, and it doesn't get soft or dull at higher temperatures like high-speed steel (which requires constant cooling). A lot of times when you read about coolant being used on mills and the like, it's not for the cutting tool and has more to do with the localized heating and expansion of whatever is being cut- this can change the tolerance of a cut by several thousands and give a crummy finish...

I think I'll make some cheese fondue to celebrate.

[KingOfSwords]

Anyone have a good source for milling bits they can recommend?

[Alex Chally]

Anyone have a good source for milling bits they can recommend?

I just picked up an assortment of bits from MSC. I don't have any affiliation with them or anything, but they manage to regularly ship items to me within 24 hours of me placing my order, and they get from their warehouse in Nevada to my house in Oregon in a day or so. With a turn around of 2-3 days from the time that I place an order, it is almost as instantly gratifying as buying it locally.

I got these:

1/8in 4 flute end mill: http://www1.mscdirect.com/CGI/GSDRVSM?PACA...000000090684357

1/8in 3 flute end mill: http://www1.mscdirect.com/CGI/GSDRVSM?PACA...000000090684369

1/8in 2 flute end mill: http://www1.mscdirect.com/CGI/GSDRVSM?PACA...000000090684377

and I also got a couple bottles of the ptfe lube that BC recomended: http://www1.mscdirect.com/CGI/GSDRVSM?PACA...000000090684386

I just got those to get started, and to see which style would work best on the micRo. Traditionally you would use the 2 flute for roughing, and the the 4 for finishing, but I have heard good things about using a 3 flute mill for aluminum so i figured I would give it a try.

Quick edit: I would have gotten 4mm end mills but they were roughly three times the price of a comparable end mill in a imperial dimension. Also, those are not the highest quality of end mills, but I figured that they would do for now, and if I needed a nicer one I would pick it up later.

This post has been edited by Alex Chally: Apr 6 2009, 03:34 AM

[Hirudin]

...
A lot of times when you read about coolant being used on mills and the like, it's not for the cutting tool and has more to do with the localized heating and expansion of whatever is being cut- this can change the tolerance of a cut by several thousands and give a crummy finish.

Isn't another function of coolant to get the chips out of the path of the end mill? People over on CNC Zone talk a lot about "chip weld", especially when using high RPMs in aluminum. They say the chips end up clogging the flutes so they end up increasing the friction between the cutter and the part. Eventually the friction will get so hot it melts and welds to the cutter making it dull, then it breaks.

[beth.null]

Heeeeyyyyyy, OooeoooeEEOOooeooOEOo, , why are you so bad to us?, you are exponentially increasing our desire for the micRo , I am falling in love .

Fantastic work, is nice to see that your predictions and test are more than confirmed, I can't wait for milling a pcb, I am thinking in milling it in cheese alum .

Is up to you guys, chheeeerrssss

[geeky]

Hmm I wonder if there will be cooling problems when trying to mill stainless steel. Most places I read about machining stainless recommends flood cooling. I am not too familiar with what that looks like, do you think we can add that to micRo?

[ddillard]

I wonder how hard it would be to integrate a mini shop vac like this one to keep the shavings cleaned up as the micro does it's thing. Or if it would even be beneficial. I was just thinking that if it could be attached correctly without interfereing with the working of the micro, it would make it easier to start a job and continue on to performing other tasks and it would help with making cleanup after a project much easier.

http://www.target.com/Shop-Vac-HangUp-Mini..._vac&page=1

[Alex Chally]

Hmm I wonder if there will be cooling problems when trying to mill stainless steel. Most places I read about machining stainless recommends flood cooling. I am not too familiar with what that looks like, do you think we can add that to micRo?

Adequate flood cooling for the micro could probably be provided by something as small as an aquarium pump, a small tank and some Loc-Line tubing. It does not take a lot of coolant to flood a 1/8in end mill.

Of course, using a flood coolant system means that you need to make a case for the entire thing so that coolant does not go everywhere. I am planning to make one out of angle aluminum like this: http://www.onlinemetals.com/merchant.cfm?p...&top_cat=60 and some plexy glass.

[Hirudin]

You aren't in the USA, right Alex Chally? If you haven't already, check out "Quick Frame" from 80/20 (and other aluminum extrusion distributors I imagine). Hopefully you can get some wherever you are. If I remember right it's somewhere in the neighborhood of 13 cents* an inch (the stuff you linked to is 9.4 cents* an inch). Then the corner pieces are around $2.50 each (again, if I remember right).

The enclosure might be nearly twice as expensive, but it'll probably be a lot easier, stronger, and nicer looking.

*That's odd, every time I insert a "cent" symbol a weird "Z" symbol is inserted to...
ŽŽŽ¢

This post has been edited by Hirudin: Apr 6 2009, 09:14 AM

[Alex Chally]

You aren't in the USA, right Alex Chally? If you haven't already, check out "Quick Frame" from 80/20 (and other aluminum extrusion distributors I imagine). Hopefully you can get some wherever you are. If I remember right it's somewhere in the neighborhood of 13 cents* an inch (the stuff you linked to is 9.4 cents* an inch). Then the corner pieces are around $2.50 each (again, if I remember right).

The enclosure might be nearly twice as expensive, but it'll probably be a lot easier, stronger, and nicer looking.

*That's odd, every time I insert a "cent" symbol a weird "Z" symbol is inserted to...
ŽŽŽ¢

Nope. I am in the US, Eugene Oregon to be more specific. That stuff does look cool, but frankly my time is worth nearly nothing, and I would rather sacrifice a few hours of shop time to make it out of the cheaper material. At school I have access to big cnc machines, bridgeports, 15+hp lathes etc etc, and with that kind of tooling a job like putting together a box our of angle alum. gets a lot easier.