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Culvan
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Joined: 20 May 2008
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Location: Kansas City, MO

PostPosted: Fri Jan 29, 2010 9:42 pm    Post subject: Reply with quote

danipe70 wrote:
You are right, i used watered down white glue.
To do the mold, try to protect de foam with a layer of epoxi resin or poliuretane resin (not poliester resin), then sand the resin and paint it.

See this videos, they could help you.

http://www.youtube.com/watch?v=VWkch-QEGkI
http://www.youtube.com/watch?v=1WMuLBNthk8


I couldn't understand the second video. What was the powder that he added to the resin? I've suspected that adding some sort of rock-like material would help absorb/distribute the heat of vacuum forming. I've been wondering if using hydrostone powder mixed with polyurethane resin would work like that.

I've been meaning to try exactly what they are recommending, but I haven't gotten around to it. Hopefully I'll find some time and post my results.

Andy
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coffeehedake
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PostPosted: Wed Feb 10, 2010 8:00 pm    Post subject: Driver Package Reply with quote

Culvan wrote:
I used a driver board package kit from Hobby CNC. The package was easy to assemble, my biggest complaints would be that there wasn't enough information provided about it up front. Had I known enough about it I probably would've bought the "kit" version instead of the "package" version. It would've saved me some money since I know enough about electronics to get it up and working without all the extra cables and stuff.


Hey Culvan. Just a question for you, as I've been through HobbyCNC's site myself (before coming here) and been a little confused as well. What are the differences between the package and the kits they sell? Just the accessories?

Culvan wrote:
As I mentioned earlier, I chose to take an old power supply from a computer and use it. Unfortunately my old spare power supplies were not in use for a reason. I ended up doing this three times. The basic gist of the modification is that you put a power resistor between the red and the black wires to make it believe there is a constant load. That keeps it from shutting down because it believes there is a open circuit. The idea of this is mentioned on hobbyCNC's web site, but I found there were many other web sites with better instructions on how to do this. (I've got more pictures of this process, but I'm summarizing here, let me know if anyone wants to see the steps.)


I'm definitely interested. I have tons of PC components lying around, and throwing a few 400W PSU's at the problem will save me a ton of money, rather than buying expensive parts from the CNC outfitters.

I'm guessing on a 20-Pin ATX PSU you wired the green to a ground to trick the PSU? I've seen this before when combining 2 PSU's in a single case (when adding an AT PSU)

Thanks for the great step by step how-to Culvan. This is going to make things so much easier for me, and it's going to make a lot of kids happy. (Donating my CNC machine to the school I work at once it's complete)
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Culvan
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PostPosted: Thu Feb 11, 2010 9:49 am    Post subject: Re: Driver Package Reply with quote

coffeehedake wrote:
Hey Culvan. Just a question for you, as I've been through HobbyCNC's site myself (before coming here) and been a little confused as well. What are the differences between the package and the kits they sell? Just the accessories?

I'm definitely interested. I have tons of PC components lying around, and throwing a few 400W PSU's at the problem will save me a ton of money, rather than buying expensive parts from the CNC outfitters.

I'm guessing on a 20-Pin ATX PSU you wired the green to a ground to trick the PSU? I've seen this before when combining 2 PSU's in a single case (when adding an AT PSU)


I've got all the documentation and pictures at home. I can provide them if you need them.

The kit contains the PCB and all the stuff you solder to it. The package also has a rectifier, fuses, fuse holders, a switch, a heat sink, wires, heat shrink tubing, a massive capacitor, screws and stuff like that. It assumes that you will further buy a massive transformer ($60-$120) and the project enclosure box (~$30). I didn't want to splurge on the massive transformer so I used the computer power supply. I later noticed that there are some stores on eBay that sell assembled kits for about $5 less than what HobbyCNC was charging for a kit.

You seem to have the idea for the power supply. You do indeed solder the green wire (softswitch) to black (ground). However you also have to put some form of load on the 5V line. Radio Shack sells some 10ohm 10 watt power resistors that work just fine. I can't remember if this site was the one that I used, but the instructions look good. http://web2.murraystate.edu/andy.batts/ps/powersupply.htm

I actually did 3 power supplies. The problem with using unused parts out of my basement was there were reasons they were unused. Eventually I used an old AT power supply. I didn't have to fiddle with the green wire for that since it had a proper power switch. The downside of using a PC power supply is that it cannot supply as much power as the transformer they had specified. I think the transformer was supposed to be 20A and the supply I used only handles 10A. This means that I could run my stepper motors with more current than I currently use. That could produce more holding force and I think I could run the machine faster on the rapids. So far that has not been enough to make me want to upgrade.

Andy
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coffeehedake
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PostPosted: Thu Feb 11, 2010 10:08 am    Post subject: Reply with quote

Awesome info. Thanks so much Culvan!

Thanks for the link, I'm tempted to see what I can do with this as this would give the necessary Amperage you mentioned, via 2 12V rails on a slightly newer PC Power Supply. I have piles of all types, including the newer 24-Pin ATX.

I'm actually thinking of taking your advice with the eBay store. I've seen some previously, and was thinking very hard about buying from there. My soldering skills are less than adequate for this project (I was much better at this stuff when I was in high school, out of practice) and I'd like to just have a working board come in the mail. Wink

Thanks again!
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LaughingCheese
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PostPosted: Wed Feb 17, 2010 9:54 am    Post subject: Reply with quote

Culvan wrote:

LaughingCheese - stormtrooperguy is correct the cost of the wood around $40 for twice what I needed. The biggest single cost was the electronics. I think it was $280-ish for the stepper motor controller kit and stepper motors. $30 for bearings and most of the rest was spent on nuts and bolts. One of the things that drew me to the plans I listed at the beginning of this was that the author had listed all of the costs of the components up front. He left off the cutting tool and software. I re-used an old tool that I wasn't using otherwise. There is lots of free software, but I did break down and buy the machine controller. It was much easier to use than the free stuff. There appears to be someone selling kits for all the wooden parts for something like $200. That makes the wood cost 10x more, but almost any estimate of value for my labor would have made that a good deal. I ended up taking nearly two weeks off work to get all this done. (I couldn't cut any of it while the kids were sleeping)

Andy


Good gravy, why $280, can you cut aluminum too??? lol

Ijust want to be able to cut foam, like EPP, etc. I did want to cut aluminum but now I'm thinking about how I can save, and buying less powerful motors is one way.

Also, are those plans easily scalable?

For instance I was considering a 3' x 2' machine instead of the 4' x 4'.


As for Z height, do you think that's enough for cutting armor pieces, and RC aircraft airfoils?

Actually, I'm not sure how you'd cut an airfoil with that, I'd think you'd need it edge on or something.
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stormtrooperguy
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PostPosted: Wed Feb 17, 2010 11:27 am    Post subject: Reply with quote

LaughingCheese wrote:

Good gravy, why $280, can you cut aluminum too??? lol


the money on this stuff adds up FAST. heck, i've spent $400 this week on resin, and it's all gone already!
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coffeehedake
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PostPosted: Wed Feb 17, 2010 11:29 am    Post subject: Resin Reply with quote

You cutting Resin with the Router, or doing Stereo Lithography? $400!!! Jeepers!
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LaughingCheese
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PostPosted: Wed Feb 17, 2010 12:42 pm    Post subject: Reply with quote

stormtrooperguy wrote:
LaughingCheese wrote:

Good gravy, why $280, can you cut aluminum too??? lol


the money on this stuff adds up FAST. heck, i've spent $400 this week on resin, and it's all gone already!


I dont want to use resin tho.

Just foam or MDF for my molds.

Also, is there any reason I couldn't replace the Dremel with a Plastruder and make it a 3D printer as well?

The issue again would be the Z height, but it depends on the part I'm making. They'd probably be small and only an inch or two at most, so it should be fine.


I really don't see why it can't be considered tool agnostic.

Heck, I could probably attach a laser to make it a laser cutter.
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stormtrooperguy
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PostPosted: Wed Feb 17, 2010 1:01 pm    Post subject: Reply with quote

The resin was just an example of how fast costs can add up. MDF, Bondo, resin, foam... they all cost a fair bit, and you go through them fast.

These hobbies tend to be very expensive. I don't want to sound like I'm trying to scare people off, but I like to try to be realistic about projects. Cutting corners on the foundational elements will cost you more in the end than if you just did it right in the first place.

To me, $280 doesn't seem like a lot for the core components of a CNC setup. That's about how much 1 silicone helmet mold costs me to make.

A commercial CNC machine would be many thousands of dollars, so $300 on bits to build one seems like a huge savings.
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LaughingCheese
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PostPosted: Wed Feb 17, 2010 1:19 pm    Post subject: Reply with quote

stormtrooperguy wrote:
The resin was just an example of how fast costs can add up. MDF, Bondo, resin, foam... they all cost a fair bit, and you go through them fast.

These hobbies tend to be very expensive. I don't want to sound like I'm trying to scare people off, but I like to try to be realistic about projects. Cutting corners on the foundational elements will cost you more in the end than if you just did it right in the first place.

To me, $280 doesn't seem like a lot for the core components of a CNC setup. That's about how much 1 silicone helmet mold costs me to make.

A commercial CNC machine would be many thousands of dollars, so $300 on bits to build one seems like a huge savings.


Well, its a lot for me since I don't have a job, and I'm working only with Christmas money here. XD

One reason I was looking at the McWire Mill, the Instrucable stated you could be up and running for around $200.

Now if I only need cheap, 50oz Nema 17 motors (or whatever oz they are) to cut foam, that's what I need.

But I still can't decide if I want a gantry type router or a McWire Mill type.

I think a McWire Mill would be slightly easier to build than a gantry type, but a gantry type would give me a bigger build area.
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stormtrooperguy
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PostPosted: Wed Feb 17, 2010 1:39 pm    Post subject: Reply with quote

LaughingCheese wrote:

Well, its a lot for me since I don't have a job, and I'm working only with Christmas money here. XD


Well... um... how to put this gently?

IMO, if you don't have a job, building a CNC machine probably isn't exactly a top priority sort of project Wink
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jdougn
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PostPosted: Wed Feb 17, 2010 3:29 pm    Post subject: Reply with quote

Wait! Since when did we put having a real job before this "hobby"? I thought the entire point was to get a job only when I needed to buy something to support this hobby? Wow, I have to rethink what I'm doing now.
(Haven't had a regular job for over a year at this point. Sold a bunch of stuff Shocked, blew out my savings Rolling Eyes, and pickup most any odd job that comes by Confused.)
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LaughingCheese
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PostPosted: Wed Feb 17, 2010 6:19 pm    Post subject: Reply with quote

stormtrooperguy wrote:
LaughingCheese wrote:

Well, its a lot for me since I don't have a job, and I'm working only with Christmas money here. XD


Well... um... how to put this gently?

IMO, if you don't have a job, building a CNC machine probably isn't exactly a top priority sort of project Wink


Shhhhhh......Wink

Quote:

Wait! Since when did we put having a real job before this "hobby"?


Yeah!

By that logic no kid should have a hobby!! Laughing

Quote:

I thought the entire point was to get a job only when I needed to buy something to support this hobby? Wow, I have to rethink what I'm doing now.


Lol...QFT bro!

Quote:

(Haven't had a regular job for over a year at this point. Sold a bunch of stuff Shocked, blew out my savings Rolling Eyes, and pickup most any odd job that comes by Confused.)


Sorry to hear that!

At least you've had a job before! =P
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stormtrooperguy
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PostPosted: Wed Feb 17, 2010 6:22 pm    Post subject: Reply with quote

LaughingCheese wrote:

By that logic no kid should have a hobby!! Laughing


Ah, that makes more sense! I was sort of just assuming you fell into the 30something hobbyist part of the house.

When I was a kid I did have hobbies, they were just cheap ones that I could afford Wink
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LaughingCheese
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PostPosted: Wed Feb 17, 2010 7:00 pm    Post subject: Reply with quote

stormtrooperguy wrote:
LaughingCheese wrote:

By that logic no kid should have a hobby!! Laughing


Ah, that makes more sense! I was sort of just assuming you fell into the 30something hobbyist part of the house.

When I was a kid I did have hobbies, they were just cheap ones that I could afford Wink


Doh!

Actually I'll be 23 next Sunday.

I was referring to kids in general, not myself! Wink
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