[jwillhite]

My interest in cnc has remained after playing around with a hacked together desktop plotter/cnc for the last couple of months(see it here: http://www.cnc.draft-design.com)

Now its time to build a real machine. I've taken inspiration from a lot of builds here on the zone, thank you guys. In particular Snowgrains I think turned out really well http://www.cnczone.com/forums/showthread.php?t=53316.

My budget for this project is 1400-1600, I'm not sure if thats possible but thats what I'm shooting for. Due to the cost of the 8020 and the fact that I have access to mostly hand tools I plan on going with an aluminum extrusion and mdf hybrid. I can order the extrusion to length then tap it myself, I don't think I want to try and cut it though. Looking at what Ahren has to offer at http://www.cncrouterparts.com/index.html, that should pretty much take care of the linear bearing assemblies.

Here's what I'm thinking so far:

The bed is 24"x36", the actual cutting area will be more like 24"x26". If anyone sees any potential flaws or anything that could be improved I'd really appreciate the feed back.

Also I'm trying to decide on the stepper motors, should I go with 282oz.in motors or would something larger be more appropriate? Does anyone have a link to a build log that shows the electronics being put together from scratch? I'm debating whether or not to try that. The electronic controls for that little plotter I built went together without a hitch, not sure how that stuff would scale though.

-Josh

[TOTALLYRC]

My interest in cnc has remained after playing around with a hacked together desktop plotter/cnc for the last couple of months(see it here: http://www.cnc.draft-design.com)

Now its time to build a real machine. I've taken inspiration from a lot of builds here on the zone, thank you guys. In particular Snowgrains I think turned out really well http://www.cnczone.com/forums/showthread.php?t=53316.

My budget for this project is 1400-1600, I'm not sure if thats possible but thats what I'm shooting for. Due to the cost of the 8020 and the fact that I have access to mostly hand tools I plan on going with an aluminum extrusion and mdf hybrid. I can order the extrusion to length then tap it myself, I don't think I want to try and cut it though. Looking at what Ahren has to offer at http://www.cncrouterparts.com/index.html, that should pretty much take care of the linear bearing assemblies.

Here's what I'm thinking so far:

The bed is 24"x36", the actual cutting area will be more like 24"x26". If anyone sees any potential flaws or anything that could be improved I'd really appreciate the feed back.

Also I'm trying to decide on the stepper motors, should I go with 282oz.in motors or would something larger be more appropriate? Does anyone have a link to a build log that shows the electronics being put together from scratch? I'm debating whether or not to try that. The electronic controls for that little plotter I built went together without a hitch, not sure how that stuff would scale though.

-Josh

Nice drawing and design.

282's should be more than enough.
Trying to run a nema 23 size motor on home made circuits is a false economy in my opinion. Going low cost on the electronics means just that, you have low cost electronics. If you go better on the drives and such, you can always move them to another machine or back and forth, when you have 2 machines. With low cost mechanicals, you can always use the machine to make parts for a better one or do parts upgrades one at a time.

Having used a Xylotex board on my Taig for a while and now seeing what the G540/250/251's can do. $299 gets you a heck of a lot of capability.

Xylotex 4 axis $185. 35v and 2.5amp absolute max 87.5 watts max/ motor.
Breakout board $75 for a decent one.
VFD control board $30 and up
Total $290
G540 All of the above bulit into 1 and the 4 drives are modular. if one goes bad it is 5 minutes to swap out.
$299 http://www.geckodrive.com/product.aspx?c=3&i=14469
50V and 3.5 amps conservative ratings. 175 watt / motor
The actual way that it drives the motors is 100 times better than any other low price drive on the market.
Double the power for a few dollars more. IT IS A NO BRAINER

Many peope will say I can go slow, after all it is just a hobby. The laws governing how well a cutter cuts don't care what your budget or wife(nuts) says, there is a certain minimum speed you have to go or it burns the work or dulls the cutter or gives a lousy finish on the part.

I have 2 machines ( router and mill) that, If I knew then, what I know now, I would have done the electronics differently. The newer gecko drives I mentioned weren't even available at the time.

[jwillhite]

Nice drawing and design.

282's should be more than enough.
Trying to run a nema 23 size motor on home made circuits is a false economy in my opinion. Going low cost on the electronics means just that, you have low cost electronics. If you go better on the drives and such, you can always move them to another machine or back and forth, when you have 2 machines. With low cost mechanicals, you can always use the machine to make parts for a better one or do parts upgrades one at a time.

Having used a Xylotex board on my Taig for a while and now seeing what the G540/250/251's can do. $299 gets you a heck of a lot of capability.

Xylotex 4 axis $185. 35v and 2.5amp absolute max 87.5 watts max/ motor.
Breakout board $75 for a decent one.
VFD control board $30 and up
Total $290
G540 All of the above bulit into 1 and the 4 drives are modular. if one goes bad it is 5 minutes to swap out.
$299 http://www.geckodrive.com/product.aspx?c=3&i=14469
50V and 3.5 amps conservative ratings. 175 watt / motor
The actual way that it drives the motors is 100 times better than any other low price drive on the market.
Double the power for a few dollars more. IT IS A NO BRAINER

Many peope will say I can go slow, after all it is just a hobby. The laws governing how well a cutter cuts don't care what your budget or wife(nuts) says, there is a certain minimum speed you have to go or it burns the work or dulls the cutter or gives a lousy finish on the part.

I have 2 machines ( router and mill) that, If I knew then, what I know now, I would have done the electronics differently. The newer gecko drives I mentioned weren't even available at the time.

Thanks for the advise/info, its invaluable at this stage when I'm buying the pieces.

Pretty sure I'm going to go with the G540, originally I was thinking about buying a kit like this from Keling Inc. http://cgi.ebay.com/3-Axis-Stepper-M...742.m153.l1262
The G540 including power supply and steppers is going to run about 500.00 not including shipping vs. the Keling kit which is 440.00. I think your right about not skimping on the electronics though, that and the G540 is such a clean simple plugin solution.

Looks like the Keling power supply I was going to buy(http://www.kelinginc.net/SwitchingPowerSupply.html) is out of stock, anyone know of some alternative power supply/stepper motor sources?

-Josh

[TOTALLYRC]

There is a supplier onn ebay that has toridial power supplies but I can't remember his name.

[ger21]

antek, I think.

[radcliffe]

http://stores.ebay.com/Antek-inc

Harold

[ahren]

Josh,
The design looks good. I'm not a big fan of mdf for uprights, even double glued the way you've drawn. If these flex, you can get racking in your system. I realize 8020 can be expensive, so my suggestion to save money would be to go with steel tube or plate for the uprights (you can get away with hot-rolled for this). Get it cut to length, but you can drill it with a good drill press and a starter punch and get a much more rigid connection than anything with mdf. Having priced out steel from various suppliers, it looks like speedy metals is one of the best values. That being said, snowgrains machine is working with mdf for the materials he's cutting, so it may work for you. You can always replace it with steel later.

Also, make sure you account for where your motors are going to mount, and where your bearing supports are going to go. Otherwise, go for it, and good luck with your build!


Ahren
www.cncrouterparts.com

[jwillhite]

Josh,
The design looks good. I'm not a big fan of mdf for uprights, even double glued the way you've drawn. If these flex, you can get racking in your system. I realize 8020 can be expensive, so my suggestion to save money would be to go with steel tube or plate for the uprights (you can get away with hot-rolled for this). Get it cut to length, but you can drill it with a good drill press and a starter punch and get a much more rigid connection than anything with mdf. Having priced out steel from various suppliers, it looks like speedy metals is one of the best values. That being said, snowgrains machine is working with mdf for the materials he's cutting, so it may work for you. You can always replace it with steel later.

Also, make sure you account for where your motors are going to mount, and where your bearing supports are going to go. Otherwise, go for it, and good luck with your build!


Ahren
www.cncrouterparts.com

Ahren thanks for the advice, yeah the gantry vertical supports are definately a concern. I was thinking of glueing the mdf together then bolting through it and the angle iron to the 8020.

Yeah your right steel tubing or even plate would probably be preferable. I have some mdf and steel angle hanging around here though so I might try that first.

As far as the motor mounts go I need to play around with the model a little and make sure the geometry works out.

[jwillhite]

this machine http://cnczone.com/forums/showthread.php?t=62271&page=2 looks so good that I'm considering doing the whole thing out of 8020. Sent the model into my local 8020 rep to get an estimate. If its not completely outrageous I might just do that, be nice to only have to worry about drilling holes in the steel plate everything else would just bolt together.

[wizardrule]

here is one to consider, it has proven to be quite stabel but I would defiantley change the Bearings to something other then precribed. The file wont load for some reason, but if you want it pm me and Ill email it to you.

[wizardrule]

if you notice on the gantry Ahren, it appears he has angle iron on the uprights. I think stiffness would be at premium with that set up.

[ahren]

I did notice the angle iron. This is a good idea, but is really only as strong as the method used to fasten the iron to the mdf. If these are just glued on, then I'm guessing the joint between the two materials will break long before the real benefit of the angle iron is reached. Then again, if the steel is bolted on, this might be a viable means of strengthening the setup.

Ahren
www.cncrouterparts.com

[wizardrule]

Agreed on the glueing for sure, but if fastened with screws it should be more then stiff enough to handle anything that gets cut.

[jwillhite]

Agreed on the glueing for sure, but if fastened with screws it should be more then stiff enough to handle anything that gets cut.

Yepp thats steel angle running up the sides of the gantry to help stiffen the mdf, I was planning on bolting straight through the angle and mdf into the ends of the 8020.

I'm no materials expert so I don't know exactly what to expect as far as deflection goes but it seems to me like that thickness of mdf combined with the steel angle should get the job done.

[ahren]

Josh,
Glacial wanderer was one of the first to build a router all with my parts. Sieg's is another build thread you might check out. Since both of these machines were made, I have released a z plate that allows a K2CNC router mount to be attached easily to the system, and provides a small cantilever to allow ~4.5" of z clearance and travel. To save money on extrusion, you might also check with t-slots (www.tslots.com), and definitely check out 8020's ebay surplus store. The stuff is not that hard to cut with a carbide blade in your miter saw. Also, you can save a lot of money on fasteners over what 8020 recommends -- 5/16 carriage bolts fit the T-slots perfectly, and the square shoulder serves as an anti-rotation feature. Instead of paying $0.75 per t-nut, you can use a $0.04 carriage bolt, and it adds up fast.

Best regards,

Ahren
www.cncrouterparts.com

[jwillhite]

Finally started to make some purchases

Here's the G540 got it in the mail this morning



I didn't realize it but Gecko includes all the serial cable connectors required, very considerate of them.

Also purchased the linear bearings/motor-mounts/bearing blocks/anti-backlash nuts from Ahren at cncrouterparts.com, should have those next week.

So far the total comes to

G540 - 299
Axis motion parts - 382
Total = 681.00

Also I went through and redrew the structure of the machine from the ground up. Got the local 8020 supplier to give me a cost estimate on the machine as it was originally designed.. it would have only been ~175.00 for the extrusions. That price seemed really reasonable so I went a little crazy and completely redesigned everything... sending them a cut list next week so I can find out how much the damage will be. Anyway here's the new and improved structure



The only thing that worries me is that the y-axis screw will be off center, I'm not sure if that will cause problems.

[jwillhite]

This machine will mostly be used on wood. But I'd really like to be able to cut aluminum and mild steel on it as well, does anyone know if that's a reasonable expectation with the regular router motors that people are using? I mean if I really want to be able to cut metal do I need some kind of spindle set up, are there any good resources on the net for learning the basics of machining metal.. feed rates, rpm's, tool usage.. etc?

Thanks, Josh

[FandZ]

I really like your design and it looks like you will be coming in under budget. But then again, the right software could blow it sky high. (nuts)

The one I'm drawing up is very similar, down to the vertical placement of the side rails. Could you tell me what the dimensions of your table will be?

[jwillhite]

I really like your design and it looks like you will be coming in under budget. But then again, the right software could blow it sky high. (nuts)

The one I'm drawing up is very similar, down to the vertical placement of the side rails. Could you tell me what the dimensions of your table will be?

Thanks, at this point though with the revised design and looking at everything that still needs to be purchased theres no way I'm going to come in under 1600.

8020 ~650
Steel Plate ~100
Stepper Motors ~150
Power Supply ~ 60
Thrust bearing assembly/connectors ~ 75
Bearings ~ 35
ACME threaded rod ~120
Router + mount ~130
Misc. ~ 100

Total remaining = 1420
Total Estimated Cost = 2101!!!! ouch wow, might have to modify the design depending on how much they say the extrusion will cost.

Won't be spending anything on the software, I enjoy playing around with linux and computer stuff in general so I was thinking of using something like this http://www.linuxcnc.org.

The overall footprint of the machine will be approx. 48"x48", the usefull cutting dimensions should be pretty close to 36"x30"x5". The reason I didn't go longer on the X-axis is the threaded rod only comes in lengths of 36" and 72", I didn't want to buy the 6' length then waste a bunch of it. Using 1/2" drill rod for coupling from the motor to the threaded rod gets a couple extra inches of travel, per Ahrens design here http://www.cncrouterparts.com/parts.html.

Hey if you have your's drawn up I'd be really interested in seeing it, do you have a build log going?

[ahren]

Josh,
Your parts went out today -- you should see them Monday or Tuesday. Your design looks quite stout. Nice rendering by the way! I wouldn't worry about the screw on the Y being off center, and I think cutting aluminum will be viable. Just use small bits, take light passes, and keep your feedrate high, since your router will be running much faster than normal metal cutting spindles. Looking forward to seeing it come together!

Best regards,

Ahren
www.cncrouterparts.com