ORD Bot Hadron Inquiries - Help Appreciated

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Re: ORD Bot Hadron Inquiries - Help Appreciated

Postby JLG » Sat Aug 24, 2013 1:30 am

Okay, so I'm going to try making a shopping list:

pre assembled mechanical kit including gears, pulleys, and stepper motors
http://item.mobileweb.ebay.com/viewitem ... 0981613057

Would it be beneficial / produce higher quality prints to switch these stepper motors to these?
https://www.sparkfun.com/products/10846

extruder, hotend, and 24v heat cartridge:
http://item.mobileweb.ebay.com/viewitem ... 1147396499
http://item.mobileweb.ebay.com/viewitem ... cmd=VIDESC
http://store.qu-bd.com/product.php?id_product=20

heat bed (it's 12v, but I could step down the voltage you said, right?):
http://www.panucatt.com/product_p/hbp200.htm
Or could you suggest an alternative?

Power Supply:
http://www.ebay.com/bhp/power-supply-24v-350w

controller + 4 stepper drivers with heat sinks (DRV8825)
http://www.panucatt.com/Azteeg_X3_repra ... ax33dp.htm

limit switches:
http://ca.mouser.com/Search/m_ProductDe ... 50F15CD1-Z


So how did I do? Anything missing or needing changes?
JLG
 
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Re: ORD Bot Hadron Inquiries - Help Appreciated

Postby JLG » Sat Aug 24, 2013 1:45 am

rickmellor wrote:Yeah, I'd really only recommend the qu-bd to someone if they have a lathe handy and know how to use it. Between the PTFE mod and the Mk7 drive gear the qu-bd works great for the money but it's a pretty steep hill to climb to get there. If you're decent with metal working then it could be worth it.

I've used the MkV J-head with 3mm filament and it never missed a beat. I'm in the process of switching to E3D 1.75 hotends with the EZStruder and I expect these to perform really well. Too early to tell though.

For 12 vs. 24 volt... mine works fine at 12v. The bed takes a while to heat up but once it's there it stays where it's supposed be. I also don't have any torque issues with my machine. The Hadron is a great frame, but it's really not stable enough to handle too much jerk. Maybe that's just me, but I don't really care about speed anyway. Waiting an hour or more for a large part is still much faster than I can design it so I don't have any trouble feeding the machine. I'm mostly concerned about precision, not fine details or speed.

-Rick


Thanks for your reply Rick, I appreciate the extrude into.

What did you mean precision instead of fine details? Aren't they the same?

As far as speed goes, I've read in a few places that the printer had the potential to run up to a meter /second. It sounds like bull to me, but is there any confirmation that it can run at faster speeds?
JLG
 
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Re: ORD Bot Hadron Inquiries - Help Appreciated

Postby rickmellor » Sat Aug 24, 2013 5:11 am

JLG wrote:Thanks for your reply Rick, I appreciate the extrude into.

What did you mean precision instead of fine details? Aren't they the same?

As far as speed goes, I've read in a few places that the printer had the potential to run up to a meter /second. It sounds like bull to me, but is there any confirmation that it can run at faster speeds?


Well, precision at a given resolution, I suppose. I primarily print mechanical devices so I don't need 100 micron or better layers, .2 or .4 mm layers usually serve me well, but that's not really what most people would call 'fine detail'. I do need things to be very precise, however, so that parts that I design will interface properly with other parts that I've purchased. This is mostly an issue of proper calibration and predictable extrusion performance. I used digital dial indicators on all axes to get my machine as well calibrated as possible.

Sure speed has lots of factors. Anyone can move an effector around rapidly, but can they get the whole system in tune so that speed is useable? Check this out: http://www.youtube.com/watch?v=Om0wTqFA-Dw That would be some screaming performance if you could extrude that fast .... however, I've yet to see an extruder that can move filament at the rates required for those speeds. Also note that in this video he's using an Ultimaker, which uses a bowden tube and significantly reduces the moving mass of the print head. Also in this video the tube is disconnected so even less mass. For the setup you're most likely to start out with you'll probably have a nema 17 stepper, a cold end and a hotend on your X carriage. I just pulled mine off yesterday and it weighed 496g (17.5oz or just over a pound). F=MA and the default acceleration of Marlin, IGSMW, is 3ms^2 so that gives a force of acceleration of about 1/3 a pound. You can see that when this thing is running and slinging that weight around rapidly you're quickly going to get to a point where it'll try to shake itself off the desk. I just put dual extruders on mine so the force is up to about 1/2 a pound ... it's gonna be running slow. :D Of course you can install a bowden setup to reduce weight and all that but eventually you'll still run into the extrusion rate problem anyway. From what I've seen it looks like non-bowden printers will cap out typically around 150mm/s and the _best_ bowden machines tap out around 300-400mm/s (a well-tuned Ultimaker is mesmerizing). These aren't absolutes and hardcore types will always find some way to crank it up, but I think these are pretty typical cases for what you can expect.
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Re: ORD Bot Hadron Inquiries - Help Appreciated

Postby rickmellor » Sat Aug 24, 2013 5:36 am

JLG wrote:Okay, so I'm going to try making a shopping list:

pre assembled mechanical kit including gears, pulleys, and stepper motors
http://item.mobileweb.ebay.com/viewitem ... 0981613057

Would it be beneficial / produce higher quality prints to switch these stepper motors to these?
https://www.sparkfun.com/products/10846

extruder, hotend, and 24v heat cartridge:
http://item.mobileweb.ebay.com/viewitem ... 1147396499
http://item.mobileweb.ebay.com/viewitem ... cmd=VIDESC
http://store.qu-bd.com/product.php?id_product=20

heat bed (it's 12v, but I could step down the voltage you said, right?):
http://www.panucatt.com/product_p/hbp200.htm
Or could you suggest an alternative?

Power Supply:
http://www.ebay.com/bhp/power-supply-24v-350w

controller + 4 stepper drivers with heat sinks (DRV8825)
http://www.panucatt.com/Azteeg_X3_repra ... ax33dp.htm

limit switches:
http://ca.mouser.com/Search/m_ProductDe ... 50F15CD1-Z


So how did I do? Anything missing or needing changes?


A couple ideas for you to consider:

For the bed: http://www.reprapdiscount.com/electroni ... d-bed.html

For the hotend this guy is reputable: https://www.hotends.com/index.php?route ... duct_id=88

Different version of the Wade's extruder: http://printrbot.com/shop/experimental- ... -extruder/
Molded gears for Printrbot's extruder: http://printrbot.com/shop/injection-mol ... -gear-set/

You should be able to find the mini/subminiature limit switches at RadioShack, they'll be a bit cheaper but won't be as nice as the Honeywells.

I wouldn't bother swapping the steppers. With 1.8deg steppers you still get around .012mm resolution (x/y) with 16x microstepping. If you find that to be your limiting factor I want you to come over and tune my machine for me! :D
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Re: ORD Bot Hadron Inquiries - Help Appreciated

Postby cvoinescu » Sat Aug 24, 2013 9:32 am

Don't buy that hot end off eBay, it's a copy. We don't know how well it's made, but most are bad. The original is at hotends.com, and even though it costs double, you'll appreciate the difference.
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Re: ORD Bot Hadron Inquiries - Help Appreciated

Postby JLG » Sat Aug 24, 2013 12:58 pm

rickmellor wrote:Different version of the Wade's extruder: http://printrbot.com/shop/experimental- ... -extruder/
Molded gears for Printrbot's extruder: http://printrbot.com/shop/injection-mol ... -gear-set/


So, not to second-guess your or anything, but what's your reasoning behind getting this extruder over the other one? It's more expensive, looks heavier, and made of wood (It just looks a little strange mounting this plywood(?) extruder on laser-cut metal parts). Just wondering your reason for this.

rickmellor wrote:I wouldn't bother swapping the steppers. With 1.8deg steppers you still get around .012mm resolution (x/y) with 16x microstepping.


But would it make a difference? If it did, I would be willing to.

rickmellor wrote:Well, precision at a given resolution, I suppose. I primarily print mechanical devices so I don't need 100 micron or better layers, .2 or .4 mm layers usually serve me well, but that's not really what most people would call 'fine detail'. I do need things to be very precise, however, so that parts that I design will interface properly with other parts that I've purchased.


So am I to understand that precision is inversely proportionate to resolution? If so, would the 0.9 degree stepper motors help that? What about hot ends with smaller nozzles (why would one want a 0.5mm when they could get a 0.35?)?
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Re: ORD Bot Hadron Inquiries - Help Appreciated

Postby JLG » Sat Aug 24, 2013 1:18 pm

How about this extruder?

http://item.mobileweb.ebay.com/viewitem ... 1254286594

It's printed in ABS, and I've read good things about Greg's Wade Reloaded Extruder. I couldn't find anything on the wooden one you recommended, except for a few ppl saying it was "alright" and various reports of missing parts. I assume that issue was fixed though, since it was back in 2012.
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Re: ORD Bot Hadron Inquiries - Help Appreciated

Postby rickmellor » Sat Aug 24, 2013 2:42 pm

All of these are just suggestions ... throwing some info out there so you can make your own decisions based on your values.

To that end: I've used both the printed Wade's and the wood version from Printrbot. The printed one needed some cleanup and tuning with a drill and Exacto. Maybe you'll get one that's printed properly, but I felt like the one I had left something to be desired. It did work though. The wooden one, I agree looks out of place (paint it :) ). I also was missing a part on mine when I got it (first week they made these available) but Brook sent me the missing parts no questions asked. It assembled easily and I never had an issue with it once it was installed. I was running two of these in a dual bowden configuration for a while. Long story short: they both work well, the same in my experience. Get what you're comfortable with.

++ on the hotends.com hotend. The same goes for buying from RepRapDiscount. These guys have good reputations and make good products. The hotend/extruder is arguably the most important part of the rig so you don't want to skimp.

On the .9deg steppers, I really don't think you're going to see a difference. I haven't tried them so I don't know for sure... perhaps someone here will chime in on the subject. Assuming that both motors will provide adequate torque, speed, etc. I think you're likely to run into issues of backlash, dirty wheels/track, calibration drift, etc. before you're going to see a benefit in resolution from 1.8 v 0.9. Now if we were talking about a ball-screw driven mill doing precision cutting then I'd probably feel different about it. If you don't mind dropping the $50, I guess it won't hurt either way. I'd rather have a Viki though.

No, precision is not inverse to resolution. You can do very fine detail work at high precision, or like me you can do very precise work at medium resolution... it's a tradeoff in speed. The same factors can affect both but you can be precise at any level of resolution ... your tolerances just change. Why you'd want to use a .5 nozzle over .35 or whatever is for extrusion rate and smallest features. There's also a difference if you're running 3mm vs. 1.75mm filament. I'm running a .4mm nozzle and that works well ... I've never had a clog but on some of the smaller ones you can get clogs because of dust or whatever. This also means that I can't print features smaller than .4mm wide, which is fine for me. I can do lower layer heights though so I can still get smooth sides when I want them. I made some custom nozzles a few weeks ago and the ones with .15mm and .2mm orifices didn't work so well. The extrusion pressure was so high that I couldn't get them to reliably extrude. I think .25mm is about the smallest practicable size but you'll probably have reliability problems. I'd suggest starting with .4 to start and get your machine calibrated then experiment later with other sizes (one problem with the j-head vs. the E3D or Qu-Bd is that the nozzle isn't exactly cheap).
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Re: ORD Bot Hadron Inquiries - Help Appreciated

Postby cvoinescu » Sat Aug 24, 2013 3:12 pm

What rickmellor said.

The smaller the nozzle, the harder it is to push the plastic out and the more likely it is for the filament to slip, or for other mishaps to happen. Also, a small nozzle extrudes less material at a time, so it takes much longer to build an object of the same size. The 0.5mm nozzle doesn't allow you to go with really thin walls or really thin layers, but it prints quickly and it's unlikely to clog (as a very rough guide, you can get 0.8mm walls and 0.35-0.4mm layers with it). I am happy with my 0.35mm nozzle, because I make mostly small parts, but it takes more than twice as long to build an object of the same volume, compared to a 0.5mm nozzle. Any smaller would be increasingly impractical. In hindsight, 0.4mm would have been perfect for me, 0.35mm is a tad too small.

About the motors: because of how the material behaves, you can't really make super-accurate parts. I don't think that positioning beyond 0.1mm resolution on X and Y is necessary, or that it makes any difference. If you have a very fine nozzle, an extruder with an excellent grip of the filament, and lots of time on your hands, it may begin to matter a little, but for the usual nozzle sizes, it makes no difference. And you can upgrade later if you need it, anyway.
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Re: ORD Bot Hadron Inquiries - Help Appreciated

Postby JLG » Sun Aug 25, 2013 2:10 pm

The extruder is driving me nuts! I want to go with this extruder, hot-end, and heat cartridge:

http://item.mobileweb.ebay.com/viewitem ... 1254286594
https://www.hotends.com/index.php?route ... duct_id=88 with a 0.35mm orifice for 1.75mm filament
http://store.qu-bd.com/product.php?id_product=20

But I can't find any source on the exact materials I need to completely assemble the thing. I can find assembly instructions, but they assume I already have all the pieces I need. For example, I see all sorts of hobbed bolts on eBay (the one that comes with the extruder doesn't seem to have a knurl on the groove, and is double-sided thread). I know I need something between the hot end and extruder to keep it from melting (PTFE?) but I have no idea what to look for (is it some sort of tube?).

Other area that been driving me nuts is the filament size. I've read the lulzbot uses 1.75mm and 3mm as well as a wades reloaded extruder, but everywhere I read it tells me "great for 3mm filament, excellent force!" but I can't find anything about 1.75mm. The "guilder" is spring loaded (what springs do I use?) so what makes the extruder compatible with 1.75mm? Is it the groove on the hobbed bolt?

I want to go with 1.75mm filament, as I hear it more controlled / precise when being ejected - less force needed to push the same amount of filament through the nozzle = better control / less blobs / more accurate . . . If I understand correctly.

I've almost got it all figured out, I think. I'll go with the heatbed recommended. I'm still a little unknowledgeable about the 24v power supply interacting with the controller. I guess I'll get to that once the hardware is finalized and I start looking at how everything should be wired up.
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