A new take on my UBMQ

[jipp]

thanks for the feed back. i have saved them to a book mark folder for future refrence.. as im sure im gonna
need a 3d printer by the end of the winter. i have no issues learning, hell i would not even be able to afford a quad if it was not for kits to get me started.. even now tho that is not true with so many quads on the market from emachine, emax, etc etc.. which just were not there less than a year ago.. amazing how fast things change in a hobby that is growing.

i can only think this has also benefited 3d printer popularity too along like you said all the things around the house that could be fixed or updated a simple part.. i know i spent a 100.00 on my ice freezer over a stupid plastic part that kept breaking. it needed a redesign... but, no way to do that i had to fork over the money to buy a new one.. and then warranty has replaced it 3 times since. my guess next time it breaks ill have to fix it my self because i bet they are going to discontinue it.. o well.

on a side note i think iv given up on getting kiss esc for my next project. i think ill j ust have to find some decent 30a esc.. and if kiss come up in decent supply and i have the cash ill update the esc..
chris.

 

[Snarls]

on a side note i think iv given up on getting kiss esc for my next project. i think ill j ust have to find some decent 30a esc.. and if kiss come up in decent supply and i have the cash ill update the esc.

Wait another day or two. KISS 24a ESC should be in stock sometime before the end of the week. Just keep an eye out and subscribe to email stock notifications so you don't miss out.

 

[C0d3M0nk3y]

But I've been trying to finish up the MPCNC before I tear things that far apart.

Whoa... I hadn't heard of the MPCNC before. I'm very intrigued.

 

[jipp]

Wait another day or two. KISS 24a ESC should be in stock sometime before the end of the week. Just keep an eye out and subscribe to email stock notifications so you don't miss out.

i am and have since you mention they should be available. just getting bored waiting on them to show up.. reminded me when i tried to get cobras to try same thing always out of stock. i give emax credit for being able to handle the supply and demand.. laughs.


but iv not bought any ESC yet so ill keep checking. right now i have them as my home page so i look every morning.

chris.

 

[jhitesma]

Whoa... I hadn't heard of the MPCNC before. I'm very intrigued.

You should check out the Toolbox forum more often

I actually heard about a week or so before djk4linux started his thread: http://forum.flitetest.com/showthread.php?24251-Cutting-foam-sheets-with-a-needle! but kind of dismissed it thinking "3D printed and conduit? What a joke!" Actually, I had seen djk's thread about 3 days before I read it as well because from the title I had an idea what he was talking about and though "But I don't have a CNC so why bother". That's what I get for jumping to conclusions

Here's the current status of mine (With the UBMQ in it's current state of half-wired half-assembly to stay on topic!):



I'm in the process of reprinting all of the PLA parts in PETG. All that's left are 2 of the lower feet but I ran out of PETG I ordered two more rolls from MakerGeeks Their PETG needs higher temps than the Atomic but prints just as well, and at $33 shipped for two rolls the price is really tough to beat but the sale is over in a few more days. Just don't get a choice of color at that price - but at that price I'm not going to be picky! I'm reprinting for two reasons:

1) My full plan is to make this thing big enough to cut full sheets of 20"x30" foamboard - but have no room to store that in my house and PLA would melt if stored in the non air-conditioned shop or shed. I did originally test assemble it at full size though:

2) The black eSun PLA I printed many of the parts in is...horrible. Just terrible. It was a pain to print with - didn't stick to the bed well, warped, smelled worse than some ABS I've printed, clogged, jammed, snapped....you name it the stuff was just utter junk. But worst of all...almost everything I printed in it is breaking. Some things that just sat on my desk have broken spontaneously, and every part I installed in the MPCNC cracked or broke somewhere

So the whole thing is being reprinted and I'm assembling it as a smaller 24"x24" ( which gives about 13.5"x13.5" working area) "Desktop" machine so I can play around with it and get it working inside before moving it outside. I actually plan on putting the original extruder from my 3D printer on it and using it to print the neck for a hovalin (hovalin.com) my wife has requested. I printed the 1st of the 3 body pieces last night:



The other 2 body pieces are 8-9 hours prints so I'll have to wait until the weekend to do them. The neck will be close to 12 hours and it won't quite fit on my 200mmx200mm printer so it will have to be done on the MPCNC which seems like a decent trial by fire for it once I have it up and running

I ordered the two rolls of PETG on Monday but they didn't ship until today and aren't expected for delivery until next Monday so probably won't have the MPCNC going this weekend yet

I did get two of the motors on the UBMQ soldered up - but then realized I'm not sure which motors are going to go which direction and started thinking about flashing blheli so I could more easily reverse the ESC's...but...these old simon series emax ESC's won't do damped light and have a filter on the input so can't be programmed over the ESC wire. I could remove the filter but on a tight quad like this I'm worried about signal integrity and removing that would only make it worse. So I have to test wire it and spin up these two motors to see if they're going the right direction before I do the rest. I'm just putting off doing that right now

Guess I should go get back to it....

 

[jipp]

wow, now that is a prety cool print.. never would of though of a fiddle for a 3d print.. but i guess it sound property's should be similar to rainsong carbon fiber acoustics. them damn things are expensive.. but sound good and with modern electronics ( you can not tell its carbon or wood ).. and best thing if you like how they sound on day one.. its gonna sound the same on day whatever, regardless of moisture in the air.. bonus.

chris.

some say the future in 3d printing is with 3d metals.. now that would be a trip. also being able to cut foam would be nice.. i would probably try more FT planes and make my own designs if i could get clean cuts from a machine.

 

[jhitesma]

wow, now that is a prety cool print.. never would of though of a fiddle for a 3d print.. but i guess it sound property's should be similar to rainsong carbon fiber acoustics. them damn things are expensive.. but sound good and with modern electronics ( you can not tell its carbon or wood ).. and best thing if you like how they sound on day one.. its gonna sound the same on day whatever, regardless of moisture in the air.. bonus.

Yeah, I'm curious how it will sound, seems a little stiff and heavy to me, I'm worried it won't resonate well. And the body being printed in 3 pieces which then apparently aren't glued together just held by the string tension on the truss rods...but it's only about $7 worth of plastic (well, if I was using $15 a spool hatchbox...I'm actually using $30 a spool Atomic because that was the only way to get the color she wanted so it's more like $15 worth of plastic) I figure it's wroth trying.

Of course the carbon fiber truss rod is another $15....plus $10 S&H Guess I'll have to toss in a few extra CF tubes for spars since it won't add more to the shipping

You can buy a cheap violin on amazon for less...but I like making things

some say the future in 3d printing is with 3d metals.. now that would be a trip. also being able to cut foam would be nice.. i would probably try more FT planes and make my own designs if i could get clean cuts from a machine.

Yep, I've got a stack of foam I've been putting off cutting because of my wrist issues. Having a machine to do it for me is going to be nice

I've already made most of the foam cutter:


Just need to finish the needle guide...and well...I'll probably print a new one with the quick release mount on it instead since it makes swapping tools on the MPCNC easier and I've got the quick release receiver on there already.

As for printing metal...Iv'e seen guys strap a MIG gun to a CNC before...don't think my microwave oven transformer stick welder is up for that though

Back to the UBMQ....Just gave it a quick test...and sure enough both motors are going backwards. Easy peasy, just swap their positions! Except...these motors are CW/CCW paired so when the spooled up going the wrong way the prop nuts went flying (made it easy to tell they were backwards ) so going to have to swap the motor->ESC wires around to reverse them. Kind of figured that was going to be the case since I got antsy and went and shrink wrapped one of them already

Oh well, iron is warm...back to it!

 

[jhitesma]

Realized I had made another mistake wiring up the first two ESC's. The one with the extra wires for the BEC to power the FC was in a position where the wires wouldn't reach the pins on the FC. Yeah, I could have rotated the FC to deal with it but since I had to resolder things anyway what's a few more connections.

Went ahead and dug out some paracord as well since I couldn't find my correctly sized red and black wire for the ESC power and used the trimmed down motor wires instead (they were the right size, just all black). Pink for positive purple for negative.


I'm not very good at subtly apparently. But quick test fit of the FC looks good. The PDB is just mounted right to the 3D printed center section - PLA isn't conductive like CF The FC is mounted with 3mm standoffs and o-rings above the PDB and it's all held down with 4 nylon screws from the bottom.


Soldered up the motor connections, confirmed everything was going the right direction and added the top plate. Then realized the FC was too close to the top plate to plug in my USB cord. Doh. Little bit of work with a utility knife on the USB cord and it fits


Added props - just have to figure out how to keep the antenna out of them now. Oh and realized I didn't leave anywhere good for a battery strap. It could wrap around the top plate...but fitting even a 1300 on the top plate is pretty tight.


Ready to fly with everything except a battery strap it came in at 463g. Bit of a porker...the original flat plywood version of this came in at around 250g with 1806 motors and no battery. But I wasn't going for ultra light here just trying to toss together something to see how angled arms work.


Wish I'd had more colors of large shrink wrap so the arms could have been more visually distinct. And still have to deal with battery strap and antenna mounting...but basically ready to fly.

Hopefully tonight I'll have a bit of time to do an autotune and give it a maiden...if I figure out a way to attach the pack and antenna....

 

[Ocean]

You should check out the Toolbox forum more often

I actually heard about a week or so before djk4linux started his thread: http://forum.flitetest.com/showthread.php?24251-Cutting-foam-sheets-with-a-needle! but kind of dismissed it thinking "3D printed and conduit? What a joke!" Actually, I had seen djk's thread about 3 days before I read it as well because from the title I had an idea what he was talking about and though "But I don't have a CNC so why bother". That's what I get for jumping to conclusions

Here's the current status of mine (With the UBMQ in it's current state of half-wired half-assembly to stay on topic!):

View attachment 67858

I'm in the process of reprinting all of the PLA parts in PETG. All that's left are 2 of the lower feet but I ran out of PETG I ordered two more rolls from MakerGeeks Their PETG needs higher temps than the Atomic but prints just as well, and at $33 shipped for two rolls the price is really tough to beat but the sale is over in a few more days. Just don't get a choice of color at that price - but at that price I'm not going to be picky! I'm reprinting for two reasons:

1) My full plan is to make this thing big enough to cut full sheets of 20"x30" foamboard - but have no room to store that in my house and PLA would melt if stored in the non air-conditioned shop or shed. I did originally test assemble it at full size though:

2) The black eSun PLA I printed many of the parts in is...horrible. Just terrible. It was a pain to print with - didn't stick to the bed well, warped, smelled worse than some ABS I've printed, clogged, jammed, snapped....you name it the stuff was just utter junk. But worst of all...almost everything I printed in it is breaking. Some things that just sat on my desk have broken spontaneously, and every part I installed in the MPCNC cracked or broke somewhere

So the whole thing is being reprinted and I'm assembling it as a smaller 24"x24" ( which gives about 13.5"x13.5" working area) "Desktop" machine so I can play around with it and get it working inside before moving it outside. I actually plan on putting the original extruder from my 3D printer on it and using it to print the neck for a hovalin (hovalin.com) my wife has requested. I printed the 1st of the 3 body pieces last night:

View attachment 67859

The other 2 body pieces are 8-9 hours prints so I'll have to wait until the weekend to do them. The neck will be close to 12 hours and it won't quite fit on my 200mmx200mm printer so it will have to be done on the MPCNC which seems like a decent trial by fire for it once I have it up and running

I ordered the two rolls of PETG on Monday but they didn't ship until today and aren't expected for delivery until next Monday so probably won't have the MPCNC going this weekend yet

I did get two of the motors on the UBMQ soldered up - but then realized I'm not sure which motors are going to go which direction and started thinking about flashing blheli so I could more easily reverse the ESC's...but...these old simon series emax ESC's won't do damped light and have a filter on the input so can't be programmed over the ESC wire. I could remove the filter but on a tight quad like this I'm worried about signal integrity and removing that would only make it worse. So I have to test wire it and spin up these two motors to see if they're going the right direction before I do the rest. I'm just putting off doing that right now

Guess I should go get back to it....

Do you use Rafts when printing?

I'm over halfway through my MPCNC Parts and removing the rafts from some pieces is proving to be a pain.

 

[jhitesma]

Do you use Rafts when printing?

I'm over halfway through my MPCNC Parts and removing the rafts from some pieces is proving to be a pain.

Very seldom. Only on designs that require it. I use brims when printing ABS but really don't care for rafts. I print on glass because I like the smooth surface it leaves and a raft defeats that. Plus removing them can be a pain.

Though in retrospect most of the problems I had with removing rafts were likely more due to overextrusion when I was first starting out and learning how to calibrate things. Once I learned how to do single wall prints and use them to fine tune my extrusion multiplier my print quality improved immensely, I can do things like the make magazine negative space test and remove all the pins (http://makezine.com/2014/11/07/how-to-evaluate-the-2015-make-3dp-test-probes/) and removing support is much easier. The last time I used a raft was before I learned how to do that level of calibration so it's probably not a fair comparison.

A raft may help with printing the improved middle z piece - I use slicer and with the columns support I usually use the columns kept falling over before it reached what they were supposed to support. But I switched to using the rectilinear grid support which has a larger footprint and was able to print the middle z MUCH better.

 

[jhitesma]

So, gave it a little maiden this evening. Just wrapped some long velcro all the way around it as a temporary battery restraint, and then wrapped the antenna around it as well. Really bad way to deal with the antenna, but don't need much range for a quick front yard shake down.

It felt really "slippery" before the autotune, but at the same time like it wanted to auto level even though it was in acro. Very odd feeling and made tuning a bit hairy.

The same motors/esc's on the emax 250 came in about the same weight but got me a 29.51ms tau, this came in at 31.50ms - not sure if that drop was just due to the windy conditions while tuning, random chance, or the tilted motors. I would have expected a bigger difference from the tilted motors. But chatting with icee he seems to feel it wouldn't affect tau much but that lower tau would give better performance with tilted motors:

6:30 PM <icee> so, the assumption with teh whole "you don't need to change the mixer" thing
6:30 PM <icee> is that the perturbations from the mixer not being quite right are small, and that the FC can react quickly to fix them
6:30 PM <icee> the worse tau is, the harder that bit is

To put some context to that one of the things the dRonin guys have been debating about tilted motors is whether you should do a custom mixer to deal with them or not. As you can see icee is of the opinion that you shouldn't but it may hurt performance a bit by throwing the mixer off - but if your tau is good enough the FC can deal with the error.

So I may toss those KISS on here to see if it feels any better with lower Tau.

After I rebuild it that is:


Broke two "arms" of the 3D printed center and both the top and bottom plate. Really I'm not that surprised. I was just using 2mm acrylic here and really it should use something stronger like lexan/polycarbonate or even ply or CF since the plates give it most of it's strength. Plus I printed the center section with really low infill to save weight. And I printed it in PLA which really isn't a good choice of material for this.

Fairly easily repaired though. I'll reprint the center and see if I can use slic3r's modifier mesh setup to give the center much higher infill while keeping infill around the arms lower to save weight. I may try it in ABS...or just wait until Monday when my order of PETG comes in which is what I'd really like to print it in. I really didn't expect the PLA to last.

The motor mounts held up fine.

The top/bottom plate...I have a sheet of lexan but kind of want to wait until I have the MPCNC going so I can cut it with that. So I may cut some out of ply to tide me over. We'll see what mood strikes me.

How did it fly? Well, you can see the video. Before autotune it felt very very odd. It felt like it wanted to autolevel...but slide sideways. So stable but slippery at the same time. After tuning it felt MUCH more locked in - but even in acro mode it still felt like it kind of wanted to be level more than tilted.

If I hadn't been so curious to try hangtime in an area that was really too small for that kind of thing it would probably still be flying. May have to print up a FPV pod of sometime for the top when I rebuild.....

So...airhawk...still want me to print a set of parts up for you? Or do you want to wait a few revisions now

 

[French]

bummer about the breaks. glad its an easy repair.

 

[MototechRyan]

I wonder if the autoleveling in acro was due to battery placement. With all that room on top, looks like the battery would be at or close to prop plane... if there's room between the props.

Pretty sweet so far. Good prices on polycarbonate here:
http://www.tkmna.com/tkmna/Products...ml?u=merchant.cfm?id=270&step=2&partnerid=130

Not sure on shipping cost, I just buy it through the sales guys at work.

 

[jhitesma]

I wonder if the autoleveling in acro was due to battery placement. With all that room on top, looks like the battery would be at or close to prop plane... if there's room between the props.

That "if" at the end is the gotcha I tried it on top first...but it's just too tight of a fit. With 5" props it could be done but with 6" not going to happen.

I wasn't too surprised by the autolevel feel as that's somewhat expected with the inward tilted motors - they're supposed to give a bit more stability in hover due to how the thrust is directed. Or so I've been told

Pretty sweet so far. Good prices on polycarbonate here:
http://www.tkmna.com/tkmna/Products...ml?u=merchant.cfm?id=270&step=2&partnerid=130

Not sure on shipping cost, I just buy it through the sales guys at work.

I actually already have a sheet. It's just a bit harder to work with than the acrylic so I used the acrylic for the initial test. I was really hoping to have the MPCNC up and going this weekend and planned on strapping my dremel to it since I have a nice endmill for it and using that to machine the plates out of the polycarb. Will just have to wait a bit longer I guess.

I'm really not at all surprised at how poorly it took that crash. The acrylic was already cracking around the screw holes, and the center of the 3D printed part was very weak. I considered eliminating the center of the 3D part entirely but wanted to keep it there so it could be used as a drilling template for the bottom plate and so it would keep the four arms correctly positioned during assembly.

I'm actually thinking about building a second version as a 450 sized setup and moving the parts off my knuckle quad to it to use as an experimental platform for navigation. Haven't decided if I'll actually do that and if so whether it would be with flat arms or angled arms. Just something I'm thinking about trying to see how it scales. But only once I have some PETG to print the center part in!

 

[cranialrectosis]

Been dealing with snow and work for a few weeks and had a bit of reading to do to catch up here.

Holy smokes, jhitesma a 3d printed violin! I saw Lindsay Sterling dancing around with greenish hair and playing a carbon fiber violin and was impressed. This just takes the cake.

Do you have any flat surfaces left anywhere in your house that does not have a printer, CNC machine, microwave welder or project parts on it?

Was that maiden done before or after autotune? It's hard to tell from your post but it's hard to imagine the copter flying that well before tuning. I have had to cut the default P gains from dRonin before I could fly to tune but of course have been flying smaller, heavier copters too.

My Corrosion X waterproofing finally arrived. It took 4 weeks and was delayed 3 times due to snowstorms but it is finally here. The snow is all gone today but we may get another 6" or so Monday so I may try flying in the snow again. Last time the Alien was flying along and just died in the air and it took a few days to dry out. I poked the ice chunks out of the USB, gently, with a toothpick.

Do you use Corrosion X or any type of light machine oil on your motors? Sand is my primary concern here for half the year and while Corrosion X might keep snow out, it may make sand stick. I am still debating whether or not to use it on my motors and since you are in a sand environment too... What are your thoughts?

 

[jipp]

i have noticed with regular oil for motor as long as i do not slop the stuff on it did not attract anymore dirt/sand/rocks than other wise. so i would imagine as long as you do not cake it on it should be about the same as it came from the factory. im not using anything special.. just some 3 in 1 oil put into a little bottle with a needle on the end.. so i can get the oil right where i need it.. i guess i should be thankful water.moisture is not a issue for me.. iv never thought twice about how to protect my quad from moisture yet..

i know that rare day, ill regret that. LOL
chris.


chris.

 

[jhitesma]

Holy smokes, jhitesma a 3d printed violin! I saw Lindsay Sterling dancing around with greenish hair and playing a carbon fiber violin and was impressed. This just takes the cake.

Well, we'll see how it comes out I didn't design it, found it here: hovalin.com

Was hoping to print the bottom section for it today which was supposed to be an 8 hour print...but my slicer is saying it's going to be more like 12 hours and my experience tells me the slicer is usually off by almost 20% so it could be more like 16 hours. And I'm not going to have time for that long of a print today or tomorrow

Plus the little $9 C.H.I.P computer I use to run the printer suddenly shut down on my a few days ago mid-print and hasn't wanted to connect to the printer since. So I'm back to printing from an SD card which is just kind of annoying. Trying to reflash the OS on the C.H.I.P today but that's not going very well so far. Seems like it keeps resetting after doing it's memory test. Worried there may be a hardware issue. At least it was only $9, and I should have another small cheap board computer I backed on kickstarter that should be able to run repetier-server anyday now so we'll see how it goes.

Do you have any flat surfaces left anywhere in your house that does not have a printer, CNC machine, microwave welder or project parts on it?

Sure, lots. The kitchen counter is covered in my wife's paperwork and mail, the coffee table is covered in my daughters toys and playdough and slime, and all of the dressers one of the couches and a few other flat surfaces are covered in laundry that's been washed but not yet put away

Was that maiden done before or after autotune? It's hard to tell from your post but it's hard to imagine the copter flying that well before tuning. I have had to cut the default P gains from dRonin before I could fly to tune but of course have been flying smaller, heavier copters too.

That was after, at the start of the video there should be a little pop-up link to the tuning video, but here it is if anyone wants to see how it was untuned and doing the autotune wiggle:

Do you use Corrosion X or any type of light machine oil on your motors? Sand is my primary concern here for half the year and while Corrosion X might keep snow out, it may make sand stick. I am still debating whether or not to use it on my motors and since you are in a sand environment too... What are your thoughts?

I put a few drops of some old motor bearing oil I've had for about 15 years on the bearings every now and then but that's about it. 2 years ago I was much better about it and would oil bearings every week. But I was flying a lot more then. Now I pretty much just add a drop or so anytime I have a motor off an arm for repairs

I try not to add too much though because it tends to just attract sand I've found. I'd rather keep the external parts of the motor as dry as possible so sand just falls off rather than sticks.

 

[airhawk]

So, gave it a little maiden this evening. Just wrapped some long velcro all the way around it as a temporary battery restraint, and then wrapped the antenna around it as well. Really bad way to deal with the antenna, but don't need much range for a quick front yard shake down.

It felt really "slippery" before the autotune, but at the same time like it wanted to auto level even though it was in acro. Very odd feeling and made tuning a bit hairy.

The same motors/esc's on the emax 250 came in about the same weight but got me a 29.51ms tau, this came in at 31.50ms - not sure if that drop was just due to the windy conditions while tuning, random chance, or the tilted motors. I would have expected a bigger difference from the tilted motors. But chatting with icee he seems to feel it wouldn't affect tau much but that lower tau would give better performance with tilted motors:



To put some context to that one of the things the dRonin guys have been debating about tilted motors is whether you should do a custom mixer to deal with them or not. As you can see icee is of the opinion that you shouldn't but it may hurt performance a bit by throwing the mixer off - but if your tau is good enough the FC can deal with the error.

So I may toss those KISS on here to see if it feels any better with lower Tau.

After I rebuild it that is:
View attachment 67924

Broke two "arms" of the 3D printed center and both the top and bottom plate. Really I'm not that surprised. I was just using 2mm acrylic here and really it should use something stronger like lexan/polycarbonate or even ply or CF since the plates give it most of it's strength. Plus I printed the center section with really low infill to save weight. And I printed it in PLA which really isn't a good choice of material for this.

Fairly easily repaired though. I'll reprint the center and see if I can use slic3r's modifier mesh setup to give the center much higher infill while keeping infill around the arms lower to save weight. I may try it in ABS...or just wait until Monday when my order of PETG comes in which is what I'd really like to print it in. I really didn't expect the PLA to last.

The motor mounts held up fine.

The top/bottom plate...I have a sheet of lexan but kind of want to wait until I have the MPCNC going so I can cut it with that. So I may cut some out of ply to tide me over. We'll see what mood strikes me.

How did it fly? Well, you can see the video. Before autotune it felt very very odd. It felt like it wanted to autolevel...but slide sideways. So stable but slippery at the same time. After tuning it felt MUCH more locked in - but even in acro mode it still felt like it kind of wanted to be level more than tilted.

If I hadn't been so curious to try hangtime in an area that was really too small for that kind of thing it would probably still be flying. May have to print up a FPV pod of sometime for the top when I rebuild.....

So...airhawk...still want me to print a set of parts up for you? Or do you want to wait a few revisions now

I would ask for it now because im impatient but for your sake ill wait for revisions

 

[jhitesma]

I would ask for it now because im impatient but for your sake ill wait for revisions

I'd say it's more for your sake - I assume you'd rather have something that can survive more than one relatively mild crash

But since you asked last night how it was going...slow.

Progress has been stalled because while I got my PETG order on Monday my printer has been down since last Thursday or Friday. Long story but the arduino mega on my printer developed some kind of fault and will no longer communicate over USB. I can still flash it so the USB isn't totally dead, but once I flash Marlin nothing can talk to it. I wasted 2 days swapping in spare arduinos and thinking they were all dying as well before realizing that it was my own fault for assuming Marlin ran at 115.2k baud while it actually runs at 250k - but by the time I figured that out I'd ordered a new mega/ramps set already, so it's got all new electronics now at least.

I finally got it printing again Wednesday night but by the time I did I barely had time to do a few initial calibrations and something was way off. Last night I got the calibration issues sorted out and tried to print a new center section but it failed partway through.

I'm trying something new on the center. I made a few very minor changes to the design - made the screw holes very slightly larger (because they were very slightly undersized before) and I made the bottom about .5mm thicker because the arm pockets were poking through just a tiny tiny bit. The thicker bottom means there's now a full layer on the bottom while before there was a small gap at the bottom of the arm pockets. So that should add a bit of strength.

But the big thing I'm trying is in how I slice it. I'm using slic3r's modifier meshes to specify higher infill in the center than at the edges since that's where it broke last time. I'm also printing in PETG instead of PLA which should give more resilience. Unfortunately I used too high of an infill for that center last night and it caused some issues that culminated in a glob of plastic building up and causing the print head to jump. Tonight I'll try again with slightly lower infill in the center. Last night I tried 80% in the center and 20% for the rest (basically the area above and below the arm pockets.) Tonight I'm going to try 60% in the center and 10% for the rest which I think will be the best strength/weight compromise. We'll see.

I'm also down to just one 2 hour print left before the MPCNC is ready to get belts motors and electronics installed then start testing. So I might be able to have it running this weekend to cut nice lexan plates. If not...I may go back to ply for now since it's lighter and stronger than the acrylic.

 

[airhawk]

I'd say it's more for your sake - I assume you'd rather have something that can survive more than one relatively mild crash

But since you asked last night how it was going...slow.

Progress has been stalled because while I got my PETG order on Monday my printer has been down since last Thursday or Friday. Long story but the arduino mega on my printer developed some kind of fault and will no longer communicate over USB. I can still flash it so the USB isn't totally dead, but once I flash Marlin nothing can talk to it. I wasted 2 days swapping in spare arduinos and thinking they were all dying as well before realizing that it was my own fault for assuming Marlin ran at 115.2k baud while it actually runs at 250k - but by the time I figured that out I'd ordered a new mega/ramps set already, so it's got all new electronics now at least.

I finally got it printing again Wednesday night but by the time I did I barely had time to do a few initial calibrations and something was way off. Last night I got the calibration issues sorted out and tried to print a new center section but it failed partway through.

I'm trying something new on the center. I made a few very minor changes to the design - made the screw holes very slightly larger (because they were very slightly undersized before) and I made the bottom about .5mm thicker because the arm pockets were poking through just a tiny tiny bit. The thicker bottom means there's now a full layer on the bottom while before there was a small gap at the bottom of the arm pockets. So that should add a bit of strength.

But the big thing I'm trying is in how I slice it. I'm using slic3r's modifier meshes to specify higher infill in the center than at the edges since that's where it broke last time. I'm also printing in PETG instead of PLA which should give more resilience. Unfortunately I used too high of an infill for that center last night and it caused some issues that culminated in a glob of plastic building up and causing the print head to jump. Tonight I'll try again with slightly lower infill in the center. Last night I tried 80% in the center and 20% for the rest (basically the area above and below the arm pockets.) Tonight I'm going to try 60% in the center and 10% for the rest which I think will be the best strength/weight compromise. We'll see.

I'm also down to just one 2 hour print left before the MPCNC is ready to get belts motors and electronics installed then start testing. So I might be able to have it running this weekend to cut nice lexan plates. If not...I may go back to ply for now since it's lighter and stronger than the acrylic.

Hopefully you will be able to get a good durable prototype this time looking forward to seeing the final product.