3D Printing Hexy

Hello All,

Just thought I’d share some experimenting I did while working on my reprap (recalibrating after a rebuild). I used the Hexy STL files to do some prints. For the most part this went smoothly; I did learn a couple things though; which are what I want to share.

  1. Hexy is bigger than I thought; I realize I should have seen this from the many pictures… but holding the parts; I realize it will be a nice sized robot.
  2. Some of the STL files have problems; so they need to be run through cloud.netfabb.com/ to fix them; they Slic3r can slice them up for printing.

I posted a couple pictures of the prints on my blog: georgefrick.blogspot.com/2012/09 … -hexy.html

Just saw your post on the kickstarter site Greg, glad you’ve joined the forums. Nicely done with getting the files (and the 3D printer) to work. Our hackerspace one is decidedly temperamental, though we’re lucky enough to have a couple of 3D printer whisperers in our midst.

I’m awesomely please to see the hexy can be printed too. Lots more of us (geeks) have access to printers than to CNC machines. Neat. What density did you use / how much does it weigh? It will be interesting to compare it with the laser cut acrylic as far as strength vs weight vs ??? compares.

PS - consider your blog added to my compulsive robotic reading list.

PPS - good news about the makerspace being so close. Hope it works out.

Well, the fill rate I believe is 85%.

I can weigh them… I think…
Ok, the parts I printed come to .7oz and the foot alone comes to .1oz.

I am currently planning to do a better print of an entire leg. I have ordered enough servos for one leg.

I may experiment with doing a “build plate” to print a leg at a time, or a “build plate” to a full hexy of each part at at time (like 6 feet).

George,

Before you print any more with the existing files, could you verify that an M3 screw fits in the screw holes? The one time we tried to print one, shrinkage issues caused the screw to not fit (the holes are dimensioned for laser cutting). There’s some automation/scripting tools in SolidWorks that I’ve been meaning to look into that should allow us to auto-save a variant with the holes resized for printing, but it’s currently on the back burner.

Foot: M3 nut/bolt fit loosely.
Calf horn (non-servo side): m3 fits perfectly.
Calf pivot (servo side): m3 does not fit, holes are very small.
thigh bottom, top: M3 fits very loosely.

I also got out my caliper, an HXT9000 would very loosely fit in the two thigh top (bottom?) holes.

The size of the hole on the calf horn seems the most perfect. There may be print errors, I want to do a reprint tonight.
I can post measurements of the printed parts if that will help?

After doing a complete reprint of the leg, I realized a mistake. The wholes in the calf horn are correct… since two of the holes are for attaching to the servo arm.

Going to stop printing these for now, something is wrong with my calibration. Hope my servos arrive soon.

This is pretty awesome. Pictures!

HXT900’s should fit. We prototyped using those.

Also, out of curiosity, are you doing this out of PLA or ABS?

[quote=“georgefrick”]Foot: M3 nut/bolt fit loosely.
Calf horn (non-servo side): m3 fits perfectly.
Calf pivot (servo side): m3 does not fit, holes are very small.
thigh bottom, top: M3 fits very loosely.

I also got out my caliper, an HXT9000 would very loosely fit in the two thigh top (bottom?) holes.

The size of the hole on the calf horn seems the most perfect. There may be print errors, I want to do a reprint tonight.
I can post measurements of the printed parts if that will help?[/quote]

That’s interesting… I don’t suppose you’re printing with PLA instead of ABS? More specifically, what nozzle temperature are you running your reprap at?

[quote=“roboalchemist”]This is pretty awesome. Pictures!

HXT900’s should fit. We prototyped using those.

Also, out of curiosity, are you doing this out of PLA or ABS?[/quote]

Ha, question-sniped me from a plane!

[quote=“jbaker”][quote=“georgefrick”]Foot: M3 nut/bolt fit loosely.
Calf horn (non-servo side): m3 fits perfectly.
Calf pivot (servo side): m3 does not fit, holes are very small.
thigh bottom, top: M3 fits very loosely.

I also got out my caliper, an HXT9000 would very loosely fit in the two thigh top (bottom?) holes.

The size of the hole on the calf horn seems the most perfect. There may be print errors, I want to do a reprint tonight.
I can post measurements of the printed parts if that will help?[/quote]

That’s interesting… I don’t suppose you’re printing with PLA instead of ABS? More specifically, what nozzle temperature are you running your reprap at?[/quote]

I am printing with PLA, at 185. My printer isn’t printing the best, but the pieces seem like they will work great. I have an entire leg(s) printed and servos on the way. Anyone have info on the best place to get hardware?

I will post some pics when I have more solid progress tuning the printer.

OK!

Here I am with updates.

I rebuilt my printer with better parts; full explanation here: georgefrick.blogspot.com/2012/09 … build.html

Aside from that, here is the latest print comparison, sorry it is upside down:

The bigger piece is one I printed before upgrading the printer.

So my question is; should the STL file be slightly larger, or is my print slightly too small? The motor seems to be ever so slightly too big for the hole. The motor is a “Hextronik HXT9000 9GR Servo”. I also can’t get the screw in. The fits both seem to be “exact”, as in the holes are exactly as big as the screw/servo measure… but they need to be slightly bigger. Is this because of your laser cutting, or is this on my end. The work continues.

Any input would be appreciated.

The holes are dimensioned slightly under-size for laser cutting, so if you get any shrinkage at all it won’t print correctly – the M3 screw holes are 2.9mm in diameter in SolidWorks. I’m going to make a variant designed for 3D printing at some point, but it won’t be until after Maker Faire at the earliest. We also don’t have a printer that does PLA in our office, so I would (initially) be designing for ABS printed at 260 C, which might be a bit of a loose fit for printing with PLA.

Believe it or not I did look but cannot find the stl files for Hexy. Could someone direct me to them?

I would like to print one.

thank you.

Roy

Never mind, I found them.

github.com/arcbotics/hexy

Hello georgefrick.
It is good to see pictures of your print on your blog. I can understand your problems with Hexy 3D Printer. I have been using 3D Stuff Maker Printer http://www.3dstuffmaker.com for past 6 months and i am not getting any problem with STL files. So far so good.

Getting ready to build my 3d printed hexy, well assemble it. Wanted to order the screws and I know the longer ones are 35mm, does anyone know what the shorter ones are?

I’ll be sure to post pics and videos once I get it built and running.

I printed mine on my Mendel max and the parts came out exactly the same size as the laser cut ones. In fact I actually swapped a part out when I lost a piece in the process of replacing the servos and it fits just fine.

The holes are slightly undersized, but this was with slic3r 9.7, haven’t tried it with slic3r 9.8 yet.

[quote=“georgefrick”]OK!

Here I am with updates.

I rebuilt my printer with better parts; full explanation here: georgefrick.blogspot.com/2012/09 … build.html

Aside from that, here is the latest print comparison, sorry it is upside down:

The bigger piece is one I printed before upgrading the printer.

So my question is; should the STL file be slightly larger, or is my print slightly too small? The motor seems to be ever so slightly too big for the hole. The motor is a “Hextronik HXT9000 9GR Servo”. I also can’t get the screw in. The fits both seem to be “exact”, as in the holes are exactly as big as the screw/servo measure… but they need to be slightly bigger. Is this because of your laser cutting, or is this on my end. The work continues.

Any input would be appreciated.[/quote]

McMaster Carr isn’t a bad place to go for screws in small quantities.

Much easier to order if you have the size :wink:

Which is why they’re both in the files on github, and in the project guide :wink: