Kapton tape on the glass works slightly better but is a bear to get in place without bubbles or overlaps.

Also look up the spring feet for reprap. They quiet down the entire printer and reduce some of the shock and recoil on the part and print head. Best of all, you print them.

We use this version and they work great.

http://www.thingiverse.com/thing:91720

 

Gopher, calling Gopher, the gopher beacon is lit.

Gopher, or anybody who's 3D printed in Nylon

This is copy & pasted from printrbottalk.com:

I'm making a prosthetic hand & arm for my father (right arm amputee) based on the theatrical prop inmoov robot hand. I'm experiencing issues with ABS. I am breaking the parts just in the course of trying to assemble the hand. I have a bad feeling about it; this is meant to be a functional prosthetic device and needs to be durable. If he slams the hand in a door, I would prefer it not shatter. I aim to make this hand as strong (think muscles, grip-strength) as a regular human hand and I would prefer the digits not deflect or deform if he squeezes something as hard as he can, so it should be relatively rigid. I would prefer it be abrasion resistant so that the wear and tear of daily use does not demand regular replacement of parts. If he mistakenly grabs something too hot, I would prefer the material not immediately turn to snot - although heat resistance is lowest on the list of importance and if I have to sacrifice, this is where I would prefer to sacrifice.

So far, Nylon 645 looks like the best option, but I'm concerned about it's flexibility. As I saw in this thread it seems superb in strength and impact resistance, but flexes like rubber. Can someone who's printed Nylon 645 weigh in; If I printed the finger digits shown in the inmoov hand link in Nylon 645, are the thin points on the joints going to be so flexible as have a negative impact on the function of the hand?

If so, what other materials should I be looking at? Currently I can only extrude up to 230C, but if the optimal material demands it, I can invest in a higher temp extruder.

Thank you in advance,

 

"Real" prosthetics are made of Kevlar, carbon fiber, fiberglass, and such as that. I was assuming you'd print negatives so you could coat them or fill them with the strong stuff.

 

"Real" prosthetics are made of Kevlar, carbon fiber, fiberglass, and such as that. I was assuming you'd print negatives so you could coat them or fill them with the strong stuff.

I hadn't even once thought about making negatives, and now that I am thinking about it, I don't think I want to think about it any more. I'd much rather just directly print the parts I need. Someone on printrbottalk has offered to print one of the fingers in Nylon 645 and assess the viability of it to be used for the hand. I'm hoping he comes back with positive results. I will order some Nylon 645 and make a friggin hand, man. This stuff is tough!

If not, I guess I will start thinking about negatives, begrudgingly.

 

Good luck. I don't know enough about plastics to name that tune. I do know that prosthetics wear out. Not just bad fit, or fit becoming sloppy over the years, fatigue cracks and such. Finger tips that actually grip things (have a reasonable coefficient of friction) will certainly suffer from wear. Don't delete your files after you make the first one.

 

I am hearing promising things about the nylon. If you're interested, here's the discussion.

 

Superglue (cyanoacrylate) is brittle. I have a bad opinion of that glue.

 

I think I can manage to melt two parts together using a combination of heat gun (continuous, to keep things toasty), and blow torch, for quick melty burst.

But I have no idea wtf I'm talking about, so we will see.

 

Nylon will be a good bet but there are many different chemistries of nylon. Nylon66 and nylon6 are common in automotive parts (knobs, gears, slides, ...). The more rubbery nylon is more difficult to glue so your heating idea may be the best.

Nylon is difficult to print but, if someone sells the 3mm filament and others give it a thumbs up, I would try it.

 

Nylon will be a good bet but there are many different chemistries of nylon. Nylon66 and nylon6 are common in automotive parts (knobs, gears, slides, ...). The more rubbery nylon is more difficult to glue so your heating idea may be the best.

Nylon is difficult to print but, if someone sells the 3mm filament and others give it a thumbs up, I would try it.

Well, I ordered some. we will see. strength tests coming soon...

 

I'm using hair spray on the glass for ABS.

I have been using an ABS "slurry" that I made with some scrap ABS and acetone, I usually use a q-tip to apply the "slurry" to the glass with blue painters tape on it. This seems to work better than hairspray on glass, and less costly than kapton tape.... I have tried sandblasted glass, aluminum, etc.... the ABS slurry really holds your print in place and prevents warping of the bottom layers... although it does make it more difficult to remove your printed part from the heatbed

Here is the "slurry" on an aluminum plate:


and another:


and here it is on some blue painters tape applied onto glass (notice the height of the part, and no support material! ):


I have stuck with the abs slurry on blue tape on glass, this seems to work very well for me, and the blue tape makes it easy to remove the part from the heatbed...
and I do not use as much slurry as I had previously done (basically just thinned it down with more acetone) as you can see (or barely see) in the pic below:

 

Are yoy using nylon, bmorse? I'm assuming abs since you are using the slurry.

Have you ever tried applying acetone while printing abs? I experience delamination when I stress my parts, especially when I use the cooling fan. I noticed that when I break a part between layers and I glue it back with acetone, and break it again, it doesn't break again in the same place. The acetone weld is stronger than the actual part. I think the acetone causes a chemical bond that is stronger than the "got hot and stuck together" layers of the print. So I was thinking that a controlled amount of acetone applied to each layer before the next layer is printed, would make for a part that could potentially be as strong as an injection molded piece.

I experimented with a crock pot to evaporate the acetone, sealed off with rubber tape, with a tube plumbed into my cooling fan duct (to create a slight suction, venturi effect) and blow a continuous acetone vapor over my print while printing. It didn't work. The acetone condensed in the short length of tube and blew droplets on my printbed and eroded my abs fan duct.

I think it needs to be vaporized or aerosolized immediately before reaching the print. I thought maybe an e-cigarette or pot vaporizer. But that's more likely to cause an explosion than anything else. Possibly a modeler's airbrush gun?

Have you heard anybody trying something similar? Think this is a workable idea?

 

I am not sure how the rest of the printer's printed parts(especially my extruder) would like acetone vapor.... What I usually do after I print a small part with a lot of details is just dip it in acetone for a quick second, then let it air dry.... this helps in controlling de-lamination and breaking off of layers.... for the larger prints, I usually do the acetone vapor wash...


and yes I am using ABS, I tried PLA, don't care for it much, I designed my printer specifically for ABS (that is why I have an enclosure around it) this helps in keeping the parts from cooling too fast and lifting off of the heatbed (ABS is really a pain to print with if you even have a slight breeze, the enclosure keeps the printing environment "stable") I have done a couple of prints with nylon (nylon 618 from taulmans)....

 

How did your nylon prints go? I've got nylon 645 on the way from taulmans. Going to give that a try. I strong prints, like injection molded strong. I've seen some nylon 645 torture tests (ran over by car, pounded with a hammer, etc.) That look promising. I keep hearing about "dribble" though...

Pics to follow...

Btw how long did taulmans take to ship?I've been waiting since last week and still haven't got a tracking number.

 

Are yoy using nylon, bmorse? I'm assuming abs since you are using the slurry.

Have you ever tried applying acetone while printing abs? I experience delamination when I stress my parts, especially when I use the cooling fan. I noticed that when I break a part between layers and I glue it back with acetone, and break it again, it doesn't break again in the same place. The acetone weld is stronger than the actual part. I think the acetone causes a chemical bond that is stronger than the "got hot and stuck together" layers of the print. So I was thinking that a controlled amount of acetone applied to each layer before the next layer is printed, would make for a part that could potentially be as strong as an injection molded piece.

I experimented with a crock pot to evaporate the acetone, sealed off with rubber tape, with a tube plumbed into my cooling fan duct (to create a slight suction, venturi effect) and blow a continuous acetone vapor over my print while printing. It didn't work. The acetone condensed in the short length of tube and blew droplets on my printbed and eroded my abs fan duct.

I think it needs to be vaporized or aerosolized immediately before reaching the print. I thought maybe an e-cigarette or pot vaporizer. But that's more likely to cause an explosion than anything else. Possibly a modeler's airbrush gun?

Have you heard anybody trying something similar? Think this is a workable idea?

Strantor,

Be very, very careful with flammable vapor clouds. Vapor cloud explosions are a good way to ruin your day. You are well above the flash point of the acetone at your heated bed and hot end. Don't burn your house down.

It is safer to take the part outside after it is finished and brush the surface with acetone. Let it air dry completely before bringing in the house. It takes a day for the acetone smell to dissipate - especially if you are printing thin walls with low fill ratios.

My days in the chemical labs, I've seen enough crazy fires - one girl lost all the skin on her hand when trying to remove her lab coat when her shirt sleeve caught fire. Acetone and crock pots switches, hot surfaces and possible pressure are not a good idea - even outdoors. One kinked hose in your setup and you suddenly have a vapor cloud bo#b.

 

... So I was thinking that a controlled amount of acetone applied to each layer before the next layer is printed, would make for a part that could potentially be as strong as an injection molded piece.
...

Don't you blow heated air on top of the part when printing, to keep the previous layer hot enough to get strong adhesion of the new applied layer?

I thought that was standard now?

 

I consulted the msds and am aware of the risks. The flashpoint is actually a negative number. The autoignition temp of acetone is double what the extruder temp is, but things can always get hotter than advertised, especially if left unattended.

It's not the safest thing to do, but also not a suicide attempt. I will post pics later of my setup and you will see what I meant by "sealed" its actually not sealed, no potential to become a presure vessel.

 

Don't you blow heated air on top of the part when printing, to keep the previous layer hot enough to get strong adhesion of the new applied layer?

I thought that was standard now?

I don't know about heated air. All I've seen is fans blowing ambient air, which seems to give me a better surface finish but weaker part. I tried blowing heated air manually with my heat gun and got excellent layer adhesion. it was actually one piece, no layers, and deformed into a blob.

 

The prints I did with nylon turned out pretty good, I didnt actually purchase it myself,, a friend did that I was doing the prints for, I did have to turn the heat up on the extruder to 255 C to get good layer adhesion. What temp is your extruder at? You may need to turn the heat up a bit to get better adhesion of your layers. I have a dual fan setup for my extruder, one fan is directly aimed at the cold end and the other is directed above the printed part,

 

the guy who sold me the printer kit said not to go above 230c, but I've gone up to 245 with no issue. Not sure how far I push that if I aim a fan at the barrel. Barrel is made of peek.